Doppler Weather Radar - METNET - India Meteorological Department

2. Range and Velocity ambiguities do no occur
3. Clutters are minimal if not totally eliminated.
4. High Data Resolution in Range/Velocity/Reflectivity values
5. Minimal noise
6. Scan to scan interval should be such that even the shortest lived phenomena like
Tornado/Thunderstorm are not missed by radar scans.
Ideally, very close-temporal spaced scans (even closer than 5 minutes) enable continuity of
data especially for better rainfall accumulation estimations, volume scans with closely spaced
elevation angles provide better data sets. But both result in high/voluminous data sets causing
data handling/storage problems.
When no weather is expected, far-temporal spaced scans will be enough to monitor the
changes in the atmosphere and to provide nearby clear-air-return based velocity data. Scan
strategy should therefore be different to suit different situations/locations of radar/seasons etc.
The scan schedule for weather seasons like Pre-monsoon season, Monsoon season and Post
monsoon season generally designed as follows:
1. A long range single elevation scan, generally up to 500 km range, with lowest elevation
angle possible is done to have general observation of the atmosphere around the radar site.
2. A medium range (upto 250 km) multiple elevations scan, called a volume scan is done for
detailed probing of atmosphere.
3. RHI scan is set in WSR-98D/S as a real-time display continually or occasionally as
required. This scan is generally done to probe the vertical extent of severe/tall clouds
which is usually seen is Thunderstorms/Cyclones/Norwesters.
D.2.1. Cone of silence
Close to the radar, data are not available due to the radar’s maximum tilt elevation. This
area is commonly referred to as the radar’s "Cone of Silence".
Figure D.6. Cone of Silence
D.2.2. Operation of Doppler Weather Radars in IMD
1. Scientific objectives
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