I was just looking through the climate records that the Met Office provide for downloading across the country. I had written an application, as is often the case it was another one of my climate and weather applications that I had sadly neglected to finish off. The Met Office are very frugal when it comes to allowing people to access climate data, and it’s no different with this historic station data series. Take a look at the scanty coverage of monthly climate data they make freely available (fig 1). The monthly climate data is limited to just 37 stations across the entire UK, three of those stations have closed. Here in the entire southwest of England, there are just three long time series available to download, Camborne, Chivenor and Yeovilton. No climate data available for St Mary’s, Plymouth, Exeter or Dunkeswell, even with the headquarters in Exeter.
Not that you get a great deal of climate information in the monthly data that they do release (fig 2). There is no information regarding the frequency of wind speed, direction or highest gust during the month, no MSLP information, no frequency of visibilities, no days of fog, thunder, gale, ground frost, hail, sleet or snow, just the barest of bones – why give it away when someone will pay you for it?
Following on from the article that I wrote about Climate changes in the UK since 1910, I thought that I would use this monthly data to see if I could find any long-term trends in annual precipitation from some of the 28 available climate records from stations across the country. I start with Sheffield, which has a long climate record that started in 1883 (fig 3). In my application I decided to display three charts for precipitation, the top one displays a 12 month rolling accumulation for the entire record. With the top graph you can select a period (yellow overlay), and display that period as a bar chart of monthly totals and monthly anomalies in the lower two charts.
As far as I can see using a simple linear trend in the accumulation series, there has been a +11.5% increase in annual precipitation in the last 133 years in the City.
Oxford has an even longer record that stretches back to 1853, but the increase there is only +2.6% in the 163 year record (fig 4).
Armagh has a rainfall record that also stretches back to 1853, but there there’s been a -1.4% decrease in annual rainfall (fig 5).
The Wick record which started in 1914 shows an increase in annual precipitation of +7.3% (fig 6).
The Stornoway record that started in 1874 shows a decrease in annual precipitation of -1.7% (fig 7).
It’s a bit difficult to find a climate station with a long climate record in the south so Heathrow which started in 1948 will have to do. It shows an increase in annual precipitation of +3.7% (fig 8).
These results obviously need plotting on a map if you are to try to make any sense from them, which I will get round to, but for now these results will have to do. I am surprised to find that a couple of stations did come up with drier trends, it could of course be down to the fact that I haven’t used a fixed time period for the linear trends.
To finish, I’ll just display the monthly England and Wales precipitation series that’s also free to download from the Met Office (fig 9). That series started in 1766, and shows a +5.3% increase in annual precipitation in the last 250 years across England and Wales. So I would say that it has been slowly getting wetter, certainly in England and Wales, but I need to do a much fuller analysis than this very limited quick look. There is one thing that I have found out conclusively though with this bit of programming, and that is rainfall records extend much further back than 1910!
Let me know if you spot any statistical howlers in this piece.