10s Rainrate Statistics for the UK. Kevin Paulson Rutherford Appleton Laboratory, Chilton Didcot, Oxfordshire, OX11 0QX. Current Situation. Currently, ITU recommendations and RA license/power calculations are based on 1 minute rain rate statistics.
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Rutherford Appleton Laboratory,
Chilton Didcot, Oxfordshire, OX11 0QX
Temporal averaging point rain-rate over one-minute is roughly equivalent to spatial averaging over 1 Km.
One-minute rain-rates will underestimate the incidence of high attenuation on short links (<1 Km)
One-minute rain-rates smooth over short-term high attenuation events on longer links.
One-minute sampling as restrictive as one-minute averaging
Collector: standard UK Meteorological Office Mk IV
Water formed into equi-volume drops which are counted optically
Range 5->200 mm/hr in 1.4mm/hr steps
Optical Scientific inc.
Rain rate dynamic range: 0.1 – 500 mm/hr
Rain rate accuracy: about 5%
Integration time: 10 s
Precipitation type: rain/snow/mixed
NOT effected by wind
NO moving parts, very low maintenance
Self-monintoring, self correcting
Cost about £2000
Users: FAA, NASA, NOAA, US military, BAS, BMO ...
Detects 11 precipitation types
Range 0-999 mm/hr with 30% accuracy
One-minute integration time reporting every 15 s
Used by UK Met. Off.
Made in UK.
Rainrates: 0.015 - 250 mm/hr
Errors: rainrate 10%, snowrate 20%
Also measures visibility and precipitation type.
Typically 10-13 years operation without ANY maintenance!
Used by Swedish Airports, FAA, USAF. ...
Laser disdrometer designed by Voss
Yields 10 s rainrate and WMO precipitation code, visibility, and particle size-velocity distribution.
Rainrate derived from drop size-velocity distributions. Reported accuracy only for one-hour rainrates of 10%.
Drops: 0.25 - 25 mm diameters
Speed 0.1 - 20 m/s
Cost: £16000 and up