Snowfall estimated by TRMM products and validated with ground-based instruments
Shuji Shimizu (1), Hideyuki Fujii (2)
(1) Earth Observation Research Center, National Space Development Agency of Japan
(2) Department of Civil Engineering, University of Tokyo
The Tropical Rainfall Measuring Mission (TRMM) satellite, launched by the National Space Development Agency of Japan (NASDA) on November 28, 1997, has been working well. It estimated global monthly rainfall in the tropical and extratropical area using its Precipitation Radar (PR) and the TRMM Microwave Imager (TMI). TRMM can observe snowfall in the winter in Japan and on high plateaus. However, precipitation by ice particles has not been validated yet. In 1997 and 1998 field observation using ground-based Doppler radar of NASDA was conducted on the Tibetan Plateau that has over 4000m altitude. TRMM and the ground-based radar detected many rainfall cases during the observation period. PR cannot measure the rain echo near the ground surface. Bright band height from the ground surface was about 1km on the plateau. Therefore PR measures snow echoes on the plateau and the validation of precipitation by ice particles is important to measure precipitation distribution on the Tibetan Plateau.
A field experiment was carried out with the TRMM satellite, ground-based radar systems, and a microwave radiometer around Wakasa Bay, Japan, where snowfall can be observed in the winter season in the TRMM observation area, from 30 January to 23 February 2001. The observation is important for developing an algorithm to estimate the snowfall amount using the Advanced Microwave Scanning Radiometer (AMSR) on the ADEOS-II and AQUA, and in the Global Precipitation Mission (GPM) project. Data of TRMM and ground-based instruments were measured simultaneously at 1050 UTC 14 February 2001. The linear radar echoes brought heavy snowfall and the height of the radar echoes from TRMM PR and ground-based radar was about 3km. The snowfall amounts will be validated with ground-based radars and instruments. The results will also help to establish an algorithm for estimating snowfall by a space-borne microwave radiometer.
