On the prediction of storm surges during super cyclone Phailin using a deterministic ensemble Kalman filter

Abstract

Deterministic ensemble Kalman filter has been used to assimilate data from the tracks of three existing altimeters in a state-of-the-art hydrodynamic model configured for the north Indian Ocean. The assimilation period has been chosen to cover the entire time history of the super cyclone Phailin occurring in the Bay of Bengal basin of the north Indian Ocean in mid-October 2013. The filter was proposed in a previous study in which the authors showed its advantage over the existing ensemble-based filter techniques. Different combinations of localization radii and inflation factors have been tried to find the optimum combination. Assimilation with this combination has been found to exhibit significant positive impact on basin-scale simulations of sea level. This conclusion has been further corroborated by comparing the surges simulated by the model with tide-gauge data acquired during the occurrence of Phailin. Assimilation has been also found to enhance the predictive capability of the model.

Acknowledgements

Dr Crystal Fulcher of the University of North Carolina is thankfully acknowledged for providing the ADCIRC model. The authors are extremely grateful to the director, Space Applications Centre, for motivation and to the deputy director, Earth Ocean Atmosphere, Planetary Sciences, and Applications Area, for encouragement. INCOIS is gratefully acknowledged for providing the Paradip tide gauge data, AVISO for the altimeter data and NCEP for the data used for forcing the model. The authors also thank two anonymous reviewers for their suggestions towards improving the quality of the manuscript.