Abstract
Myanmar and Thailand often experience severe droughts and floods that cause irreparable damage to the socio-economy condition of both countries. In this study, the Southeastern Asian Summer Monsoon variation is found to be the main element of interannual precipitation variation of the region, more than the El Niño/Southern Oscillation (ENSO). The ENSO influence is evident only during the boreal spring season. Although the monsoon is the major factor, the existing Indian Monsoon Index (IMI) and Western North Pacific Monsoon Index (WNPMI) do not correlate well with the precipitation variation in the study regions of Southern Myanmar and Thailand. Therefore, a new set of indices is developed based on the regional monsoon variations and presented here for the first time. Precipitation variations in Southern Myanmar and Thailand differ as well as the elements affecting the precipitation variations in different seasons. So, separate indices are proposed for each season for Southern Myanmar and Thailand. Four new monsoon indices based on wind anomalies are formulated and are named as the Indochina Monsoon Indices. These new indices correlate better with the precipitation variations of the study region as compared to the existing IMI and WNPMI.
Highlights
We show that ICMI indices better explain the variations in SMI and TI as compared to the traditional indices of IMI and WNPMI
ICMIs have partial correlation coefficient equal or above 0.5 for all the combinations. This means that the set of ICMI is a better indicator for the monsoon for the two domains, and determining the factors that influence ICMI may lead to better precipitation predictions in SMMD and TMD
We suggest that heavy monsoon precipitation in September of 2011 after the normal monsoon season of JJA would have charged the catchment area of the affected region preconditioning the extreme flood event when the typhoon hit Thailand in the beginning of October
Summary
Myanmar and Thailand often experience severe droughts and floods that cause irreparable damage to the socio-economy condition of both countries. Because the precipitation in Southern Myanmar and Thailand is influenced by local monsoon winds, a new set of indices incorporating these winds was explored To account those regional variations, a total of four monsoon indices based on local monsoon wind anomalies are developed for MAM, JJA and SON in both domains. This monsoon early signal can be detected from the changing zonal wind east of Sri Lanka. ICMIs have partial correlation coefficient equal or above 0.5 for all the combinations This means that the set of ICMI is a better indicator for the monsoon for the two domains, and determining the factors that influence ICMI may lead to better precipitation predictions in SMMD and TMD. We suggest that heavy monsoon precipitation in September of 2011 after the normal monsoon season of JJA would have charged the catchment area of the affected region preconditioning the extreme flood event when the typhoon hit Thailand in the beginning of October
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