Detection and analysis of growth of Sea - Ice using MSMR brightness temperature data

Vinod Binyala, Sharad V. Oberoi
Under Graduate Student, Department of Civil Engineering, Banaras Hindu University, Varanasi

Dr. K. S. Rao
Principal Research Scientist, CSRE, IIT Bombay


Abstract
Observations by Multi-channel Scanning Microwave Radiometer (MSMR) for a period of one year are studied using the data collected by IRS-P4 over polar region. It is demonstrated that analysis by passive radiometer is very helpful for monitoring temporal and spatial variation of complex sea-ice cover.

The Brightness Temperature Data (BTD) for different regions, when compared shows an abrupt rise in the values than those expected for the month of October 2000 for a location in the Siberian Sea. Besides, an increase by about 60-70 degrees is found to have taken place over a short interval of 15 days after which it remains constant for about eight months and then decreases gradually. Such a rise is very atypical, as brightness temperature generally does not vary much over long periods of time. Hence, graphical analysis for the surrounding areas and few other areas of the polar region for the same time period has been carried out which shows a similar trend consistently. Consequently, further assistance provided by U.S. National Ice Center in the form of ice charts prepared from DMSP and SSM/I data for East Siberian Sea, one of the areas of our concern, help to confirm and analyze our observations.

Thus, this rise is inferred to be due to the accumulation and growth of ice cover over the previously ice-free oceans which give a peculiar brightness temperature pattern during the process of growth. This shows that there is a definite correlation between the BTD and the sea-ice cover. Also, from the ice charts it is concluded that the process of freezing up is very quick, in contrast to the melting down process which takes at least a few months. So, using the various passive remote sensing techniques available, the extent of ice cover over oceans in the polar region can be monitored and further precautionary measures can accordingly be taken to guide the ships traversing these routes, using communication satellites. The monitoring process can be done on a day-to-day basis, as well as for preparing sea-ice maps for future work. Moreover, further efforts would be made by us to prepare a model for sea-ice thickness determination and a thermodynamic model to predict the global climatic changes.