Before the science data reaches the hands of the science community in the world, the raw data collected by the TOPEX/Poseidon satellite must go through some processing, which takes place at the Project Operations Control Center (POCC) at JPL. Each day, altimeter and microwave radiometer science data records (ALT SDRs and TMR SDRs) are produced by removing some of the engineering data from the direct data collected by the altimeter and the microwave radiometer on the previous day. Then, a sea surface meteorology file provided by CNES is added to those ALT and TMR SDRs, which compose the intermediate geophysical data records (IGDRs). Moreover, a precise orbit ephemeris (POE) information file provided by the NASAšs Goddard Space Flight Center is added to the IGDRs, which finally compose the (final) geophysical data records (GDRs). As soon as the processing is done, the science data products are sent to the Science Data Team's Library and the JPL Physical Oceanography Distributed Active Archive Center (PODAAC), which distributes them to the science community in the world. (All the data products in the GDRs are distributed every 10 days except for the ALT SDRs being distributed daily due to the highest priority.)
The scientific data collected by TOPEX/Poseidon is used not only in pursuit of the primary objectives but also in a number of practical applications. The followings are a few examples of those applications and their relevant links are provided for further information.
The ocean and the atmosphere are the two great fluid envelopes of the Earth. The interaction between them is the key to understanding changes in climate and weather. The ocean absorbs the heat from the Sun, some of which is stored in the ocean and some is released into the atmosphere. This heat exchange between the ocean and the atmosphere takes place regularly in a cycle and it is greatly influenced by the movement of ocean currents. Dramatic changes in this cycle can cause severe weather patterns and climate changes. For example, El Niño is a disruption of the ocean-atmosphere system in the tropical Pacific that is accompanied by abnormally high rainfall in western and central South America and drought in Indonesia, Australia, Mexico, and southeast Africa and that prevents upwelling of nutrient-rich cold deep water causing a decline in the regional fish population. This phenomena is believed to be initiated by a complex interaction process between the ocean and atmosphere for which the ocean circulation is responsible. TOPEX/Poseidon data can help scientists not only to calculate the transport of heat but also to understand or possibly predict some changes in weather and climate such as El Niño.
Visit the following websites for more.
Eddies are quasi-circular movement of water currents contrary to the main current. Their areas are relatively small in comparison to the main current. However, there are some large eddies in the world which could cause serious damage to offshore areas where oil companies are drilling. For example, the Gulf of Mexico has some of the largest eddies ranging up to 300 to 400 km in diameter. In 1989, an eddy cost some offshore oil company $30 million by halting the drilling operation for 30 days. Therefore, it is very important to offshore oil companies to monitor, track, and possibly predict this kind of large eddies. With the state-of-the art altimeter, TOPEX/Poseidon can spot and track the eddies and even determine their size and strength. In addition, in 1993, it was found possible to locate marine mammals such as sperm whales by monitoring counterclockwise eddies, which bring up nutrient-rich deep water with a lot of microscopic plant life to the surface for the whales.
Visit the following website for the graphic data from TOPEX/Poseidon.
As the US Vice President Al Gore has described the greenhouse effect, it is a very dangerous environmental problem to mankind. Since the industrial revolution, tons of carbon dioxide have been emitted into the atmosphere, due to combustion of fossil fuels, oil, coal, and natural gas and also through changes in land use and deforestation. The increased atmospheric concentration of carbon beyond normal levels causes an accumulation of energy and thus the overall warming of the atmosphere, which also results in climate changes. The ocean circulation can slow down the increase in carbon dioxide a little by absorbing. Therefore, it is very helpful to understand more about ocean circulation in order to identify the global threat from the increased atmospheric concentration of carbon dioxide, where TOPEX/Poseidon comes into play.
Ocean waves can cause serious damage to shore structures. For example, a storm surge, which is the local change in sea level along a shore due to a storm accompanied by a wind, is potentially catastrophic specially to low-level coasts with gently sloping offshore topography. With TOPEX/Poseidonšs capability to measure wind speed and wave height simultaneously, scientists can improve their wave prediction models.
The ocean has been a big supplier of seafood to the world for a long time. However, the major fisheries are very limited and they even disappear and reappear partly due to the change in the ocean temperature and partly due to the change in nutrient distribution over the global ocean, both of which are heavily influenced by the ocean circulation. Better understanding of the ocean currents with TOPEX/Poseidon data can help us to locate more fisheries and preserve the existing precious ones in the world.
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This page is created by Masaharu Suzuki The University of Texas at Austin
Last Modified: Wed Feb 11, 1999