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|Title:||Assessment and hydrological Application of Integrated Multi-Satellite Retrievals for GPM (IMERG) precipitation products over Thailand.|
การประเมินและการประยุกต์ใช้ทางอุทกวิทยาของข้อมูลปริมาณน้ำฝน จากผลิตภัณฑ์ข้อมูลดาวเทียม Integrated Multi-Satellite Retrievals for GPM (IMERG) ในประเทศไทย
Burapha University. Faculty of Geoinformatics
|Abstract:||Precipitation is an important component of the earth's water system. It is the major source that refills underground aquifers and surface water such as rivers and lakes and also provides freshwater for plants, animals and countless human activities. Currently, climate change is having a serious impact on the earth's temperature and global precipitation, resulting in excessive rainfalls and droughts in different regions over the world. Acquiring knowledge about precipitation characteristics is vital for improving climate prediction and water resources management, which is a significant issue in many countries including Thailand. Located near the equator, Thailand has a tropical rainforest climate and is under the influence of the Northeast and Southwest monsoons with high average rainfall. There are three seasons in Thailand, where dry weather is often experienced in winter under the influence of the Northeast monsoon, while thunderstorms are frequent in summer due to the influence of the Southwest monsoon which causes heavy rainfalls in this period. The highest rainfall occurs in the rainy season which starts in mid-May and ends in mid-October, with August and September as the wettest months of the year. Local rainfall amount data is important for many works including agriculture, irrigation, electricity production as well as for basic human activities. However, in poorly gauged areas or high-mountain areas still lacks to measure the precipitation and ground-based rainfall measurement is not yet sufficient.
In recent decades, the development of meteorological satellites, remote sensing techniques and satellite-based precipitation products is an important data source for the knowledge of climate characteristics and hydrological applications. An alternative method to measure rainfall in a large area that ground observation network measure only in a point scale, and the coverages of weather radar network has limits capability by a blockage by high mountains. The Integrated Multi-Satellite Retrievals for GPM (IMERG) is a multi-satellite precipitation algorithm Level 3 of The Global Precipitation Measurement (GPM) to deliver next generation of satellite rainfall measurement after the success of the Tropical Rainfall Measuring Mission (TRMM). Precipitation data from the Global Precipitation Measurement (GPM) is available free download source data on website www.pmm.nasa.gov with a variety of formats for utilization precipitation data in research.
The main purpose of this research, to assess the performance of daily precipitation and spatial characteristics of Integrated Multi-Satellite Retrievals for GPM (IMERG) Version 06 (V06) products: the near-real-time (IMERG-Early and IMERG-Late) and the post-real-time (IMERG-Final) comparing with 121 ground-based observation station from the Thai Meteorology Department (TMD) that still lacks to study the performance of IMERG over the whole area of Thailand. The assessment was used reliability assessment (the correlation coefficient (CC), Mean Absolute Error (MAE), Root Mean Square Error (RMSE), Relative Bias (RB) ) and quality assessment method (A probability of Detection (POD), False alarm radio (FAR), A probability of false detection (POFD) and Critical Success Index (CSI)), And evaluation the IMERG V06 precipitation product in hydrological modelling. The assessment was conducted at daily, monthly, annual, and seasonal scales on period 16 February 2014 to 15 February 2019.
The results showed All IMERG V06 precipitation products performed a good correlated and excellent precipitation detection capability compared with a ground-based observation from the Thai Meteorology Department (TMB) rain gauge station. Overall, the performance of all IMERG V06 precipitation products has tended to overestimation of rainfall over Thailand for daily, monthly, annual, and seasonal scales. The MAE and RMSE is high in the rainy season with good correlation in seasonal scale but a moderate correlation in summer. The IMERG precipitation products can successfully capture the spatial distribution of rainfall over Thailand. Similarly, to the spatial pattern of TMD gauge station. The daily precipitation accumulates increasing from the Northern to the Southern region with high among of precipitation on the Eastern coast and the Western side of the Southern region of Thailand. In contrast, lower among of precipitation can be found in the Northern, Central and North-East region of Thailand.
For hydrological simulation, all IMERG precipitation products perform a high correlation with the inflow rate in NAM model simulation than ground-based precipitation data from the Electricity Generating Authority of Thailand (EGAT) Telemetering stations. However, IMERG precipitation products underestimated the inflow rate compared with observed inflow over Upper catchment of Vajiralongkorn Dam. Overall, IMERG precipitation products performed better performance than EGAT telemetering data. Furthermore, future research should be considering the performance of both IMERG near-real-time products (IMERG-Early and IMERG-Late) for flood events and more studies about IMERG precipitation products for hydrological modelling on a local scale. Moreover, the performance of IMERG Half-hourly precipitation products needs to study in future work in a different region of Thailand.|
|Description:||Master Degree of Science (M.Sc.)|
|Appears in Collections:||Faculty of Geoinformatics|
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