The Use of Comparison and Calibration of Reflectivity from the TRMM Precipitation Radar and Ground-based Operational Radars in China

Give the decade-long and highly successful Tropical Rainfall Measuring Mission, it's now possible to provide quantitative comparison between ground-based radars and space-borne radar. Some helpful results has been given with radars' condition in the U.S.. Different to most countries, there are now total five types of weather radars working for the China operational radar net including multi hardware parameters and wavelengths (e.g., s-band includes three types as SA, SB, and SC c-band includes two types as CC and CD ). During past years, we found much of differences among each ground radars and usually the maximum difference could arrive at 5dBZ or larger, and it's hard to tell which one is reliable. This research uses PR to compare with three main s-band type (SA/SB/SC) radars in China during JJA flood season in 2011 and 2012. Data from each instrument resample into three-dimensional by 4×4km from horizontal and 0.5km from vertical direction. Compares suggest that both SA and SB radars have much better agreement to PR than SC radar. The mean correlation coefficient of SA, SB, and SC radars are 0.82, 0.80 and 0.56 respectively. Vertical profiles of radar reflectivity of different rain types detected by the three kind radars also showed the same characteristic that SC radar had much difference with PR. It's given from the scatter plot density figures that there is a significant systematic bias with SC radars, which reflectivity is lower than PR nearly about 5-8dBz.