El Niño Impact on Thailand

1. Introduction

In Thailand, there have been a lot of media coverage about El Niño and its impact. Most of Thai people have heard about the 1997-98 El Niño, but may not have a clear picture of the impact. It appears that when there is a severe or unusual weather, the media and people will blame it on El Niño. Several seminar on El Niño have been arranged. However, there is no conclusion about El Niño impact on Thailand as government agencies have different opinions on this matter. This paper presents a short report of El Niño impact on rainfall and temperature in Thailand.

2. Rainfall

It is widely believed that El Niño will bring drought to Thailand. However, statistical analysis reveals no significant correlation between rainfall amount and previous El Niño events. In some El Niño year rainfall amount was even more than the average. Nevertheless, the 1997-98 El Niño results in less-than-average annual rainfall over many parts of Thailand. Figure 1 shows the 1997 rainfall anomaly in percentage.

Fig. 1. 1997 rainfall anomaly in percentage.

3. Temperature

Analysis of previous El Niño events shows that there is significant correlation between El Niño and monthly mean temperature in winter. During El Niño year the temperature in winter will be higher than normal. The 1997-98 El Niño results in much warmer than normal in Thailand, especially in December in which the temperature anomaly in many areas are more than 3 degree Celsius. Figure 2 shows the December 1997 temperature anomaly in degree Celsius.

Fig. 2. Temperature anomaly in December 1997 in degree Celsius.

4. Summary

Statistical analysis shows that for Thailand El Niño results in higher than normal in temperature during winter, but shows no significant effect on rainfall amount. However, the result is based on a short period of data (thirty years) and did not include the 1997-98 El Niño. Further study is required before conclusion can be made.