Doppler Weather Radars "EMPOWER IAS"

Context :

• Recently, Ministry of Earth Sciences commissioned two indigenously built X-Band Doppler Weather Radars (DWR) which will closely monitor the weather changes over the Himalayas. The DWR has been designed and developed by ISRO and manufactured by Bharat Electronics Limited (BEL), Bengaluru.

 

Significance of it :

• Covering the central and western Himalayas, these dual polarised radars will gather atmospheric variations and pick signals of extreme weather events.
• Uttarakhand and Himachal Pradesh are highly prone to cloud bursts, landslides, heavy rain and snowfall. Timely weather forecasts and warnings would ensure the governments make advance plans and initiate rescue measures.

 

Radars :

Radar (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.

 

What is Doppler effect?

• When the source and the signal are in relative motion to each other there is a change in the frequency observed by the observer. If they are moving closer frequency increases and vice versa.
• It does this by bouncing a microwave signal off a desired target and analysing 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.

 

About Doppler Weather Radar

• The Doppler Weather Radar (DWR) provides advance information, enhancing the lead-time so essential for saving lives and property, in the event of natural disaster associated with severe weather. Though the conventional radars are able to track and predict cyclones, the DWR provides detailed information on storm’s internal wind flow and structure.

 

• The severity of the weather systems can thus be quantitatively estimated more accurately than ever before and more precise advance warnings can be generated for saving human lives and property. The polarimetric capability of the Radar will significantly improve the accuracy of rainfall estimation leading to accurate and timely flash flood warnings.

 

Applications

• Doppler Weather Radar Products can be used for the following applications
  a) Weather surveillance
  b) Severe weather monitoring
  c) Hurricane, typhoon, and cyclone tracking
  d) Hail detection
  e) Hydrometeorological applications, such as flood forecasting
  f) Airport wind-shear detection
  g) Meteorological research
  h) Weather modification
  i) Agriculture
  j) Radiosonde Launch support systems
• A state-of-the-art, indigenous doppler weather radar, capable of predicting with increased accuracy weather events such as cyclone occurring in 500-km radius from Kochi has been established.

 

 

Polarimetric Doppler Weather Radar

• • India’sfirst Indigenously developed Polarimetric Doppler Weather Radar (DWR) installed at Cherrapunjee, to Nation on May 27, 2016 remotely from Polo ground in Shillong, Meghalaya.
  • The DWR has been designed and developed by Radar Development Area, ISRO Telemetry Tracking and Command Network (ISTRAC), ISRO and manufactured by Bharat Electronics Limited (BEL), Bengaluru.
  • The North East, a land of beauty and adventure, has been hit by several natural calamities in the recent past, on account of heavy rain and landslides. This Weather Radar System will enable better weather forecasts, especially for the North Eastern region. This should help in minimising the threat posed by extreme weather conditions
  • The polarimetric capability of the Radar will significantly improve the accuracy of rainfall estimation leading to accurate and timely flash flood warnings.
  • The DWR, being the first S-band (operating at 2.7 - 2.9 GHz) dual polarimetric Doppler Weather Radar can detect Weather phenomenon upto 500 km.
  • This system installed at a place that receives the highest rainfall in Planet Earth, shall open up tremendous research opportunities in the areas of monsoon dynamics, Cloud Physics, impact of orography in precipitation process, precipitation characterisation, thunderstorm and hailstorm genesis and evolution, etc.
  • The data from the DWR is also expected to support a host of operational programmers of IMD and NESAC/ISRO. The near real time precipitation estimates from the DWR shall improve the Flood Early Warning System (FLEWS), being developed by NESAC for NE states.
  • It will also enable IMD and NESAC to take up operational activities on thunderstorm now-casting and hail now-casting for NE states.