backscattered from the object). The third technology is to facilitate reception of
information / data on Earth from orbiting satellites. This is achieved by so-named
Earth Stations. All these technologies have to be supplemented with such advanced
scientific exercises as Data Processing and Physical (or Statistical) Modelling of
interaction between Object and – Electromagnetic Radiation. The more we perfect this
field of science, the better can we derive characteristics of the object of our interest.
Sonali: What are the advantages and limitations of Remote Sensing? Please provide
some examples of contributions of Remote Sensing technology in Earth Sciences.
Dr. Sarkar: Remote Sensing being a tool for gathering information about objects at a
distance, it is unobtrusive. It does not change characteristics of the object or
phenomenon being observed. It is useful in sensing many inaccessible areas, such as
snow/ice-covered Polar Regions or forest fires. It provides a synoptic view with a
regular periodicity. For example, the orbiting satellite provides sea surface
temperature of global oceans every day. Present-day Remote Sensing technology can
collect information in wavelength bands beyond the sensing capabilities of human
eye. For example, Radiometers and Radars operating in Microwaves can provide
information of soil wetness under cloud cover or deployment of tanks during night.
Remote Sensing has severe limitations of operations under moderate to heavy rains.
Also, with time the calibration settings of on-board sensors drift affecting its
performance, and there is no scope of its rectification in space.
Remote Sensing has wide ranging applications in Earth Sciences. It is used for crop
forecasting, urban planning, water resources management, forest mapping, monitoring
oceanic winds, waves and currents, sea surface temperature, concentration of
biological species in oceans, suspended sediments in coastal and offshore waters,
atmospheric water vapour, cloud water amount, precipitation rates, snow and ice
cover, and many more. Active research is being pursued all over the world, including
in India, towards newer areas of applications and improving the accuracy of the
existing ones.
Sonali:
What are the operational applications