Better knowledge with more gauges? Investigation of the spatiotemporal characteristics of precipitation variations over the Greater Beijing Region

摘要

Using the hourly precipitation observations from 118 gauge stations and a weather radar in the Greater Beijing Region (GBR) during 2008-2012, we investigate the spatiotemporal characteristics of precipitation and discuss the appropriate observational approach for capturing variability of precipitation over this region. In general, the south central and northeastern GBR receives more intense precipitation than other parts. The diurnal cycle of precipitation amount (PA) peaks in the evening and decreases till noon, whereas precipitation intensity (PI) and precipitation frequency (PF) both have two peaks. The stronger peaks of PI and PF occur in the evening whereas the weaker ones appear in the early nighttime and in the afternoon. Remarkable spatial heterogeneity also exists in the diurnal patterns of PA, PI and PF over the GBR. Rainstorms extracted from radar data feature in short duration (11.4 h in average) and highly localized patterns (4.31-20.58/1.85-9.10 km in major/minor radius direction). The estimated diurnal cycles of PA, PI and PF are found to depend on the gauge density in a sensitivity analysis, where a gauge density ratio of 0.6 (corresponding to 30 gauges in total with a representative area of 239.5 km(2) per gauge) is identified as adequate to capture the temporal characteristics of precipitation in the plain area of GBR. However, such a gauge density ratio (i.e. 0.6) is incapable for resolving the spatial characteristics of precipitation in GBR. As such, different instruments (e.g. gauge network, weather radar, etc.) and multiple data sources are suggested to be jointly utilized to better capture the characteristics of rainstorms in GBR.