The Union Minister for Earth Sciences recently commissioned two indigenously built X-Band Doppler Weather Radars (DWR) to monitor weather changes over the Himalayas. The project also saw the introduction of a new multi-mission meteorological data processing system, developed in cooperation with the Indian Space Research Organisation (ISRO). This efficient technology will process and avail satellite data for use within seven minutes, a significant improvement from the previous 20-minute duration.
Development and Significance of the DWR
The ISRO designed the DWR, while Bharat Electronics Limited (BEL), Bengaluru undertook its manufacturing. These dual polarised radars, designed to cover the central and western Himalayas, will detect variations in atmospheric conditions and identify signs of extreme weather events. Places such as Uttarakhand and Himachal Pradesh, being highly prone to heavy rains, landslides, cloud bursts, and snowfall, particularly stand to benefit from this technology. Accurate and prompt weather forecasts and warnings will enable governments to develop advanced plans and initiate necessary safety measures timely.
Understanding Radar Technology
A radar (Radio Detection and Ranging) is a device that employs electromagnetic waves in the microwaves region to detect various properties of both stationary and moving objects. These include location (range and direction), altitude, intensity, and movement.
Doppler Radar
A Doppler radar is a specialized device that uses the Doppler effect to capture velocity data about distant objects. The Doppler effect refers to the change in frequency observed by an observer when the source and signal are in relative motion. If the source and signal approach each other, the observed frequency increases and vice versa. The Doppler radar achieves this by reflecting a microwave signal off the target and analysis of how the object’s motion has affected the returned signal’s frequency. This provides accurate measurements of the radial component of a target’s velocity relative to the radar.
Doppler Weather Radar
Designed based on the Doppler principle, a Doppler Weather Radar improves precision in long-range weather forecasting and surveillance. It uses a parabolic dish antenna and a foam sandwiched spherical radome. The cutting-edge technology can measure rainfall intensity, wind shear and velocity, pinpoint a storm centre, and detect the direction of a tornado or gust front.
Categories of Doppler Radars
Doppler radars vary based on their wavelength and include L, S, C, X, K types. X band radars work on a wavelength of 2.5-4 cm and a frequency of 8-12 GHz. Their small wavelength allows them to detect even tiny particles, making them more sensitive compared to other types.
Applications of X Band Radars
The primary application of X band radars is in studying cloud development due to their ability to identify tiny water particles. These are also used in detecting light precipitation like snow. However, X band radars become less effective over greater distances and are, therefore, limited to very short-range weather observation.
Their small size also lends them portability, as seen with the Doppler on Wheels (DOW). Major airplanes use X band radar to pick up turbulence and other weather phenomena. The X band also shares frequencies with some police speed radars and space radars.
