The BoM Cobar Meteorological Office is adjoining housing on the north edge of Cobar, a mining and pastoral town in remote New South Wales population ~4,000. A BoM MO is professionally staffed.
The Airport is several km away to the SW – these minimum temperature readings for May show a UHI of a few degrees most mornings. 
Obviously if mornings are too breezy – the relationship gets perturbed. You can see here that lately there are only light zephyrs in the early mornings when minimum temperatures are recorded.
The BoM classifies Cobar MO as “non-urban” – despite housing a stones throw away. Not on this planet.
C’mon Warwick
Even you can figure this out – the hint is in the site altitude.
Though I’ve never been there – the met office site is higher – and more exposed to winds. You can see that the wind at the AWS at the Airport drops down to calm overnight as an inversion set in – and consequentially gets colder than the windy Met Office. Colder temps in valleys is meteorology 101.
I’m disappointed you didn’t note that that the Met Office is warmer even when the winds are blowing from a different direction to where the town is located!
On another subject – no doubt dear to your heart – I do see that an excellent paper has recently been published on Australian temperatures prior to 1910. Didn’t seem to reference any of your work though.
Kind regards
George
(ps good luck with the upcoming El Nino – looks like being an exceptionally hot year – unless we can manufacture a decent volcanic eruption)
Hey George
The guys at Cobar ( possibly at other High Quality Station too) have an interesting aid to helping the AGW mantra.
The official Stevenson Screen Box is mounted on the top of a 65mm gal post.
A primary school kid [ we will call him little Johnnie* ] could work out this post acts as a radiant heat collector as soon as & as long as the sun illuminates it.
Now little Johnnie would probably work out that when the days are relatively still this warmed steel heat sink would conduct/convect its collected radiant heat into the adjacent air .
Further, little Johnnie could picture in his mind’s eye that warmed air rising up to the bottom of the said Stevenson Screen Box briefly flowing sideways & then up against the down tilted louvers on the sides which “harvest” the thermally enhanced air right where that BoM thermometer can record it for scientific posterity. Sweet!
So when the teacher asks for comments after the obligatory showing of Al Gore’s movie, she might just get a couple of smart arse but truthful responses from little Johnnie.( the little bastard!)
*All names & identities altered to protect the innocent ( except Cobar Met Office)
George – glad to see you are still taking a lookin now and again – if you check out these two BoM pages with statistics for the MO and AP you will see the Annual mean min for COBAR AIRPORT is 11.6 and for the MET office is a UHI assisted 12.8.
MO
www.bom.gov.au/climate/averages/tables/cw_048027_All.shtml
AP
www.bom.gov.au/climate/averages/tables/cw_048237_All.shtml
Now you raise the issue of altitude – yet you know the lapse rate would require a slightly cooler T at the slightly higher MO. I note too that differencing the annual mean mins just for the years the stations overlap – 1994-2014 – the difference is 1.4 degrees. 13 at the MO minus 11.6 at the Airport. That means for over 7500 days – averaging out all the variations in wind – all your inversions George – averaging 80 odd seasons – the MO minimums are stubbornly warmer.
Warwick
Here’s a hint – the January mean minima are identical – and the July minima are separated by 2.9 degrees C. It is meteorology 101 – cold air drains into the valleys and produces colder minima. I’m very very very surprised that you are not familiar with the impact of inversions and valleys – and you an expert on homogenisation – especially in a place like Canberra!
George
Tom
Go hug a tree in the middle of the night during winter (I’m sure you’re not a tree hugger by nature – but give it a crack) and then go and hug a lamp pole.
Guess which one will keep you warm and cosy – and the other make you cold?
Regards
George
Ahoy George
Actually my job & life has me averaging between 50 – 100 nights a year in the swag My work is pretty much hands ( & boots ) on out in the field ( since 1978).
Further, I have been known to have the odd fire to ward off the cold ( a bit of short cycle carbon so I guess that is ok).
As for getting a grip on big wooden things at night; I’ll leave that to the experts & aficionados, mostly politicians & their blinkered bedazzled self-righteous hubristic support teams from both ends & all diverticles on the spectrum.
YAY GetUp NOT!!!
“from both ends & all diverticles on the spectrum”.
Sorry I should have said both ends of the colon.
So we agree then that the “65mm gal post” is not making the slightest difference to the minimum temperature. Excellent.
George.
Sounds like as classic case of UHI.
Cobar AP started in 1994 so I calculated the minimum av temp for the past 21 years for both the AP and the MO.
AP – 11.6C
MO – 13.1C
These w/s are only a few kms apart and around the same elevation yet show a 1.5C difference over 21 years.
On the other hand, both the MO and AP’s annual max temps have been comparable until 2012 when the AP began to show an increase in warming by margins of 0.3/0.4C.
BTW, the max temps haven’t changed much in Cobar.
Cobar PO (1881-1965) av max mean was 25.9C compared with the AP (25.9C) . The MO (1962-2015) at only 25.3C.
Unless they have shifted the AP station I believe it is not well located being quite close to the terminal and bitumen apron. When planes turn in front of the terminal the exhaust can affect temperature and wind readings. The pilots I flew with (up the front a few times) trusted their own sight and readings on the instrument panel. They always circled at least once before landing.
It is correct that the AP is only a few kms from the town. There is an industrial estate just outside the airport terminal gates.
George Bailey of course as an BOM and AGW apologist does not know what he is talking about. Anything he says is likely to be the opposite of the truth.
Warwick (part 1 of 2 – 6th attempt to post)
Following your reasoning temperatures should average 1.3 degrees warmer at the MO than at the Airport. Given that this should be evident only when the wind blows from the direction of the town – temperature differences should be even higher when the winds blow from the SW or S. here is the data from the last day when winds blew from the SSW.
While the wind blew at both sites – the average difference was only 0.17C
Time of obs MO T APT T Diff MO Wind
08 10:00pm 10.4 09.8 +0.6 SSW
08 09:30pm 10.6 10.8 -0.2 S
08 09:00pm 11.3 11.2 +0.1 SSW
08 08:30pm 11.4 11.2 +0.2 SSW
08 08:00pm 11.9 11.2 +0.7 SW
08 07:30pm 12.2 11.0 +1.2 SW
08 07:00pm 12.7 11.9 +0.8 WSW
08 06:30pm 13.4 13.4 +0.0 WSW
08 06:00pm 14.3 14.9 -0.6 SW
08 05:30pm 15.6 16.0 -0.4 SW
08 05:00pm 16.2 16.7 -0.5 SW
(part 2 of 2)
If inversions are the likely mechanism then the difference should become apparent only when the winds go calm at the Airport but not at the MO. Look what happened when the wind went calm at the airport.
Time of obs MO T APT T Diff
09 05:00am 6.2 2.9 +3.3
09 04:30am 5.3 3.0 +2.3
09 04:00am 6.0 3.4 +2.6
09 03:30am 7.1 3.4 +3.7
09 03:00am 6.8 3.6 +3.2
09 02:30am 6.6 4.3 +2.3
09 02:00am 6.9 4.5 +2.4
09 01:30am 7.4 4.8 +2.6
09 01:00am 8.0 4.4 +3.6
09 12:30am 8.7 5.5 +3.2
09 12:00am 8.8 6.4 +2.4
The average difference is 2.87c.
Science is a powerful weapon.
George
Cementafriend
I’m not sure about cement – but google should be your friend if you don’t want to embarrass yourself.
It is very easy to call up the site survey for Cobar AWS.
The apron is 175 m away at its closest point from the AWS. The runway is 250m. It hasn’t moved since 1993.
Maybe an A380 at full thrust may be able to tweak the temperatures a little – but I doubt it. The twin engine Metroline turbo props that flew into Cobar for a while in 2010 would struggle to blow a fly off your face at 50m. There is no regular RPT into Cobar now.
As far as the “industrial estate” – I almost fell off my seat laughing when I “satellite mapped” the location on google!
Anyway – kind regards and best wishes to your family.
George.
Cementafriend
I’m not sure about cement – but google should be your friend.
It is very easy to call up the site survey for Cobar AWS.
The apron is 175 m away at its closest point from the AWS. The runway is 250m. It hasn’t moved since 1993.
Maybe an A380 at full thrust may be able to tweak the temperatures a little – but I doubt it. The twin engine Metroliner turbo props that flew into Cobar for a while in 2010 would struggle to blow a fly off your face at 50m. There is no regular RPT into Cobar now.
As far as the “industrial estate” – I almost fell off my seat in amusement when I “satellite mapped” the location!
Anyway – kind regards and best wishes to your family.
George
Ahoy Ian George ( & George B)
I was having a chat to a local cockie from Cobar a couple of days ago, He was an “exchange” operator for a node on a party line probably around the 60s era. He has also at times been a Cobar councillor. The Council chambers are currently directly opposite the PO & were formerly adjacent to the PO so I guess he knows what he was talking about.
He told me the PO Stevenson Screen box was in a small tin fenced back yard at the back (west) of the PO which itself is a brick ( thermal mass?) building.
I guess it stands to reason that plonking a new Cobar MO box in open exposed ground on the top of a local hill ( there is a town surge tank water storage ~120m north of the box) would expose the contained thermometer to a bit less extreme UHI.
However as George B’s first table suggests( & having been based in Cobar for 20 years can anecdotally confirm) the dominant wind direction is W-SW.
Taking this & the google map showing town, it is a no brainer that when the air is moving through town, the “Rural” Cobar MO station does get a bit of a helping hand ( & George B; when it is not moving the post probably helps)
Most of the 40 or so weather balloon radiosonde carcases I have encountered have been north & east of Cobar. ( but that is arguably work subjective).
This chart of MO minus Airport monthly differences for max & min over full 1994-2014 period the stations overlap clinches it for me – classic UHI signature with the urban area influencing the nearby MO night-time readings to be warmer mainly in the colder months.
If the lapse rate was 6.4 degrees C per km that would make the Airport ~0.25 warmer than the MO – note that the annual average for the MO minus AP max is -0.4.
Warwick
I guess when the only tool in your kit is a hammer – then everything looks like a nail.
When the winds are blowing from the SW – according to your hypothesis – then overnight temperatures should be 2 degrees warmer at the met office than at the Airport.
Guess what – it doesn’t happen. Take tonight for example
Cobar MO
12th 07:30pm t:15.2 wind: SW 17
Cobar Apt
12th 07:30pm t: 15.5 wind: SW 19
According to your hypothesis – Cobar MO should be 2 degrees warmer. It isn’t.
The reason that Cobar Apt eventually gets colder at night is that it is in a valley – a shallow inversion develops and the wind drops off, nocturnal surface radiation kicks in and the temperature drops.
It is simple basic meteorology.
George.
Warwick
You might find this a good read on the subject – then again it is a Met Office project – so I suspect that you may be inclined to ignore this.
onlinelibrary.wiley.com/doi/10.1002/qj.2159/abstract
George
Thanks cementafriend.
Not sure what to make of this, Warwick.
This morning (13th May) temps for Cobar.
AP min 7.5C v MO min 10.0C.
Winds from the SSW.
At midnight:
Apt Wind SW 9 km/h – Temp 5.8
MO Wind SW 9km/h – Temp 5.4
UHI => Negative 0.4c
We can keep doing this all winter long, Warwick. Simple basic meteorology.
George.
George,
This morning (14 May)
MO min 3.0C (4:00am)
AP min 0.2C (6:35am)
As ACORN uses the MO, the 3 degrees will stand.
MO min average for May is 9.0C.
AP min average for May is 6.7C.
Exactly Ian.
One set of values will illustrate a exposed hilltop environment, the other a shallow valley environment subject to nocturnal winter inversions. Simple basic meteorology.
Geroge
Hardly call the Cobar AP ‘in a valley’.
www.google.com.au/maps/place/Cobar+Airport/@-31.535,145.79333,2a,90y,90t/data=!3m5!1e2!3m3!1s12237899!2e1!3e10!4m2!3m1!1s0x6b0261b0fbde4b29:0x1d0609b5909e1d10!6m1!1e1?hl=en
For today (15th May)
AP lowest min was 1.2c at 5:34am
MO lowest min was 4.7C at 4:45am.
Hi Ian
Nice way to misquote me. I said shallow valley. Google earth is your friend – elevations are 10m higher to the NNW and 17m higher to the ESE over a distance of 1.5 to 2km. If you look at the satellite image you can actually see that the airport is part of a shallow river valley extending away to a (dry?) river system to the SW.
I also see that you believe in magical UHI. When the winds blow at both sites from the SW – there is no UHI. It only appears “by magic” when the wind dies down at the airport.
Here’s a tricky question for you all to answer. When the night time winds blow from the N or NE at Cobar – what will happen? Remember there is no town site upstream – so will there be a difference between Cobar and the airport (when the airport goes calm) – or not?
Warwick – what do you think will happen?
George
Sorry George,
Where did I ever say above that I ‘believe in magical UHI’ in this particularly case? I’ve just looked at the data and have seen a disconnect between the two stations which are only a few kms apart (which you have explained above in detail).
If BoM used the AP records instead of the MO records for its ACORN data, what would the min temps look like?
UHI does have some effect over time in urban areas but adjusting temps are a bigger problem.
A case in point is GISS data for Cobar (presumably the MO as it starts in the ’60s).
‘Raw temp’ GISS v2
data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=501947110003&dt=1&ds=1
‘Adjusted temp’ GISS v4
data.giss.nasa.gov/cgi-bin/gistemp/show_station.cgi?id=501947110000&dt=1&ds=14
Correct Ian – you didn’t mention UI specifically until your post.
However – the two sites are not “only a few kms apart ” – in fact it is about 6.8 km.
Apart from that I’m not quite sure what point you are making! Having the Airport nearby is great – and will allow for estimates of change in characteristics at Cobar – but don’t for a second think that the 1, 2 or 3 difference in temperatures between the sites is due to UHI. It isn’t.
And that is simple basic meteorology.
Still waiting for your response Warwick on the question above ..
Regards
George
I didn’t say UH effect was a factor in a place the size of Cobar.
My point was that if the ACORN data was based on the AP there would be a marked difference in the overall mean temp range for Cobar.
MO
www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=38&p_display_type=dataFile&p_startYear=&p_c=&p_stn_num=048027
AP
www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=38&p_display_type=dataFile&p_startYear=&p_c=&p_stn_num=048237
Just for interest, what comment do you have to make on the ‘adjustments’ to Cobar’s mean temp by GISS?
Still mystified Ian
ACORN exists to establish trends – the absolute value performs no useful function. How will the Airport having a wider temperature range (on average) be significant?
I don’t have any comment to make about the GISS as I haven’t seen what is driving any apparent change. No process is perfect – that’s why there are different solutions in play. But from what I’ve looked at they all work very hard to made justifiable changes to data.
George
Holy calamity Batman
Winds on morning of the 21st were E to ESE
Mins: Airport 0.9, Met Office 2.4
Winds on the 22nd were E to ENE
Mins: Airport 3.1, Met Office 4.4
So winds aren’t blowing from the town – but the met office is still warmer.
How do you wish to explain this Warwick?
George
Hi all
-40.9 today – starting the rebound back up – never the less looks like June’s SOI will fall below -7 before months end.
I’m wondering where all those commenters are that claimed El Nino was over? Or that the future couldn’t be forecast with a good level of accuracy?
George