Thursday, 13 February 2003
Frequency Distribution of Rain Rate With Cloud Top Brightness Temperature, and near-real time calibration of GOES Multispectral Rainfall Algorithm
Biased corrected radar rain estimates and GOES observations are used to study the distribution of rain rate with cloud top brightness temperatures. First, radar estimates are used to select the actual raining clouds. The frequency of distribution is then computed using classes of 5 mm/hr of rain rate. Preliminary results for the summer months (May, June and July 2001) show interesting results characterized by two distinct classes of raining clouds for light to moderate rain rates: very cold cloud tops centered about 218K, and a second warm cloud top about 260K. Very few raining clouds with cloud tops between 235K and 253K are observed for these three months of data. For rain rates greater than approximately 25 mm/hr, only one class with Guassian-like distribution is observed with the modal value centered around 218K with a cut-off of rain at approximately about 235K. This paper will present our findings for both the summer and winter seasons and discuss how these findings will be useful to IR/visible based rainfall techniques.