Central London might have been the warmest place in the UK once again yesterday but is it healthy? The latest forecast of carbon monoxide from the Copernicus site suggest that the air quality here and other European centres is very poor for so early in the year. I only came across the Copernicus website thanks to a tweet, but it does seem to have all the answers when it comes to aerosols, pollution and the quality of the air we breathe.
At midnight in SYNOP reports the total of the previous incoming net solar radiation is reported (or so I think). Many countries report it at this time, others like the French don’t just to be awkward. Here are the values from yesterday across the UK and the near continent (fig 1). I’m not overly clear about the values that I’m displaying or the units I’m using because the WMO manual is suitably vague, and I don’t know what typical daily values to expect at this time of the year. If you know exactly what these totals are please drop me a comment.
Provisionally, yesterday was the warmest 18th of April since the daily series of the CET began in 1772. The mean temperature of 16.7°C was a whopping 1.8°C higher than the previous for that day back in 1945, and almost 8.3 °C above the 1961-1990 long-term average (fig 1). There looks little doubt that today will see another extreme record set for the 19th of April as well. Here’s a look back at yesterdays 06-18 maximum temperatures (fig 2).
The ECMWF model being used for the BBC forecast by MeteoGroup is not really handling the sea fog that’s rolling into west of Cornwall and along the north coast of Devon too well this morning (fig 1). The UKMO model has at least captured something in the way of cloud across the southwest, what exactly it is in looking at the graphics is a little bit harder to work out, is it cirrus, or stratus or just sea fog? Alex Deakin doesn’t seem overly concerned about it though, he says that’ll it be “just some of these western coasts that may stay a little murky”.
I’ve been watching this fog and low stratus as it rolls in across the southwest and it’s moving quite smartly to say there’s very little gradient (fig 2). I just wonder how much further east it will progress during the rest of the day as well as how far inland it’ll make it.
In the national forecast just after the main BBC news the graphics looked very similar to the ones used during the morning, but in the regional forecast at 1.40 pm it appeared as if they had updated the model which gave a much more realistic fit with the satellite image (fig 3). Ben Rich was too busy demonstrating how proficient he is with the count-up method (you know the one – “temperatures reaching 24 or 25 quite widely, and maybe even a 26 or 27 and possibly a 28 or 29 in one or two spots”) to even be bothered to show any detail of low cloud in the southwest.
The sunniest places in Europe yesterday* were to be found on top of mountains, such as the Sonnblick Observatory on mount Hoher Sonnblick in the Austrian Alps and the Zugspitze Observatory in the Wetterstein Mountains in Germany (fig 1).
* This is only the sunniest of the places that report sunshine in their SYNOP. For some reason most of Scandinavia don’t or won’t, the Netherlands and Belgium do report sunshine, but I think they include it in their midnight observations rather than at the more conventional 06 UTC the next day. I should imagine that the sunshine totals north of the Arctic Circle on a cloudless day in summer are 24.0 hours, speaking of which…
Sunshine in Tromso
Here are the climate statistics for Tromso in northern Norway courtesy of Wikipedia (fig 2) which makes interesting reading (crampons when you’re out shopping on the High street and no frost in June since 1997). Having the advantage of sunshine 24 hours a day in summer I would have thought that the average of 221 hours for the month of June would have been a lot higher. Apparently the sunniest month in Norway was in July 1980 when Tromso recorded 430 hours of sunshine. It’s interesting to see the zero hours of sun for the month of December, there can’t be too many weather stations in the world were the average is in fact a constant like this. I still can’t see why across northern Norway the maximum possible sunshine total for June can’t approach 720 hours (30 x 24)? I suppose it’s back to the question of what constitutes ‘bright’ sunshine I raised in the last blog. All I can imagine is that even when the sky is cloudless, the sun when it’s low on an Arctic summer’s night just isn’t strong enough for maybe four or five hours or so to exceed the threshold set for ‘bright’ sunshine.
UK Sunshine card
These are the hourly sunshine totals for yesterday across the UK (fig 1). As you can see Shoeburyness was marginally the sunniest place with 13.0 hours, but many place across southern areas were close to 100% of the maximum possible. Places like Shoeburyness with the sun rising over the North Sea in the east, and setting over a flat Essex to the west must have a slight advantage over places like Exeter for example, where the sun is slightly blocked by the Blackdown hills to the east and by Dartmoor to the west, which may shave off 0.2 hours on a cloudless day.
Interestingly in my application I made the 13.0 hours at Shoeburyness only 92.2% of the theoretical maximum. Checking on the timeanddate.com website tells me that the day length at Shoeburyness was 14:07:30 for yesterday, so the 13.0 hours of reported sunshine was indeed only 92.0% of the total possible, so the algorithm I use is quite accurate. But what happened to the missing 1:07:30 seconds of sunshine? The total day length would of course start when the top limb of the sun first appeared over the horizon until it disappeared below the horizon in the west, this process may account for 15 minutes or so, but I can’t imagine haze in the atmosphere making up for remaining 0:52:30 on a cloudless day with good visibility like yesterday (fig 2). Who knows perhaps there was some thicker cirrus that went undetected by the LCBR, or maybe we have the threshold for bright sunshine set too high these days, in order to mimic the totals we used to get from the old Campbell-Stokes recorders?
Adding hourly totals works
Reassuringly, as long as you collect all the hourly SYNOP observations, then adding the hourly sunshine totals does produce a figure that’s very close to the one reported at 06 UTC the next day (fig 3).
It shouldn’t be too long before people across the rest of the country see some of the strong spring sunshine we are experiencing at the moment in the more southern parts of the country (fig 1).
Another classic series of forecast charts from the Met Office this morning with another front that refuses to die (fig 1). The front in question tried to cross the country yesterday as a cold front, and at the moment is returning northward as a warm front pushed northward by continental air. It’s set to make another attempt to introduce cooler Atlantic air on Thursday and Friday as it undergoes frontolysis. This front seems likely to become a real fly in the ointment in the next few days, forecast to be sprawled through the heart of an anticylcone by Saturday and spoil the first decent spell of weather we’ve had this spring.
I must admit that models seem to have handled the clearance northward of the cloud from that frontal system extremely well (fig 2) from what I could see looking through the Velux windows in our attic bedroom this morning!
There’s no doubt that the Earth has been warming since 1970, but the rate of increase in the warming seems to have stalled between +0.16 and +0.18°C per decade since around 1992. I don’t have any particular axe to grind in the AGW debate, and I’m no climate expert, but I can knock out code and generate a good graph from the applications that I develop. Such is the power of modern computers I constructed the top graph (fig 1) by calculating around 1,296 monthly 30 year linear trends since 1910. Using GISS land and sea data the first “y” value is the 30 year linear trend for the period from January 1880 to December 1909, and the last “y” value using data from April 1988 to March 2018, as you can see I didn’t choose to centre the graph but kept it right aligned. I don’t know how valid this technique is statistically, but for all I know it’s a well-known method that’s widely used!
I suppose I decided to publish this particular blog after reading so many snippets of news saying how the latest GISS temperature for March made it “the 6th warmest on record” – so what? Dig just a little deeper into the data series and you’ll find that the 12 month moving average has now been falling now since the start of 2016 which is to be expected at the end of an El Niño event (fig 2), but the pause in the rate of change runs much longer than this, especially as climate experts say that it should accelerating.
I’m not saying global warming has stopped because it’s quite obvious it hasn’t – and if global temperatures continue at this rate they’ll be 1.8°C higher than they are now in 2118 – I’m just saying the rate of change in that warming has flattened out, and seems to be holding steady at the present time.
There may well be a warm spell coming later this week, but I’m afraid that even with these high temperatures, April 2018 won’t be a patch on the exceptionally warm April of 2011 (fig 1), which in fact was the warmest since the data series began in 1659 (fig 2) with an anomaly of +3.93°C. It didn’t just sneak past the previous warmest April it smashed past it (fig 2) by over 0.6°C (2007), which in itself was over 0.5°C warmer than the previous warmest April. Is it just me, or do we all have short memories of memorable warm spells?
Here’s April 2011 in a little more detail from the daily series of the CET (fig 3).
To give you an idea of just how warm it was, here are the hourly temperatures and running 24 hour mean from Heathrow airport courtesy of OGIMET (fig 4).