An Evaluation of a new AMSU-derived falling snow retrieval algorithm

The retrieval of falling snow and rain over snow-covered land surfaces has been a never-ending challenge for passive microwave remote sensing. This is because of the non-uniqueness of the scattering signature associated with precipitation and snow on the ground in the frequency range between 18 and 90 GHz. However, for many parts of the world, snowfall is the primary source of precipitation.

Based on the ground breaking study of Kongoli et al. (2003) which utilizes measurements near the 55 GHz oxygen and the 183 GHz water vapor absorption bands, NOAA/NESDIS implemented an enhanced precipitation retrieval algorithm in November 2003 that includes the detection of rainfall and snowfall over cold surfaces (e.g., frozen land and snow covered land). This algorithm is presently operational for the Advanced Microwave Sounding Unit (AMSU) on board the NOAA-15, -16 and -17 satellites through a product system known as the Microwave Surface and Precipitation Product System (MSPPS). It is limited for use in temperate latitudes which are near the southern limit of the established snow pack.

It is the purpose of this paper to present an evaluation of this algorithm for the 2003-04 winter season through both case study and global analyses. In addition, an expansion of the current technique to colder climate regimes is being developed and tested, so the paper will also describe the performance of this enhancement, which is to be implemented in the fall of 2004.