Projected changes in means and extremes of temperature and precipitation over Thailand under three future emissions scenarios

Abstract

This study quantifies the potential future changes in temperature and precipitation over Thailand for the mid-21st century years (2031 to 2070) under the 3 emissions scenarios of the Intergovernmental Panel for Climate Change (IPCC; A2, A1B and B1) using fine-resolution (20 km) RegCM3 simulations driven by output of ECHAM5/MPI-OM global climate model experiments. In addition to mean characteristics, 4 temperature extreme indices (numbers of cool days, cold nights, warm nights, and hot days) and 4 precipitation extreme indices (number of consecutive dry days, maximum 5 d precipitation, number of very heavy precipitation days, and precipitation amount due to very wet days) are included. Simulated results over the present year period (1961 to 2000) were also evaluated using surface observations and gridded data. Under all future scenarios considered, it was found that temperature is expected to increase across Thailand by 0.4 to 3.3°C, being most pronounced under A2 and A1B during the summer of the final future decade (2061 to 2070). The South sub-region is least impacted in terms of average temperature. Warm nights and hot days tend to occur more frequently in the future decades while cold nights and cool days occur less. Their trend magnitudes are largest under A2 for cold nights and warm nights, and under A1B for cool days and hot days. For precipitation, a shift to drier conditions was found over the Central-East and South sub-regions in every season under all scenarios and some associated large-scale features were discussed. No substantial changes in average precipitation are seen in the upper sub-regions (the Central-East, North, Northeast sub-regions combined), but less rain is expected for the South in most seasons. Each sub-region tends to experience more consecutive dry days. Trends in the other precipitation indices are increasing in the upper sub-regions. These suggest heavy precipitation and dry spells to be intensified or to occur more frequently in the upper sub-regions.

Projected future changes in mean precipitation over Thailand based on multi‐model regional climate simulations of CORDEX Southeast Asia

“…However, the drying tendency in both wet and dry seasons in the southern parts of Thailand appears consistent with Manomaiphiboon et al . () that used a single GCM (i.e., ECHAM5) downscaled with a single RCM (i.e., RegCM3) for the middle of 21st century. Similarly, the drying condition for the central‐eastern region (R3–R4) during wet season is also indicated in Manomaiphiboon et al .…”

“…Similarly, the drying condition for the central‐eastern region (R3–R4) during wet season is also indicated in Manomaiphiboon et al . (). However, future changes in rainfall noted in other regions (see Figure ) are not shown in Manomaiphiboon et al .…”

Performance evaluation of RegCM4 in simulating extreme rainfall and temperature indices over the CORDEX‐Southeast Asia region

“…Note that the bias of the extreme temperature indices is likely to be systematic and associated with the cold bias in RegCM over the SEA region, which was reported in several previous studies (e.g. Phan et al , ; Octaviani and Manomaiphiboon, ; Manomaiphiboon et al , ; Ngo‐Duc et al , ). There are some exceptions at some stations in the Maritime Continent region, especially in the west of Indonesia and Malaysia, where a positive bias for TNn and TNx was found for all 18 experiments.…”

“…Similar findings have been reported in other studies in the region, e.g. Phan et al (), Octaviani and Manomaiphiboon (), Manomaiphiboon et al () and Ngo‐Duc et al (). The reason was attributed to the more intense convection in the MIT‐Emanuel scheme, imposing fewer low‐level clouds, more short‐wave radiation absorbed at the surface and hence warmer near‐surface temperatures.…”

Development of a Global Fire Weather Database

“…Missing data were interpolated temporally or spatially, and subject to established homogeneity tests for temperature and precipitation (Alexandersson, 1986;Manomaiphiboon et al, 2013). Wind siting was rated at least "fair" for all stations, indicating the absence of large barriers to unobstructed wind measurements.…”