Utilization of a rain-gauge-based daily precipitation dataset over Asia for validation of precipitation derived from TRMM/PR and JRA-25

摘要

We upgrade the East Asia rain-gauge-based daily analysis of precipitation (Xie et al, 2006) for 1998 by utilizing daily rain-gauge precipitation data over Southeast and South Asia those are archived in GAME-T data center. This GAME enhanced version shows significant improvements in precipitation amounts in those regions where we input additional data, especially along Himalayas. We compare TRMM/PR monthly product with the GAME Enhanced version for future improvement of the orographic rainfall patterns in our rain gauge analysis. We found that TRMM/PR underestimates wet (summer) season of monsoon rainfall ~100 mm/month. Then we validate precipitation derived from JRA-25, the ongoing Japanese 25-year reanalysis project, with the new gauge-based data set for 1998. JRA-25 reproduce precipitation pattern well in time and space, but it tends to overestimate precipitation in most of the Asian monsoon region. The simulated precipitation along Himalayas shifts southward. JRA-25 reproduces the trend of extreme events that leads a flood of the Yangtze River (July 1998), but it overestimates at extreme events. The change of the precipitation amount due to re-gridding (T106 to 2.5degree) is sometimes comparable with the difference between simulation and observation. We need to be careful about the bias caused by the regridding in extreme events. APHRODITE's (Asian Precipitation -Highly Resolved Observational Data Integration Towards Evaluation of the) water resources, a project to develop a long-term rain-gauge-based daily precipitation dataset over Asia n started, and it consolidates the data-model interfaces. We welcome a wide spectrum of collaborations, particularly for collection of rain gauge data.