New Method for Retrieving Liquid Water Path over Land using AMSR-E Observations

Improved satellite-based methods for retrieving cloud liquid water path (LWP) are needed for climate studies, numerical weather prediction, and aircraft icing analysis. Current methods for retrieving LWP over land using satellite observations are typically based on visible and infrared observations. Microwave-based methods are complementary to visible/infrared methods because (1) they are applicable to both daytime and nighttime observations and (2) are unaffected by non-precipitating ice particles (e.g., cirrus). The new method we are developing employs polarization-difference signals at 37 and 89 GHz produced by the Earth Observing System (EOS) Advanced Microwave Scanning Radiometer – EOS (AMSR-E) instrument and exploits a simple radiative parameterization. The dual-channel method effectively retrieves LWP even in the presence of substantial surface temperature and surface emissivity variability.

We will describe the new method in detail and compare results to ground-based LWP retrievals from the Atmospheric Radiation Measurements (ARM) Southern Great Plains site and the AIRS II (Alliance Icing Research Study II) field campaign near Montreal, Canada. In addition, retrieval errors associated with the ancillary data, instrumental noise, and radiative parameterization will be estimated and compared to validation results.