Some Important Microwave Payloads And Their Applications

As mentioned earlier, microwave sensors have played a very important role in providing valuable information for meteorological applications. These include both active and passive type of sensors. Wind scatterometer, altimeter, and precipitation radar are the examples of active microwave sensors. Scatterometer with operating frequencies in C-Band ( ~ 5 GHz), or K-Band (~ 13 GHz) is an indispensable tool for monitoring the ocean surface wind speed and wind direction with high resolution ( ~ 25 km ) and global coverage. Ocean surface winds have a number of applications. These winds are important factors in the computation of air-sea energy and mass exchange, and they also provide input to the global ocean and wave forecast models. The use of scatterometer winds in assessing the situations leading to the formation of tropical cyclones have been demonstrated. Precipitation radar (PR) onboard Tropical Satellite Measuring Mission (TRMM) satellite is the first precipitation radar in space. This instrument operating at 13.6 GHz is capable of taking observations of vertical profiles of rainfall over the global tropics.

Among passive microwave meteorological systems, Special Sensor Microwave/Imager (SSM/I) onboard US Defense Meteorological Satellite Program (DMSP) satellite is arguably the most successful sensor. Different versions of this sensor have been providing valuable meteorological observations across the globe for nearly 16 years. The operating frequencies of this radiometer are 19.36, 22.23, 37.0, and 85.5 GHz. All the channels except 22.23 GHz operate in dual polarization (V and H), while 22.23 GHz is a single polarization (V) channel. SSM/I provides the global observations of vertically integrated water vapour (PW), sea surface wind speed ( SW), cloud liquid water (CLW), and rainfall rates (RR), though due to the limitation of microwave observations, most of these observations are available only over the ocean surfaces. SSM/I provides these observations with a wide swath ( ~ 1400 km) and high resolution ( ~ 25 km). TRMM satellite launched in October 1997 carried a payload similar to SSM/I, and it is known as TRMM Microwave Imager (TMI). TMI is similar to SSM/I in characteristics however there are some significant differences. TMI is equipped with one additional channel that operates at around 10 GHz (V & H polarization). This sensor makes TMI capable of sensing global sea surface temperature (SST). A combination of observations from TMI and other visible/IR sensor onboard TRMM is being utilized operationally for measurement of daily SST with a significantly improved accuracy of ~ 0.5 K. This channel is also useful in providing improved estimates of rainfall rates. Moreover, TRMM satellite operates from a smaller altitude ( ~ 350 km) compared to SSM/I ( ~ 800 km), which ensures that the TMI observations are available at finer resolution. 85 GHz channel of TMI is highly useful in detecting the regions of active and deep convection ( both over the land and the ocean surfaces ) that are generally associated with the development of thunderstorm and are accompanied by heavy precipitation.

Advance Microwave Sounding Unit ( AMSU) onboard the latest series of NOAA satellites, is a sounding instrument that provides the temperature and humidity sounding in presence of clouds, using the absorption bands of oxygen ( ~ 50 GHz), and water vapour ( ~ 183 GHz) respectively.

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

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