Impact of Climate Variability on Drought Events in Northern Thailand Using Fast Fourier Transform

Abstract

This work aims to study the influences of climate variability and climate change to the drought events in the northern Thailand during monsoon rainfall (June-September) 1981– 2018. The ENSO mechanisms and their impacts are taken into account on this analysis in term of the principal component. The Fast Fourier Transform (FFT) is performed to reveal the link between the ENSO impacts and drought events in the northern Thailand under global warming. The Empirical Orthogonal Functions (EOFs) is also performed to truncate the Sea Surface Temperature (SST) anomaly and Gamma distribution is applied to fitting the monthly precipitation data as a Standardized Precipitation Index (SPI). The results show that the average drought period changes from 7.5 years in 1981-1995 to a new average period of 5 years since 1996 onwards in terms of many SPI time scales (e.g. SPI3, SPI6 and SPI12). Under the climate change forcing, it clearly shows the correlation that the signal of strong ENSO events affects the drought periods in Northern Thailand more frequently for the last two decades.