Why is it in the news?

• Following devastating floods and landslides that killed over 200 people in Kerala’s Wayanad district in July 2024, the Union Ministry of Earth Sciences approved the installation of an X-band radar in the area.
• The torrential downpour that caused the landslide in the Punchirimattom region was exacerbated by a massive debris flow.

Working of Radars

• Radar, short for ‘radio detection and ranging,’ uses radio waves to determine the distance, velocity, and physical characteristics of surrounding objects. A transmitter emits a signal aimed at a target object (e.g., a cloud). Some of this signal reflects back to the device, where a receiver analyzes it.
• Doppler radar, a common weather radar application, uses the Doppler effect to measure the speed and direction of cloud movement by analyzing frequency changes in the radiation that interacts with the cloud.
• Pulse-Doppler radar measures rainfall intensity by emitting pulses and tracking how often they are reflected back, allowing it to monitor weather conditions and predict storms.

About X-Band Radar

• Doppler radar relies on Rayleigh scattering, which occurs when the scatterer is much smaller than the wavelength of the radiation. To detect smaller particles like rain droplets or fog, X-band radar operates within the 8-12 GHz frequency range (wavelengths of about 2-4 cm).
• The smaller wavelengths enable higher-resolution images, but they also mean a shorter operational range due to greater signal attenuation.
• In Wayanad, the new radar will monitor soil movements to issue timely landslide warnings and perform high temporal sampling to detect rapid particle shifts.

Current Radar Network in India

• The India Meteorological Department (IMD) began using radar for weather applications in the early 1950s, installing its first indigenously designed X-band storm detection radar in New Delhi in 1970. In 1996, the IMD replaced ten outdated X-band radars with digital versions.
• India’s X-band radar network includes wind-finding and storm-detecting radars, along with S-band radars (2-4 GHz) for long-range detection. The first S-band cyclone detection radar was installed in Visakhapatnam in 1970, with a locally made variant commissioned in Mumbai in 1980.
• As of September 2024, the Ministry of Earth Sciences announced plans for 56 additional Doppler radars in the coming years. The Union Cabinet approved the ₹2,000-crore ‘Mission Mausam’ initiative to enhance meteorological infrastructure, which includes installing up to 60 radars by 2026.
• The government is also procuring 10 X-band Doppler radars for improved weather forecasting in northeastern states and Himachal Pradesh’s Lahaul and Spiti district, alongside a C-band radar (4-8 GHz) in Mangaluru.