Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

Sister Satellites CALIPSO and CloudSat

CALIPSO and CloudSat Over Hurricane Maria and Tropical Storm José

CALIPSO and CloudSat Over Hurricane Maria and Tropical Storm José

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Hurricane Maria near the Caribbean Sea and Tropical Storm José off the northeast U.S. coast on September 20, 2017. Data from the CALIPSO lidar and CloudSat radar appear as vertical slices in the atmosphere. CALIPSO lidar data is visualized as a bluish slice, with red and yellow colors denoting more scattering off of clouds and aerosols. CloudSat radar data is superimposed on the CALIPSO slice in brighter colors. Areas of heavier precipitation, found in each storm’s spiral bands, appear in red and pink.


In February 2018, facing a mechanical challenge, CloudSat had to exit the A-Train, or afternoon constellation, of Earth-orbiting satellites, and move to a lower orbit. Following an exit maneuver of its own in September, CALIPSO has joined CloudSat, forming what NASA scientists are calling the C-Train — C being the first letter of each satellite.


CALIPSO began its exit from the A-Train Sept. 13 and entered its new orbit Sept. 20. The C-Train orbit is approximately 428 miles (688 kilometers) above the Earth's surface. It'll take some time to get the satellites in phase with one another and they'll be a little farther apart than they once were — about 60 seconds. But once they're completely settled in — likely in late October — they'll continue to provide indispensable, complementary views of clouds and aerosols for what scientists hope will be another two years or more.


CloudSat and CALIPSO are known as "active" sensors because they direct beams of energy at the Earth (Radio wave signals in the case of CloudSat and laser light in the case of CALIPSO) and measure how these beams reflect from the clouds and aerosols in the atmosphere. Other orbiting science instruments use "passive" sensors that rely on collecting reflected sunlight or radiation emitted from the Earth or clouds to make measurements.


Credits: NASA/Roman Kowch; NASA LaRC/ Joe Atkinson


Read the full article: Sister Satellites, Briefly Separated, Working Together Again