Comparison of TRMM Rainfall and Daily Gauge Data in Thailand
Abstract
Daily rainfall data collected from more than a hundred gauges over Thailand have been used to study the climatology, seasonal and non-seasonal variations of Thailand rainfall and to compare rainfall characteristics with rainfall estimated from Tropical Rainfall Measuring Mission (TRMM) rain algorithms. In this study, Thailand regions are separated into the northern (north of 12°) and southern part. Climatologically, Thailand has a tropical climate, influenced by monsoon winds that vary in direction according to the season. The northern region rains mostly during the JJA season and the southern region rains dominantly during the SON season. Statistical analyses showed that the gauge data is very close to gauge analyses produced by the Global Precipitation Climatology Center (GPCC) and TRMM satellite and gauge merged analysis (3B43) estimates, respectively. In contrast, TRMM microwave calibrated IR (3B42) estimates are much higher than the rain gauge measurements. The gauge data are binned at daily 1 x 1 degree resolution. Preliminary results show that TRMM 3B42 has about 20% false alarm rate and about 5% non-detection rate. The daily rainfall data from TRMM microwave imager (TMI) and precipitation radar (PR) are also extracted from the TRMM mission index to calculate the false alarm and non-detection rates for different seasons. Moreover, the Normalized Difference Vegetation Index (NDVI) data is used to study the effect of land cover changes to rainfall over Thailand. The results show that the northern part has the most vegetation greenness in the SON season and there is an increasing trend of NDVI in the past 20 years over Thailand.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSM.H23A..10C
- Keywords:
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- 1854 Precipitation (3354)