Tropical Cyclone Genesis Potential Index for Bay of Bengal During Peak Post-Monsoon (October-November) Season Including Atmosphere-Ocean Parameters

ABSTRACT

Several studies on tropical cyclone genesis potential index (GPI) mainly using atmospheric parameters (relative/absolute vorticity, relative humidity, vertical wind shear, potential instability, vertical velocity etc.) have been reported earlier. Though the ocean plays a vital role in the genesis and intensification of cyclones, no ocean parameter has been included in most of the studies. In this study, we have made an attempt to develop a new GPI for Bay of Bengal during peak post-monsoon (October-November) season including upper ocean heat content (UOHC) using the data for the period 1995–2015. It is found that the new GPI is better correlated with the total number of depressions, cyclones and severe cyclones (TNDC) compared with the existing GPI which was developed for the north Indian Ocean and presently used by India Meteorological Department (IMD), New Delhi. The correlation has significantly enhanced (r=0.86:significant at >99% level) by using the first differences [year(0) –year(−1)] of the time series data. Since, the new GPI which considers atmosphere and ocean (UOHC) parameters, it appears to be more suitable for Bay of Bengal during the peak post-monsoon season.

KEYWORDS:

• Bay of Bengal
• cyclones
• Genesis potential index
• upper Ocean heat content peak post-monsoon season

Acknowledgments

The authors would like to thank Dr.S.Prasanna Kumar, Acting Director, CSIR-NIO, Goa, and Dr.V.S.N.Murty, Scientist-in-Charge, CSIR-NIO Regional Centre, Visakhapatnam for their support and encouragement. The authors are grateful to all the project teams of NCEP/NCAR for making the data sets available. The authors thank CSIR-New Delhi for sanctioning Emeritus Scientist scheme. Thanks to IMD, New Delhi for making the data on cyclones available on the website. The authors are very much thankful to the reviewers for their valuable suggestions/comments which helped to improve the original version of the manuscript. NIO contribution No 6119.

Additional information

Funding

Council of Scientific and Industrial Research (21(968)/13/EMR-II).