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Doppler Weather Radar (DWR) Systems

2023 JAN 25

Preliminary   > Science and Technology   >   Miscellaneous   >   Miscellaneous

Why in news?

  • Recently government affirmed the relevance of the increased number of doppler radars and also announced that by 2025, the entire country will be covered by the doppler radars.

About Doppler Effect:

  • The Doppler Effect or Doppler shift is the change in frequency of a wave in relation to an observer who is moving relative to the wave source.
  • A common example of Doppler shift is the change of pitch heard when a vehicle sounding a horn approaches and recedes from an observer.

What is Doppler Radars?

  • A Doppler radar is specialized radar that uses the Doppler Effect to produce velocity data about objects at a distance.
  •  It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal.
  • This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar.
  • Doppler radars of varying frequencies — S-band, C-band and X-band — are commonly used by the IMD to detect and track the movement of weather systems, cloud bands and gauge rainfall over its coverage area of about 500 km.
  • The radars guide meteorologists, particularly in times of extreme weather events like cyclones and associated heavy rainfall.
  • With the radar observations, updated every 10 minutes, forecasters can follow the development of weather systems as well as their varying intensities, and accordingly predict weather events and their impact.
  • India’s east coast, which is frequently affected by the cyclones formed in the Bay of Bengal, has radars operational at eight locations — Kolkata, Paradip, Gopalpur, Vishakhapatnam, Machilipatanam, Sriharikota, Karaikal and Chennai.
  • Along the west coast, there are radars at Thiruvananthapuram, Kochi, Goa and Mumbai. Other radars are operating from Srinagar, Patiala, Kufri, Delhi, Mukteshwar, Jaipur, Bhuj, Lucknow, Patna, Mohanbar, Agartala, Sohra, Bhopal, Hyderabad and Nagpur.
  • The radars can oversee an area of up to 500 km, with effective range of up to 250 km.

Add ons:

  • The number of doppler radars in the country has increased from 15 in 2013 to 37 in 2023 and the minister informed that India will add 25 more radars in the next two to three years which will take the number to around 62.
  • The entire country will be covered by doppler radars by 2025.


Consider the following statements regarding Doppler Radar:

1. They are highly useful for weather forecasting.

2. United States and China are the only countries with Doppler radar technology.

Which of the statements given above is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1 nor 2