Geoscience Reference
In-Depth Information
when approaching the shallow region of coastlines, their height increases to
as high as 30-50 m and strikes the shore with a devastating force.
9
-
12
Apart from land related changes, issues like changes in the ocean related
to sea level rise, transfer of materials from land to sea and vice versa,
biodiversity and biological productivity are also important. Earthquakes
can induce sudden changes in the ocean-atmosphere interaction, for which
the consequences in terms of anomalous behavior of numerous oceanic and
atmospheric parameters are believed to show precursory signals.
13
,
14
How-
ever, only very few studies have been carried out pertinent to tsunami and
ocean Chlorophyll associated with phytoplankton, possibly due to less num-
ber of such incidents. Taking advantage of satellite data, we have made an
attempt to address some of these concerns.
2. Materials and Methods
2.1.
Study area
The sea surface area extending between 5
◦
to 25
◦
Nand75
◦
to 105
◦
E,
adjoining Southeast Asian countries was investigated (Fig. 1). To cover
with the consequences of the tsunami, time-series data for Chl-
a
and SST
were also examined from an area close to the epicenter of the earthquake.
While daily information on Chl-
a
was extracted from 4.5
◦
to 7.5
◦
Nand
93
◦
to 96
◦
E (box-X with checks on December 26-31, 2004, Fig. 1(A)), the
8-day average (Chl-
a
and SST) covers the area from 3
◦
to 9
◦
Nand90
◦
to
96
◦
E (box-Y on December 26-31, 2004, Fig. 1(A)).
2.2.
Satellite data
Chlorophyll-
a
(level-3) data observed from Moderate Resolution Imag-
ing Spectroradiometer (MODIS) onboard the Aqua of Earth Observ-
ing System (EOS) was obtained from the Ocean Color Web (http://
oceancolor.gsfc.nasa.gov) at daily and 8-day intervals (spatial resolution
9 km), between 2002 and 2005 (October-January). Discontinuity of infor-
mation was encountered in both cases due to missing values for several
days (i.e. 22 in daily and eight days in weekly datasets). The data was pro-
cessed through logarithm (log 10) transformation using Matlab and GrADS
Version 1.8 (Grid Analysis and Display System) software.
Microwave optimally interpolated SST data (daily/resolution, 25 km)
was acquired from Remote Sensing Systems (http://remss.come.sst).
