Geoscience Reference
In-Depth Information
RAINFALL OVER THAILAND DURING ENSO (1997-2000)
WONLEE NOUNMUSIG
∗
and PRUNGCHAN WONGWISES
The Joint Graduate School of Energy and Environment,
King Mongkut's University of Technology Thonburi,
126 Pracha-U-Thit Rd., Bangmod, Tungkru,
Bangkok 10140, Thailand
∗
wonlee n@yahoo.com
In this chapter, the yearly mean rainfall taken from the Thai Meteorological
Department during 1972-2001 in each region of Thailand was analyzed comp-
aring with 30 years' averaged rainfall in order to study the influence of ENSO.
The rainfall in Thailand during ENSO 1997-2000 was selected as the case
study. The results show that the amount of rainfall in most regions of Thailand
during 1997/1998 (El Nino) is less than the long-term mean, while the amount
of rainfall is strongly more than long-term mean for the whole Thailand
in La Nina 1999/2000. The amount of rainfall during 1997-2001 shows the
strong anomalies in early rainy season (May-June). Moreover, the Regional
Atmospheric Model System (RAMS) version 6.0 is used to simulate the rainfall
pattern in May and June 1997 and 1999. The trends of model results agree well
with the observed data analysis.
1. Introduction
Thailand is situated in the southwestern part of Indo-Chinese Peninsula
between latitudes 5
◦
37
Nto20
◦
27
N and longitudes 97
◦
22
E to 105
◦
37
E.
The climate of Thailand is influenced by the southwest monsoon and
northeast monsoon, which can be classified generally into three seasons:
mid-October to mid-February of the next year is the moderate winter
season, mid-February to mid-May is the summer season, and mid-May
to mid-October is the rainy season. Her national economies are mainly
the agricultural products, which largely depend on the weather and
climate conditions. Favored by the southwest monsoon, plenty of rainfall
is precipitated all over the tropical country of Thailand during the rainy
season. This is the normal case. But in some abnormal years, stronger or
weaker southwest monsoon may cause flood or droughty disaster, which
affect the agricultural products.
11
