Atmospheric Measurements at Capel Dewi field station. Prof. Geraint Vaughan. Where is it?. Aerial view of site. Lidar container. Bungalow. Field of antennae. Instruments on site. UK Mesosphere-stratosphere-troposphere (MST) radar Boundary-layer wind profiler Surface weather station
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Atmospheric Measurements at Capel Dewi field station
Prof. Geraint Vaughan
Field of antennae
This is a VHF radar: 47.5 Mhz, or a wavelength of about 6 m. It consists of a field of 400 antennae (the aerial) and transmitter/receiver equipment in the bungalow.
It runs continuously, measuring profiles of winds, atmospheric structure and turbulence every 2 minutes, from 2 to ~16-20 km altitude
Plot shows 24 hours wind measurements on 15 June 2005.
High winds near 10 km show a jet stream – note that it changes direction over the course of the day.
Note strong wind shear above and below the jet.
Same day, 15 June 2005.
Radar measures tropopause height (crosses) where the signal increases with height. Note relation between tropopause and jet stream.
Low power at lower levels is due to water vapour, but rain suppresses echoes. Note:
Low power 0300 – 0600 as front passes over
Strong layering later in the day, indicating descending air and stability to convection
Similar to MST radar but measures at lower heights – 100 m to around 3 km.
Radar system working at 1.29 GHz – around 24 cm wavelength
Antennae are much smaller and each panel contains an array of 64 of them (8x8)
Three panels pointing in different directions measure winds
Measurements of winds and echo power every 2 minutes, continuously.
Signal to noise ratio,
15 June 2005
15 June 2005
Vector Instruments Anemometer on 10 m tower on top of hill nearby
Campbell Scientific Weather station:
Temperature, rainfall, RH, sunshine
Note zero rainfall: rain did not reach ground during frontal passage
LIDAR instrument using infra-red wavelengths to measure cloud height
Lidar using five ultraviolet wavelengths to measure aerosol and ozone profiles
Black line denotes top of boundary layer – below this the air is polluted with lots of aerosol. But ozone is relatively low: note how the ozone increases above the boundary layer on this day
Nd-YAG laser (SPECTRON)
X10 Beam expander (refracting telescope)
Aberystwyth Dec 9 2001
Above: tropospheric measurements from 289/299 nm pair.
Below: stratospheric measurements from 299 alone. (We now do DIAL with 299/316 for stratosphere)
Stratospheric Nitrogen dioxide column measurements from Aberystwyth, 1990-2005