Geoscience Reference
In-Depth Information
2. Data and Analysis
The SCS is a marginal sea located in the west Pacific Ocean, lying in
the tropical monsoon zone between the equator and the tropic of Cancer
(Fig. 1). Our study focuses mainly on the western SCS with wide continental
shelf in the south and north, and comparatively narrow continental shelf in
the mid-west of the study area near Phan Ri Bay (PRB in Fig. 1), where
the depth reaches 4000 m at its narrowest width of 2 km.
The Chl-
a
data acquired from SeaWiFS Version 4 has been used
to derive the Chl-
a
estimates. Monthly Standard Mapped Image (SMI)
Products (Level 3) (spatial resolution, 9
9km
2
) were procured from the
Distributed Active Archive Center (DAAC) of Goddard Space Flight Center
(GSFC), NASA (http://oceancolor.gsfc.nasa.gov/cgi/level3.pl) The sum-
mer Chl-
a
image averaged for June-August from 1998 to 2003 were pro-
duced with the help of Matlab Version 6.5 and Grid Analysis and Display
System (GrADS) Version 1.8 software from monthly data sets.
The SST data derived from Advanced Very-High Resolution Radiome-
ter (AVHRR) of Ocean Pathfinder channel-5 (spatial resolution 4 km/
month-daytime) was provided by Physical Oceanography Distributed
Active Archive Center (PO.DAAC), Jet Propulsion Laboratory (JPL),
NASA (http://podaac.jpl.nasa.gov/sst). The seasonal average SST images
were generated by the means similar to SeaWiFS Chl-
a
data processing
using Matlab and GrADS to show the spatial variations of SST during
summer.
The wind stress data entitled, Tropical Indian Winds from 1970 to 2004
are obtained from the Center for Ocean-atmospheric studies of Florida State
University (http://www.coaps.fsu.edu). The data is pseudo-stressed based
on surface marine observations (TD-1129) for the years after 1980 produced
by the National Climatic Data Center (NCDC) and for the years 1970-1979
they are based on the COADS CMR5 individual ship observations with a
resolution of 1
◦
grid, expressed in (m/s).
2
×
3. Results
3.1.
Spatial distribution of Chl-
a
A relatively high concentration of Chl-
a
(
>
0.13 mg/m
3
)isobservedoff-
shore of southeast Vietnam (oval area marked in Fig. 2(A)) compared with
other locations, while the Chl-a in areas east of the SCS, north of Borneo
and southwest of Luzon Island, display lower concentrations (
<
0.1 mg/m
3
).
Figure 2(A) also shows an extreme high band of Chl-
a
parallel to the
