Climate Feedback Studies Using 4D Distributions of Clouds and Aerosols

Abstract:

CALIOP, the dual wavelength, polarization sensitive lidar flying aboard the CALIPSO satellite, has been operating since June 2006 and is expected to last for more than 10 years. The combination of CALIOP and CloudSat measurements, and those acquired by future space-based lidar/radar missions, forms an extended time series of three-dimensional aerosol/cloud distributions. The global lidar/radar observations help us understand fast atmospheric processes that are relevant to aerosol-cloud-radiation-climate interactions and the energy/water cycle. If calibration errors are small enough, the lidar/radar observation time series can also provide better constraints for studying atmosphere/ocean interaction processes on inter-annual and decadal time scales.

CALIOP provides the best aerosol/cloud detection, discrimination and vertical distributions. CALIOP’s depolarization ratio is one of the best calibrated measurements made by the A-Train sensors. Over the life of the CALIPSO mission, the vertical distribution measurements and the stability of the CALIOP depolarization ratio calibration has remained within 1%. CALIOP’s depolarization ratio measurements can be used for studying changes in aerosol and ice cloud characterizations, multiple scattering processes of water clouds, and the backscatter of ocean subsurface particulates. Using depolarization ratio measurements from CALIOP together with collocated A-train instruments, we will evaluate the seasonal and inter-annual changes in global and regional aerosol and cloud profiles, as well as ocean subsurface properties, in order to answer the following questions:

• How do cloud properties, such as cloud fraction, cloud vertical distributions, cloud phase and cloud temperature, of Northern and Southern Hemispheres respond to changes in SST and solar insolation? 
• Do we see global and/or regional changes in microphysical properties of water clouds during the past 8 years?
• Are the changes in water cloud microphysical properties correlated with changes in aerosols, ocean surface or subsurface properties?