f98u2le4 - Lesson IV. TOPEX/Poseidon Measuring Currents...

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Lesson IV. TOPEX/Poseidon Measuring Currents from Space The goal of this unit is to explain in detail the various measurements taken by the TOPEX/Poseidon satellite. Keywords : ocean topography, geoid, and sea surface variability Science Objectives and Goals The objective of the TOPEX/Poseidon mission is to obtain an ongoing global view of Earth’s ocean topography with sufficient accuracy to improve models designed to forecast global ocean circulation. By meeting this objective, scientists are: determining ocean circulation and variability; learning to understand the wind’s role in circulation; developing the descriptions of the nature of ocean dynamics; contributing to the understanding of the transport of heat, mass, nutrients and salt through the oceans; determining geocentric ocean tides; investigating the interactions of currents with waves; improving our knowledge of the marine geoid and increasing our understanding of lithospheric and mantle processes.
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Ocean Topography Ocean topography is a measure of sea level in relation to Earth’s geoid , the shape the ocean surface would have if it were covered with water at relative rest to a rotating Earth. The geoid will be pulled away from a perfect sphere due to mass concentrations. Note also that the rotation rate of the Earth affects the geoid. The geoid is the sum of gravity effects and rotational effects. Ocean topography is the changing height of sea level relative to the Earth’s geoid after various corrections due to tides have been subtracted. While patterns of the oceans currents have been charted for hundreds of years, TOPEX/Poseidon is the first space mission that allows scientists to use ocean topography to calculate the speed and direction of ocean currents almost everywhere in the ocean. With maps of ocean topography, scientists can observe in detail the movement of water through the world’s oceans. In the Northern Hemisphere, ocean currents flow clockwise around the highs of ocean topography and counterclockwise around the lows; this process is reversed in the Southern Hemisphere. These highs and lows are the oceanic counterparts of similar circulation systems in the atmosphere. Oceanographers use ocean topography maps to calculate the speed and direction of ocean currents in the same way meteorologists use maps of atmospheric pressure to calculate the speed and direction of winds. TOPEX/Poseidon is the first space mission that allows scientists to map ocean topography with sufficient accuracy to study the large-scale current systems of the world’s oceans. Global Ocean Circulation Ocean circulation is the large-scale movement of waters in the ocean basins. Winds drive surface circulation, and the cooling and sinking of waters in the polar regions drive deep circulation. Surface circulation carries the warm
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This note was uploaded on 07/31/2011 for the course OCB 6050 taught by Professor Staff during the Spring '11 term at University of South Florida.

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f98u2le4 - Lesson IV. TOPEX/Poseidon Measuring Currents...

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