New Doppler Radars in Maharashtra: IMD


    In News

    The India Meteorological Department (IMD) will install seven new doppler radars in Maharashtra.


    About :

    • 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. 
      • During the next couple of months, four X-band and one C-band radar will be deployed over Mumbai. 
      • In addition, Ratnagiri will get a new C-band and Vengurla will get an X-band radar, each of which will operate for multiple purposes,” 
        • An X-band radar is used to detect thunderstorms and lightning whereas C-band guides at the time of cyclone tracking.
    • Existing  Radars
      • East coast
        • 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, Visakhapatnam, Machilipatanam, Sriharikota, Karaikal and Chennai.
      • West coast
        • 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 modernisation and upgrade of existing radars are ongoing and the IMD plans to have a network of 55 doppler radars. 
        • The Chennai radar, which is presently defunct, will be upgraded soon.


    • 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.


    Radars (Radio Detection and Ranging)

    • It is a device which uses electromagnetic waves in the microwaves region to detect location (range & direction), altitude, intensity and movement of moving and non-moving objects.
    • It has its own source of illumination (a transmitter) for locating targets. 


    Doppler Weather Radar (DWR)

    • It is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance.
    • It is designed to improve precision in long-range weather forecasting and surveillance using a parabolic dish antenna and a foam sandwich spherical radome.
    • It has the equipment to measure rainfall intensity, wind shear and velocity and locate a storm centre and the direction of a tornado or gust front.
    • It provides advanced information, enhancing the lead-time so essential for saving lives and property, in the event of natural disaster associated with severe weather. 
    • Types Of Doppler Radars : Doppler radar can be divided into several different categories according to the wavelength which are L,S,C,X,K.

                            Image Courtesy


    About Doppler effect

    • Doppler Effect refers to the change in wave frequency during the relative motion between a wave source and its observer. 
    • It was discovered by Christian Johann Doppler who described it as the process of increase or decrease of starlight that depends on the relative movement of the star.
    • Description: Doppler Effect works on both light and sound objects



    • X-band radars:They operate on a wavelength of 2.5-4 cm and a frequency of 8-12 GHz. Because of the smaller wavelength, the X band radar is more sensitive and can detect smaller particles.
      • It is used to detect thunderstorms and lightning.
    • S band radars: They operate on a wavelength of 8-15 cm and a frequency of 2-4 GHz. Because of the wavelength and frequency, S band radars are not easily attenuated. This makes them useful for near and far range weather observation. 
      • The drawback to this band of radar is that it requires a large antenna dish and a large motor to power it.
    • C band radars: They operate on a wavelength of 4-8 cm and a frequency of 4-8 GHz. Because of the wavelength and frequency, the dish size does not need to be very large. 
      • This makes C band radars affordable for TV stations. The signal is more easily attenuated, so this type of radar is best used for short range weather observation.
    • K band radars: They operate on a wavelength of .75-1.2 cm or 1.7-2.5 cm and a corresponding frequency of 27-40 GHz and 12-18 GHz. This band is split down the middle due to a strong absorption line in water vapor. This band is similar to the X band but is just more sensitive.


    About India Meteorological Department (IMD)

    • The India Meteorological Department (IMD) was established in 1875.
    •  It is an agency of the Ministry of Earth Sciences of the Government of India.
    • It is the principal agency responsible for meteorological observations, weather forecasting and seismology.
    •  IMD is one of the oldest, scientific service organizations in the country.
    • IMD has been continuously redefining its focus for accurate Prediction of Monsoon and cyclones as our GDP is mainly based on agriculture.



    Source :IE