16
OCT
2017

Terengganu monsoons: Its influence on current circulation and our life

Have you heard the great story about the great Chinese mariner, Laksamana Cheng Ho and the Ming Voyage? Did you curious about his sailing from China across the sea and ocean to Arabia and Africa?  The key secret is the power of monsoons!   Interestingly, that’s my research topic for my master thesis.  I studied the dynamic of current circulation in southern South China Sea specifically in Terengganu waters during monsoon seasons using numerical modelling.

The hydrodynamic model at the southern South China Sea basin was developed using DHI Mike 3 Flow Model Flexible Mesh. This software used as the tool to simulate the coastal hydrodynamics, wind sensitivity and tidal residual currents analysis. The study conducted a wind sensitivity analysis to determine the influence of wind on currents circulation. The response of the Terengganu currents and water movement to wind was investigated under constant and uniform wind stress. Adopting the without wind influence, moderate and extreme situation on both wind direction and wind speed in model was tested.  The sensitivity analysis simulated with 7 experiments with different forcing conditions. Meanwhile, the residual current analysis set up in 8 simulation cases. The same method was applied for Bidong Island area with the aim to understand the island current circulation. The model outputs were verified, examined and discussed in detail for the research findings.  Does it look complicated for you?  Of course, it was a master research project!  To put it in simple way, I was testing the current flows response under certain wind forcing condition.  Looking for the answer, does the Laksamana Cheng Ho set his sail according to the monsoon wind during Northeast Monsoon?

The result showed that the  wind factor  in  the  current circulation is a dominant factor followed by tides  for  the coastal  flow  and  central  in open area. Higher wind speed and northeasterly wind give strong impact to current circulation in Terengganu waters. As well in residual current circulation study. Comparing by season, Northeast (NE) monsoon gives large wind impact to Terengganu circulation waters. While Southwest (SW) monsoon gives less impact but still define the present of SW monsoon influence.  This finding gave an idea that the Ming voyage might take opportunity from the strong northeasterly wind to set their sailing downwind from China to southern South China Sea region to Champa (central Vietnam), Siam (today’s Thailand) and then to Java island, and then proceeded along the Straits of Malacca towards the Indian Ocean region.  This could save their power or energy but still they probably face the huge waves like mountains during the storm as it mentioned in the literature.  This study only answered small part of the Ming voyage and I have high curiosity to reveal more about this great journey therefore I extend the research work and further my study to PhD.  =)

Rabitah Daud

rabitahnurul@gmail.com

 

Bathymetry of Southern South China Sea and the Ming Voyage route

 

 

Current circulation in ECPM and Bidong Island during Southwest monsoon and Northeast monsoon

 

Current speed and direction during Southwest monsoon and Northeast monsoon

 

Temperature and salinity distribution in South China Sea during Southwest monsoon and Northeast monsoon