Marine Data of Indian
Seas for Improving Cyclonic Storm and Flood Forecasting
Dr. J.V.M. Naidu
Cyclone
Warning Centre, Visakhapatnam, India
(Lecture at The Second Regional technical conference on Tropical
Cyclones, Storm surges and Floods on 1 to 3rd July 2004 at Brisbane, Australia)
Ocean data is of utmost use for storm and monsoon
forecasting. The oceans, which play the major role in the formation Cyclonic
Storms and monsoonal flow over the land are less understood of their physical
and chemical characteristics. Although some data are available from satellites,
many times these data are not available on real time. The data resolution is
also poor even if it is available.
To bring out the necessity of these data on operational
forecasting a few specific cases are presented. The Cyclonic Storm formed on
5-9 May 2004 over Arabian Sea and the 14-19 May 2004 Severe Cyclonic Storm over
Bay of Bengal are studied. The Arabian Sea system was initially moving
northwestwards was seen as a low pressure area when it emerged from land areas
into Arabian Sea. Soon it intensified into a Cyclonic Storm and moved north /
north-northeast wards and weakened before crossing the Gujarat coast of the
country. The Quickscat data, which was available, could give the advance
information about the likely weakening and the change in the track of the
storm. But the limited Quickscat data could not be adequately useful for
confirming the hourly disintegration of the storm. The Sea Surface Temperature
(SST) data were also not available on daily basis at proper resolution to
identify areas of warm and cold areas so as to predict the systems
intensification. Consequently many of the models predicted the storm to move in
a northwesterly direction. Similar was the case for the Bay Severe Cyclonic
storm
The SST data also play an important role in the forecast
of monsoon performance in India. Besides ENSO, the Indian Ocean dipole appears
to play an important role in modifying the negative effects of ENSO on Indian
monsoon. It was shown that a difference of the order of less than one degree
centigrade of the SST between Arabian Sea off African coast and the Indian
Ocean off Indonesian coast (Dipole Mode Index) appear to make an enormous
difference in the southwest monsoon rainfall over India. For such a dynamical
predictions the SST and Salinity data availability on real time basis would be
of great importance for timely forecasts. This will help for advance prediction
of monsoon performance and subsequent draught or floods arising out of the
monsoon rainfall.
Some of these aspects are presented using the recent
synoptic data over Indian continent. It is suggested that all the remote
sensing data from satellites, data buoys and ship observations to be
strengthened with international cooperation and make available on real time
basis, the high resolution marine data available to the forecasters for
improving the advance warning and contain loss of life and property in all the
member countries.
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