CloudSat - Looking at clouds in 3D
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Shadowing Satellite Science
The CloudSat Ground Validation Program - November 28, 2007
Canadians have a natural fascination with cold weather - especially with our unpredictable winter season filled with everything from wet snow to icy rain. Scientists need to have a better understanding of the physics behind winter clouds that are a mix of ice and water droplets mix and the resulting weather conditions.
Traditional satellites studying the atmosphere can portray the cloud surface accurately, but are limited to a two-dimensional representation of cloud cover. No data has been available on cloud thickness that would help to determine volume and the quantity of water, snow, or ice clouds contain. CloudSat is a satellite that gathers new data and improves our knowledge of clouds and their effect on climate. CloudSat was developed by the National Aeronautics and Space Administration (NASA) in partnership with the Canadian Space Agency (CSA).
Clouds influence the amount of solar energy retained in the atmosphere and the amount reflected back into space. Even small changes in cloud cover can alter climate in a major way. Some scientists think clouds may affect our climate even more than greenhouse gases and other factors linked to climate change.
CloudSat is doing the first comprehensive three-dimensional study of clouds. It gathers data on their structure, frequency and volume, and helps improve our understanding of how they influence the weather. It uses a radar hyperfrequency device to probe the cloud cover and determine its thickness, its altitude at base and peak, and the quantity of water and ice contained.
CloudSat is also analyzing the way light is absorbed by the various layers of the atmosphere, particularly the influence of atmospheric aerosols on this process. Scientists are also filling in gaps in their knowledge of how radiation energy from the Sun and the Earth is distributed between the Earth's surface and the atmosphere
The mission also refines and validates data gathered by other atmospheric and cloud research satellites.
A constellation of satellites
A distinct feature of CloudSat is its role in a constellation of scientific research satellites. This constellation, known as the A-Train, also includes: CALIPSO, which was launched at the same time as CloudSat aboard a Delta rocket, as well as Aqua, Aura, and PARASOL. A sixth satellite, OCO, was launched in 2008.
CALIPSO is a joint United States/France mission. It collects data on the role played by transparent, thin clouds and aerosols in the transfer of solar energy to the atmosphere.
The Aqua satellite, the head of the pack, has numerous instruments on board to collect data on the Earth's atmosphere. Aura, at the back of the formation, is studying air quality, the ozone layer, and climate change. PARASOL, a mission led by France, researches how light is diffused by clouds and atmospheric aerosols. This mission affords a better understanding of the impact of human activity on global warming.
Canada is in the thick of it
Since Canada has expertise in space radar, NASA invited the CSA to participate in the CloudSat mission in 1998.
Ontario companies CPI, of Georgetown, and COM DEV, of Cambridge, answered the CSA's call for tenders for this mission. These two space industry leaders developed a key element of the cloud profiling radar, the extended interaction klystrons (EIKs), as well as a central component of an electronic receiver: the radio frequency electronics subsystem or RFES. A klystron is a specialized electronic tube similar in concept to those used in microwave ovens. It generates radar waves that are used by CloudSat to probe the vertical structure of clouds.
CSA is also providing support to Canadian scientific investigations related to the mission. David Hudak, Ron Stewart, and Howard Barker of the Meteorological Service of Canada are helping the U.S. team. Jean-Pierre Blanchet, of the Université du Québec à Montréal, is also a member of the CloudSat mission research team. Together, they bring to the mission their expertise in a variety of disciplines ranging from general atmospheric science to the improvement of computer algorithms and data checking.
The American Principal Investigator for the CloudSat mission is Graeme Stephens of Colorado State University. Construction of the satellite platform was the responsibility of Ball Aerospace.
A multipurpose mission
Cooperation with other space agencies, governments, and scientists is part of the CSA mandate for supporting Canada's role in international space development. Canadian space technology advances the body of knowledge available about climate and enhances the forecasts developed by the scientific community for weather and climate change.
Canada is investing in the CloudSat program to encourage remote sensing and telecommunications applications design and development.
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