Language selection


Top of page

CloudSat - Looking at clouds in 3D

Canadians have a natural fascination with cold weather, especially with our unpredictable winter season filled with everything from wet snow to icy rain. In order to improve weather and climate forecasts, scientists need to have a better understanding of the physics behind winter clouds that are a mix of ice and water droplets.

Since 2006, CloudSat has been gathering data and improving our knowledge of clouds and their effect on climate and weather. CloudSat was developed by the National Aeronautics and Space Administration (NASA) in partnership with the Canadian Space Agency (CSA).

Why clouds?

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.

The mission

Traditional satellites are generally limited to observing the upper layers of clouds and are unable to see inside them. Before CloudSat, little data was available on cloud thickness, and this type of information helps determine the quantity of water, snow, or ice contained in the clouds.

CloudSat supports the first comprehensive three-dimensional study of clouds. It gathers data on their structure, occurrence 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 data (in synergy with CALIPSO data on aerosols) also helps scientists analyze the influence of atmospheric aerosols on the way light is absorbed and reflected by the cloud layers. Using this information, scientists are filling in the 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, OCO-2 and GCOM-W1 ("Shizuku").

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 has numerous instruments on board to collect data on the Earth's atmosphere. Aura is studying air quality, the ozone layer, and climate change.

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 and COM DEV International Ltd. (now Honeywell Canada) 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 (RFES). A klystron is a specialized electronic tube that generates radar waves used by CloudSat to probe the vertical structure of clouds.

The CSA has also provided 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 their expertise to the mission in a variety of disciplines ranging from general atmospheric science to the improvement of computer algorithms and data validation.

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.

For more information, please visit:

Explore further

Date modified: