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About the Hartland ( Stoke ) AWS equipment




The weather station Integrated Sensor Suite and indoor Console

close up picture of Davis VP2 AWS on mast
This AWS is a Davis Vantage Pro 2 with wireless connection from this Integrated Sensor Suite ( ISS ) to the Console indoors.
Davis console
The Davis Vantage Pro 2 Console. As with most AWS, barometric readings are made from sensors within this indoor console.
From this a Weatherlink Datalogger has a USB link to Weatherlink software on an internet-connected PC.





Rainfall

Tipping buckets of rain gauge
This AWS has a "Tipping Bucket Raingauge" (TBR) . Rain falling into a collecting funnel (removed for this photo) runs into the TBR mechanism ; in this AWS a small spoon on each end of a little see-saw tips when full generating an electronic recording of 0.2mm of rain with each event.

The software measures how many events (tippings) occur and records the time interval between each event.

The number of events gives the "Rain" figures - the total rainfall over a chosen period of time

The time interval between events enables calculation of the "Rain Rate" (or rain intensity) figures - how much rain would fall in an hour if this rate of tipping were to be maintained.
Davis VP2 on mast, in relation to immediate ground level
The ISS is mast-mounted ; the rain collector and temperature/humidity sensor are 2m above ground level to the SW quadrant, 0.3m above grass hedgebank to the SE and NE quadrants, and 0.3m above a covered compost heap to the NW quadrant



Wind speed and direction


AWS and anemometer mast
The anemometer is mast-mounted 7m above ground level



anemometer
Mounted underneath the weather vane is a "cup anemometer", with three (outside diameter 1.5") cups located 120° apart on a vertical shaft with low friction bearing.



Solar Radiation


AWS and solar sensor




This is a Davis Instruments solar radiation sensor.
It is a silicon photodiode detector with a spectral response across the wavelength range 300 to 1100nm - from the near ultraviolet, through the visible spectrum, into the near infrared.

The photodiode sensor is fairly insensitive to rapid changes in solar radiation, with its 60 second time response time being long enough to fail to record accurately the rapid swings in solar radiation on a day of broken cloud. Nonetheless, it should give daily total values within 5% of "true".

This solar radiation sensor measures 'global solar radiation', which is the combined direct (in a direct line from the sun) and indirect (scattered by clouds etc) solar radiation across the measured spectrum. It is, roughly speaking, a "brightness recorder" and not a "sunshine recorder", where sunshine is generally taken to mean a clear enough sun to cast shadows.

 
For an information leaflet (pdf file) on measuring equipment, visit the Met Office by clicking the link at the bottom of this page