Geog 5 Part 2

What is the Koeppen System?

A climate classification scheme based on temperature and precipitation. Temperature and precipitation regimes are derived from natural vegetation types.

Global Warming Potential (GWP)

A measure of the total energy that a gas absorbs over a particular period of time, compared to carbon dioxide.

Ocean Deposits

A paleoclimate proxy. Deep cores of material that has been deposited over long periods, with more recent material burying older material, is extracted. Cores include bones and shells of plankton and other animal life. Information contained in the oxygen of calcium carbonate is most important for determining past climates. Temperature det. using O18/O16 ratio. RATIO OF OXYGEN ISOTOPES IS RAD, APPARENTLY.

What are RCPs named according to?

According to radiative forcing in Watts per square meter they predict at the end of the century.

Source Regions

Areas of the globe where air masses form.

Climate Normal

Average atmospheric conditions for the most recent 30-year period ending on a decade (e.g. 1980-2010).

How does the Koeppen System delineate climate?

By capital letters responding to latitude, continentality, topographic features. Tropical (A), Dry (B), Mild Mid-Latitude (C), Severe Mid-Latitude (D), Polar (E), Mountains (H).

What are air masses defined by?

By source.

Global Climate Models (GCMs)

Climate scenarios that provide plausible representations of future climate conditions (temperature, precipitation, and other climatological phenomena). Produced using a variety of approaches including: incremental techniques, analogues, and a variety of physical climate and Earth system models.

Paleoclimates

Climates across the entire history of Earth, assessed through proxies and numerical modeling.

Cold-Type Occlusion

Cold front associated with cP air meets mP air ahead. (Usually occurs in eastern North America.)

Warm-Type Occlusion

Cold front associated with mP air migrates to an area that is occupied by cP air. (Usually occurs in western North America.)

What are the four types of fronts associated with mid-latitude cyclones?

Cold fronts, Warm fronts, Stationary fronts, Occluded fronts.

Continental Arctic (cA) Air Masses

Contain extremely cold and dry conditions, form farther north than cP air. The boundary between cA and cP air is the arctic front. Some meteorologists believe distinction between cA and cP is minor.

Carbon Dioxide Equivalent (CO2-e)

Convert the emissions from various greenhouse gases to CO2 based on GWP. CO2-e derived by multiplying the tons of the greenhouse gas by relevant GWP. (amount of CO2 emissions that would generate equivalent change in temperature as given quantity of a greenhouse gas)

Arctic Oscillation (AO)

Correlated with NAO. Positive AO Index: lower than normal atmospheric pressure over the Arctic. Negative AO Index: higher than normal atmospheric pressure over the Arctic

Climographs

Depict seasonal cycle of temperatures and precipitation, with line and bar graphs plotted simultaneously.

Mediterranean (Csa, Csb)

Distinct summer dry period due to subtropical high interactions. Variable winter precipitation and mild winter temperatures. Mild to hot summers.

How does continental surface heating cause monsoons?

Dry air flows southward from the Himalayas in Winter. In Summer, moist air is drawn northward from the equatorial oceans.

What is the east Asian monsoon characterized by?

Dry, offshore flow conditions during cool months and wet, onshore flow conditions during warm months.

Why do Monsoons occur?

Due to seasonal thermal differences between landmasses and large water bodies.

Humid Subtropical (Cfa, Cwa)

Eastern continental areas of the lower mid-latitudes. Abundant precipitation, primarily a result of convection. No dry season or a winter dry season. Long hot and humid summers. Winter temperatures are lower than Mediterranean, frost and snow occur but likelihood decreases toward the lower latitudes.

El Nino vs. la Nina and Walker Circulation.

El Nino: weakening or reversal of Walker Circulation. La Nina: strengthening of Walker Circulation.

Representative Concentration Pathways (RCPs)

Emissions Scenarios that describe potential future discharges to the atmosphere of substances that affect the Earth's radiation balance (such as greenhouse gases and aerosols). Provides inputs to climate models. Factors in land use and land cover, produced using integrated assessment models based on assumptions about driving forces such as patterns of economic growth and population growth, technology development, and other factors.

Tropical Wet (At)

Even precipitation and high humidity throughout the year. Diurnal range in temperature often exceeds seasonal range in temperature. Most rainforests are contained in Tropical Wet.

Forcing Agent

External factor that drives climatic change.

Boundary Conditions

External factors that influence a planet's climate system.

Ice Cap (EF)

Extremely cold temperatures, warmest monthly average temperature below freezing. Constant ice cover. Low precipitation totals because of low temperatures. Greenland and Antarctica, as well as Arctic.

Which regional downslope winds bring dry, warm conditions to surrounding areas

Foehn, Chinooks, and Santa Ana

Continental Tropical (cT) Air Masses

Form during the summer over hot, low-latitude areas. cT air masses are hot and dry. Very unstable but usually do not produce precipitation.

Continental Polar (cP) Air Masses

Form over large, high latitude land masses. The cold, dry air associated with this air mass is typically stable. E.g. Canada and Siberia. During winter short days, low sun angle, and are usually snow covered.

Maritime Polar (mP) Air Masses

Form over the North Pacific and Northwestern Atlantic. More moderate than cP.

Maritime Tropical (mT) Air Masses

Form over warm tropical waters. High moisture content and instability creates opportunities for thunderstorms and heavy rains. (Influence Southeast primarily in the summer).

What separates air masses and brings about changes in temperature and humidity as one air mass is replaced by another?

Fronts

Highland Climates (H)

Governed primarily by topography and not by geographic location. Vertical zonation, as climate changes with height. Local climates contain high variability.

What causes sea breezes?

Heating and cooling differences between land and ocean. Temperature differences produce a circulation. Air converges into surface low, ascends, and produces clouds and possibly precipitation.

Direct observation of atmospheric variables

High accuracy, geologically temporal coverage is limited. One means of assessing climate change.

Subtropical Deserts (BWh)

High diurnal temperature ranges with low dew point and humidity. Contains largest deserts. Areas with atmospheric subsidence associated with high pressure or on the western sides of continents adjacent to cold ocean currents.

Polar Climates (E)

High latitudes, typically poleward of 70 degrees. Very cold. Transition between coniferous forests of Subarctic and a largely treeless landscape.

Santa Ana

High pressure develops in the Great Basin, air flows out of Rocky Mountains (westward, into California) warming by compression as it descends. Most prevalent during the transitional seasons, especially autumn. Contributes to the spread of wildfires.

Mid-Latitude Deserts (BWk)

Higher precipitation and lower potential evaporation than Subtropical Deserts. Very high diurnal and seasonal temperature ranges. Nighttime and winter temperatures are very cool. Created by extreme continentality and/or rain shadows. (HOW THEY MANAGE TO EXIST AT THESE LATITUDES)

Proxies

Indicators of past climates from geological or biological records. Temporally expansive, accuracy limited with uncertainty.

Foehn

Initiated when mid-latitude cyclones pass to the southwest of the Alps. Bring unseasonably warm conditions to northern Europe. Most prevalent in Winter.

The Southwestern US "Monsoon"

Intense heating of Southwest desert causes a surface low. Warm, moist air from the south and southwest, as well as strong surface heating, can trigger heavy convection and precipitation. Unlike Asian monsoon, no climatic switch from dry to wet, desert conditions remain.

What does climate analysis for an area include?

It includes many variables, including temperature, precipitation, air mass types, and seasonal variations in water balances.

What is change in atmospheric pressure distribution called the Southern Oscillation linked to?

It is inherently linked to SST variations during most El Nino events.

How is the strengthening of El Ninos and La Ninas intuitive from Walker Circulation

La Nina: increasing trades, warm water piles up in the west, enhances western surface low and westward transport of warm water (greater pressure gradient) El Nino: decreasing trades, warm water sloshes east, increases pressure in east, reducing westward transport of warm water (or reversing, if significant enough) (lesser pressure gradient)

Day-Night sea-breeze cycle

Land surfaces are warmer than large water surfaces during the day. Water surfaces are warmer than land surfaces during the night.

Air mass formation over source regions.

Large bodies of air must remain over a source region for substantial length of time for an air mass to form. The air mass reflects the temperature and humidity characteristics of the source region. These characteristics are categorized using a lower- and upper-case letter naming system.

Pacific Decadal Oscillation (PDO)

Large, long-lived oscillation patterns of SSTs across two nodes in the Pacific Ocean. One exists in the northern and westerly part of the basin, the other in the eastern Tropical Pacific. There is enormous heat content in oceans, so PDO may exert a direct, major impact on the pressure distribution of the atmosphere.

Subtropical Steppes (BSh)

Like a subtropical desert, but to a lesser degree. Commonly border subtropical deserts. High aridity but often summer precipitation, high precipitation and temperature variability, large diurnal temperature range, extreme summer temperatures.

Mild Mid-Latitude Climates (C)

Located primarily between 30 and 60 degrees in both hemispheres. Varying precipitation systems with mild winter temperatures. Summer temperatures may be high, but can also be warm or mild.

Chinooks

Low pressure systems east of Rocky Mountains pull air down eastern slopes. Can cause large surface temperature shifts. Most prevalent in winter.

Cold Front

Mass of cold air displacing warm air upward (cold air advances on warm air). Typically associated with heavy precipitation, rain or snow, combined with rapid temperature decreases.

Warm Front

Mass of warm air overrunning cold air (warm air advances on cold air). Shallow clouds dominate and bring light precipitation. Stable regions above the warmer air create vertically limited clouds and light precipitation.

General Circulation Models

Models used to predict future climate. They are used to solve primitive equations (conservation of momentum, mass, and energy) to predict fluid flow on a spherical surface. Can be atmospheric (AGCM), oceanic (OGCM), or coupled with atmospheric-oceanic general circulation models (AOGCM). AOGCMs are the core of full global climate models.

Three types of wind systems we discussed.

Monsoons, Downslope Winds, Sea Breezes

Thornthwaite's System: Climate Classification based on Water Balance

More sophisticated and physically based climate classification system. - Moisture Index that compares precipitation to potential evaporation: Arid, semi-arid, subhumid, humid, perhumid. - Total amount of potential evaporation, seasonality of precipitation, seasonality of potential evaporation.

Humid Continental (Dfa, Dfb, Dwa, Dwb)

More temperate of two Severe Mid-Latitude Climates. Eastern continents of 40 North to 55 North. Warm to hot summers and cold winters. Abundant annual precipitation with no dry season or a winter dry season.

Slow Carbon Cycle

Movement of Carbon over 100-200 million years. Carbon fluxes between rocks, soil, ocean, and atmosphere. 0.01-0.1 gigatons of carbon move through the slow carbon cycle every year. Carbon sequestered as calcium carbonate in ocean sediments or as organic matter embedded in mud. Carbon returned to atmosphere by Volcanoes.

Fast Carbon Cycle

Movement of carbon over 1-100 years. Largely the movement of carbon through life forms on Earth, or the biosphere. Balanced between photosynthesis and respiration/decay.

What causes cold air outbreaks in the US?

Negative NAO or AO Index. (weakening of pressure difference between Icelandic Low and Bermuda-Azores High, weakening of polar jet stream)

Net Primary Productivity

Net carbon consumed by plants both on land and in the oceans.

Stationary Front

Nonmoving frontal boundary: Neither air mass is displacing the other. Frontal surface, however, is still inclined. Clouds and precipitation are possible. Air masses can dissipate to merge or start moving again.

Climate Models

Numerical representations of the Earth's natural systems used to study how climate responds to changes in natural and human-induced perturbations.

Dry Climates (B)

Occur in areas where potential evaporation is greater than precipitation. 30% of Earth's land surface. Semideserts are transitional zones that separate the true deserts from adjacent climates, also called steppes.

Marine West Coast (Cfb, Cfc)

Occur poleward of Mediterranean. Cold ocean currents moderate temperatures, resulting in mild summers and winters. Often has fog and/or low cloud cover. High frequency of rain days, can have relatively low or very high annual totals (of precipitation?)

El Nino

Occurs every two to five years when trade winds, pushing equatorial waters westward, reduce in strength, allowing warm water to migrate east. Characterized by unusually warm sea surface temperatures (SSTs) in the eastern equatorial Pacific Ocean. Higher water temperatures lead to increased evaporation rates and reduced surface air pressure (eastern basin). Cooler waters in the east are replaced by warmer waters (a pgf eastward - either reduces westward transport of warm, surface water, or if strong enough, causes a reversal and leads to eastward transport of warm water), causing a weakening or reversal of the Walker Circulation (east->west at the surface).

Why do the Himalayas have some of the highest precipitation amounts on Earth?

Orographic lifting brings larger precipitation amounts to locations in the Himalayas.

North Atlantic Oscillation (NAO)

Oscillation in pressure differences between Bermuda-Azores High semi-permanent pressure cell and Icelandic Low semi-permanent pressure cell. Atmosphere over the North Atlantic Ocean is dominated by the Bermuda-Azores High and Icelandic Low. Some years are marked by enhanced or reduced differences in pressure between the two semipermanent cells.

Rosby Waves

Patterns of the atmosphere are strongly influenced by the position of Rosby waves. Standing high or low pressure systems affect not only local weather conditions but also the overall size, shape, and position of Rosby waves.

Permafrost

Permanently frozen layer below the surface.

Tropical Wet and Dry (Aw)

Poleward sides of the tropics, border between dry climates and tropical wet climates. Unreliable precipitation due to movement of ITCZ. Savannas, which consist mainly of grasses with widely separated trees, are found in tropical wet and dry.

PDO Index

Positive index = episode with warm waters in east tropical Pacific. (negative SOI - warm waters in east pacific) Negative index = episode with cold waters in east tropical Pacific. (positive SOI - cold waters in east pacific0

Ice Cores

Proxy. Cores obtained from Greenland and Antarctic ice sheets and from alpine glaciers at lower latitudes. Temperatures determined using O18/O16 ratio. On top of that, chemical composition of atmosphere can be determined from bubbles of air trapped in ice.

Remnant Landforms

Proxy. Earth's landforms shaped by processes that build up and wear down features at the surface. Mechanisms for eroding and depositing material leave signatures that can be used to infer climatic conditions at the time of erosion or deposition. Mechanisms for eroding and depositing material include movement of water, ice sheets expanding across the surface, wave action along coastlines, wind transporting soil, floating icebergs carrying land debris.

Past Vegetation

Proxy. Vegetation occupies a region, some of its pollen and spores can be deposited and preserved indefinitely in lake beds or bogs. Age of pollen can be determined using radiocarbon dating. Climate inferred from vegetation characteristics and extent. PRESERVED POLLEN,SPORES.

La Nina

Refers to cooling of water in the Eastern Equatorial Pacific

Teleconnections

Relationships between weather or climate patterns at two widely separated locations

Integrated assessment models

Represent key features of human systems, such as demography, energy use, technology, the economy, agriculture, forestry, and land use.

What causes dissipation of El Ninos and La Ninas.

Result from delayed negative feedbacks that are still debated.

When is the SOI positive? When negative?

SOI is positive during La Nina events, when we see a stronger than average pressure gradient east to west. SOI is negative during El Nino events, when we see a weaker than average pressure gradient east to west.

Land breezes vs. sea breezes.

Sea breezes blow from the sea to land, land breezes blow out to sea from the land.

Numerical models

Seasonal forecast models, decadal models, global climate models. LIMITS: Temporal and spatial coverage limited by computational resources and understanding of the climate system. Accuracy limited with uncertainty.

Future Climates

Seasonal to multi-century predictions

Tundra (ET)

Severe winters, cool summers with long daylight. At least one month with an average temperature above freezing. Low temperatures and atmospheric stability from radiative cooling inhibits precipitation. Permafrost present.

Fronts

Spatially limited boundaries between air masses; usually linked to mid-latitude cyclones.

What does the ENSO describe?

The El Nino Southern Oscillation describes SSTs and Pressure.

What is the Southern Oscillation Index?

The difference in pressure between Tahiti and Darwin, Australia.

What happens after an ENSO event?

The equatorial Pacific returns to a normal phase or a strengthened normal phase.

Climate

The long-term statistical properties of the atmosphere.

Walker Circulation

Trade winds move equatorial surface waters westward, causing higher surface temperatures and a difference in sea surface height. Warm water in western Pacific leads to a surface low. Pressure gradient causes surface air to move east to west. Higher up in atmosphere, west-to-east winds complete the circulation.

Tropical Monsoonal (Am)

Transition climate between Tropical Wet and Tropical Wet and Dry. Precipitation not as steady as Tropical Wet, some months experience heavy rainfall while others are nearly dry. The wet months in monsoonal climates yield far more rain than does the wettest month for tropical wet climates.

Mid-Latitude Steppes (BSk)

Transition zone between dry climate and mild mid-latitude climate. Same temperature characteristics as mid-latitude deserts but HIGHER ANNUAL AVERAGE PRECIPITATION.Majority of arid regions in the United States.

Occluded Front

Two cold fronts meet, and the warm air mass between them is displaced aloft (warm air mass is cut off from surface by two cold air masses).

Severe Mid-Latitude Climates (D)

Very cold winters. Large continental areas within the middle-high (40-70) latitudes. Continentality causes large seasonal temperature ranges. Evenly distributed seasonal precipitation, no true dry season. (Due to continentality - why we see severity - large seasonal temperature ranges, resulting in very cold winters, which is why we call them severe).

Air Masses

Volumes of air with uniform temperature and humidity characteristics, affect vast areas.

Tropical Climates (A)

Warm annual temperatures, with little seasonal temperature variation. Distinguished by precipitation. Exist almost exclusively between the Tropics of Cancer and Capricorn. Dominated by seasonal movement of the inter-tropical convergence zone (ITCZ).

NAO Index (Negative Phase)

When negative: lesser pressure difference between Icelandic Low and Azores High. Weakens polar jet stream. Northern Europe experiences a cold, dry winter. Eastern US experiences increased cold air outbreaks.

NAO Index ( Positive Phase)

When positive: greater pressure difference between Icelandic Low and Azores High. Intensification and northward shift of the polar jet stream. Northern Europe experiences mild temperatures, increased storminess during winter. Eastern US experiences mild, wet conditions during winter.