it would be interesting to see a graph of aircraft take off and landings for that day and just wonder if they were just clearing a bit of a delay on long distance 747's at around the time the maximum occurred.

On 07/07/2015 15:01, Scott W wrote:

Puts to bed my criticisms from last week

http://blog.metoffice.gov.uk/2015/07...ng-a-heatwave/


I wonder whereabouts on the airport the weather station is actually
located? Yes, I could check Google Maps, but the area is so large, it'd
be a needle-in-a-haystck search.

--

Paul Hyett, Cheltenham

From comments here and elsewhere the biggest criticism seems to be that the probe at Heathrow may be too sensitive - the spike that people seem to be worried about would not have been recorded with the old style Mercury-in-glass thermo. I think a solution could be a full article on on the Heathrow climate station is needed - where it is, what material is it made from, what instrumentation is used etc. Perhaps they could record something for the One show - send John Hammond and Carol Kirkwood down there together with someone, say Stephen Burt, from the CoL community, to let viewers make their own conclusions?

"Scott W" wrote in message
...

From comments here and elsewhere the biggest criticism seems to be that the
probe at Heathrow may be too sensitive - the spike that people seem to be
worried about would not have been recorded with the old style
Mercury-in-glass thermo.

I don't think that's necessarily the correct conclusion. Without knowing the
response times of the relevant glass and electronic sensors it's difficult
to say, but my first instinct would be that the two are probably not very
different.

What I was flagging up elsewhere in the thread is that the peak was very
transient and being able to see this is a result made possible by the
one-minute resolution in the data record offered by a modern electronic AWS
as compared to the traditional one-shot Tx value in each 24-hour period.
It's entirely possible that many other records and near-records might show a
similar transient effect, but that will only become evident over time as the
records are studied and published in more detail.

But the other points were wondering to what extent this might be an internal
instrumental peak that's not fully representative of the surrounding air
mass and/or, as others have said, whether central Heathrow is a special
case. Just to repeat, this doesn't invalidate any record - it appears to be
a valid site-specific reading, but it might help to understand what was
happening.

Vidcapper wrote:

On 07/07/2015 15:01, Scott W wrote:

Puts to bed my criticisms from last week

http://blog.metoffice.gov.uk/2015/07...ng-a-heatwave/


I wonder whereabouts on the airport the weather station is actually located?
Yes, I could check Google Maps, but the area is so large, it'd be a
needle-in-a-haystck search.


The meteorological instrument enclosure is on the north side of the airport.
It's about 130 metres north of the edge of the northern runway and about 20
metres south of the northern perimeter road. It is about 180 metres ESE of the
northern entrance to the tunnel at the south end of the M4 spur. Co-ordinates
are 51°28'45"N 0°27'2"W. It's probably broadly representative of the airport
environment but if the area was farmland rather than an airport no doubt the
temperatures would be somewhat different at times. Not only are there areas of
airport concrete in the vicinity there are also very large expanses of car park
nearby.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

https://tallbloke.wordpress.com/2012...3772-heathrow/

On Wednesday, July 8, 2015 at 8:26:49 AM UTC+1, JohnD wrote:
"Scott W" wrote in message
...

From comments here and elsewhere the biggest criticism seems to be that the
probe at Heathrow may be too sensitive - the spike that people seem to be
worried about would not have been recorded with the old style
Mercury-in-glass thermo.

I don't think that's necessarily the correct conclusion. Without knowing the
response times of the relevant glass and electronic sensors it's difficult
to say, but my first instinct would be that the two are probably not very
different.

What I was flagging up elsewhere in the thread is that the peak was very
transient and being able to see this is a result made possible by the
one-minute resolution in the data record offered by a modern electronic AWS
as compared to the traditional one-shot Tx value in each 24-hour period.
It's entirely possible that many other records and near-records might show a
similar transient effect, but that will only become evident over time as the
records are studied and published in more detail.

But the other points were wondering to what extent this might be an internal
instrumental peak that's not fully representative of the surrounding air
mass and/or, as others have said, whether central Heathrow is a special
case. Just to repeat, this doesn't invalidate any record - it appears to be
a valid site-specific reading, but it might help to understand what was
happening.

Agreed. I also think some may be missing the point here, especially with Len's 6/10 comment, which I feel was very harsh and was effectively judging the MetO on something the writer of the article never intended to do. The point here is not so much about whether Heathrow is the best recording station, due to the tarmac and aircraft exhausts (most would question, including me), but whether the excessive (and record for this site) heat experienced was commensurate with other sites.

I think the MetO article shows that it clearly was. Other sites exceeded records by a similar and in some cases, a greater degree than did Heathrow.

On 08/07/2015 08:54, Norman wrote:
Vidcapper wrote:

On 07/07/2015 15:01, Scott W wrote:

Puts to bed my criticisms from last week

http://blog.metoffice.gov.uk/2015/07...ng-a-heatwave/


I wonder whereabouts on the airport the weather station is actually located?
Yes, I could check Google Maps, but the area is so large, it'd be a
needle-in-a-haystck search.


The meteorological instrument enclosure is on the north side of the airport.
It's about 130 metres north of the edge of the northern runway and about 20
metres south of the northern perimeter road. It is about 180 metres ESE of the
northern entrance to the tunnel at the south end of the M4 spur. Co-ordinates
are 51°28'45"N 0°27'2"W. It's probably broadly representative of the airport
environment but if the area was farmland rather than an airport no doubt the
temperatures would be somewhat different at times. Not only are there areas of
airport concrete in the vicinity there are also very large expanses of car park
nearby.

I used to work at Heathrow in the 70s and was one of the observers. The
enclosure is still where it was then. Looking at the Google satpic, the
tarmac in the enclosure's vicinity doesn't appear to be that different
to nowadays (perhaps less in the immediate area) and the nearby car
parks have been there since the 70s as well. So not a lot of change
there. The road just to the north (colloquially called the peri track)
wasn't as wide though. One thing to note is that the taxiway just to its
west (now has a big X on eh entrance to the runway) was live in those
days. There's obviously been a few changes as aircraft could be taxied
along that and in front of the enclosure (where the now narrow strip of
road is heading west/east). So jets could be much closer to the screen
than nowadays. I have photos which show this.

Even the hotels along the A4 were there at the time (though some have
been replaced AFAIK).

And the airport centre has always been a heat island - I've seen fog
drift in from the west and just dissolve as it got to the centre and in
a NEly, slight showers of snow being beefed up and dropping a lot of
snow to the Airport's SW.

No doubt there have been changes which may have been significant, but
then don't the climatologists make allowances for this. I know that even
such mundane things as SST measurement had to be adjusted by the method
and material of actually measuring the sea temp - the buckets used to
get the water had different characteristics and work was done to
homogenize the results.

Just my 2 pennyworth

Metman2012 wrote:

snip

No doubt there have been changes which may have been significant, but then
don't the climatologists make allowances for this. I know that even such
mundane things as SST measurement had to be adjusted by the method and
material of actually measuring the sea temp - the buckets used to get the
water had different characteristics and work was done to homogenize the
results.

Just my 2 pennyworth


As you imply, the sea surface temperature measurement can vary significantly
dependent on what method is used for the measurement. Unfortunately, the method
used is not usually recorded. For example, on the Ocean Weather Ships (at least
on the British ones) any one of the following could be used:

- canvas bucket (usually used only in relatively benign weather)
- rubber bucket (usually used only when under way)
- thermistor loctated somewhere in the engine-room sea water intake
- direct measurement of the engine-room sea water intake (turn on
a tap and stick a thermometer into the water)

The first 2 methods sampled the water at, or very close to the surface. The
other 2 sampled the water a few metres below the surface. It was up to the
individual observer to decide which method was used at each observation. I
don't know if any comparative tests were ever made. I can't recall any during
my time on the Weather Ships.


--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org

"Norman" wrote in message
...
Metman2012 wrote:

snip

No doubt there have been changes which may have been significant, but
then
don't the climatologists make allowances for this. I know that even such
mundane things as SST measurement had to be adjusted by the method and
material of actually measuring the sea temp - the buckets used to get the
water had different characteristics and work was done to homogenize the
results.

Just my 2 pennyworth


As you imply, the sea surface temperature measurement can vary
significantly
dependent on what method is used for the measurement. Unfortunately, the
method
used is not usually recorded. For example, on the Ocean Weather Ships (at
least
on the British ones) any one of the following could be used:

- canvas bucket (usually used only in relatively benign
weather)
- rubber bucket (usually used only when under way)
- thermistor loctated somewhere in the engine-room sea water
intake
- direct measurement of the engine-room sea water intake (turn
on
a tap and stick a thermometer into the water)

The first 2 methods sampled the water at, or very close to the surface.
The
other 2 sampled the water a few metres below the surface. It was up to the
individual observer to decide which method was used at each observation. I
don't know if any comparative tests were ever made. I can't recall any
during
my time on the Weather Ships.


So the years of research put into homogenizing the SST dataset was a waste
of time as vital information would be missing?

Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------