Geoscience Reference
In-Depth Information
1 Introduction
Borneo Island, the southern border of South China Sea (SCS) comprises of the East
Malaysia (Sabah and Sarawak) and Brunei in the north western part and the Indo-
nesia (Kalimantan) in the southern part. The island is surrounded by the South China
Sea in the northwest, the Sulu Sea in the northeast, the Celebes Sea and Makassar
Strait in the east, and the Java Sea in the south. The oil exploration and shipping
industries in the northwest coast of Borneo Island have been growing rapidly and
have played an important role in the development of the Malaysian economy.
However, oil pollution of this region waters largely arises from vessel operation,
tanker accidents, oil exploration and production activities, is one of the main
problems affecting the marine coastal environments. Thus, to mitigate and control
the oil pollution, an accurate knowledge of the ocean circulation is very essential.
Most of the previous investigations by Malaysian researchers focus on the
Peninsular Malaysia water region (Saadon and Marghany
1996
; Taira et al.
1996
;
Akhir
2011
) whereas, northwest coast of Borneo Island is less studied. The
information of surface currents of this region so far relies on early observational
studies of Dale (
1956
), Wyrtki (
1961
), and Xu et al. (
1982
). They have pointed out
that surface circulation in the region is greatly controlled by the monsoons.
Generally, it is very hard to predict the exact monsoon timing, duration and
severity of each season. According Malaysian Meteorological Department
(MMD), the north-east monsoon (NE) usually dominates the Malaysian region in
early November and ends in March. Meanwhile, the south-west monsoon (SW)
usually established in the later half of May or early June and ends in September.
Earlier studies by Wyrtki (
1961
) and Xu et al. (
1982
) have produced surface
current chart based on the observation data. However, the sampling stations were
too sparse to demonstrate in detail the surface circulation in the northwest coast of
Borneo Island. Therefore, the main objective of this paper is to illustrate the
surface circulation in the northwest coast of Borneo Island in detail using space
based technology; satellite altimetry.
2 Data and Method
2.1 Altimeter Data
Nineteen years (1993-2011) of sea level anomaly (SLA) data from six satellite
altimetry mission are used for this study. The altimeter data from six satellite
missions: TOPEX, Jason-1&2, ERS-1&2 and ENVISAT are extracted and pro-
cessed from January 1993 until June 2011 using Radar Altimeter Database System
(RADS). The sea surface height observation from altimetry data have been cor-
rected for orbital altitude, altimeter range corrected for instrument, sea state bias,
ionospheric delay, dry and wet tropospheric corrections, solid earth and ocean
