TRMM PR analysis on how extreme storms may influence 2011 Thailand floods

Rung Panasawatwong

In 2011, Thailand observed a historic flood that lasted over six months and cost $46.5 billion in economics and 13.6 million people affected. The Hydro and Agro Informatics Institute of Thailand argued that the flood is the result of extreme total rainfall, influenced by La Nina and the higher-than-usual number of tropical cyclones. This project aims to investigate if the extreme total rainfall was produced by an unusual extreme storm pattern. The yearly trend and monthly distribution of rain rate, rain volume, and extreme storm type will be explored. The preliminary result shows the overall number of extreme storms occurring in 2011 was not especially higher than in other years. However, the number of broad stratiform regions (BSRs) is especially high in 2011. Even though BSRs are low-intensity storms, they can produce large amounts of volumetric rain thanks to their size and potentially their long lifetime. We will explore the environmental factors that may affect the number of BSRs, and whether BSRs and other extreme storm types produce significantly more rainfall total than usual.