Welcome to Ashington Met!

This is an amateur weather station based near Ashington in West Sussex. Ashington is a village situated midway between the towns of Worthing and Horsham, and is approximately 7 miles from the south coast of the UK.

The weather station itself is at 50.9°N, 0.4°W with an elevation of 46m (151ft) above sea level in a rural location about half a mile north of the village.

The aim of this site is to provide current and historic weather data, along with local forecast information gleaned from external sources, all in one place. The collection of data at this site commenced on 17th August 2020.

Equipment

Our weather data is supplied by a Davis "Vantage Pro2 Plus" Automatic Weather Station (AWS). Davis AWS products are designed and built to a high standard and Davis is a worldwide leader in the sector extending between the serious enthusiast and professional markets (agriculture and other businesses that rely on weather information). The equipment was purchased in the UK from Prodata Weather Systems, a specialist supplier offering extensive expertise and support for Davis products.

The system consists of an anemometer and wind vane for measuring wind speed and direction, and a suite of sensors providing temperature, humidity, air pressure, rainfall, solar radiation, and ultra violet radiation measurements. The rain gauge contains a tipping spoon designed to empty each time it has collected rainfall equivalent to 0.2mm, and the number of tips is counted electronically. The temperature and humidity sensors are protected from radiation during the day by a daytime fan aspirated radiation shield to maintain accurate readings. The main sensors are mounted (along with a solar panel for power) at a height of 1.25m, except the anemometer and wind vane which are at 3.6m, and the barometer, which is indoors. Anemometer readings are corrected to the normal 10m measurement height for wind speed, as required by meteorological organisations, using a standard adjustment factor (because wind slows down near to the ground).

The whole instrument package and mounting pole are sited away from obstructions and can be seen in this image.

Data collection and processing

Data from the AWS sensors is transmitted to a remote indoor console at various different periods, depending on the nature of the measurement. For example wind speed and direction are updated every 2.5 seconds, whereas temperature is every 10 seconds and solar radiation once a minute. The console (which also contains the barometer) then consolidates the data and acts as a simple display, but in our case we use its serial data port as an interface to a Raspberry Pi computer, where the data can be further processed. The connection to the computer is made via a "Meteo Pi" daughterboard which sits on the input/output pins of the computer board and allows a simple cable link to be made.

The Raspberry Pi is ideal for this task as it uses very little power and can be left running 24/7. The main software package running on it is Cumulus MX, a powerful tool which allows us to derive further measurements such as sunshine hours, and also plot trends, maintain averages/maxima/minima etc. After all this processing, it then enables us to send the data elsewhere. For example data is transferred peridiodically to this website where it can be displayed more clearly, and it is backed up to a separate storage device. Our data is also shared with the UK Met Office as part of the Weather Observation Website (WOW) network.

The image below shows the Raspberry Pi being tested for the first time with the blue Meteo Pi daughterboard mounted and Console data link in place. The bottom image shows the finished operational version in a small case.

Data provided on this site

Whilst these figures cannot be guaranteed, the accuracies quoted by Davis for the main AWS measurements are as follows:

Please note:

• This is purely an amateur weather station. The data is not therefore guaranteed but is offered as a general guide to local conditions only. Never base important decisions on any information provided by this website.
• Some derived values wil be less accurate, depending on method of calculation. Sunshine hours in particular are difficult to obtain accurately from the solar radiation figures, as radiation from the sun whilst shining varies during the day and throughout the year. The algorithm used here provides an approximation, but it is almost impossible to quote a tolerance on these figures.
• All baromteric pressure measurements are corrected to sea level values.
• All times quoted are local (GMT/BST).
• The meteorological day in use starts and ends at midnight.