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3. Results and Discussion
3.1. Variability of Chl-
a
Spatial and temporal variability of Chl- a may occur due to large scale dis-
turbances in the ocean circulation patterns, derived from sudden changes of
thermal structure 15 of the water. Very few articles in the literature available
on earthquakes and ocean productivity indicated that concentration of Chl-
a rises particularly before the occurence of earthquake events. 16 It is note-
worthy that present observations also show the tendency of increasing Chl- a
from the second week of December (December 10-17, 2004, Fig. 1(A)) which
continued throughout the third week (December 18-25, 2004, Fig. 1(A)),
while dispersing to its maximum extent in the fourth week (December 26-
31, 2004, Fig. 1(A)). In this context, the increased Chl- a may be associated
with upwelled water and also thermal energy released from the point of
earthquake, which can alter the in situ thermal structure of the water.
Moreover, plankton in the coastal waters of Southeast Asian countries, for
example, along the east coast of India and around Sri Lanka, is signifi-
cantly diluted and diffused by the action of the giant waves. This could be
the reason for dispersed/increased levels of Chl- a in the Bay of Bengal and
the Andaman Sea soon after the disaster (Fig. 1(A)).
3.2. Changes of SST
The variations in SST following the tsunami are evident (Fig. 1(B)). The
high surface temperature (29-30 C) before (December 20, Fig. 1(B)) the
earthquake decreased to 28-29 C on the day of the tsunami (December
26, Fig. 1(B)). Further lowering of SST (27-28 C) was exclusively observed
along the east coast of India in the Bay of Bengal (December 31, Fig. 1(B)).
The area close to the epicenter of the earthquake was however indicating
warm water conditions, namely, SST ranging between 29 Cand30 C, with
only a small change of 0.5-1.0 C prior to and after the event, probably
due to the release of thermal energy. 17 When wind speed is considered
(Fig. 1(C)), mostly northeast winds prevailed accompanying the winter
monsoon (November-February). On December 20, the wind speed reached
5.0 m/s covering most of the study area and reached a peak of 10 m/s on
December 26 on the southeast coast of India and Sri Lanka, where severe
damage was reported from the States of Tamil Nadu and Andhra Pradesh
(India) and all around Sri Lanka. The high Chl- a together with low SST
and high wind speed was evident at the time of observation.
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