Role of Sea Surface Temperature in Simulation of Arabian Sea Cyclone - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 333

the TCs. It is demonstrated in several previous observational studies that the
SST has increased globally in the context of warming scenario (Webster et al.,
2005; Mohanty et al., 2012). Mohanty et al. (2012) examined the 120 years'
observational data for the North Indian Ocean (NIO) and found an increasing
trend in the occurrence of severe cyclones with the increase of SST over Indian
seas during the current warming era. A number of scientists worldwide have
carried out experiments to study the changes in TC activity in the global warming
scenario (Gualdi et al., 2008; Zhao and Held, 2010; Lavender et al., 2011).
Most of these studies are conducted using general circulation models (GCMs)
and the results show an increasing trend in the rate of TC intensification.
Modelling studies also indicate an increasing trend of SST during 20 th century
and rate of intensification is higher during the second half of the century.
Previous studies (Ali et al., 2007; Mandal et al., 2007) suggest that the
representation of SST in numerical models is crucial in simulating the TCs. Ali
et al. (2007) have carried out experiments using mesoscale model to simulate
TCs over NIO and suggested that the representation of SST converted from
sea surface height anomalies are better than National Center for Environment
Prediction (NCEP) reanalysis skin temperature in predicting the track of the
cyclone. Mandal et al. (2007) simulate TC over the Bay of Bengal (BoB) and
indicate that the representation of SST and its gradient are closer to observation
enhancing the skill of the model in predicting the TCs intensity and track.
Several scientists indicate that the future SST may exceed 28.25 °C (Henderson-
Sellers et al., 1998; Micheal et al., 2006). A large number of modelling studies
are carried out to examine the linkage between the rate of increase in SST
warming and tropical cyclone intensity using GCMs (Gualdi et al., 2008; Zhao
and Held, 2010; Lavender et al., 2011). However no study has been reported
so far to investigate role of SST gradient as well as changes in intensity of TCs
due to changes in SST over the Indian basin using a mesoscale model. In this
study, we have conducted several sensitivity experiments to understand the
representation of SST in mesoscale model MM5 (version 5) to simulate a TC
over the Arabian Sea that had unusual west-northwestward movement and
occurred during 6-11 May 2002. Brief description of the model that is used in
the present study is provided in section 2. Experimental design, methodology
and data used are presented in section 3. The results and associated discussions
are provided in section 4 and the conclusions are provided in section 5.
2. Model Descriptions
The Pennsylvania State University (PSU)/National Center for Atmospheric
Research (NCAR) fifth generation mesoscale model MM5 (version 5) is used
in the present study. The MM5 model is a non-hydrostatic model and its vertical
coordinates are terrain following sigma coordinates. Model top is considered
at 10 hPa pressure levels and from surface to model top total 23 vertical sigma