Sampling effects on radar measurements and rain rate estimation

In this paper, we have studied sampling effects on radar measurements and on parameter retrievals. A two-level DSD model is proposed and illustrated for calculating statistical moments. The numerical results show that variations of DSD contribute to the over-estimation of statistical moments and biases the parameter retrieval. A range correction has been applied to radar estimated rain rate for accurate rain rate estimation based on the two-level Gamma DSD model. Although the two-level DSD model is proposed to include the DSD variation, the effects due to incomplete beam filling can also be compensated, since incomplete beam filling will alter DSD and hence the parameters of DSD. The model and numerical results have been applied to radar rain estimation with a range correction. In this study, we randomize DSD parameters to include sampling effects while their fluctuations are assumed to be independent random variables. Some of the observations show that DSD parameters may be mutually dependent, but the fluctuations in DSD parameters are less correlated. So, the independence among the fluctuations of DSD parameters can be a valid assumption for some cases. Even if the correlation among the fluctuations of DSD parameters is found, the two-level model does not lose its generality