lunedì 24 ottobre 2011

Acquarius :Overview: Why study the ocean?

Gulf Stream
Covering about 70% of Earth's surface, our oceans serve as huge "sinks" for solar energy. Ocean circulation - including currents and eddies -- transports this energy as heat from the tropics to the poles. Evaporation at the sea surface releases energy into the atmosphere as water vapor. Over time, water returns to the oceans and land through the precipitation of rain or snow. This global cycling of water and energy helps to make Earth's overall climate hospitable to human and other life forms.

Spacecraft Illustration
Until recently, the oceans' vast expanse has made studying them a daunting task. A new age of satellite oceanography is being fueled by data from instruments quantifying global ocean circulation, marine primary productivity, sea surface winds and temperature, and tropical rainfall over the oceans. However, despite all the progress in understanding our ocean-atmosphere system, Sea Surface Salinity (SSS) - the principal surface tracer of fresh water input to / output from the ocean and a direct contributor to seawater density - is rarely measured by satellite. Aquarius will collect NASA's first-ever measurements of SSS in our global seas, thus providing a missing piece of the "global climate puzzle.


atmosphere: Gaseous layer surrounding a planet; the whole mass of air surrounding the earth. climate: The prevailing or normal pattern of weather at a place, or in a region, averaged over a long period of time; in contrast to weather, which is the state of the atmosphere at a particular time.
current: A smooth and steady onward movement of a fluid (i.e., liquid or gas). The part of any body of fluid that has a continuous onward movement.
density: Mass per unit volume of a substance. Usually expressed as grams per cubic centimeter. For ocean water with a salinity of 35 at 0°C, the density is 1.028 grams per cubic centimeter.
eddy: A current of any fluid forming on the side of or within a main current. It usually moves in a circular path and develops where currents encounter obstacles or flow past one another.
precipitation: Water released from the atmosphere in the form of rain, snow, hail, or sleet from the atmosphere onto Earth's surface.
primary productivity: The amount of growth and reproduction of organisms that only need sunlight, water and basic nutrients.
solar energy: Thermal and electromagnetic energy from the sun.
system: 1) A regularly interacting or interdependent group of items forming a unified whole. 2) A manner of classifying. 3) A group of interacting bodies under the influence of related forces.
tracer: An identifiable substance that can be followed through the course of a physical or biological process providing information on the pattern of events in the process or on the redistribution of the parts or elements involved.
tropics: The low-latitude climatic zones centered on the equator, extending between the tropics of Cancer and Capricorn (i.e., 23° N and 23° S latitude), and characterized by year-round hot weather.

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