High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding

Show simple item record

dc.contributor.author Sreejith, K.M.
dc.contributor.author Rajesh, S.
dc.contributor.author Majumdar, T.J.
dc.contributor.author Rao, G.S.
dc.contributor.author Radhakrishna, M.
dc.contributor.author Krishna, K.S.
dc.contributor.author Rajawat, A.S.
dc.date.accessioned 2013-03-05T07:27:41Z
dc.date.available 2013-03-05T07:27:41Z
dc.date.issued 2013
dc.identifier.citation Journal of Asian Earth Sciences, vol.62; 2013; 616-626
dc.identifier.uri http://drs.nio.org/drs/handle/2264/4247
dc.description.abstract Geoid data are more sensitive to density distributions deep within the Earth, thus the data are useful for studying the internal processes of the Earth leading to formation of geological structures. A much improved version of high resolution (1'x1') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites is presented. The geoid map of the Indian Ocean is dominated by a significant low of -106 m south of Sri Lanka, named as the Indian Ocean Geoid Low (IOGL), whose origin is not clearly known yet. The residual geoid data are retrieved from the geoid data by removing the long-wavelength core–mantle density effects using recent spherical harmonic coefficients of Earth Gravity Model 2008 (EGM2008) up to degree and order 50 from the observed geoid data. The coefficients are smoothly rolled off between degrees 30-70 in order to avoid artifacts related to the sharp truncation at degree 50. With this process we observed significant improvement in the residual geoid data when compared to the previous low-spatial resolution maps. The previous version was superposed by systematic broad regional highs and lows (like checker board) with amplitude up to plus or minus 12 m, though the trends of geoid in general match in both versions. These methodical artifacts in the previous version may have arisen due to the use of old Rapp's geo-potential model coefficients, as well as sharp truncation of reference model at degree and order 50. Geoid anomalies are converted to free-air gravity anomalies and validated with cross-over corrected ship-borne gravity data of the Arabian Sea and Bay of Bengal. The present satellite derived gravity data matches well with the ship-borne data with Root Mean Square Error (RMSE) of 5.1-7.8 mGal, and this is found to be within the error limits when compared with other globally available satellite data. Spectral analysis of ship-borne and satellite data suggested that the satellite gravity data have a resolution down to 16-18 km. Further, the geoid, residual geoid and gravity anomalies are integrated with seismic data along two profiles in the Bay of Bengal and Arabian Sea, and inferences have been made in terms of density distributions at different depths. The new residual geoid anomaly map shows excellent correlation with regional tectonic features such as Sunda subduction zone, volcanic traces (Chagos-Laccadive, Ninetyeast and 85 degrees E ridges) and mid-ocean ridge systems (Central Indian and Carlsberg ridges).
dc.language.iso en
dc.publisher Elsevier
dc.rights An edited version of this paper was published by Elsevier. Copyright [2013] Elsevier
dc.subject geoid anomalies
dc.subject gravity anomalies
dc.subject satellite sensing
dc.subject satellite altimetry
dc.title High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding
dc.type Journal Article


Files in this item

This item appears in the following Collection(s)

Show simple item record

Search DRS


Advanced Search

Browse

My Account