摘要
Satellite precipitation estimation has become a major source of data for global moisture and regional environmental monitoring.This preliminary study first reviews the current status of such applications especially for tropical cyclone landfalls,and the science behind rainfall estimation based on microwave emission.One of the most popular integrated rain retrieval product,the NASA TRMM 3B42 data,is validated by ground-based observations for ten landfalling tropical cyclones during 2007-2010 in the Taiwan Region.While there is a general trend of underestimation by most satellite rainfall products compared with ground observations,the rainfall distributions within tropical cyclones are quite well revealed.This gives a reasonably good volumetric total rainfall within the cyclones,and thus sub-synoptic-scale rainfall footprints.However,there are large case-to-case variations for satellite rainfall estimates to capture individual convective episodes.In addition,land effects including those from topography are still the major difficulties.As a consequence of these factors,mesoscale rainfall footprints can deviate quite largely from those observed by ground measurements during tropical cyclone landfalls.Potential pathways to improve the current satellite rainfall products are discussed,which include development of statistical correction methodologies that consider different rainfall mechanisms;consideration of topographic effect and disaggregation of current rainfall products.
