In response to the floods and landslides in Wayanad, Kerala, which resulted in over 200 fatalities in July 2024, the Union Ministry of Earth Sciences has approved the installation of an X-band radar in the district. This decision aims to enhance early warning systems for landslides and other weather-related disasters.

HOW DO RADARS WORK?

  • Definition:
    • Radar stands for "radio detection and ranging." It uses radio waves to measure the distance, speed, and characteristics of objects around it.
  • Operation:
    • A transmitter emits radio signals towards an object. The object reflects some of these signals back, which are received and analyzed by the radar system.

TYPES OF RADAR

  • Weather Radar: A specific application called Doppler radar that assesses the movement and intensity of weather phenomena.
    • Doppler Effect: Changes in frequency of the radio waves are analyzed to determine the speed and direction of moving objects like clouds.
  • Pulse-Doppler Radar:
    • This type of radar measures rainfall intensity by emitting signals in pulses and tracking how frequently they are reflected back.

WHAT IS X BAND RADAR?

  • Frequency Range:
    • X-band radars operate in the electromagnetic spectrum between 8-12 GHz, with wavelengths around 2-4 cm (microwave range).
  • Resolution and Range:
    • The shorter wavelengths provide higher resolution images, making them effective in detecting smaller particles like raindrops or soil. However, they have a shorter operational range due to greater attenuation at higher frequencies.
  • Application in Wayanad:
    • The new radar will monitor particle movements, such as soil shifts, which is crucial for issuing timely landslide warnings. It will also perform high temporal sampling, enabling it to detect changes quickly.

CURRENT RADAR INFRASTRUCTURE

  • Historical Background:
    • The India Meteorological Department (IMD) has used radar for weather applications since the 1950s, installing its first X-band radar in 1970.
  • Network Expansion:
    • India’s X-band radar network includes both wind-finding and storm-detecting radars. There is also a network of S-band radars for long-range detection.
  • Future Developments:
    • The Ministry of Earth Sciences announced plans to add 56 Doppler radars in the coming years as part of the ₹2,000-crore ‘Mission Mausam’, aimed at upgrading meteorological infrastructure.
  • Recent Initiatives:
    • The government has begun procuring and installing additional X-band Doppler radars, particularly for northeastern states and specific regions in Himachal Pradesh.

WHAT IS NISAR?

  • Collaborative Satellite Project:
    • The NASA-ISRO Synthetic Aperture Radar (NISAR) satellite is being developed by NASA and the Indian Space Research Organisation (ISRO). It will utilize radar imaging to create high-resolution maps of Earth’s landmasses.
  • Payload Specifications:
    • NISAR will be equipped with an L-band radar from NASA and an S-band radar from ISRO, designed to monitor and record natural changes on Earth.
  • Launch Details:
    • The satellite is expected to launch in 2025 on an ISRO GSLV Mk II rocket, with a total development cost of approximately $1.5 billion, mostly funded by NASA.