Radio remote sensing of the atmosphere and precipitation microphysics

Experimental study of atmospheric remote sensing, particularly on the rain and related atmospheric parameters are the key area of this research group. At IIT Indore, continuous measurements are going on for different atmospheric parameters, such as electric field, lightning, water vapor, rain drop size distribution, Ionosphere etc. In addition, we are involved in field campaigns in the Arctic and other locations in India with collaboration with Indian Institute of Tropical Meteorology (IITM), Indian Space Research Organization and National Centre for Polar and Ocean Research (NCPOR).  

India is probably the place with the highest degree of spatial inhomogeneity when it comes to rainfall. Each part of the country comes with a different set of rain features, uncertainties and behavioural variations. The tropical rain has very distinct features. The occurrence of convective systems as well as the monsoon have different impacts on precipitation structure. Understanding and successful prediction of rainfall asks for detailed microphysical analysis in several rain aspects. The country being a zone of tropical convergence provides a wonderful opportunity to study severe convective systems. 

Polar (Arctic) precipitation on the other hand is very critical for understanding climate change. Polar precipitation is mostly of frozen type and has completely different microphysical characteristics.

Our research interest includes study of various microphysical aspects of both tropical and polar rain with a principal focus on quality improvement of satellite and ground radar retrieval of rainfall. Experimental observation of tropical rain is a key criterion to understand the underlying physics. Radar and satellite observations are primarily used to understand the rain and cloud microphysics.

Fig. 2 shows the rain microphysical behaviour under different rain condition. Measurements of varied rain microphysics helps in better representation of the process in NWP models.

Fig 2: Rain microphysics in (a) Stratiform rain and (b) Convective rain observed through Micro Rain Radar

On the other hand, understanding the atmospheric interaction with microwave and millimeter wave is crucial for both remote sensing and communication applications. Since several Indian and international satellites (GSAT-4, GSAT-14, Ka –band altimeter in SARAL-Altika, Megha Tropique, GPM etc.) are utilizing Ka band, the study on this topic is very pertinent to scientific priorities. This not only helps in improving the radar retrieval of the atmospheric parameters but also in channel modelling Ka and higher frequencies for SATCOM applications. We are also working on developing IoT based cost-effective sensors for  atmospheric instrument. Fig. 3 shows the in-house developed Ku/Ka band rain attenuation measurement system based on SDR and commercial LNA.