Two months of data collected by the meteorological radar in Hualien, Taiwan, and the available rain gauge data in the radar-covered area, are examined. These periods correspond to the times of the Algorithm Intercomparison Program conducted by the Global Precipitation Climatology Project in the Japan area. Statistical analysis showed little range dependence of radar reflectivity, in contrast to the findings of Petty and Katsaros for the Taiwan Area Mesoscale Experiment (TAMEX), indicating that the range dependence of the radar has been accounted for. A period of anomalously high reflectivity was detected. Infrared imagery from the GMS satellite showed the absence of cloud for the same period, suggesting the possibility of anomalous propagation (AP). Monthly mean radar rain rates compare favorably with the gauge averages, GOES Precipitation Index, and with Special Sensor Microwave Imager (SSM/I) estimates.
The threshold technique r estimating areal average rain rates proposed by Chiu and others was tested using Z-R relations typical of the Taiwan area. Despite the uncertainty in the Z-R relation and the VIP level processing of the radar, the variance of areal rain rate explained by the optimal threshold is about 90%.
Our analysis demonstrated the applicability of the threshold technique in estimating areal rain ll in the Hualien radar-covered area, and the use of IR observations in detecting A Higher spatial and temporal (at least every 15 minutes) resolution rain gauge observations and concomitant satellite visible, infrared, and/or microwave observations will prove to be vital to the advancement of quantitative rainfall estimation in Taiwan.