Remote Sensing Cumulative Final
What is the slogan for Spectral Mixture Analysis?
"Mixed Pixels"
What is the GCOM-W1 all known as?
"SHIZUKU" satellite.
What is the Slogan for the Spectral Angle Mapper (SAM) method?
"Winner Take All"
What two wavelength bands do most remote sensing applications make use of?
3.5 to 5 and 8 to 13 micrometers range
What are the Specs of Hyperion ?
30 m resolution, 220 bands from 0.4 to 2.5 um. Test mission for NASA science validation team. Push-Broom fashion.
What is the SAM method?
An automated method for directly comparing image spectra to a known spectra (usually determined in a lab or in the field with a spectrometer) or an end member from the image.
How does the IAR reflectance calibration method work?
An average spectrum is calculated from the entire scene and is used as the reference spectrum, which is then divided into the spectrum at each pixel of the image
What sort of technique is GPR?
An electromagnetic technique
What does AMSU-A stand for?
Advanced Microwave Sounding Unit.
What is ASTER ?
Advanced Spaceborne Thermal Emission and Reflection Radiometer. Part of NASA (EOS) Earth Observing System on Terra Platform
What does AVHRR stand for?
Advanced Very High Resolution Radiometer. Has spatial resolution of 1.1 and 4 km in five or six bands with a swatch width of 2400 km by 1500 km.
What does AMSR-E stand for?
Advanced microwave scanning radiometer for EOS
What are the MODIS Atmosphere products?
Aerosol, water vapor, ozone, and temperature measurements. Cloud parameters, optical thickness, Global distribution of total precipitable water.
What is the Quantum theory?
All molecules in a solid can vibrate with the amplitude of the vibrations directly related to the temperature.
What is Emissivity?
All selectively radiating bodies have emissivities ranging from 0 to <1 that fluctuate depending upon the wavelengths of energy being considered.
What is ATCOR3?
An atmospheric correction and haze removal software used to correct changes in the spectral reflectance of materials on earth's surface.
What is band 9 used for on LDCM Landsat 8?
Cirrus 1.360 - 1.390 um 30m
What is CLOUDSAT equipped with?
Cloud Profiling Radar instrument.
What does CALIPSO stand for?
Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation satellite.
What is band 1 used for on LDCM Landsat 8?
Coastal / Aerosol 0.433-0.453 um 30 m
What does CZCS stand for?
Coastal Zone Color Scanner
What do shiny reflective objects have?
Cold radiant temperatures.
How does CALIPSO work?
Combines an active lidar instrument with passive infrared and visible imagers to probe the vertical structure and properties of thin clouds and aerosols over the globe.
What does CASI stand for?
Compact Airborne Spectrographic Imager.
What is the equation for Stefan-Boltzmann law?
Fb= kT^(4) where: where k is the Stefan-Boltzmann constant equaling: 5.6697 x 10^(-8) W/m2/K-4
What terrain properties affect the return?
Feature orientation, Surface roughness, dielectric properties
What are the relative radiometric correction methods in ENVI?
Flat Field Calibration and IAR reflectance Calibration.
What did ships use to calculate the distances from one another?
Fog horns.
What does FLIR stand for?
Forward looking infrared.
What does ohmic conduction require the presence of?
Free electrons such as those found in metals
What is a big difference in hyper spectral vs multispectral?
Hyper spectral has more bands and they are narrower in wavelength.
What are the specs of CASI?
Hyper spectral: 288 channels between 0.4-0.9 um, each channel 0.018 um wide. Spatial resolution depends on flying height of aircraft and number of channels required.
What are the satellite Hypspectral Sensors?
Hyperion- NASA EO-1 Mission, NEMO, HICO
What does HICO stand for?
Hyperspectal Imager for the Coastal Ocean.
What does HyMap stand for?
Hyperspectral Mapping
What are the Indian Remote Sensing Satellites?
IRS-C, IRS-D, IRS-P6, Resource Sat and Cartosat. They have sun-synchronous orbits with an altitude of 907 km. 24 days.
What is the future of hyper spectral?
Satellites, Ultraspectral (thousands of bands), components of aerosols, gas plumes, other effluents, specific minerals.
When does the IAR reflectance calibration method work best?
In arid areas with no vegetation.
How does the OCO-2 record data?
In bar code-like spectra, or chemical signatures, of molecular Oxygen or carbon dioxide in the atmosphere.
Where does dielectric conduction occur?
In highly resistive soil, sediment, or rock and requires the atoms to slightly polarize in order to produce displacement in current.
What are the principle mechanisms for remote sensing?
Scattering, Absorption, and Transmission.
what is the radar altimetry technique?
Sea surface height = Orbit (Satellite altitude) - Range Involves determine the distance form the satellite to target measuring radar pulse-trip time Measurements are all nadir Averaging everything in the foot print vertical accuracy of 2 cm
What affects underwater sound?
Sea surface, seafloor, temperature and salinity currents and turbulence
What did the Precision Depth Recorder (PDR) help confirm in the 1950's?
Sea-floor spreading
What are the pre-processing methods?
Subsetting, Geometric, and Atmospheric correction (very important)
What is near-bottom sonar?
Operates close to seafloor (10-150 m above); high resolution surveys in shallow water; 1.5 km swath
What is near-surface sonar?
Operates from long range; provide regional-scale image of deep seafloor at moderate resolution swath width : 30 km per side in 5 km water depth
What is the minimum altitude recommended?
Over 1300 km
What is band 8 used for on LDCM Landsat 8?
Panchromatic 0.500 - 0.680 um 15 m
What are the specs of GeoEye-1?
Panchromatic and multispectral only. Resolution: 0.41 m pan, 1.65 multispect. 681 km altitude. Sun- sync
What are the specs of IKONOS bands?
Panchromatic: 1 m spatial resolution 0.45-0.90 um Multispectral: 4 m spatial resolution. Repat interval of 1-3 days.
What are the specs of Orbview 3?
Panchromatic: Spatial resolution 1 m. Swath width of 8 Km image area: user defined Revisit area: less than 3 days Altitude of 470 km
What is the quantum theory of also known as?
Particle Theory or Plank's Law.
How may external errors be corrected?
Relating empirical ground observations. Radiometric and geometric ground control points. to sensor measurements.
What is a general statement of Wien's displacement law?
Relationship between the wavelength of radiation emitted and the temperature of the black body.
What are the image issues with radar?
Relief of displacement, image foreshortening, layover, shadows, speckle
What happens when you increase the frequency?
Resolution improves, but there is a decrease in penetration
What are some applications of Atmospheric LiDAR?
Resonance Fluorescence Lidar : ranging from probing of the trace- constituent distribution as well as temperature and wind in the upper atmosphere Differential Absorption lidar : Lower atmosphere constituents Coherent doppler lidar and direction-detectoin lidar : Boundary layers, wind and temperature Fluorescence lidar : Airborne chlorophyll mapping of the oceans to establish rich fishing areas
What is the principal contribution of Electrical conductivity to GPR studies?
Respect to Signal propagation and penetration
What does "Mining" a Single Pixel do?
Reveals the spectral signature of the pixel.
What is Diffuse, isotropic?
Rough surfaces, scattered in all directions.
How does Side-looking-Airborne Radar work?
SLAR works by sending short pulses at objects and recording their return signals. SLAR produces continuous strips of imagery and has radar reflectivity.
What is the difference between the Earth's peak and the Sun's peak?
Sun's is experience as light and the Earth's as heat.
What is the NOAA AVHRR sensor?
Sun-synchronous, near polar orbiting satellites. Operates in visible and thermal infrared to collect measurements of the earth's surface, atmosphere and cloud cover. All carry sensors to receive emergency identification and location signals from ships, and aircrafts, weather balloons, and even migrating animals.
What is fuzzy classification?
Supervised and unsupervised classification Algorithms typically use hard classification logic to produce a classification map that consists of hard, discrete categories (e.g. Forest, Agriculture) Conversely it is also possible to use fuzzy set classification logic, which takes into account the heterogeneous and imprecise nature of the real world
How does soil and rock affect scattering?
Surface and volume scattering if penetration
What are the applications of hyper spectral?
Surface mineralogy, water quality, bathymetry, soil type and erosion, vegetation type, plant stress, leaf water content, and canopy chemistry. Crop type and health condition, snow and ice properties.
What causes the double peak in quartz's spectral reflectance information?
The double peak is caused by the crystallographic asymmetry (hexagonal) in quartz.
How does this all work?
The echo train is intercepted by transducers and is converted into an electrical signal and relayed to ship via tow cable for direct image construction or digital recording.
What does TRMM stand for?
Tropical Rainfall Measuring Mission
What is interesting about radiant and kinetic temp?
Two objects can have same kinetic temperature but different radiant temperatures.
How many operating satellites does NOAA maintain with AVHRR?
Two, and they have coverage every 12 hours, and twice daily thermal infrared coverage.
What is MLS?
Uses microwave emissions measure stratospheric temperature and upper tropospheric constituents.
What is the hybrid method?
Uses the decision trees for the best unsupervised method.
What is the maximum likelihood method (supervised)?
Uses the probabilities to overcome the limitation of minimum distance and parallelepiped. Calculates the conditional probabilities of membership in each class. A class assignment is made to the class to which the pixel is most likely to belong. Equiprobability contours are drawn around each training set to define class membership.
What is emitted?
Usually at longer wavelengths; function of structure and temperature (e.g Fluorescence)
What does the theory of this look like in an equation ?
Velocity v of EM wave in insulator is: v = c / (εμ)½ Where: c = vel. of light in free space (3*108 m/s or 0.30 m/ns) ε = relative permittivity μ = magnetic permeability Velocity of EM wave in a conductor requires complex permittivity (K) and loss tangent
How are modern day infrared detectors?
Very fast mercury doped germanium (Ge:Hg), indium antimonide (InSb).
What does transmissivity decrease with?
View angle.
How does vegetation affect scattering?
Volume - Scattering, volume - surface scattering, surface scattering.
How does snow affect scattering?
Volume scattering and surface scattering
What does the AMSR2 measure well?
Water vapor, Cloud liquid water, precipitin, SST, sea surface wind speed, sea ice concentration, snow depth, and soil moisture.
What radar properties affect the return?
Wavelength, depression angle, polarization
How do we see the spatial frequency?
We loot at the local (neighboring) pixel value changes
What is necessary to use this part of the spectrum?
Weak energy source so need large IFOV and wide bands and the spatial resolution is usually low
What is anisotropic scattering?
depolarization
What is multiple scattering?
depolarization
What are advantages and disadvantages of the unsupervised method?
( + ) No extensive prior knowledge of the region, minimized human error, Unique classes are recognized as distinct units ( - ) Classes may not correspond to informational categories - Analyst has limited control - Spectral properties will change over time
What is dynamic topography?
- The ocean circulation comprises a permanent mean component linked to earth's rotation, mean winds, and density patterns - and a highly variable component (wind variability, tides, seasonal heating, mesoscale eddies)
What is the wavelength of X-Rays?
0.03-240 nm
What is the wavelength of microwave/radar?
0.1-100 cm
What is the wavelength size that is blocked by Mie scattering?
0.2 - 10 um.
What is the wavelength of ultraviolet?
0.24-0.38 um
What are some applications of radar and what are some useful features?
1. Penetrates clouds and works at night 2. Topography ( plus ultra fine scale changes) 3. Geological mapping 4. Other planets Venus (gaseous)
What is the wavelength of shortwave IR?
1.0-3.0um
How far in earth with direct contact?
10s of meter to detect objects
How far can it travel in the bedrock?
10s-100s m to detect bedrock and water table
What is the size of the largest ozone hole?
11.4 million square kilometers (4.4 million square miles). Larger than the area of North America.
What are the dimensions of the data from MODIS?
2,330 Km wide swatch, MODIS sensor provides one-to-two-day coverage of the earth in 36 spectral bands.
What are the specs of NEMO?
200 spectral bands over 0.4 to 2.5 um. 60 m resolution. Developed for ocean applications
When did the AMSR-E fail?
2003
What are the specs for AVIRIS?
224 contiguous bands from 400-2500 nm. Bands are 10 nm wide. Spatial resolution = 20 m at high altitudes. 4 m at low altitude. Usually flys at 20 km above sea level.
What is the band break down of the spatial resolution of the MODIS bands?
250 m (2 bands), 500 m (5 bands), and 1 km (29 bands)
What is the spectral range of HIRDLS?
6-18 mm.
What are the specific details about ASTER?
705 km altitude, sun-synchronous, polar orbit, repeat interval of 4-16 days. It is the only high resolution instrument on TERRA platform. Spatial resolution of 15 m to 90 m. It is complimentary to coarser resolution instruments, MODIS, MISR,
What is the wavelength of long wave IR?
8.0 -1.4 mm
What is the Infrared window for the CERES sensor?
8.0-12.0 microns (spectral range)
What is the Earth's peak emittance wavelength?
9.7 um, in the thermal IR
What is the wavelength of gamma rays?
< 0.03 nm
What is the property of ultraviolet?
< 0.3 um absorbed by ozone
What is the wavelength of radio?
> 100 cm
What is an example of minimum distance?
A "centroid" for each class is determined from the data by calculating the mean value by band for each class. For each image pixel, the distance in n-dimensional distance to each of these centroids is calculated and the closest centroid determines the class. ( + ) mathematically simple ( - ) Insensitive to different degrees of variance in spectral response data
What is the Cloud profiling Radar Instrument?
A 94-GHz nadir-looking radar which profile the vertical structure of clouds. It also measures the profiles of cloud liquid water and ice water content.
What does the solar curve approximate?
A blackbody
What is the relationship between true kinetic temperature and radiant flux radiated from the object?
A high positive correlation between the true kinetic temperature of an object
What is a Lambertian reflector?
A perfect isotropic reflector that scatters radiation equally in all directions. The ideal diffuse reflector.
What are the basic radar principles?
A radar is an active remote sensing system that operates in the microwave ( 1mm to 1m ) portion of the spectrum.
What is AAS?
Airborne ASTER simulator. 24 bands, 17 in TIR built by Japan Recourses Observation System Organization.
What is AHI?
Airborne Hyperspectral Imager. Push broom scanner. 32 or 256 bands in 8-12 um; 3 color bands in visible. Operated by University of Hawaii.
What does AIS stand for?
Airborne Imaging Spectrometer
What is ATLAS?
Airborne Terrestrial Applications Sensor. 15 bands, 6 TIR
What does AVIRIS stand for?
Airborne Visible/infrared Imaging Spectrometer. 128 bands, 10 nm bandwidth vs 100-200 nm for TM. Early 1980's.
What is the property of X-rays ?
All absorbed by atmosphere
What is band 2 used for on LDCM Landsat 8?
Blue 0.450-0.515 um 30 m
What does reflectance affect?
Both brightness and color/spectra.
What do stronger radar returns produce?
Brighter signatures on the image
What is radiometric?
Changes the Digital numbers calibration
What are the drawbacks of Hyperspectral?
Data volume, cost, Difficulty of analysis, Spectral libraries, More complex.
What are the ASTER brightness temperature sensor data products?
Day and night.
What does CERES stand for?
Earth's Radiant Energy System.
What is atmospheric absorption?
Energy is lost to the atmosphere and subsequently reradiated longer wavelength (water vapor, carbon dioxide, and ozone) account for most absorption.
How often does DMSP provide global monitoring?
Every 6 hours.
What is the behavior of EMR?
It may be emitted and absorbed one photon at a time, or it can be a beam of EM wave when it is directed and focused.
How much power does it usually emit?
Less than one percent of cell phone transmitted power
What are the forms of active remote sensing?
LiDAR, Satellite Altimetry, Side - Scan Sonar ; Bathymetry, Radar, Ground Penetrating Radar
What does LIDAR stand for?
Light Detection and Ranging ~ to RADAR but uses the near UV, visible, and near IR portion of EM spectrum
What is band 10 used for on LDCM Landsat 8?
Long wavelength infrared 10.30 - 11.30 um 100 m
What is band 11 used for on LDCM Landsat 8?
Long wavelength infrared 11.50 - 12.50 um 100 m
What is the property of radio?
Longest wavelength portion of the spectrum
What do dryer purer soils have?
Low emissivities in the region of 3 to 5 um region.
What is multispectral?
Many Spectra bands
What is mie scatter also known as?
Selective scattering.
Why do soils and mineral exhibit?
Strong spectral features.
What is the property of photo UV?
Transmitted, but scattered severely
At what range does water behave like a blackbody?
in the range of 6-14 um.
What is the equation for Transmitted?
n = ca / cs ca is velocity in vacuum; cs is velocity in substance ...radiation passes through substance without significant attenutation...
What are the two types of radar and their applications?
non-imaging : doppler measures speeds of vehicles, plane positions, Air traffic control, weather forecasting. imaging : SLAR, RAR, SAR,
What is the only method of heat transfer through vacuum?
radiation.
What are aperture antennas?
real aperture : - 1-2 meter antennas Synthetic aperture : - 1-2 meter = 600 m - 11 m = 15 km
How do you find the sea surface height?
ssh = altitude minus range
Why use thermal infrared?
to see at night, to check temerpatures, to see energy fluxes, to see material properties (resistance to temperature change, or thermal inertia), and composition (emissivities).
What is the property of near-infrared?
0.7-0.9 is photographic IR, film
What is the wavelength of infrared?
0.7-1000 um
What is the wavelength of near-infrared?
0.8-2.5 um
What is Hyperspectral?
Huge numbers of continuous bands > 1000 with ~ 5 nm resolution
What does HSB stand for?
Humidity Sounder for Brazil
What wavelength is thermal infrared radiation?
3 to 15 um
What is the speed of light in a vacuum?
3 x 10^8 m/sec
What are the wavelengths of Thermal infrared?
3-5 um and 8-14 um
What is the wavelengths of Medium wave IR?
3.0-8.0 um
What is the wavelength of photo uv?
0.3-0.38 um
What is the wavelength of the MODIS spectral bands?
0.4 um-14 um
What band length, swath width, and spatial resolution is DMSP?
0.40-1.10 um and 8-13 um (thermal infrared) with a swath width of 3000 km and spatial resolution of 0.55-2.7 km.
What region is passive microwave?
1-200 GHZ (0.15 cm to 30 cm )
How is edge enhancement usually implemented?
1. A high frequency component image is produced containing the edge information 2. All or a fraction of the grey level in each pixel of the Original seen is added back tot he high frequency component image 3. The composite image is contrast stretched
What is the k-means method (unsupervised) ?
1. A set of cluster centers are positioned randomly through the spectral space. 2. The pixels are assigned to their nearest cluster 3. The mean location is re-calculated for each cluster 4. Repeat 2 and 3 until movement of cluster centers below the threshold. 5. Assign class types to spectral clusters
What are some microwave radiometers?
1. Advanced Microwave Sounding Unit (AMSU) 2. Scanning Multichannel Microwave Radiometer (SMMR) 3. Special Sensor Microwave / Imager ( SSM / I ) 4. Tropical Rainfall Measuring Mission (TRMM) 5. Advanced microwave scanning Radiometer (AMSR-E) 6. The goal change observation mission - water
what is classification?
1. Association by spectral similarity of pixel into units. 2. Naming those units, generally using independent information such as; 1. Reference spectra 2. Field - Determination 3. Photo Interpretation
What are the five common enhancements?
1. Brightness and contrast enhancement 2. Edge enhancements 3. Band ratio 4. Mosaic or subset 5. Spatial filters
What is LiDAR?
1. By accurately timing the round-trip travel time of laser pulses, the slant range distance from the laster to the ground can be measured. 2. Active Sensing system 3. Day or night operation 4. Lidar is not only replacing conventional sensors, but also creating new methods with unique properties that could not be achieved before
How may the spatial frequency be enhanced or subdued?
1. By spatial convolution filtering : based primarily on the use of convolution masks. 2. By Fourier Analysis : mathematically separates an image into its spatial frequency components
What is the iso-data method (unsupervised)?
1. Cluster centers are randomly placed and pixels are assigned based on he shortest distance to center method 2. The standard deviation within each clusters, and the distance between cluster centers is calculated 3. Clusters are split if one or more std deviation is greater than or equal to the user defined threshold 4. Clusters are merged if the distance between them is less than the user defined threshold
What are the disadvantages of sonar?
1. Data can be noisy from surface turbulence and ship 2. Need accurate water velocity sea surface measurements give less detail than those near bottom 3. Difficult to repair 4. Not suited for highly sedimented low relief areas
What are the basic step in image classification?
1. Data reconnaissance and self - organization 2. Application of the classification algorithm 3. Validation
What are the advantages of sonar?
1. Easy to operate 2. Lower operating cost 3. operates at ship speeds 4. real time data display 5. can find ships
How does the process flow for supervised?
1. Form images of data 2. Choose training pixels for each category 3. Calculate statistical descriptors 4. Satisfactory? 5. If yes then classify data into defined categories. 6. if no then repeat steps 1-3
What are the three steps to a common midpoint survey?
1. Get reflections off horizontal reflector 2. Increase antenna spacing, repeat 3. Produces hyperbola
What are some geological applications?
1. Hydrocarbon reservoir characterization, whether an actual reservoir or analogues 2. Environmental site characterization - contaminant transport 3. Hydrogeology, including fracture characterization of aquifers. 4. Geology hazard analysis, including volcanogenic, seismic of landslide related 5. Analysis of stratigraphic facies development, including aeolian, fluvial, glaciological, coastal
What is the special sensor microwave/imager (SSM/I)
1. It was onboard the Defense Meteorological Satellite Program 2. It measure the microwave brightness temperature of atmosphere, ocean, and terrain, at 19.35, 22.23, 37, and 85.5 GHz 3. The Special sensor microwave imager/sounder (SSMIS) is the continuation on defense meteorological satellite program (DMSP) Satellites it was launched in 2003
What are the disadvantages of passive microwave remote sensing from space?
1. Larger field of views (10 - 50 Km) compared to VIS/IR sensors 2. Variable emissivity over land 3. Polar orbiting satellites proved discontinuous temporal coverage at low latitudes (need to create weekly composites)
How does the laser range finder operate?
1. Laser range finder, mainly determines the range information 2. The time-of-flight information from a LiDAR system can be used for laser range finding / laser altimetry from airborne or space-borne platforms to measure the heights of surfaces with high resolution and accuracy 3. Downward-pointing laser systems are operated in a mode where surface scattering and reflection represent the dominant form of interaction. 4. The reflected pulses from the solid surface (earth ground, ice sheet, vegetations, etc ) Dominant return signals, which allow a determination of the time-of-flight with much higher resolution than the pulse duration time.
Why is this altitude recommended?
1. Less atmospheric drag 2. Ground stations can much better track the satellite 3. Less gravity errors due to earth's gravitational field
What are the two type of measuring bathymetry?
1. Measure water depths - bathymetric sonars ; Fathometers ; echo-sounders 2. Image bottom topography and characteristics -sidescan imaging sonars
How does passive microwave sensing of rain work over the ocean?
1. Microwave emissivity of rain is about 0.9 2. Emissivity of the ocean is much lower 0.5 3. Changes in emissivity as seen by the measured brightness temperature provide and estimate of surface rain rate
How does passive microwave sensing of rain work over the land?
1. Microwave scattering by frozen hydrometeors is used as a measure of rain rate. 2. Physical or empirical models relate the scattering signature to surface rain rates.
How does LiDAR work?
1. Mirror Sweeps laser beam across the ground 2. Range to target is determined by measuring time interval between transmission and return of reflected laser pulse 3. Aircraft position is determined using GPS techniques 4. Pointing Direction of laser determined with inertial measuring unit and recording of mirror position 5. Data streams recorded and synchronized for post processing.
What is the bare earth model?
1. Models the natural ground 2. Some automated procedures may be used - imagery backdrop may be necessary 3. In some cases, traditional photogrammetry may be necessary to add breaklines
What are the change detecting techniques?
1. Multi-temporal display 2. Interval-scale variables : - Different, ratios, principle component analysis, regression, vector analysis, Thresholds need to be Estimated afterwards. Classified Variables : - Cross tabulation of two dates - Multi-temporal Classification
What are the advantages of passive microwave remote sensing from space?
1. Penetrating through non-precipitating clouds 2. Radiance is linearly related to temperature ( i. e. The retrieval is nearly linear) 3. Highly stable instrument calibration 4. Global coverage and wide swath
What are the advantages of LiDAR?
1. Provides a highly accurate means of elevation data collection . 2. Elevation accuracy 10 to 25 cm depending on survey height of aircraft. 3. Acquisition can take place day or night. Shadows that are problematic of mtn. areas are not an issue 4. Very cost effective for larger projects. 5. Swat width up to 1,500 meters at 2,000 meter altitude 6. Records first and last returns on individual pulses. 7. Records intensity 8. Installable in a variety of aircraft including a single engine cessna 206. 9. Time to collect 1 million points (6.7 seconds) traditional surveying takes 15.5 years and photogrammetry 1.5 years.
What are the basic principles of satellite altimetry?
1. Radar Altimeters onboard the Topex Poseidon permanently transmit signals at high frequency to earth, and receive the echo from the sea surface. 2. This is analyzed to derive a precise measurement of the round - trip time between the satellite and the sea surface. 3. The time measurement, scaled by the speed of light yields a measurement of the satellite-to-ocean range
What are the scattering mechanisms?
1. Reflection of a smooth surface (snell's law) 2. Scattering off of a rough surface - the variation in surface height is on the order the incoming signal's wavelength 3. Double bounce (corner reflector) E.g. Tree stump and grass. 4. Volumetric - Tree, or dry snow.
How does the process flow for unsupervised?
1. Separate data into groups with clustering 2. Classify data into groups 3. Assign name to each group 4. Satisfactory? 5. If yes then stop If no then repeat steps 1-4.
What does inSAR record?
1. Time for the reflected signal to return 2. The strength of the return (intensity) 3. The exact point int he oscillation at which the signal was received (phase)
What three primary functions does radar perform?
1. Transmits microwave pulses toward a target 2. Receives a return portion of the transmitted signal afterwards 3. Has interacted with the target and it observes the strength, temporal behavior, and the tie delay of the returned signals
What are the four possible polarized combinations?
1. VV - Sends and receives only vertically polarized energy. 2. VH - Send vertical and receive horizontally polarized energy. 3. HV - Send horizontal and receive vertically polarized energy. 4. HH - Send and receive only horizontally polarized energy
What is the digital outcrop model?
1. measurements can be made without parallax 2. Reduce uncertainties that in stochastic geologic models. 3. Collect information that is not possible traditionally (seismic well)
How does inSAR processing work?
1.) Image co-registration : for generating interferograms ; two images are co-registered with sub-pixel accuracy. 2.) Noise - Reduction : Filters are applied to reduce noise 3.) Interferogram generation : interferogram generated and the coherence image is calculated. Coherence is simply the complex correlation between the two co-registered images, calculated locally over small say 5 x 5 or 10 x 10 pixel window in the image pair. The Coherence tells us the quality of the interferometric phase. 4. Unwrapping : The process of phase unwrapping converted the cycles of phase in an interferogram to a monotonic variation in phase crosses the image. 5. Convert unwrapped phase to height : the next step is to convert the entire phase unwrapped image, which still has phase unites either radians or cycles into height value in meters 6. Geocoding This process is good for change detecting.
What are the three ways that electrical current can propagate through rock and minerals?
1.) Ohmic 2.) Electrolytic 3.) Dielectric
In what region do the silicates exhibit their most intense features?
10 um called restrahlen band or Si-O stretching region
How far can it penetrate in concrete?
18 " to 30 " in concrete
What is blackbody?
A blackbody is a hypothetic, ideal radiator, that perfectly absorbs and reemits all energy that is incident upon it.
What does it require?
A contrast in dielectric to see targets
What do water, ice, and snow generally have?
A high emissivity 0.94 to 0.99, across the thermal region.
What is the parallelepiped method (supervised)?
A pixel is assigned to a class if its spectral values fall within the minimum-max, range measured in the training data. ( + ) Techniques works best when the min-max ranges are ~ equal in each band ( - ) Range in one band different than in another band, the region of class expands to include a lot of pixel that may not, in fact be valid representations of that feature
What is Interferometric Synthetic Aperture Radar? (InSAR)
A process whereby radar images of the same location on the ground are recorded by two antennas off one platform separated by a few meters (single pass). - The same radar system at different times (multi - pass or repeat - pass) - InSAR can resolve surface displacements with ~ cm precision, 10s m spatial resolution and monthly temporal resolution using remote satellites - global coverage : day/night, all-weather imaging capabilities
What does the GPR system include?
A radio and a transmitter
What is HIRDLS?
A scanning Infrared sounder that observes global distribution of temperature and concentrations of O3, H2O, CH4, N2O, HNO3, N2O5, CFC11, CFC12, CION2.
What is one way of calibrating the data to reduce the shadows?
A shaded relief model.
What causes n-line striping in the imagery?
A single detector becoming uncalibrated. Usually Radiometric correction can fix this.
What is the Lightning Imaging Sensor?
A small, highly sophisticated instrument that detects and locates lightning over the tropical region of the globe.
Where is the end member collection matched with?
A spectral library on the USGS or in-situ spectra collection using a hand-held spectrometer (ASD).
What is SAR?
A synthetic aperture radar. The signal is back scattered and images are built based on the time and intensity of their return. ( a ) In general the larger radar antenna, the better the spatial resolution ( b ) Employs small antenna that transmits relatively broad beam ( c ) Uses successive positions of small antenna to simulate large antenna ( d ) Acquiring complete history of signal scattered form object during passage of instrument permits later reconstruction of signals as if they came from a single long antenna ( e ) Applies doppler principle in data-processing
What does green vegetation typically have?
A very high emissivity because it is structured and contains water.
What is band ratio?
A way to counter - act the differences in brightness values from identical surface materials due to topographic slop or shadow.
What is a method of atmospheric measurement and modeling in ENVI ?
ACORN 'FLASH
What are the six instruments onboard the Aqua satellite?
AIRS, AMSU-A, HSB, AMSR-E, MODIS, CERES.
What are the Airborne Hyperspectral Sensors?
AIS, AVIRIS, HyMap, Probe-1, Ecoprobe-Probe-3, GER, CASI, AISA, TRWIS III, HYDICE, HyperCam, AURORA
What five instruments does TERRA have onboard?
ASTER, CERES, MISR, MODIS, and MOPITT
What is the property of infrared?
Absorption bands
What is the property of shortwave IR?
Absorption bands for many minerals.
What type of energy does it use?
Acoustic energy (sound) transmitted through water column using explosives, water, or airguns
What are corner reflections?
An object with tow or more reflective surfaces orientated in such a way as to scatter much of the incident radar energy directly back to the sensor.
What is radiant flux?
An object's internal kinetic heat is also converted to radiant energy (often called external or apparent energy). The electromagnetic radiation exiting an object is called radiant flux and is measured in watts.
What are the applications for GPR?
Archaeological investigation , Borehole inspection, bridge deck analysis, Building condition assessment, Contaminated land investigation, Detection of buried mines, evaluation of reinforced concrete, forensic investigations, geophysical investigations, geological studies, medical imaging, Pipes and cable conditions, planetary exploration, rail track and bed inspection, remote sensing, road condition survey, security applications, snow, ice glacier, timber condition, tunnel lining, wall condition.
What is the SAM method generally used for?
As first cut for determining surface materials and works well in areas of homogenous surface materials.
What is Wien's Displacement law?
As the temperature of an object increases, the total amount of radiant energy (area under the curve in W/m^(2)) increases and the radiant energy peak shifts to shorter wavelengths .
What does atmospheric corrections assume?
Assumes similar atmospheric conditions over entire image.
How does Dark Pixel subtraction work?
Assumes that the darkest objects in the image should have a DN of 0 (no reflectance). Find the minimal pixel value from each band (using Histograms). Subtract that value from all of the pixels in the band. It can be sometime an average based upon a user defined region of interest, or a specific value.
What may cause external errors?
Atmosphere, Terrain elevation, slope, and aspect.
What does AIRS stand for?
Atmospheric Infrared Sounder.
What is significant wave height?
Averaging out the effect of ocean waves.
What is geometric?
Changes the spatial arrangement of pixels or adjust digital numbers based on their neighbor's values (registration). Visualization
What are the three formats that remote sensing data are often organized and stored in?
Band interleaved by Pixel (BIP), Band Interleaved by Line (BIL), Band sequential (BSQ)
Why are these two bands used?
Because of absorption bands.
Why is the sun red during sunset?
Because the lower sun angle allows only longer wavelengths to pass through the atmosphere, resulting in the appearance of an orange/red sunset.
Why does the 'sky' look black in the lunar photos?
Because there is no rayleigh scattering.
How do bathymetric systems work?
Bounce sound waves off submerged features, producing topographic bathymetric profiles - early sounds used single beams - Modern systems use multiple beams
What is unique about TIMS?
Breaks the 8-12 um thermal IR interval into six bands.
What does surface roughness affect?
Brightness
What does topography affect?
Brightness.
What is radar interferometry?
Broadly defined by use of phase measurements to precisely measure the relative distance to an object when imaged by synthetic aperture radar two or more observations separated either in time or in space.
How is the data organized?
By asking the following questions ; How many data clusters in N-space can be recognized? What is the nature of the cluster borders? Doe the clusters correspond to the desired map units?
How does the TRMM operate?
By carefully measuring the minute amounts of microwave energy emitted by the Earth and its atmosphere. I
How do you improve the contrast?
By the linear techniques : Min-max contrast stretch, percentage linear contrast stretch, standard deviation stretch, piece-wise linear contrast stretch.
What are Statistical algorithms?
Characterizes or compares groups of radiance data. Spectral similarity. A : Classification, B : Spectral matching.
What are the ASTER surface temperature data products?
Day and night; corrected for atmospheric effects, topography
What is the general equation for waves?
C = vλ
What is modeling?
Calculates non-radiance parameters from radiance and other data. 1. Estimates Geophysical parameters 2. Makes thematic maps 3. Input to GIS
What is Raster data and what is it use for?
Conducting digital image analysis. Each image is treated as an X,Y, array of digital numbers. This structure allows for manipulation of pixel values by an image processing system.
What are the ASTER Surface radiance data products?
Corrected for atmospheric effects
What are the ASTER reflectance sensor data products?
Corrected for atmospheric effects
What are the ASTER surface emissivity data products?
Corrected for atmospheric effects digital elevation models (DEM) with 10-50 m accuracy.
How do you derive the dynamic topography?
D = ssh minus geoid = alt - range - geoid Only for long wavelengths the Geoid is not yet known well enough for shorter wavelengths
What can ATCOR3 be integrated with?
DEM for atmospheric correction in images of rugged terrain.
What are the atmospheric correction methods?
Dark pixel subtractions, Regression techniques, atmospheric measuring and modeling (requires detailed atmospheric measurement at time of satellite overpass).
How does color influence the emissivity of an object?
Darker colored objects are usually better absorbers and emitters.
What is the SOFAR channel?
Depth of 1250 m below north atlantic depth / temperature interact to promote long-range propagation of sound waves ( 1000's of kms )
What is permittivity?
Describes the ability of a material to polarize, support polarization, and store energy in response to an external electric field.
What did the first sonars allow for?
Detection of icebergs and submarines ASDICS : anti-submarine detection investigation committee
What is the general approach for Hyperspectral Data Analysis?
Develop spectral library, Construct spectral curve for relatively "pure" materials, Specific reflectance peaks and absorption troughs are read from these curves. Compare to lab spectra (mixture analysis).
What is an echo sounder?
Device attached to the bottom of the ship that allows a person to find fish.
What is the MLS useful for?
Diagnosing the potential for severe loss of Arctic Ozone when abundances of stratospheric chlorine will still be high, and slight cooling of the stratosphere could exacerbate ozone loss due to chlorine chemistry.
What two properties of materials does it depend on?
Dielectric constant and Conductivity?
What is the "Linear Edge" technique?
Directional , laplacian, highlight points ; lines, edges, suppress uniform, and smooth regions
What is the OMI instrument able to do?
Distinguish between aerosol types, such as smoke, dust, and sulfates, and measures cloud pressure and coverage, which provides data to derive tropospheric ozone.
How does fine particles affect spectra?
Dominated by surface reflection. High surface / volume ratio. Path is shorter.
What is the equation for emissivity?
E = Fr / Fbb Emissivity for blackbody is 1; for real materials < 1 emissivity is wavelength-dependent Fr= radiant flux from real material Fbb= radiant flux from blackbody
What algorithm does ENVI use and how does it work?
ENVI uses ISAC (In-Scene Atmospheric Compensation Algorithm) 1. single layer ~ of atmosphere used. 2. Determines the wavelength that most often exhibits the maximum brightness temperature. Then used as reference value. 3. Only spectra that have their brightest temperature at this wavelength are used to calculate the Atmospheric compensation. 4. The reference blackbody radiance values are plotted against the measured radiances. A line is fitted to the highest points in these plotted data and the fit is weighted to assign more weight to region with denser sampling.
What is the Flat Field Calibration technique useful for?
Effective for reducing hyper spectral data to relative reflectance.
What are InSAR's applications?
Elevation (DEM) derivation (single or multi-pass) - Can be as accurate as DEM from traditional optical photogrammatic techniques - Surface displacement study only (multi-pass)
What does radiant temperature depend on?
Emissivity
What is a selective radiator?
Emissivity of object varies with wavelength.
What is the band ratio for Landsat TM Bands 5/1 good for?
Emphasizing overall variations due to opaque mineral content
What is the band ratio for Landsat TM Bands 5/7 good for?
Emphasizing variations in content of hydroxyl bearing minerals
What is the band ratio for Landsat TM Bands 5/4 times 3/4 good for?
Emphasizing variations related to ferrous electronic transition bands in silicates (e.g. Amphiboles) near 1.0 um
How does the OMI instrument work?
Employs hyper spectral imaging in a push-broom mode to observe solar backscatter radiation in the visible and ultraviolet.
What happens to sun energy under Wien's Displacement law?
Energy radiated by Sun and Earth; Solar radiation come in and is re-emitteed by Earth at longer wavelengths;
What are some applications for LiDAR?
Engineering and construction, topographic mapping, urban infrastructure mapping (Flood risk ; Insurance assessment), Wildland resource management, Coastal engineering (shoreline mapping), image rectification, urban modeling, disaster response, and damage assessment, Wetland and other restricted access areas, motion picture, video games, landslide studies...
What are external errors?
Errors introduced by phenomena that vary in nature through space and time.
What are internal errors?
Errors introduced by the remote sensing system. They are generally systemic and very predictable.
What does Hypspectral require?
Extensive pre-processing to correct for reflectance v radiance.
What wavelength is the visible naked spectrum?
From 0.4 um to 0.7 um
What is non-selective scattering?
From particles with diameters > than wavelength of energy source; independent of wavelength. (dust, water droplets, fog). Example clouds contain aerosol particles that scatter all wavelengths < 0.1 cm: counts are white.
What is an example of a modern day bathymetry measuring device?
GLORIA, and Sea MARC multi-beam echo sounder - sea beam
What are the Geostationary Meteorological satellite families?
GOES, Fengyun (China), Meteosat (European Space Agency), Insat (India), GMS (Japan), GOMS (Russia).
What are the differences in waves between GPR and Seismic?
GPR : EM waves, Microwaves / radio waves. Frequency : 10-2000 MHz Velocity : in air 3 x 10^5 km/s (Speed of light) Seismic Surveys : Seismic waves P, S, R , L waves Velocity : 0.4-14 km/s Frequency = 0.1-100 HZ depends on source
What are the four methods for image restoration and rectification?
Geometric, Radiometric, Rectification and registration, Mosaic and subset.
What is the low-spatial-resolution sensors?
Geostationary Orbits. Ex. GOES
Which ship identified the midatlantic ridge?
German Meteor ship 1925
What is absorbed?
Giving up every to matter; mostly as head
What are the AVHRR sensors used for?
Global climate research, rescue operation, regional drainage networks, physiographic, and geology.
What are the forensic applications?
Graves, remains, excavation, test grave sites, case histories.
What is band 3 used for on LDCM Landsat 8?
Green 0.525-0.600 um 30 m
How does atmospheric problems affect bands?
Green radiation is scattered by the atmosphere 4x more than Near Infrared. Atmospheric effects are much stronger in visible part of the spectrum in general than in IR.
What does transmissivity increase with?
Ground elevation.
What are the high-spatial-resolution satellites?
Ground resolution of 1m or better (military intelligence) . IKONOS, OrbView-2, QuickBird, OrbView-3, GeoyEye-1, WorldView-1, WorldView-2, GeoEye-2.
What are AURA's four instruments?
HIRDLS (High-Resolution Dynamics Limb Sounder), MLS (Microwave Limb Sounder), OMI (Ozone Monitoring Instrument), TES (Tropospheric Emission Spectrometer)
What is Mie Scattering?
Haze/Dust
What does HCMM stand for?
Heat capacity mapping mission
What is its frequency range?
High frequency greater than 1000 kHz technique
What is the one non-linear technique for improving contrast?
Histogram
What is a unique feature of blackbodies?
Hot blackbodies emit more energy per unit area than do cool blackbodies.
What is color enhancement?
Image processing procedures that improve the visual interpretation by changing the brightness, sharpness, or increasing contrast among various features. - Does not give any more info than the original - Often enhancements alter the original digital numbers in the image data, and the enhanced image should be used with caution. "Screen" values vs Original Data values in ENVI.
What is image spectroscopy better at than multispectral remote sensing?
Imaging spectroscopy is more likely to resolve absorption bands.
What is radiometric correction concerned with?
Improving the accuracy of surface spectral reflectance, emittance, or back-scattered measurements obtained using a remote sensing system. Detector error correction, Atmospheric and topographic corrections.
When was TRMM launched?
In 1997 and it is at an altitude of 402 km. It has the Following sensors aboard CERES, LIS, VIRS, TMI, PR (Japan).
When was OrbView-2 launched?
In 1997 and it is at an altitude of 705 km. It has the SeaWiFS sensor aboard.
When was ACRIMSAT launched?
In 1999 and alternates b/e 713 km and 672 km. It has the ACRIM3 sensor aboard it.
When was Terra launched?
In 1999 and it is at an altitude of 705 km. It has the CERES-2, MISR, MODIS, ASTER, and MOPPIT. Sensor aboard it.
When was Landsat 7 launched?
In 1999 and it is at an altitude of 803 km. Has the malfunctioned SeaWinds antenna.
When was NMP/EO-1 launched?
In 2000 and it is at an altitude of 705 km. It has the ALI, HYPERON, and LAC sensor aboard it.
When was QuikTOMS launched?
In 2001 and it is at an altitude of 800 km. It has the TOMS sensor aboard it.
When was Jason-1 launched?
In 2001 by France and it is at an altitude of 1336 km. It has the JMR, TRSR, LRA, Poseidon 2 and DORIS sensor aboard it.
When was METEOR 3M/SAGE III launched?
In 2001 by Russia and it is at an altitude of 1020 km. It has the SAGE III sensor aboard it.
When was Aqua launched?
In 2002 and it is at an altitude of 705 km. It has the AIRS, AMSU-A, CERES(2), MODIS, HSB, and AMSR-E sensor aboard.
When was ADEOS II launched?
In 2002 by Japan and it is at an altitude of 803 km. It has the SeaWinds, AMSR, GLI, ILAS-2 and POLDER season onboard.
When was ESSP/GRACE launched?
In 2002 by both the U.S. and Germany. It is at an altitude of 460 km and has the GPS, HAIRS, USO, SCA, and SSA sensors aboard it.
When was ICESat launched?
In 2003 and it is at an altitude of 600 km. It has the GLAS and GPS sensor aboard it.
When was SORCE launched?
In 2003, and it is at an altitude of 640 km. It has the TIM, SIM, SOLSTICE, and XPS sensor aboard it.
When was PARASOL launched?
In 2004 by France and it is at an altitude of 705 km, it has the POLDER sensor. It is no longer in operation as of Dec. 18, 2013.
When was AURA launched?
In 2004, and it is at an altitude of 705 km. It has the MLS, TES, HIRDLS, and OMI sensor aboard it.
When was ESSP/CALIPSO launched?
In 2006 and it is at an altitude of 705 km. It has CALIOP, WFC, and IIR sensors onboard.
When was ESSP/CloudSat launched?
In 2006 by France and it is at an altitude of 705 km. It has the CPR sensor aboard it.
When was OSTM launched?
In 2008 by France, and it is at an altitude of 1336 km. It has the AMSR, GPSP, LRA, Poseidon Altimeter, and DORIS sensor onboard.
When was ESSP/OCO launched?
In 2009 Launch Failure.
When was Suomi NPP launched?
In 2011 and it is at an altitude of 824 km, it has the ATMS, CERES, VIIRS, CrlS, and OMPS sensors onboard.
When was ESSP/Aquarius launched?
In 2011 by Argentina and it is at an altitude of 657 km. It has the L-Band Radiometer and L-band Scatterometer onboard.
When was Glory launched?
In 2011 launch failure.
When was GCOM-W1 launched?
In 2012 and it is at an altitude of 705 km. It has the AMSR2 onboard.
When was LDCM launched?
In 2013 and it is at an altitude of 705 km. It has the OLI and TIRS onboard.
When was Rapid-SCAT Int.Space Station launched?
In 2014 and it is an at altitude of 420 km. It has the Rapid-SCAT sensor onboard.
When was GPM Core launched?
In 2014 and it is at an altitude of 407 km. It ha the GMI and DPR sensors onboard.
When was CATS int. Space station launched?
In 2014 and it is at an altitude of 420 km. It has the LiDAR season onboard.
When was ESSP/OCO-2 launched?
In 2014 and it is at an altitude of 705 km. It has Three Grating Spectrometers onboard.
When was SMAP launched?
In 2015 and it is at an altitude of 670 km. It has the L-band radiometer and L-band radar onboard.
What is supervised classification?
In a supervised classification, the identity and location of some of the land-cover types (e.g. urban, agriculture, or wetland) are known a priori through the combination of field work, interpretation of aerial photography, map analysis, and personal experience. That analysis attempts to located specific sites in the remotely sensed data that represent homogenous examples of these known land-cover types. These areas are commonly referred to as training sites, because the spectral characteristics of these known areas are used to train the classification algorithm for eventual land - cover mapping of the remainder of the image. Multivariate statistical parameters (means, std deviations) are calculated for each training site. Every pixel both within and outside the training sites is then evaluated and assigned to the class of which it has the highest likelihood of being a member.
What are the Geological applications of Emissivity?
In the 0.4-2.5 um wavelength region iron, hydroxyl, sulfate, water, and carbonate bearing minerals display spectral features.
What happens at the earth's surface?
Incident radiation may be: transmitted, Absorbed, emitted, reflected [ Specular, diffuse, isotropic]
What about selective scattering?
Influences longer wavelengths. Greatest in the lower part of the atmosphere.
What can the Empirical Calibration account for?
Instrument and atmosphere.
What impacts the resolution of and level of S/N ratio?
Intensity of EMR.
What are the two sources of error?
Internal and external
What is relative permittivity?
Is is the equivalent of dielectric constant.
What does CALIPSO do?
It Assesses the role of clouds and atmospheric aerosols (airborne particles) in regulating Earth's weather, climate, and air quality.
What is the major difference between hyper spectral and Multispectral?
It can detect individual mineral species and differential vegetation species.
What does affect?
It can regionally affect images.
what does the ENVI thermal Atm correction tool do to the thermal image data?
It converts it to radiance.
What theory does GPR follow?
It follows wave theory like seismic not em theory like conductivity or resistivity
Why is the SPOT program better than the Landsat-TM program?
It has Off-nadir viewing, Pushbroom scanning, and HRV (SWIR) higher spatial resolution.
How is snow unusual?
It has a high reflectance in the solar (visible) region where most of the downwelling energy is during the day, and a very high emissivity in the thermal region.
What is a blackbody's distinguishing feature?
It has an absorptivity of 1.
What is a neural network and how does it work?
It has one input layer, one output layer, and no or some hidden layers in between. Neurons in one layer are connected to all neurons in the next layer for passing information. - Neural networks process information in a similar way the human brain does. The network is composed of a large number of highly interconnected processing elements (Neurons) working in parallel to solve a specific problem. Neural networks learn by example, they cannot be programed to perform a specific task. ( - ) Because it figures out itself its operation can be unpredictable.
What does the presence of moisture do?
It increases the material's dielectric constant - The reflectivity and hence image brightness of most natural vegetated surfaces is increased with increasing moisture content
What is image spectroscopy?
It is a technique for obtaining a spectrum in each position of a large array of spatial positions so that any one spectral wavelength can be used to make a coherent image (data cube)
What is the property of Gamma rays?
It is all absorbed by the upper atmosphere
What is Edge enhancement applied for?
It is applied to improve the appearance of spatial patterns in the the data ; an edge is any place where there is abrupt change in pixel value
What is "reconnaissance" ?
It is asking yourself the following questions about the data ; What is in the scene? What is in the image? What bands are available? What questions are being asked of the image? Can these questions be answered wit image data? Are the data sufficient to distinguish what's in the scene?
What is the property of visible?
It is imaged with film and photodetectors.
Is the GPR destructive or nondestructive of earth and infrastructure?
It is non-destructive
What is the OCO-2?
It is the Orbiting Carbon Observatory. It provides space-based global measurements of atmospheric carbon dioxide on regional scales.
What is GOES?
It is the abbreviation for Geostationary Operational Environmental Satellite. a. Operated by NASA and NOAA b. Orbits the Earth at an altitude of 36,000 Km, in the same direction and rate as Earth's rotation. c. Views hemispherical disk, full earth, and selected smaller areas at 1,4, or 8 km resolution, every 30 minutes or 4 minutes. d. Monitors Temperature, humidity, cloud cover, and other data for weather forecasting.
What is the "A-Train"?
It is the afternoon constellation and consists of U.S. and international Earth Science satellites the fly within approximately 14 minutes of each other to enable coordinated science.
What is the DMSP?
It is the defense meteorological satellite program and is operated by the U.S. Air force. Orbits at an altitude of 830 Km in 101 minutes, sun-synchronous orbit.
What is kinetic energy?
It is the energy of motion. The greater it's speed, the greater it's kinetic energy. The greater it's mass, the greater it's kinetic energy.
What is electrical conductivity?
It is the measure of the ease of electron movement within a material that is under the influence of an external electrical field.
What is a mosaic subset?
It is the operation of combining two or more images into single "mosaic". The objective is for the mosaic to be "seamless" so that the you cannot tell where one ends and the other(s) begin.
What is the EOS?
It is the primary component of concept originally called Mission to Planet Earth (MTPE) and latter renamed Earth Science Enterprise.
What is ocean color used to measure?
It is used to estimate the concentration of chlorophyll and other plant pigments present in the water as an estimate for type and quantity of marine phytoplankton.
What is spectral reflectance?
It is what is used to differentiate materials. S.R. = [(Energy of wavelength reflected) / (Energy of wavelength of incident)] times 100.
What is spatial filtering?
It is when the spatial frequency is the number of changes in brightness value per unit distance for any particular part of an image. If there are very few changes in brightness values over a given area in an image.... then it is a low frequency area and conversely if the there are a lot of changes in the brightness values over a given area in an image then it is a high frequency area.
What does a gray body do?
It outputs a constant emissivity that is less than one at all wavelengths.
What does Hypersepctral remote sensing do that is unique?
It provides a continuous, essentially complete record of spectral responses of materials over the wavelengths considered.
What does GPR use and for what?
It uses electromagnetic waves to probe the changes in the electromagnetic properties of the shallow subsurface.
What is special radiance a linear function of?
Kinetic temperature
What are the six steps for Calibration?
Know the basic properties of the image and how, when, and where it was acquired. Find out how the page has been processed. Be alert for cosmetic enhancements that may have altered the spectral fidelity. Know the illumination and viewing geometry. Know the images and histograms of each channel for defects, dynamic range, saturation, gradients, atmospheric effects and noise. Visually verify channel-to-channel registration using color composites or ratios. Prepare a well-stretch color composite image to use a photo-interpretive reference during further analysis.
What are the intermediate spatial resolution satellites?
Landsat, Spot, IRS and ASTER
What does LIDAR rely upon?
Lasers, which are produced by devices that generate a stream of high energy particles ( photons ), usually within an extremely narrow range of radiated wavelengths. Produces a coherent light source
What were early infrared detectors?
Lead salt photodetectors.
What does it depend on the least?
Magnetic permeability (u) relative permeability close to 1 .
What materials have the lowest emissivity values?
Mandmade materials such as refined polished metals.
What are multi beam echo sounders used for?
Mapping the seafloor by estimating the range in a different direction .
What is the only form of matter that does not emit EMR?
Matter that is at absolute zero.
What does MOPITT stand for?
Measurement of Pollution in the Troposphere. An instrument designed to enhance our knowledge of the lower atmosphere and to observe how it interacts with the land and ocean biospheres.
What is bathymetry?
Measures the vertical distance from the ocean surface to mountains, valleys, plains, and other sea floor features.
What are scanning microwave radiometers?
Mechanical rotation of mirror focuses microwave energy onto horns.
What are atmospheric corrections?
Methods used to convert the radiance measured at the satellite to radiance (or reflectance) measured at the ground. May also be used to calculate reflectance form satellite radiance.
How does the Passive microwave sensing of land surface differences function?
Microwave emissivity is a function of the dielectric constant Most earth materials have a dielectric constant in the range of 1 to 4 ( air = 1, veg = 3, ice =3.2 ) Dielectric constant of water is 81. Thus, moisture content affects brightness temperature Surface roughness also influences emissivity .
What can be discerned from mixture analysis?
Mixtures of two or even three different materials can be identified as the components of the compound spectral curve.
What is Bendix-24?
Operated in 1970-1980 in VNIR and SWIR and TIR, 6 bands in 8-14 in um
What is the MODIS sensor?
Moderate Resolution Imaging Spectro-Radiometer. Designed to measure physical properties of the ocean and land. It is a continuation of AVHRR with several important enhancements.
What does MODIS stand for?
Moderate Resolution Imaging Spectroradiometer.
What affects the thermal infrared?
Molecular vibration modes in silicates.
What are the two types of antenna for GPR?
Monstatic antennas : a single antenna as both the transmitter and receiver Bistttic antennas : Separate transmitter and receiver.
What does Senescent (dry) vegetation have?
More variable emissivity, especially in the 3 to 5 um region.
What does MISR stand for?
Multi-Angle Imaging Spectroradiometer. Views Earth with cameras pointed at nine different angles.
What is MIVIS?
Multispectral infrared and visibile imaging system that has 102 bands scanner (0.4-13 um) built by Daedalus. Operated in Italy.
What does NEMO stand for?
Navel Earth Map Observer
What is band 5 used for on LDCM Landsat 8?
Near Infrared 0.845 - 0.885 um 30 m
What does CALIPSO provide?
Never before seen 3D perspectives of how clouds and aerosols form, evolve, and affect weather and climate.
Where did OCO-2 collect its first data over?
New Guinea.
What is point scattering?
No polarization
What satellites are in the A-Train?
OCO-2, GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura.
What satellites are apart of the NASA Earth Science Division Operation Missions?
OCO-2, GPM, Landsat 8 (USGS), Suomi NPP, Aquarius, OSTM/Jason 2, CALIPSO, Cloudsat, SORCE, GRACE(2) EO-1, QuikSCAT, TRMM, Aura, Aqua, Terra, and Landsat 7 (USGS)
What current satellites have ocean color sensors on them?
OCTS - Japan, Meris -ESA, SeaWiFS and the MODIS (USA).
What are some passive microwaves applications?
OVER LAND 1. Soil moisture 2. Snow water equivalent 3. Sea/lake ice eaten, concentration type OVER OCEANS 1. Sea surface temperature 2. Atmospheric water vapor 3. Surface wind speed 4. Cloud Liquid water 5. Rainfall rate
What is the only way radar velocity may be determined in a Fixed offset survey?
Only if diffraction hyperbolas are encountered. - Typically via point sources
What is passive Microwave radiometry?
Passive microwave sensors use an antenna to detect photons at microwave frequencies which are then converted to voltages in a circuit.
What do most atmospheric corrections attempt to remove?
Path radiance (Lp)
What is the property of Microwave/radar?
Penetrates clouds, fog, rain
What are the three different data spaces that we use for spectral mixture analysis?
Perceptual : How we sense color intuitively ( hue, saturation, intensity ) Radiance : How the color stimulus is described by the image data Transformed digital numbers : A mathematical description of the color that is related to radiance
What does PARASOL stand for?
Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a LiDAR.
What are the key LiDAR Components?
Positioning 1. Gps 2. Airborne 3. base station 4. Typically a "Post-processed kinematic" solution Inertial measurement unit (IMU) 1. Navigates between GPS Updates Angular Measurement 1. IMU accurate pitch, roll and yaw Range measurement 1. Scanning laser
What are the features of ATCOR3?
Produce sharp and brilliant satellite images, Reduce the shadow effect in mountainous terrain, obtain better classification results by using real reflectance values, compare multi-temporal and multi-sensorial values, calculate value added products such as sky view factor and cast shadow calculation.
How does AVIRIS build an image?
Pushbroom-like, by a succession of lines.
What is the equation of the Quantum Theory?
Q = h ν Q = h c/ λ Q = Energy of a quantum, Joules (J) h = Plank's constant (6.62 x 10-34J sec) ν = frequency c= velocity of light λ = wavelength
What are TerraSar - X applications?
Quantitative Measurements : Digital elevation models, Ground control points, surface monitoring Qualitative measurements and mapping : Topographic mapping, change detection, and ship detection
How is radiance at satellite calculated?
Radiance satellite = Radiance from Target + Atmospheric (path) radiance. L = Etr/π+ Lp where L is radiance, E is irradiance, t is atmospheric transmittance, r is reflectance
What is the basis for thermal infrared sensing?
Radiant Temperature
What is reflectance spectroscopy?
Radiation incident on a material is selectively absorbed by molecules. it may be expressed by. Wt = We + Wv + Wr We = Electronic energy Wv = Vibrational Energy Wr = Rotational energy
What is RADAR and acronym for ?
Radio Detection and Ranging
What does topographic slope and aspect introduce?
Radiometric distortion (in areas where shadows are).
What is speckle?
Random constructive and destructive interference. Causes - Salt and Pepper grain - Multiple look reduction - Image smoothing (water is dark due to specular reflection)
What are the types of sensors?
Ranger Finders : The simplest LiDARS that measures the distance, then create the topographic map over land and water. Atmospheric LiDAR : this type detects atmospheric properties. The first application of this type of LiDAR was the detection of atmospheric aerosols and density, basically it is to know whiter there are aerosols/density in the regions and how much.
What makes the sky appear to be blue?
Rayleigh scattering
What are the three different types of scattering?
Rayleigh, Mie, and Non-selective
What are two versions of the Radar?
Real aperture and Synthetic aperture
What is band 4 used for on LDCM Landsat 8?
Red 0.630 - 0.680 um 30 m
What is pre-processing dimensional transformation?
Reduces the impact of topography or outcome ratoing
What is the IAR reflectance calibration method particularly useful for?
Reducing hyper spectral data to relative reflectance in an are where no ground measurements exists an little is known about the scene.
What controls the brightness of surfaces?
Reflectance, material roughness, and the effect of topography.
What is albedo?
Reflectivity (ratio of reflected energy to incident energy)
What are the MODIS ocean products?
Sea-surface temperature (Daytime and Nighttime), concentrations of organic matter, suspended solids, chlorophyll, ocean aerosol, color, and primary production measures.
Wha are the differences between Seismic Reflection and GPR?
Seismic Reflection : One source Lots of Geophones Stacking and velocity performed in one step GPR One source (transmitter) One receiver (Both are antennas) Stacking performed by repeating the EM pulse
What does the Flat field calibration method require?
Selecting a ROI (region of interest) prior to execution.
What are brightness and contrast enhancement?
Sensors are calibrated for full range of data, but range of values in typical image are less than half of the brightness values.
What are Ocean Color Sensors?
Sensors designed for measurements of physical and biological oceanographic conditions.
What are the ASTER relative spectral reflectance sensor data products?
Separate for VNIR and SWIR relative spectral emissivity.
What is an annoying effect of topography?
Shadows on the hill, that give the illusion of 3-d.
What is band 7 used for on LDCM Landsat 8?
Short Wavelength infrared 2.1 - 2.3 um 30 m
What is band 6 used for on LDCM Landsat 8?
Short wavelength infrared 1.560 - 1.660 um 30 um
What is the correlation between wavelength and frequency of EMR?
Shorter wavelength is equal to a higher frequency and a shorter wavelength is equal to a lower frequency.
What minerals have special features in thermal infrared?
Silicate minerals.
What is a side scan imaging sonar?
Similar to Real-aperture system Three components : Transducers; Cable link; Recording system. Transducers : Generate signal by converting electrical energy into acoustical energy for transmission and by converting backscattered acoustical energy back into electrical energy. housed in "fish" towfish torpedo-shaped vehicle.
When aren't Atmospheric corrections necessary?
Single scene studies, Atmospheric differences can be reduced by ratio based vegetation indices like NDVI.
What is Specular reflection?
Smooth surfaces, returned from surface with an angle of reflection equal and opposite of angle incidence.
What is a problem with the GPR method?
Some of the signal reflects off any object with different electrical properties than the host material
What does SONAR stand for?
Sound Navigation And Ranging
What is SEBASS?
Spatially Enhanced Broadband Array Spectrograph System. Has 128 bands in the 7.5-14.5 micron spectral region and a spatial resolution of 2-3m.
How does coarse particles affect spectra?
Spectra is dominated by absorption inside grains, low surface/volume ratio. Average optical path is long.
What are the end members of Hyperspectal Data Analysis?
Spectral characteristics of an image that represent classes of interest, usually assigned based on lab spectra. Can be done manually: Manual end member selection tool (MEST).
What information from GOES data can be derived?
Storm tracking, cloud cover, cloud height, and cloud temperature profiles, sea surface temperature, water vapor, and hot spot detection.
How does surface properties influence the wavelengths?
Surface of pebbles (smooth) = Specular reflection Surface of Cobbles (rough) = Diffuse reflection
What are the MODIS land data products?
Surface reflectance, Land-surface temperature and emissivity, vegetation and land-surface cover, conditions, and productivity, land-cover change, vegetation indexes, thermal anomalies/fire, vegetation parameters (e.g., leaf area index), bidirectional reflectance and albedo, fire occurrence, temperature, and burn scars.
What does the relevant importance of these contributions depend on?
Surface roughness and dielectric properties of the medium
How does water affect scattering?
Surface scattering
What does the back scattered signal result from?
Surface scattering, volume scattering, multiple volume -surface scattering
How do band lengths affect surface roughness?
Surfaces that appear rough in shorter wavelengths are smooth at longer wavelengths X-band ~~> C-band Weather penetration improves with longer wavelengths
What are the specs for QuickBird?
Swath width 16.5 Km, Panchromatic band: 61 cm resolution, 4 multispectral bands: 2.44 m resolution.
What is WorldView-2 specs?
Swath width of 16.4 km, altitude of 770 km. Panchromatic band : 46 cm , 8 multi-spectral bands 1.85 m
What is WorldView-1 specs?
Swath width of 17.7 km, Panchromatic band: 50 cm resolution.
What are the important Thermal IR satellite sensors?
TIROS, GOES, HCMM, CZCS, AVHRR, MODIS, Landsat, ASTER
What does sensor-reflectance involve?
Taking into account temporal changes in solar illumination due to Earth-Sun geometry. (Zenith angle)
What does TIROS stand for?
Television IR Operational Satellite
What satellites is the MODIS sensor on?
Terra and Aqua
What does low emissivity mean?
That absorptivity is low and that reflectivity is high.
What is the AMSR2?
The Advanced Microwave Scanning Radiometer 2. It is a sensor onboard the GCOM-W1
What does ASTER stand for?
The Advanced Spaceborne Thermal Emission and Reflection Radiometer
What is the band ratio for ASTER Bands (7 / 5) times bands (7 / 8 ) useful for?
The Alunite index
What is the band ratio for ASTER Bands (6 / 8) times bands (9 / 8 ) useful for?
The Calcite index
What is the GCOM-W1?
The Global Change Observation Mission - Water. Launched by Japan Aerospace Exploration Agency (JAXA)
What is the band ratio for ASTER Bands (4 / 5) times bands (8 / 6 ) useful for?
The Kaolinite index
What is the band ratio for ASTER Bands (12 / 13) useful for?
The Mafic index.
What is the band ratio for ASTER Bands (11 x 11) divided by bands (10 x 12 ) useful for?
The Quartz index
What is AMSS?
The airborne multispectral scanner developed by Geoscan Pty Ltd.
How does the Flat Field Calibration method work?
The average spectrum from the ROI is used as the reference spectrum, which is then divided into the spectrum at each pixel of the image.
What is radiant temperature?
The concentration of the amount of radiant flux exiting (emitted from) an object is its radiant temperature.
What does it depend on?
The dielectric properties of materials (ability to hold or pass charge)
What is the dielectric constant?
The electrical conductivity of the feature
How does wavelength influence the emissivity of an object
The emissivity of an object is generally considered to be wavelength dependent.
What are the five families of algorithms used for processing remote sensing data?
The five families are Radiometric, Geometric, Spatial analysis, Statistical, and modeling.
How does surface roughness influence the emissivity of an object?
The greater the surface roughness of an object relative to the size of the incident wavelength, the greater the surface area of the object and potential for absorption and re-emission of energy.
What is unsupervised classification?
The identities of land-types to be specified within a scene are not generally known a priori because the ground info is lacking or surface features within the scene are not well defined. The computer is required to group pixels with similar spectral characteristics into unique clusters according to some statistically determined criteria. The analyst then re-labels and combines the spectral clusters into information classes
What are atmospheric windows?
The infrared atmospheric window is the overall dynamic property of the earth's atmosphere, taken as a whole at each place and occasion of interest, that lets some infrared radiation from the cloud tops and land-sea surface pass directly to space without intermediate absorption and re-emission, and thus without heating the atmosphere
What is magnetic permeability?
The measure of magnetic field energy stored and dissipated in a material that is subject to an induced magnetic field.
How does FLIR work?
The mirror points forward about 45 degrees and projects terrain energy during a single sweep of the mirror onto a linear away of thermal infrared detectors.
How does moisture content influence the emissivity of an object
The more moisture an material contains, the greater its ability to absorb energy and become a good emitter. Wet soil particles have a high emissivity similar to water.
What is NDVI?
The normalized difference vegetation index. The NDVI takes advantage of the the ability of vegetation to strongly reflect near - IR and poorly reflect red, resulting in a high contrast between bands and a high NDVI. - Dimensionless, Radiometric measures relative abundance of and activity of green vegetation - Produces measures between -1 and 1 - NDVI = (NIR-Red) / (NIR+red)
What is the altimeter most dependent upon?
The orbit of the satellite so that it may be successfully calibrated and interpreted.
What does electrolytic conduction require?
The presence of ions to carry the charge such as those found in dissolved ground water DOMINANT process in moist or wet material
What is the determining factor for the velocity of the EM waves?
The propagation of EM waves is determined by the relative permittivity (dielectric constant) contrast between different layers.
What do all of these factors depend on?
The radar frequency, the polarization, and the incidence angle.
What is feature orientation?
The relative orientation of the radar beam and the direction and alignment of linear surface features
What is emissivity?
The remote measurement of the radiant temperature always being slightly less than the true kinetic temperature of the object. Emissivity is a measure of an object's efficiency as an absorber and emitter of EMR.
What is a Geoid?
The sea surface height that would exist if the ocean were not moving. - It is a geopotential surface - Major Bathymetric features deform sea level by tens of meters and are visible as hills and valleys of the geoid
What does scattering types depend on?
The size of particles, their abundance, wavelength radiation, depth of the atmosphere.
What are mixed pixels?
The spectral signature of a pixel is a combination (assumed linear) of the spectral signatures of the surface components.
What layers of the atmosphere is the Ozone in?
The stratosphere
What is Stefan-Boltzmann Law?
The total emitted radiation (Fb) measured in watts/m^(2) leaving a blackbody is proportional to the fourth power of its temperature in Kelvins.
How does the GPR system work?
The transmitted radio signal penetrates a short distance into the ground and is reflected back up to the receiver
What is transillumination or radar tomography?
The transmitter and receiver are on the opposite side of the medium. Used in boreholes or underground mines
What are the types of "classification" algorithms?
The types are supervised, unsupervised, hybrid, decision tree, fuzzy, and neural networks.
What characteristics of light are responsible for diffraction and refraction?
The wave-like features
What does THEMIS stand for?
Thermal Emission Imaging Spectrometer
What is TIMS?
Thermal IR, multispectral scanner.
What is the difference between near infrared and thermal infrared?
Thermal infrared is emitted energy whereas the near is reflected energy, similar to visible light.
What is the medical application of thermal infrared called?
Thermography.
What is good about TIMS?
These bands taster varying amounts of spectral thermal energy that we can relate to more discrete narrower absorption features associated with surface materials.
What is object orientated classification ?
These technologies allow the analyst to decompose the scene into many relatively homogeneous image objects (referred to patches or segments) Using a multi-resolution image segmentation process. The various statistical characteristics of these homogeneous image objects in the scene are then subjected to traditional statistical or fuzzy logic classification. Object - orientated classification based on image segmentation is often used for the analysis of high - spatial resolution - imagery ( IKONOS / QUICKBIRD)
What wavelength are the multispectral satellite sensors?
They are both visible and infrared wavelengths.
What orbit are the A-Train satellites in?
They are in Polar orbit, and cross the equator northbound at about 1:30 PM.
Why don't you need to worry about atmospheric effects when classification or photo interpretation is done?
They are removed through scene-based calibrations such as the empirical line approach.
What are the high spatial resolution sensors and what are they?
They are sun-synchronous. DMSP, AVHRR, MODIS, SeaWiFS
How does radiative transfer models work?
They compute a "standard" atmosphere, the effects which of which are subtracted from the image.
What does diffuse reflections contain?
They contain spectral information on the "color" of the reflecting surface. *Mostly used in RS.
How can brightness temperature be related to kinetic temperature?
Through emissivity
Why should one calibrate?
To compare images at different times or places. To compute ratios such as NDVI. To correct for topography. To compare field data.
What is VIS-SWIR used for?
To determine alteration products .
What is TIR used for?
To determine the Composition
What is the EOS's purpose?
To develop an understanding of the total Earth system, and the effects of natural and human-induced changes on the global environment.
How must Atmospheric corrections be done?
To each band separately.
What is the purpose of the AMSR2 sensor?
To monitor the land, ocean, and atmosphere measuring weak microwave emission from the Earth's surface through clouds data, can characterize storms to better anymore precisely understand the internal structure, such as the eye of a Hurricane.
What is the Internal Average Relative Reflectance calibration method useful for?
To normalize images to a scene average spectrum.
What is the aim of Imaging Spectroscopy?
To produce laboratory quality reflectance spectra for each pixel in an image.
What is the purpose of TRMM?
To provide quantitative rainfall information over a wide swath, with a passive microwave sensor.
What is the goal of Slope-aspect correction?
To remove topographically induced illumination variation so that two objects having the same reflectance properties show the same brightness value or (DN) in the image despite their different orientation to the sun's position .
What is the first step in SMA?
To select end members.
What is AURA's purpose?
To study the atmosphere's chemistry and dynamics.
What factors affect the amount of radiance the satellite measures?
Top of atmosphere irradiance, Atmospheric transmittance (Downward), Surface reflectance, Atmospheric transmittance (upward), and atmospheric scattering (Path radiance)
How is Kinetic temperature related to radiant temperature?
Trad = e^(1/4)T for e= 0.97 Fris 3.5 x 10-2Wcm-2; Trad= 281°K (8°C) for e= 0.06 Fris 2.2 x 10-3Wcm-2; Trad= 140°K (-133°C)
What is conviction?
Transfer by physical motion of heated matter; circulation.
What is radiation?
Transfer of heat in form of electromagnetic waves; heat from sun.
What is conduction?
Transfer of heat through a material by molecular contact.
What is spectral transformation principal components analysis?
Transformation of the raw data using P.C.A. - Will result in new principal component images that may be more interpretable than the original data - May also be used to compress the information content of a number of bands of imagery ( e.g. Fourteen aster bands into just two or three transformed principal component images) - Designed to reduce redundancy in multispectral bands - Topography - shading - Spectral correlation from band to band
What are the detailed workings of the SAM method?
Treats both spectra as vectors and calculates the Spectral angle between them. The result is an image showing the best match at each pixel.
When are Atmospheric Corrections Necessary?
When comparing multiple scenes. Scene matching (mosaics), Change detection studies (sometimes), applying statistics to multiple scenes.
What physical phenomena causes specular reflectance?
When the wavelength is longer than the surface height variation.
What is the wavelength size that is blocked by non-selective scattering?
When wavelength is less than the diameter of the particle.
When are atmospheric corrections always necessary?
When you need to calculate ground reflectance or compare satellite to ground reflectance measurements.
What is WARR?
Wide-angle reflection and refraction. The transmitter is kept at a fixed location and the receiver is moved away at increasing offset. The location of WARR sounding should be in an area where main reflectors are either horizontal or dipping only at low angles.
What is the property of Thermal, Medium, and Long wave IR?
Windows, optical-mechanical scanners.
How is the dispersion of the spectrum of AVIRIS determined?
With Diffraction grating.
What is geometric correction concerned with?
With placing the above measurements or derivative products in their proper locations.
What is spectral mixture analysis?
Works with spectra that are mixed together to estimate mixing fractions for each pixel in a scene. * we use three different data space to work with color
Does the earth emit these waves?
Yes
Is it possible to convert at-sensor radiance to apparent at-sensor spectral reflectance?
Yes but it must be done before atmospheric correction.
Does phase affect spectra?
Yes, the amount of absorption increases with optical length. This is a particle size affect.
What produces EMR?
a. A change in the direction the electric or magnetic field. b. Whenever particles collide with each other, thereby changing their energy states, and emit EMR in the process.
When do you need atmospheric compensation the most?
a. Desiring to do quantitative spectral analysis. b. When comparing image spectral data with lab data - for composition type identification, for example
When do you need atmospheric compensation?
a. Low elevation (variable elevation) b. Off-Nadir viewing c. Image channels near water bands. d. haze, dust.
What exactly is rayleigh scatter?
a. Occurs in the absence of atmospheric impurities. b. The particle diameters are < wavelength of energy source e.g. atmospheric molecules:( O2, N2, CO2, fumes) c. Dominant scattering process in the atmosphere (up to 9 & 10 km) d. Blue light is scattered 4 times as much as red light and UV as 16 times as much as red light. e. Rayleigh law states this form of scattering is in proportion to the inverse of the fourth power of wavelength.
When don't you need to worry about atmospheric effects?
a. Photointerpretation b. classification.
What is the intensity of the EMR?
a. The brightness of the light observed. b. The number of quanta or the amplitudes (height of the EM wave) of the electric and magnetic fields c. The more quanta there are at a particular wavelength, the greater the energy (higher amplitudes) that is transmitted.
Why is scattering important?
a. it is the fundamental process in radiative transfer and remote sensing. b. Must be accounted for to recover quantitative data about surfaces.
What is the equation for Wien's displacement law?
λmax= k/T Where k = 2898 um K and T is the temperature in Kelvin.
How does the microwave brightness temperature work?
•Microwave radiometers can measure the emitted spectral radiance received (Ll) •This is called the brightness temperature and is linearly related to the kinetic temperature of the surface •Matrix of brightness temperature values can then be used to construct a passive microwave image •The Rayleigh-Jeans approximation provides a simple linear relationship between measured spectral radiance temperature and emissivity •To measure soil moisture, precipitation, ice water content, sea-surface temperature, snow-ice temperature, and etc
