June CET

[chionomaniac]

Now if I am right I think the official June CET has come out at 14.8C (0.4C downward correction)

http://hadobs.metoffice.com/hadcet/cet_mean_2009

Edited July 1, 2009 by chionomaniac

[Eugene]

Only the late very warm spell saved me from recording my coldest June in 10 years, earlier in the month i recorded my coldest June day since 1997 and a ground frost, the first i've ever recorded this decade in June, so the final figure kind of flatters this June which was pretty poor to me.

Edited July 1, 2009 by Eugene

[Stargazer]

As for the June CET - after the cool first half I'm surprised my guess of 14.7 has been exceeded by a fair margin.

Well well - after an unusually large downward correction that margin wasn't as fair as I expected - I was only 0.1 deg C too low :lol:

Edited July 1, 2009 by Stargazer

[Scorcher]

Now if I am right I think the official June CET has come out at 14.8C (0.4C downward correction)

http://hadobs.metoffice.com/hadcet/cet_mean_2009

Why such a big downward correction? Anyone know? 14.8C seems too cool to me considering the very warm last 10 days.

[Snowly does it]

Why such a big downward correction? Anyone know? 14.8C seems too cool to me considering the very warm last 10 days.

Manley has been consistently 0.3 to 0.4 below the Hadley figure - some of the minima during the colder spell from 4th to 20th June seemed rather high and perhaps these or the maxima have been corrected.

The period 4th - 20th June was pretty cool with a colder snap involved and its only really 24th onwards that was really warm and only the last 3 days that were 'hot'.

More 'time' this month was cool but the warm spells were very warm, hence a month that is above average, but not by much.

Just under 15 seems spot on to me - a few hot days doesn't undo all the work of a cool fortnight.

[AtlanticFlamethrower]

Why such a big downward correction? Anyone know? 14.8C seems too cool to me considering the very warm last 10 days.

If the official figure has to be corrected by nearly half a degree (-0.4C) you have to wonder how scientific the series actually is now.

Human judgment should be at a minimum, yet human judgment may account for +/- 0.3 (or even 0.4) degrees in a month, the size of corrections we have had over winter and now in a summer month.

This is particularly staggering considering the official Hadley series is citied by many as a reliable indicator of global warming.

Edited July 1, 2009 by AtlanticFlamethrower

[Snowly does it]

Yes, just had a look at the quality controlled series and some downward correction during the cooler snap.

June 6th 2009 now stands out like a sore thumb - it came in at 9.8 and is therefore the only summer day so far in the 21st century to come in in single figures for the CET zone and is the coldest summer CET day since the cold June of 1991.

The hot spell is really quite something against that backdrop!

[❄️❄️❄️❄️❄️❄️❄️❄️❄️]

Yes, just had a look at the quality controlled series and some downward correction during the cooler snap.

June 6th 2009 now stands out like a sore thumb - it came in at 9.8 and is therefore the only summer day so far in the 21st century to come in in single figures for the CET zone and is the coldest summer CET day since the cold June of 1991.

The hot spell is really quite something against that backdrop!

Wow, just 3.5 weeks ago and the average temp was (10.4?) and yet on the 29th it was 21.4C!

[Snowly does it]

Wow, just 3.5 weeks ago and the average temp was (10.4?) and yet on the 29th it was 21.4C!

Yes, the controlled 6th June has actually come in at 9.8, so the temperature acorss the board was 11.6 degrees higher on the 29th - this is slightly less than the difference between December's average temperature and July's!!!

[AtlanticFlamethrower]

Yes, just had a look at the quality controlled series and some downward correction during the cooler snap.

So there is a parallel control series against which they double check the results of the main Hadley series to see if there is any disagreement.

This month the parallel series read 0.4C cooler over the cooler spell. That explains the big downward adjustment at the end of the month.

Presumably the weather stations of the parallel series are in a slightly different location to those in the official series so the transposition of data from one series to the other requires an element of judgment.

The Netweather temperature tracker read 15.61°C for June, +0.8C from Hadley. But I guess this tracker is unadjusted for Heat Island effects because the previous five months have also been consistently above Hadley (+0.6C, +0.4C, + 0.3C, +0.4C, +0.5C).

Edited July 1, 2009 by AtlanticFlamethrower

[Thundery wintry showers]

The Hadley version of the CET does indeed seem to be prone to an inhomogeneity of up to 0.3-0.4C per month relative to Gordon Manley's original work- if I remember rightly this was even acknowledged in one of their papers that was linked to from N-W. However, it is not part of any kind of AGW bias. If anything, I think some of the Hadley CET values have been a bit on the low side, indeed in 2005 they corrected some of their values upwards. In addition, such inhomogeneities will tend to cancel each other out over the course of a year.

I strongly believe that the warming shown by the Hadley series is well in excess of any uncertainties in the final values, and in addition it is backed up by Philip Eden's series.

The N-W tracker does tend to overestimate by about half a degree for whatever reasons.

Yes, the end of June has seen quite a remarkable contrast with the cold weather early in the month, especially the 6th. I think that for many parts of the country it's been a very interesting month indeed with plenty of variety.

[J10]

The latest scores are now in,

Three players got it right this month, so well done to The PIT, sufc and Potent Gust

Overall Stargazer leads from Don with RAIN RAIN RAIN in 3rd place, but it remains very close at the top.

[AtlanticFlamethrower]

Congratulations to the winners this month.

The N-W tracker does tend to overestimate by about half a degree for whatever reasons.

So do you think heat island is a reasonable explanation?

It must be an interesting "discovery" for you anyway, in the sense that it seems to consistently run above the Hadley series. The discovery being the reason why that happens.

[Snowly does it]

So do you think heat island is a reasonable explanation?

It must be an interesting "discovery" for you anyway, in the sense that it seems to consistently run above the Hadley series. The discovery being the reason why that happens.

I could be wrong but I assume its because the NW is a 'tracker' and Hadley measures minima plus maxima/2

Maxima will maintain for a large part of the day, minima tend to represent a shorter period (the dawn dip for example) and as such, a tracker will tend to be higher than a min/max measure as it is tracking a higher temperature for most of the night but a fairly consistent temp during the day.

I would expect this to work the opposite way around under an inversion HP in winter however.

[Guest Mike W]

It's in the series section at 14.8 also: http://hadobs.metoffice.com/hadcet/cetml1659on.dat

[damianslaw]

Bit of an odd month with the CET starting off on an exceptional high note thanks to the warm 3 opening days, then it took a dramatic nose dive thanks to what turned out to be a noticeably cold couple of days on the 6th and 7th, then we saw only a slow climb of the CET thanks to relatively cool conditions, only for it to rapidly rise during the last week.

In this context it has been a very interesting month, on a par with January and February this year in terms of variance of CET from average values at different stages.

[Iceberg]

I've read all the comments above, but that figure just doesn't seem right as it's lower even than Manley.

This is also incredibly early to release the figure which makes me a bit suspicious as well, possibly the earliest I've ever know. !

[The PIT]

I ain't protesting too much. Got one right hurray hurray.

[Snowly does it]

I've read all the comments above, but that figure just doesn't seem right as it's lower even than Manley.

This is also incredibly early to release the figure which makes me a bit suspicious as well, possibly the earliest I've ever know. !

Its been out on the 1st before Iceberg, its not that unusual.

It is a large downward correction, but January was corrected down by 0.3 this year also (and corrected to 0.1 below Manley also)

0.3 above Manley is surely a far more suspicious figure than 0.1 below it??

I think expectations get skewed by the most recent conditions - yes a hot end to the month but it was never 'flaming June.'

[Weather-history]

Very confusing stats on the media wires about the status of June 2009. Reported as the hottest, driest and sunniest since July 2006.

That implies it was the hottest, sunniest and driest month since July 2006. September 2006 was far warmer, indeed June 2009 was cooler than June 2007 for the CET. April 2007 was far drier as well.

[AtlanticFlamethrower]

I could be wrong but I assume its because the NW is a 'tracker' and Hadley measures minima plus maxima/2

Let's test this then.

Hadley: max 28C min 13C = 20.5C

Sample average of 24 data points, one for each hour in the day (a "tracker")

15 (One O'clock)

14

14

13

13

13 (Six AM)

16

18

20

23

25

27 (Noon)

27

28

28

28

28

28 (Six PM)

27

24

22

19

17

15 (Midnight)

Average 24 records: 20.9C

That's +0.4C over Hadley's and what you would expect if they were using a different way - a tracking methodology - to average temperature.

This can yield consistently higher figures over Max/Min when the periods of maxima are long and the periods of minima are short.

I would expect this to work the opposite way around under an inversion HP in winter however.

For February and January the Netweather tracker ran +0.6/+0.4C over Hadley, this at a time when the minimum temperature hangs around for the longest time.

etweather's +0.8C over Hadley in June was an exceptionally large bias. Perhaps therefore there is a +0.4C bias in addition to the methodology bias, which is due to location of weather stations and urban warming effects.

[Stargazer]

Very confusing stats on the media wires about the status of June 2009. Reported as the hottest, driest and sunniest since July 2006.

That implies it was the hottest, sunniest and driest month since July 2006. September 2006 was far warmer, indeed June 2009 was cooler than June 2007 for the CET. April 2007 was far drier as well.

I think that just shows how confused the media can get - and sometimes...er...just plain wrong

[Snowly does it]

For February and January the Netweather tracker ran +0.6/+0.4C over Hadley, this at a time when the minimum temperature hangs around for the longest time.

That's true.... maybe the discrepancy is less in winter due to less daylight and homogenous maxima tracking?

[AtlanticFlamethrower]

If there is any urban heat island effects these will be more pronounced when there is greater solar radiation about to heat up, and reflect off surfaces.

I'd imagine a tracker methodology, as I imagined it above, would exacerbate heat island effects.

[Optimus Prime]

If there is any urban heat island effects these will be more pronounced when there is greater solar radiation about to heat up, and reflect off surfaces.

Corrent me if I'm wrong but in urban area, Asphalt usually absorbe the energy (heat) and reflects the light which would result in much higher temperatures in the Urban area.

Perhaps August 1976 being a good example. Warm by night in the city centres but cold out into the countryside as the heat is released slowy in Metropolitans and quicker in Rural areas.

There can be as much as 10c difference between Urban areas and Rural spots.

Edited July 2, 2009 by Optimus Prime