HR: 1330h
AN: H23A-09    [Abstracts]
TI: Satellite Rainfall Retrieval from Microwave Radiometry: Effect of Spatial Inhomogeneity in Bias Reduction
AU: * Shin, D
EM: dshin@scs.gmu.edu
AF: George Mason University Center for Earth Observing and Space Research, 4400 University Drive, MS 5C3, Fairfax, VA 22030 United States
AU: Chiu, L
EM: lchiu@gmu.edu
AF: George Mason University Center for Earth Observing and Space Research, 4400 University Drive, MS 5C3, Fairfax, VA 22030 United States
AB: The spatial variability of rainfall within the sensor field of view coupled to the non-linearity in the physical connection between microwave brightness temperature and rainfall contributes to the so-called beam-filling error. This study interprets this error as an inherent error that depends only on the rainfall characteristics and sensor responses. Thus, the inherent error cannot be reduced by using more accurate cloud-radiative models, but by the detail knowledge of the rainfall characteristics, which is needed in the first place. This study explores the relation between the spatial variability of the high frequency radiometric data and the rainfall characteristics that may be used for reducing the inherent error in the instantaneous rainfall estimations from passive microwave sensors. Analyses of Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Precipitation Radar (PR) data suggest that the inherent error can be examined in terms of the coefficient of variation (CVr, rain rate standard deviation divided by mean within a field of view). It is also observed that the spatial variability of TMI 85.5 GHz brightness temperature (CVtb) shows good correlations with CVr, especially for higher rain rates. We showed that both CVtb and CVr are useful in classifying rain type. It implies that the spatial inhomogeneity and vertical distribution of rainfall combine to contribute to the uncertainty in the retrievals. In synthetic retrievals, we demonstrate the spatial variability of the high frequency Tb (CVtb) reduces the retrieval error (bias) from -5.3% to 2.4% for the east Pacific and from -12.4% to -5.4% for the west Pacific for the winter season.
DE: 1854 Precipitation (3354)
SC: Hydrology [H]
MN: 2005 Joint Assembly