Figure 1 – Courtesy of the Spectator
Now that I’ve parsed and run an objective LWT analysis on the six hourly 20th century reanalysis data from NOAA, I can finally start putting some graphs together on what I’ve found. The gale index [GI] is a good place to start, and gives you a quick overview of how stormy it’s been over the British Isles in the last 145 years. Of course the calculation for the GI is for a fixed location 55° north and 5° west, so it has to be used with caution. The way round this would be to adjust the position of the grid, and generate the GI for other grid points, but for the moment GI values from a single point will have to suffice.
Without a doubt, the 1990’s was the windiest in the last 145 years, and it could be that 1990 was the windiest year looking at the graph of the total days when the GI>=30, approximately gale force 8 (fig 2). The winter of 1989-1990 was very stormy and of course that was the year of the Burns day storm. The best fit curve seems to be suggesting the number of gale force days per year has fallen since a little since then, it’s obviously only a rough guide, and the figures for the incomplete year of 2017 will be playing some part in that decline.
If you just examine all the six hourly charts in which the GI>=50 you get a slightly different picture (fig 3). The number of storms seems to have started to increase again since the peak in the 1990’s, and it looks like the stormiest year using the GI>=50 as a threshold was 2014. This finding corresponds well with what the Met Office said about the storminess of the winter at the time in a report entitled The Recent Storms and Floods in the UK so I must be on the right track (fig 3).
Figure 4 – Record of the number of stations reporting wind gusts in excess of 60 kts during December (Courtesy of the Met Office)
What the experts are saying about increased storminess
I’ve scoured the internet to find what climate scientists are saying about any increased storminess in recent years, with little success. I did find a PDF from Rob Allen of the Met Office about storminess from 2006 – Impacts of climate change on storminess – in which he said:-
Efforts are underway in the Hadley Centre at the Met Office to extend the 3-hourly pressure change analysis back to 1920 over the UK, while the potential exists to investigate whether very long-term pressure data series with coarser 12-hourly resolution at about 6 locations in the UK back into the 18th-19th century can provide a truly centennial scale picture of severe storm nature and changes.
I can’t say that I’ve seen any fruits from the efforts that the Hadley Centre were planning to make, but then again the wheels do tend to grind exceedingly slowly at the Hadley Centre, they are still under the illusion that climate data about frost only started in 1961, and temperature and rainfall in 1910. Perhaps I should point them at the masses of reanalysis data that I’ve downloaded from NOAA. It might only be on a 2° x 2° MSLP grid but at least the Americans encourage people to access the climate data that they produce.
If you have access to the Weather Magazine, there is an article about the subject – Historic storms of the northeast Atlantic since circa 1700: a brief review of recent research (Volume 69, Issue 5, May 2014, Pages: 121–125), in fact it mentions just how valuable the reanalysis approach might be in investigating changes in storminess.
Global warming and increased storminess
According to the Spectator in February 2014, Met Office scientists were privately furious with Professor (now Dame) Julia Slingo when she said that there was a link between global warming and recent storminess and the jet stream getting stuck. Professor Mat Collins of Exeter University was quoted in the Daily Mail as saying that:-
‘There is no evidence that global warming can cause the jet stream to get stuck in the way it has this winter. If this is due to climate change, it is outside our knowledge.’
The magazine claimed that Dame Julia had been hung out to dry by the Met Office because of these claims, one can only wonder about if there was a grain of truth in it, because by November 2016 she had been replaced by Stephen Belcher as Chief Scientist. Did she jump or was she pushed, or maybe she just thought sod it I’ve just had another £30,000 bonus, I’m 65 and I’m off.
There was a response to clarify what Mat Collins had actually said in the Met Office blog, which produced dozens of comments from people who totally disagreed with them. I must live a sheltered life because I never noticed all these shenanigans going on the time, and have only just noticed that Dame Julia had retired.
I’ll be back to revisit this reanalysis data when I’ve done a bit more development work…