GENERAL CIRCULATION IN THE MALACCA STRAIT AND ANDAMAN SEA: A NUMERICAL MODEL STUDY

Rizal Rizal

doi:10.3844/ajessp.2012.479.488

Abstract

In the Andaman Sea and Malacca Strait, as in other parts of the Indian Ocean, the seasonal change of the wind plays a most important role: the south-west (hereafter SW) is monsoon active from June through September and the north-east (hereafter NE) monsoon is active from December through February. During the NE monsoon the winds are directed from the north and northeast to the south-west, and during the SW monsoon from the south-west to the north-east. Strong winds between June and September lead to maximum rainfall over most parts of the Indian subcontinent. These areas are also greatly influenced by the tides. The circulation in the Andaman Sea and the Malacca Strait is simulated with a three-dimensional baroclinic primitive equation model. In order to run the model, the HAMSOM model is used. The model is forced by tides at the open boundaries as well as by wind and heat flux. We use also the NCEP/NCAR data. The M2-tide amplitudes are bigger in the shallow areas in the northwest part coast of Andaman Sea and in the Malacca Strait. The phases of M2 tide shows that the M2 tidal wave come from Indian Ocean and bifurcates to the Andaman Sea and Malacca Strait. The current ellipses of M2-tide are also stronger in the shallow areas both in the Andaman Sea and Malacca Strait. There are two types of tidal distribution in the Andaman Sea and Malacca Strait. In the Indian Ocean part and in the middle of the Malacca Strait, the type is mixed tide prevailing semi diurnal, while in the Andaman Sea and the southern part of the Malacca Strait the type is semi diurnal tide. Generally, the general circulation caused by tides, heat flux and wind both for NE and SW monsoon shows the same pattern. These general circulation patterns, vertical structure of temperature and salinity in the Malacca Strait are compared with the observations carried out by other researchers. Based on those comparisons, the results of the model are reasonable. It means, the HAMSOM model can be used for the simulation of the Andaman Sea and Malacca Strait.

Highlights

The Andaman Sea is located along the northeastern side of the Indian Ocean between the Malay Peninsula to the east and the Andaman-Nicobar islands chain to the west
In the Andaman Sea and Malacca Strait, as in other parts of the Indian Ocean, the seasonal change of the wind plays a most important role: the south-west is monsoon active from June through September and the north-east monsoon is active from December through February
There is no real amphidromic point in the Malacca Strait and Andaman Sea, because Malacca Strait and Andaman Sea are located in low latitude, see the explanation in Rizal (2002)

Summary

INTRODUCTION

The Andaman Sea is located along the northeastern side of the Indian Ocean between the Malay Peninsula to the east and the Andaman-Nicobar islands chain to the west. In the Andaman Sea and Malacca Strait, as in other parts of the Indian Ocean, the seasonal change of the wind plays a most important role: the south-west (hereafter SW) is monsoon active from June through September and the north-east (hereafter NE) monsoon is active from December through February. Strong winds between June and September lead to maximum rainfall over most parts of the Indian subcontinent This background, together with the complex topography, makes the Andaman Sea and the Malacca Strait a great challenge for hydrodynamicnumerical modelling. In order to validate the model results, the vertical structure of salinity and temperature in the Malacca Strait obtained by HAMSOM are compared with the observation carried out by Keller and Richards (1967)

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION