A study of air–sea interaction following the tsunami of 26 December 2004 in the eastern Indian Ocean

Abstract

A time series analysis of various atmospheric as well as oceanic parameters derived from different satellites covering eastern Indian Ocean and Bay of Bengal has been carried out for the period December 2004 to February 2005. The purpose is to assess the likely perturbations in the air–sea exchanges associated with the tsunami event of 26 December 2004. Satellite derived sea level anomaly in the northern Bay of Bengal show a rise in the sea level of roughly about 5–6 cm after 26 December 2004. A significant cooling of the order of 0.5°C in a span of 5 days (21–27 December 2004) in the sea surface temperature (SST) is observed near Andaman and Nicobar Island. The formation of such anomalies is certainly associated with the rising of the sub‐surface water towards surface due to the enhanced turbulent exchange. An enhanced turbidity near Sumatra seen in the MODIS colour data in the week following 26 December 2004 is also suggestive of turbulent mixing. After an initial dip in the integrated water vapour (IWV) on 27 December 2004, an apparent growth in the water vapour loading is observed in the Tropical Rainfall Measuring Mission/Microwave Imager (TMI) data from 31 December 2004 to 11 January 2005 near Andaman and Nicobar Island. An analysis of the boundary layer parameters suggests that the increased water vapour loading in the atmosphere following the tsunami is not due to the winds and neither due to the increase in SST. One of the possible reasons could be direct injection of water into the atmosphere. The study could be used as an indicative to understand changes in a global context under sea level rise scenario.

Acknowledgements

The authors are very grateful to Dr K. Kasturirangan, ex‐Chairman, ISRO, who suggested the topic of this study. We are also thankful to Dr. R. R. Navalgund, Director of Space Applications Centre, Ahmedabad for encouragement and Dr B. Manikiam, ISRO HQ for technical support. TMI and MODIS turbidity data were downloaded from www.ssmi.com and http://modis.gsfc.nasa.gov, respectively. The sea level data were taken from jason.oceanobs.com.