Geographia Technica, Vol 16, Issue 1, 2021, pp. 48-66
SEASONAL CHARACTERISTICS OF PRECIPITATING CLOUD PROPERTIES AND STRUCTURES IN THE INLAND OF THE INDOCHINA PENINSULA: A LEGACY OF 16 YEARS OF THE TROPICAL RAINFALL MEASURING MISSION (TRMM) SATELLITE
Nattapon MAHAVIK 
, Sarintip TANTANEE
ABSTRACT: Seasonal characteristics of cloud properties and structure based on mesoscale properties of precipitation systems over the inland Indochina Peninsula (IP) and surrounding regions during the years 1998-2013 were investigated in this study. Using daily product from Tropical Rainfall Measuring Mission, the monsoon season, firstly, was demarcated to find onset and withdrawal dates for each year, and then to divide the period into the premonsoon, monsoon and postmonsoon seasons. In the 16-yr “climatology”, on average, the variations were found both in physical properties and structures of precipitation features (PFs) for each season. Based on applied definition, the intra-seasonal and the inter-seasonal variation of rainfall intensity and periodical duration length were considered to identify the seasonal period of each year. Mesoscale Convective Systems (MCSs) played a significant role through their contribution of rainfall for all periods. Sub-MCSs were major contributors of rainfall during the postmonsoon season, while the highest percentage of intense MCSs (IMCSs) was found in the premonsoon season. The enhancement of IMCs for the premonsoon season is the largest over the inland IP based on microwave signal and radar reflectivity sensors. Distinct spatial concentration was found over west and north IP for sub-MCSs during monsoon seasons. Convection intensity proxies and vertical radar reflectivity demonstrate intra-seasonal variation over land, were identified through cumulative density function analysis by enhancement of MCSs during the premonsoon season. Spatial distribution of PFs based on maximum height cloud average over the inland IP has shown at height exceeding 8 km over the western inland IP during premonsoon season. Spatial variation of the microphysical structure of cloud is distinctly shown by seasons based on scattering of microwave signals, and lightning flash counts. The most frequent lightning was found during premonsoon season over inland IP, while the most flash count average was also found over inland IP especially over west, north in highland of IP during premonsoon season. Further study should be conducted to analyze on seasonal periods for understanding on the variations of microphysical structure and cloud properties.
Keywords: TRMM 16 years, Cloud Structure, Indochina Peninsula, Convective Cloud, Precipitation Features
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