Demarcation of land-water boundary of Indian coast using MSMR data of IRS-P4 satellite at 10.65 GHz

摘要

The microwaves are a part of electromagnetic spectrum. The frequency range from 3GHz to 30GHz is designated as microwaves. The microwaves are used extensively in remote sensing because of its unique capabilities like day and night capability and all weather capability. Because of these they have stand alone applications. Microwave sensors are either active or passive type. These sensors provide the required database with the help of emission and scattering properties of terrain under study. To mark the land water boundary of Indian Coast passive sensor radiometer is used. The brightness temperature varies with the presence of water in the soil. It is different for soil and water. The brightness temperature is different for different locations based on the emissivity. The emissivity of dry soil is more and so it has a high value of brightness temperature (TB) whereas the emissivity is low for ocean surface and so it has lower values of TB. Coastal areas contain mixture of soil and water and so its microwave temperature lies between the TB values of ocean and land surface. The multi-frequency scanning microwave radiometer (MSMR) was placed onboard IRS-P4 satellite which was launched in May 1999. This radiometer operates at 6.6, 10.65, 18 and 21GHz frequencies with dual polarization. MSMR data contains information about different geophysical parameters. From this large set of database, microwave temperature (TB) values taken at 10.65GHz with dual polarization are used to identify the land water boundary for the Indian Coast. MSMR data is available for Grid-1, Grid-2 and Grid-3 which correspond to spatial resolution of 150, 75 and 50 Km respectively. In the present study, TB data for Grid-1 is used at frequency 10.65 GHz. From the MSMR data, brightness temperature values for Indian Coast are retrieved using the data retrieval program developed in ‘C’. The program output gives the day, latitude and longitude at which data is retrieved for both vertical an--d horizontal polarizations. Data has been retrieved for 28 months from June03, 1999 to September 30, 2001. TB data values obtained are used for demarcation of land-water boundary of Indian Coast. Data values are obtained along the coastline, adjacent land surface and ocean touching the coastline. The analysis of the data at 10.65GHz frequency for land and water helps in explaining the utilization of microwave temperature for marking the land-water boundary. In the present paper analysis has been done to identify the land-water boundaries of Indian peninsula for the month of June 1999, 2000, 2001 and December 1999 and 2000. It can be used to study the coast of other locations as well.