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Abstract:
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Satellite remote sensing is being effectively used in monitoring the ocean
surface and its overlying atmosphere. Technical growth in the field of satellite sensors
has made satellite measurement an inevitable part of oceanographic and atmospheric
research. Among the ocean observing sensors, ocean colour sensors make use of
visible band of electromagnetic spectrum (shorter wavelength). The use of shorter
wavelength ensures fine spatial resolution of these parameters to depict oceanographic
and atmospheric characteristics of any region having significant spaio-temporal
variability.
Off the southwest coast of India is such an area showing very significant
spatio-temporal oceanographic and atmospheric variability due to the seasonally
reversing surface winds and currents. Consequently, the region is enriched with
features like upwelling, sinking, eddies, fronts, etc. Among them, upwelling brings
nutrient-rich waters from subsurface layers to surface layers. During this process
primary production enhances, which is measured in ocean colour sensors as high
values of Chl a. Vertical attenuation depth of incident solar radiation (Kd) and Aerosol
Optical Depth (AOD) are another two parameters provided by ocean colour sensors.
Kd is also susceptible to undergo significant seasonal variability due to the changes in
the content of Chl a in the water column. Moreover, Kd is affected by sediment
transport in the upper layers as the region experiences land drainage resulting from
copious rainfall. The wide range of variability of wind speed and direction may also
influence the aerosol source / transport and consequently AOD.
The present doctoral thesis concentrates on the utility of Chl a, Kd and AODprovided by satellite ocean colour sensors to understand oceanographic and
atmospheric variability off the southwest coast of India. The thesis is divided into six
Chapters with further subdivisions |