SAMPLING-INDUCED CONDITIONAL BIASES IN SATELLITE CLIMATE-SCALE RAINFALL ESTIMATES

The effect of temporal sampling error in satellite estimates of climat e-scale rainfall is to produce a ''conditional'' bias where the algori thm overestimates high rainfall and underestimates low rainfall. Thus, the bias is conditional on the value of the estimate. This paper illu strates the problem using satellite infrared rainfall estimates togeth er with a well-known satellite algorithm and shows it to be a function of the averaging scale, the sampling rate, and the temporal autocorre lation structure of the satellite estimates. Using realistic sampling rates, it is shown that significant biases exist in satellite rainfall estimates if polar-orbiting data are used in their construction. A si mple correction for this bias based upon the estimated autocorrelation structure is given.