MICROWAVE RESPONSE TO SOIL MOISTURE AND SURFACE ROUGHNESS

Abstract

Remote sensing is a very wide subject and is growing faster day-by-day due to its applicability in. various fields viz, hydrology, agriculture, meteorology, etc. Remote sensing of the earth has become a reality with the advent of the space age. The microwaves are used due to their capability to penetrate rain, cloud and crop/vegetation upto a certain extent. The microwave remote sensing has been in use since 1960, whereas, the aerial photography has been in use for over hundred years and the coloured one for over last forty years. Over the last two decades, microwave remote sensing has evolved as an important tool for monitoring the atmosphere and surfaces of planetary objects with special emphasis on observations of our mother planet earth. The term microwave remote sensing is concerned with the physics of radiowave propagation and its interaction with material media, including surface and volume scattering and emission, the techniques used for designing microwave sensors and processing the data they acquire and the translation of measured data into information about the temporal or spatial variation of atmosphere or surface and medium parameters or properties. During the past decade, progress has been made in the development of theoretical models. Usually the sensors have been divided into two groups according to their modes of operation; active sensor and passive sensor. Active sensors are those which provide their own source of illumination and therefore, contain a transmitter and a receiver, while passive sensors are simply receivers which measure the radiation emitted from the scene under observation.