Improved bathymetric datasets for the shallow water regions in the Indian Ocean |
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| Authors: | B Sindhu I Suresh A S Unnikrishnan N V Bhatkar S Neetu G S Michael |
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| Institution: | (1) National Institute of Oceanography, Dona Paula, Goa, 403 004, India |
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| Abstract: | Ocean modellers use bathymetric datasets like ETOPO5 and ETOPO2 to represent the ocean bottom topography. The former dataset
is based on digitization of depth contours greater than 200 m, and the latter is based on satellite altimetry. Hence, they
are not always reliable in shallow regions. An improved shelf bathymetry for the Indian Ocean region (20°E to 112°E and 38°S
to 32°N) is derived by digitizing the depth contours and sounding depths less than 200 m from the hydrographic charts published
by the National Hydrographic Office, India. The digitized data are then gridded and used to modify the existing ETOPO5 and
ETOPO2 datasets for depths less than 200 m. In combining the digitized data with the original ETOPO dataset, we apply an appropriate
blending technique near the 200 m contour to ensure smooth merging of the datasets. Using the modified ETOPO5, we demonstrate
that the original ETOPO5 is indeed inaccurate in depths of less than 200 m and has features that are not actually present
on the ocean bottom. Though the present version of ETOPO2 (ETOPO2v2) is a better bathymetry compared to its earlier versions,
there are still differences between the ETOPO2v2 and the modified ETOPO2. We assess the improvements of these bathymetric
grids with the performance of existing models of tidal circulation and tsunami propagation. |
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| Keywords: | Shelf bathymetry Indian Ocean ETOPO Red Sea Persian Gulf Arabian Sea Bay of Bengal Andaman Islands |
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