Sunshine



East Anglia tops the Summer Index for 2017

Figure 1

Of all the regions in the UK, East Anglia has the highest Summer Index for 2017, with an index of +10 (fig 1). Western Scotland came bottom of the table with an SI of -11, mainly because the summer was so dull. The UK as a whole returned a disappointing SI of -1, which was lower than the +10 of 2016 (fig 2). Don’t forget the maximum SI a summer can achieve is 48 which it did in 1976. The last really good summer across the UK as a whole according to the SI at any rate, was 2013, with an SI of 32 (fig 2). If you’re new to what the Summer Index and how it’s calculated you can read an article that fully describes how it’s calculated here.

Figure 2

The scatter graph for mean maximum temperature and total rainfall indicate that although the summer had been a little warmer than usual, it was also a lot wetter than average too (fig 3).

Figure 3

The scatter graph of maximum temperature and total sunshine indicate that the summer has been slightly duller than average (fig 4).

Figure 4

Let me know if you notice anything wrong with the various terciles and quintiles, I’m far from perfect.

August 2017 – sunshine

Shoeburyness in Essex came out as the sunniest place in the British Isles in August with 229.6 hours of bright sunshine, knocking sunny Jersey into second place for a change, in what was a below average August as far as sunshine goes, especially in northwestern parts. I still don’t believe the 108.1 hours of sunshine at Liscombe in Somerset despite receiving 100% of the 06 UTC observations from here it still looks low.

Is Liscombe in Somerset, the dullest place in the British Isles?

Figure 1 – Courtesy of Google Maps

 An apology to any residents of Liscombe who may be reading this before I start, because when I say  – is Liscombe the dullest place in the British Isles? I mean with regard to sunshine and nothing else! 

Liscombe, believe it or not, isn’t in Devon as I had always thought, but in Somerset. I forget that the county of Somerset stretches westward almost as far as Foreland point and Lynmouth in the west. The only reason I know about the village of Liscombe is that there is an AWS there, that generates hourly SYNOP reports (fig 1). Here’s a better look at the topography of the immediate area from the OS Map (fig 2). As you can see the Ordnance Survey have even marked where the ‘Meteorological Station’ is on the 1:50,000 map, which incidentally is at around 348 M above sea level, and almost due south of Winsford Hill (428 M) in the Exmoor National Park. I should imagine that hill see’s a good deal of snow in the right situation in winter, but must offer some protection to the village of Liscombe itself from the worst of any weather that comes in from the north.

Figure 2 – Courtesy of Bing Maps and the OS

Well the reason for the blog is that I suspect the sunshine totals are too low this year. Not a heinous crime I know, but I do think sunshine at Liscombe is a bit on the low side this year by quite a margin. I realise that a climate station at well over 1,100 feet does attract a lot of hill fog and upslope stratus, and I’m sure that’s quite a common feature of Winsford Hill in a southwesterly, but even allowing for that, the sunshine this year has been abysmally low. If you look at the sunshine totals across the UK there is usually a lower contoured area across Exmoor that seldom seems to be mirrored over the larger area of high ground over Dartmoor to the southwest in the first seven months of this year (fig 3). It could be the weather patterns have not favoured this part of Exmoor for sunshine of course, and maybe the map is skewed because there isn’t a climate station at a similar height and exposure on Dartmoor reporting sunshine.

Figure 3 – Courtesy of the Met Office

All I know is that the sunshine totals at Liscombe since February have been 30% lower than at Exeter, just over 40 km to the south, which seems a wee bit too excessive to my mind (figs 4 & 5). Although as I’ve said sunshine at hill stations may be reduced by the incidence of hill fog and low cloud at times throughout the year, they do have one advantage over places lower down the valley especially in the autumn and winter months, they get off to a better start in the morning, because they often go unaffected by any radiation fog.

Figure 4

Figure 5

Here’s a map with the total number of sunless days (0.0 hours) of sunshine so far this year (fig 6).

Figure 6

As you can see from the map (fig 6) and the table below (fig 7) Liscombe so far this year has the highest number of dull days in the British Isles by some way, with 56 out of the last 235 days being without sun, second in the table is the nearby station of Camborne in Cornwall. By total sunshine accumulations, Liscombe is only the fourth dullest out of 55 stations. I have received 99% of the 06 UTC observation for Liscombe, so it’s not because they haven’t been transmitted.

Figure 7

What may be going on with the AWS at Liscombe, is that the sunshine sensor is somehow malfunctioning, perhaps not all the time, but enough to reduce the sunshine totals each day in some way, and without the Met Office perhaps even noticing. I do know that because there aren’t that many sunshine recorders across Devon, that the lower than average total is picked up on by the monthly sunshine charts (fig 3), as they are based on gridded data which the Liscombe observation will be used in.

Seville sunniest this Summer in Mediterranean

Figure 1

Seville in Andalusia, Spain, is the sunniest place across the central and western mediterranean so far this summer, with 1071.5 hours of sunshine up until the 22nd of August, which as far as I can see is 89.4% of the theoretical maximum, and gives them a daily average of 14.4 hours of sun. If you like watching clouds float by, then Seville is not the place for you, because clouds their in summer have been a scarce commodity this year. There are 16 stations across the area with totals in excess of 1000 hours so far this summer. Wikipedia is a great resource for climate data, and for many larger cities they have a climate table, and the Seville entry is no exception. It seems that the average total for the three meteorological summer months is 999 hours, which is quite handy, because already with a week to go the total is already 7% above average.

I can’t compute the anomalies for all the other stations, because I just don’t have access to the detailed climate averages for across Europe, which is a pity. What we need is a global organisation that could collect and collate climate data from all the nations of the Earth, this organisation could then take the lead in the climate change debate, providing accurate climate and observational data for anyone to access. Let me think what should we could call it? I know, why don’t we call it the World Meteorological Organisation!

Jersey still holding onto sunniest place this summer

Figure 1

With just over a week left of the meteorological summer of 2017, it’s still neck and neck at the top of the sunniest places in WMO block #03. The race has been between Shoeburyness in Essex and Jersey in the Channel Islands, and at the moment Jersey has a slight lead of just 5.7 hours over Shoeburyness, with a total of 614.6 hours since the start of June, so it’s all still all to play for. The Essex site might actually have a higher total, because although I’ve received 100% of the Jersey daily totals in the SYNOP reports, I’ve only received 92% of the Shoeburyness sites. I look forward to the day when I can collect the latest daily climate data for the whole of the UK from the Met Office, without having to use external sources, but I feel I might be in for a very long wait.

The cold wet August of 1912 and the Novarupta eruption

Figure 1 – Courtesy of Wetterzentrale

The coldest August since 1910 was that of 1912. It was both wet, cold and dull. At many coastal stations around the UK the sea temperature was higher than the air temperature. In the monthly weather report for 1912 the review of the month concludes by saying

Observers in various parts of the United Kingdom noticed in the rare intervals of fine weather the sky seldom assumed its ordinary blue tint, but appeared to be covered with a hazy film “producing grey whiteness of the unclouded sky, and extreme weakness of all sunshine”. A similar appearance was noted by several continental observers.

The mean temperature for the UK was just 11.7°C which is 3.26°C below the 1981-2010 long-term average. The mean maximum anomaly for the month was even lower at 3.94°C below average. Looking at the regional temperature anomalies (fig 2), the cold was across the board.

Figure 2 – August 1912

As well as being very cold, it was also very wet, especially in more southern regions, and particularly in East Anglia which saw over three times the monthly average rainfall (fig 3).

Figure 3 – August 1912

In fact August 1912 was and still is the wettest August in the entire EWP rainfall series that started in 1766 (fig 4).

Figure 4

As you probably noticed in the daily charts for the month (fig 1), August 1912 was a very cyclonic month as you can see in the Lamb Circulation types for the month (fig 5).

Figure 5

As regards the CET for the month, I can’t remember ever seeing a summer month as cold as this one (fig 6). August 1912 was, and still is the coldest August on record back to 1659, beating even the cold year of 1695 into second place.

Figure 6

Not only was it the coldest August on record, it was also ushered in the start of a three-month cold spell in central England, with a cold September (mean anomaly -2.5°C) and October (mean anomaly -2.4°C) to follow (fig 7).

Figure 7

At this point I would like to produce some statistics to show that August 1912 was also the dullest on record, but I can’t, the Met Office maintain that they only began measuring sunshine from 1929. The MWR comes to the rescue though, because it says about sunshine:

Sunshine was very deficient, a large number of stations situated in nearly all parts of the kingdom recording considerably less than half the average amount. In the Channel Isles and at a few places in the extreme southeast of England the mean daily duration ranged between 4 and 4½ hours, and was equal to about 30 percent of the possible. Over Central and Southern Scotland and at a few places in the northeast of England the daily duration was less than 2 hours; at Crathes, Glasgow and Eskdalemuir it amounted to only 1o percent of the possible.

What caused it?

Here’ a graph of 12 month rolling CET values for around that time, forget the date in the subtitle, another bug for the programmer to fix. I’ve overlaid the volcanic dust index events that were greater, or equal to 4, on the VEI on top of the line series, and as you can see the Novarupta event (VEI 6) looks like it may well have been responsible for global cooling that also affected our own CET series back in 1912 across, and fits well with the reports of a greyish white haze from the Monthly Weather Report for August 1912.

Figure 8

Novarupta

Figure 9 – Novarupta’s lava dome in July 1987

I had never heard of the Novarupta eruption until I started researching this article today. I never even realised it was the most powerful volcanic eruption of the 20th century, here’s what the Wikipedia article had to say about it:

The eruption of Novarupta in the Aleutian Range began on June 6, 1912, and culminated in a series of violent eruptions. Rated a 6 on the Volcanic Explosivity Index, the 60-hour-long eruption expelled 13 to 15 cubic kilometers (3.1 to 3.6 cu mi) of ash, 30 times as much as the 1980 eruption of Mount St. Helens. The erupted magma of Rhyolite, Dacite, and Andesite resulted in more than 17 cubic kilometers (4.1 cu mi) of air fall tuff and approximately 11 cubic kilometers (2.6 cu mi) of pyroclastic ash-flow tuff. During the 20th century, only the 1991 eruption of Mt. Pinatubo in the Philippines were of a similar magnitude; Pinatubo ejected 11 cubic kilometers (2.6 cu mi) of tephra. At least two larger eruptions occurred in the 19th century: the 1815 eruption of Tambora (150 km3 (36.0 cu mi) of tephra), and the 1883 eruption of Indonesia’s Krakatoa (20 km3 (4.8 cu mi) of tephra).

Figure 10 – Novarupta map: Approximate location of the June 6th, 1912 eruption. Ash fell on the town of Kodiak for three days, and although the town was about 100 miles from the volcano, it was covered with over one foot of ash which collapsed many buildings. Courtesy of Geology.com and MapResources.

There’s a interesting article on the Geology.com website about the eruption that you might find useful.

The latitude of the Novarupta eruption was just about perfect at 58° north for maximum effect across the northern hemisphere, as was the timing of the 6th of June to coincide with the cold months of August, September and October of 1912 in the CET series. I should imagine that the ash from the eruption would have taken at least a month or so to completely encircle the northern hemisphere and reduce the amount of sunlight. I am of course completely guessing that this was the cause of the cold August of 1912, I’ll have to spend some more time looking at NCEP reanalysis surface temperature data for 1912 to see just what affect it had on other countries across the northern hemisphere to completely be sure of my assertion.

Finally here are the daily CET values for the Summer of 1912 (fig 11), which I think says it all. This is one of the better articles that I’ve put together for my blog, I found little evidence of any link between the cold August of 1912 and Novarupta in any of my climate and weather books, and even though Philip Eden does mention the poor summer of 1912 in his book ‘Great British Weather Disasters’, he doesn’t make the link with the volcanic ash of Novarupta. August 1912 does get a short mention as the worst on record in the book ‘The Wrong Kind Of Snow’, but again no mention of why. So if you thought that August 2017 has been cool in its first ten 10 days, the mean temperature for the first 10 days of August 1912 was 2.5°C colder still.

Figure 11

Has the summer gone to pot?

Figure 1

The summer has just been going down hill since the end of the first week of July sunshine wise. The sunshine accumulations for Jersey, which is currently the sunniest spot in the British Isles this summer, traces its decline quite well (fig 1). And if you thought it was bad where you are, spare a thought for those in Aviemore Scotland (fig 2), they’ve only seen 211 hours of sunshine compared to the 481.9 hours in Jersey, so perhaps the cooler and cloudier conditions further north and west have now spread across the entire country.

Figure 2

Temperatures are not doing much better either, here as a guide are the daily CET values so far for this summer (fig 3). The heatwave in the middle of June now seems just a distant memory, and there has been a definite cooling trend in the second half of July.

Figure 3

The poor old southeast

Figure 1

It’s not often that you can say this, but the poor old southeast didn’t score very high on yesterday’s (24 July) summer index. It was cloudy and cool in the moderate northerly airstream, I’m sure that there’s a much better chance of the cloud clearing today. I thought that Exeter might be the sunniest place in the UK (fig 2 & 4), but the time of year and the 23.5° inclination of the Earth put paid to that, and Edinburgh, with 15.3 hours took the honours.

Figure 2

As regards highest temperature, again I thought Devon might have topped that table, but Hurn in Dorset, with a late burst of 6.6 hours of sunshine in the afternoon took that accolade with 24.5°C (fig 3). I reckon it’s about time that the Met Office put an AWS in mid-Devon, because in yesterdays northerly flow down from off Exmoor, gave Bradninch a maximum of 25.9°C, which although a bit on the high side, are seldom reflected in temperatures from Exeter airport just 10 km to the south.

Figure 3

Figure 4

 

Sunny start to July 2017

Sunniest place is Jersey with an average of almost 10 hours a day for the first week, but very dismal in the Highlands of Scotland and the west of Ireland, with Connaught seeing only 7.3 hours during the whole week.

June 2017 – sunshine

Jersey just pipped Manston in June as the sunniest place in the British Isles from sunshine figures available in the 06 UTC SYNOP reports (fig 1).

Figure 1

The sunshine network available from the SYNOP reports is a little bit on the holy side (fig 2), I realise that there are many more stations that the Met Office collect daily sunshine data from that don’t report in SYNOP format, but for goodness sake why not? I notice that recently Tibenham has come on-line in Norfolk, I am not sure if it’s a completely new AWS station, or if they’ve promoted a climatological station by giving it a SYNOP number. Of course, there is no obvious reason why the Met Office can’t just provide all the climate stations with a WMO station number and fill in the holes in the SYNOP network across the UK, not only as regards sunshine, but also rainfall, temperature and wind. The SYNOP format is not great for reporting climate data with, but it’s much better than just sitting on the daily data as they’ve been doing for many years.

Figure 2