KEYWORDS: Satellites, Meteorology, Databases, Data archive systems, Data modeling, Data centers, Data conversion, Climatology, Meteorological satellites, Atmospheric modeling
Precipitation data measured by rain gauges are important in validating estimates from satellite data and model simulation.
Gridded precipitation products based on rain-gauge data improve the accuracy of forecasts. However, it is not widely
understood that quality control is important in developing a rain-gauge-based precipitation product. In this study, we
present examples of abnormal precipitation data for South Asia found in the work of the Asian Precipitation-Highly
Resolved Observational Data Integration Towards Evaluation of the Water Resources (APHRODITE) project. We also
discuss the use of satellite-based estimates in the quality control of rain-gauge records.
The Precipitation Radar (PR) data acquired by the Tropical Rainfall Measuring Mission (TRMM) over its 10 years of
observation can be used to show the monthly rainfall patterns over the Himalayas. To validate and adjust these patterns, we
used a dense network of rain gauges to measure daily precipitation over Nepal, Bangladesh, Bhutan, Pakistan, India,
Myanmar, and China. We then compared TRMM/PR and rain gauge data in 0.05-degree grid cells (an approximately
5.5-km mesh). Compared to the rain gauge observations, PR systematically underestimated precipitation by 28% to 38% in
summer (July-September). Monthly PR climatology was adjusted based on the monthly regressions between the 2 sets of
data, and depicted.
KEYWORDS: Data modeling, Climatology, Meteorology, Data archive systems, Data centers, Atmospheric modeling, Analytical research, Floods, Data integration, Satellites
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 2.5 degree) 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.
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