CloudSat

CloudSat is a NASA satellite. It is studying clouds in detail to better characterize the role they play in regulating Earth’s climate. It is providing a global survey of the vertical structure and overlap of cloud systems and their liquid and ice-water contents.

The CloudSat satellite was launched on April 2006, together with Calipso, for an initial mission duration of 3 years but, given its good performance, its mission has been extended until 2022. It initially joined the A-Train constellation at an altitude of 705 km, with a nominal inclination of approximately 98.2 degrees. Since February 2018, its orbit has been modified and it continues science operations in a new orbit under the A-Train.

CloudSat flies an advanced cloud-profiling radar to “slice” through clouds to examine their inner structure. It provides the capability to look jointly at clouds and at the precipitation that comes from them and allows to study the processes that convert the tiny cloud particles to precipitation.

CPR (Cloud Profiling Radar)

The Cloud Profiling Radar (CPR) is a 94-GHz nadir-looking radar which measures the power backscattered by clouds as a function of distance from the radar. The CPR was developed jointly by NASA/JPL and the Canadian Space Agency (CSA).

The design of the CPR was driven by the science objectives adapted to satellite resources.

• Nominal frequency   94 GHz

• Pulse width 3.3 µsec

• PRF             4300 Hz

• Minimum detectable reflectivity factor < -29 dBZ

• Antenna size            1.85 m

• Dynamic range        70 dB

• Integration time        0.16 sec

• Nadir angle             0.16°

• Vertical resolution    500 m

• Cross-track resolution          1.4 km

• Along-track resolution**        1.7 km

Products currently available at AERIS:

• Level 1 Radar Backscatter Profiles
• Level 2 Cloud Classification
• Level 2 Cloud Water Content
• Level 2 Cloud Mask and Radar Reflectivities
• Level 2 Cloud Optical Depth
• Level 2 Radiative Fluxes and Heating Rates

Synergy with CALIPSO

The combination of the CloudSat radar and the CALIPSO lidar collocated measurements is very useful for the retrieval of cloud properties and their vertical distribution since the radar and lidar backscatter are proportional to very different powers of particle size and then provide very complementary information. Furthermore, the radar can penetrate deep ice clouds while lidar cannot but due to its higher sensitivity can identify very thin ice clouds. The radar is also mainly sensitive to ice (larger diameters) while the lidar is more sensitive to liquid water (higher concentration) which allows to distinguish efficiently cloud phase.

The DARDAR (raDAR/liDAR) algorithm provides a clouds/aerosols mask, derived from both radar and lidar, and ice cloud retrievals. It has been elaborated through a collaboration between the IPSL/LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales) and the Cloud Group of the Department of Meteorology, University of READING.

Products currently available at AERIS:

• DARDAR Cloud and Aerosol Classification
• DARDAR Ice Cloud Retrieval

• SODA Optical Thickness of Aerosols and Fine Clouds
• SODA Level 3 Monthly Average