Currents

La Niña (The Little Girl)

La Niña is the counterpart to El Niño and is characterized by cooler than normal surface water temperatures in Pacific Ocean. It has nearly the opposite effect on weather as El Niño. The 2010-2011 La Niña was the strongest ever observed and caused major drought in East Africa and flooding in Eastern Australia.

Deep ocean currents

Differences in water density, resulting from the variability of water temperature (thermo) and salinity (haline), also cause ocean currents. This process is known as thermohaline circulation. In cold regions, such as the North Atlantic Ocean, ocean water loses heat to the atmosphere and becomes cold and dense. In polar-regions, water is intensely cooled by winds. Winds also cause evaporation, which causes further cooling. When ocean water freezes, forming sea ice, salt is left behind causing surrounding seawater to become saltier and dense. Dense-cold-salty water sinks to the ocean bottom. Surface water flows in to replace the sinking water, which in turn becomes cold and salty enough to sink. This "starts" the global conveyer belt, a connected system of deep and surface currents that circulate around the globe on a 1000 year time span. This global set of ocean currents is a critical part of Earth's climate system as well as the ocean nutrient and carbon dioxide cycles. These currents move slower than surface currents because of the greater friction between the greater volume of water.

El Niño (The Little Boy)

El Niño is the name for the periodic warming of surface water in the parts of the Pacific Ocean that occurs every 3-7 years and lasts 9 months to 2 years. A 0.9 degree Fahrenheit rise in temperatures can trigger the designation of El Niño and it can have drastic effects on weather from the United States to Australia. In our area of the country, El Niño results in warmer winters with less precipitation. El Niño also tends to suppress hurricanes.

Biological influence

Ocean currents are an important abiotic factor that significantly influences food webs and reproduction of marine organisms and the marine ecosystems that they inhabit. Many species with limited mobility are dependent on this "liquid wind" to bring food and nutrients to them and to distribute larvae and reproductive cells. Even fish and mammals living in the ocean may have their destinations and food supply affected by currents. Upwelling currents bring cold nutrient-rich waters from the ocean bottom to the surface, supporting many of the most important fisheries and ecosystems in the world. These currents support the growth of phytoplankton and seaweed which provide the energy base for consumers higher in the food chain, including fish, marine mammals, and humans. Fisheries also depend on upwelling to sustain their business.

Rip currents

Rip currents Rip currents are serious hazards that pose daily threats to surf zone swimmers and waders in all coastal regions. According to the U.S. Lifesaving Association statistics, rip currents cause more than 100 drowning fatalities each year, and 80% of all rescues on surf beaches nationwide are rip current related. Rip currents can occur along any beach with breaking waves, and may become especially hazardous during high-surf conditions. Be aware of rip currents - browse through this Web site to learn more. Remember -- the beach is a beautiful place to visit, but never underestimate the power of the ocean.

The gulf stream

The Gulf Stream is an example of a very important surface ocean current. It runs from the Caribbean Sea past Florida and the eastern United States coast up into Northern Europe. It makes northern Europe much warmer than it would otherwise be.

Wind @ Surface Currents

The sun creates temperature differences over different locations above the ocean and this in turn creates differences in pressure. This pressure differential causes the air to move from areas of high pressure to areas of lower pressure. This movement of air is known as wind. Winds create friction with ocean water, driving the water near the surface in the same direction that the wind is blowing.

Oceans, Weather, & Climate

Weather describes short-term, day-to-day variations in temperature, wind, precipitation and pressure. Climate, on the other hand, describes long-term regional and global weather trends. Because of the high heat capacity of water, the land areas close to oceans have more moderate climates than inland areas. The high heat capacity of water, ability to absorb a lot of heat, is due to the hydrogen bonds between water molecules. This is the same reason that water has a surface tension that allows bugs to crawl across its surface.