Dublin Airport weather station - photos

Su Campu

There's been a lot of talk here about the differences between the temperature readings at Dublin and Casement Airports, and that the location of the Dublin station is less than ideal, leading to anomalously cold readings at night. I was there today and I can tell you that of all the stations in the country, it's probably the BEST located one!

The station was moved to its current location a few years ago. It is now located in a level grassy area, about 450 metres away from the threshold of runway 10, and about 130 metres south of its extended centreline. It's about 50 metres in from the small R108 road, which is too narrow to have any effect on the temperature readings. The old station was located about 2 kms to the east, south of the tower and much nearer the concrete apron, taxiways and general aeroplane traffic. They have now concreted in the location to make a new aircraft parking area (large white area at Huntstown).









The station is located on perfectly level ground, apart from a slight ridge around 100 metres to the west, as in the photo below, but I see no way that this station can be exposed to cold pooling. I think it's perfectly representative of the surrounding area, and any talk of it being relocated should now be put to bed. If anything the one at Casement is less well located, being only about 20-30 metres from a building, and not much more from the apron where the Garda chopper is parked.

compsys

Interesting thread though I still want to know why on cool, clear nights the station is often the coldest one in the entire country by a long shot? It just doesn't make sense.

Last May, there was a settled spell of weather mid month and almost every night Dublin Airport was colder than stations further north, and stations further inland. It just doesn't make sense. It was also colder during the day (makes sense cause of sea breezes) but the result was that Dublin Airport was the only station to record below average temps that month. The same happened in April.

During summer, the station often suffers from sea breezes on clear calm days, which obviously keeps the temperature a few degrees cooler than inland stations during the day. However, the opposite should be the case at night, as the sea breeze keeps temperatures slightly higher than inland locations. But this doesn't happen at Dublin Airport.

Su Campu

There is no sea breeze at night. The winds reverse to a land breeze, so cooler air will blow from inland towards the coast. So you have the case where Dublin Airport is several degrees cooler during the day, which means it's easy for it to cool quicker during the night.

I'm going to have a good look at data when I get a chance. I have noticed what you speak of, but I also noticed that many times it warmer than Casement. Last week for instance, some nights it was warmer, some it was colder. But what we can say is that whatever the reason, the station is located in the perfect spot, as per the WMO guidelines, better than its previous one.

Sponge Bob

Thatks for that Su, it certianly seems to be a very well located station for the site.

Is it possible that cold arir funnels east out of the midalnds more easily to the Irish Sea across Meath / North Dublin than it does across Kildare/South Dublin or indeed Meath>Castleknock>Phoenix Park....where the latter site appears to have become more sheltered over the years as per a post of mine on the site aspects some months back.

If the cold air 'builds' earlier of a winter evening the temperature trough could be lower. Is the Malahide Estuary an attractor ??

Mothman

compsys wrote: »

It was also colder during the day (makes sense cause of sea breezes) but the result was that Dublin Airport was the only station to record below average temps that month. The same happened in April.

Because it is a new site, there are no proper averages for this site. Most of the Met E reports for Dublin AP don't give averages, but unfortunately this page does and I believe it misleading

Also the old site that Su refers to is not the oldest. The station moved to here in the early 90s from a site outside the main terminal building, I was told near the Chapel, perhaps someone more familiar knows where this is.

Su Campu

The site previous to this would have been more prone to reading higher daily maxima in fine summer weather with an easterly breeze as it would be receiving air from the warm concreted areas to its east. The current site, being totally surrounded by grass, as recommended by WMO, will be free from that anomalous heat, and should therefore be the best tracker of climate in the decades to come.

I think there should be some mention of the change in location made on the met.ie site, because as Mothman said, long-term data means nothing now.

compsys

Su Campu wrote: »

There is no sea breeze at night. The winds reverse to a land breeze, so cooler air will blow from inland towards the coast. So you have the case where Dublin Airport is several degrees cooler during the day, which means it's easy for it to cool quicker during the night.

I'm going to have a good look at data when I get a chance. I have noticed what you speak of, but I also noticed that many times it warmer than Casement. Last week for instance, some nights it was warmer, some it was colder. But what we can say is that whatever the reason, the station is located in the perfect spot, as per the WMO guidelines, better than its previous one.

Aren't areas near the coast supposed to be kept cooler during the day because of the sea but then slightly warmer at night? I remember when I was in Sydney the weather in the city could be 5-6 degrees cooler than the Western suburbs during the day but way warmer and closer at night.

During the spring/summer, Dublin Airport is often cooler during the day (effect of the sea) but then way cooler at night too. Just cold all round sometimes! Surely the logic is that if the sea has enough influence to keep a station cool during a spring/summer day then it also has the influence to keep it slighter warmer at night?

compsys

Current readings - Dublin Airport 4 degrees, Casement 9!

Can there really be a 5 degree difference in temp over such a short space?

lord lucan

compsys wrote: »

Current readings - Dublin Airport 4 degrees, Casement 9!

Can there really be a 5 degree difference in temp over such a short space?

Just looking at IrishMotorists Lucan weather station(http://members.upc.ie/brian.oneill87/lucanweather/CumulusRealtime.html) and it's showing 8.1c at 22.55. I've no idea why there are such variances but i well believe they're possible as i've experienced them travelling from North Dublin to West Dublin.

highdef

Well I'll be heading pass Dublin airport on the M50 soon - It's not exactly the same site as the weather station itself so I expect a higher reading but it may give some sort of inclination as to the temperatures in the area. I'll also be passing the Lucan area on the N4 and I will be leaving the M4 at Kilcock/Clane and onwards to my cold pool village where I will bet money that it will be coldest part of the journey, as it usually is 95% of the time.

I'll report back with temperatures I experienced along the way tomorrow morning

highdef

Well the journey home did not give any support to the Dublin Airport station theory. Although at the same time, I was not expecting it to be nearly as low as the station itself. Between the beginning of the M50 and ballymun heading west on the M50, the car was showing 8c. This was just midnight when the station reading was 3c - A very large difference over a fairly short distance. Although I was in a slightly more built up area and on a tarmacced road, however at this time of night (and year) and at such a late time with so little traffic, I don;t think there would be very much heat coming from the road.

Between Ballymun and Blanchardstown, it rose to 8.5. I turned off at Lucan to head westbound. At this point it was back down to 8. Between here and Maynooth, it varied between 7.5 and 8.5. From Maynooth to my turnoff at Kilcock, it varied between 7 and 8. From kilcock to my turnoff about 3km heading west on the R148, it rose from 7 to 7.5....it normally drops a little along this stretch. From the turnoff to the top of the hill near my village, it rose from 7.5 to 8....this is very unusual as it normally drops about 1c. And finally from the top of the hill to my home at the bottom of the valley, about 1.5km in distance, it dropped to 6c. At home, the weather station was reporting 5.9 in the back garden which supports the car thermometer reading. this was at about 00:30ish.
Heading to bed an hour later, the temp had dropped to 3.2.

Going by the above info, it would appear that there was an inversion over the areas I drove through. I only get higher temperatures at the top of the local hill compared to the R148 during an inversion but I could be wrong. Very high pressure and calm conditions would support this theory too.

So there's the info....make what you want of it. It might be too much info but hopefully it's not too little

compsys

compsys wrote: »

Current readings - Dublin Airport 4 degrees, Casement 9!

Can there really be a 5 degree difference in temp over such a short space?

yes,over a few miles,of course there can.
Driving home from Dublin last night,the car temp dropped at least 5 c in about a half hour-reaching it's coldest south of the beehive.

Danno

Read this... http://www.irelandsweather.com/forum/index.php/topic,2010.msg45253.html#msg45253

A difference of 6c in just 55 metres, using Met Eireann standard thermometers, amazing but true!

octo

Su Campu wrote: »

The site previous to this would have been more prone to reading higher daily maxima in fine summer weather with an easterly breeze as it would be receiving air from the warm concreted areas to its east. The current site, being totally surrounded by grass, as recommended by WMO, will be free from that anomalous heat, and should therefore be the best tracker of climate in the decades to come.

I think there should be some mention of the change in location made on the met.ie site, because as Mothman said, long-term data means nothing now.

The long term averages are based on the 61-90 values, the standard WMO climate period - before the enclosure was moved.

The two enclosures will have been run in parallel for some period of time following the installation of the new station. The data is then compared side by side in a process called homogenisation.

Personally, I think the main 'problem' with Dublin Airport is its proximity to the sea, making it more of a coastal station and not really representative of the city. The effect is to 'flatten out' the highs and lows.

Elmer Blooker

octo wrote: »

Personally, I think the main 'problem' with Dublin Airport is its proximity to the sea, making it more of a coastal station and not really representative of the city. The effect is to 'flatten out' the highs and lows.

The sea has a moderating effect on temperatures so proximity to the sea doesn't really explain the unusually low readings at the airport.
At the moment its 2c at the airport, 6c at Casement and I'm 4c (about 3 miles from the airport)

octo

Elmer Blooker wrote: »

The sea has a moderating effect on temperatures so proximity to the sea doesn't really explain the unusually low readings at the airport.
At the moment its 2c at the airport, 6c at Casement and I'm 4c (about 3 miles from the airport)

Yes, but the wind is from the east....

Compare the mean daily max's and mins http://www.met.ie/climate-ireland/30year-averages.asp . Dublin Airport has lower average max's and higher average mins.

compsys

Danno wrote: »

Read this... http://www.irelandsweather.com/forum/index.php/topic,2010.msg45253.html#msg45253

A difference of 6c in just 55 metres, using Met Eireann standard thermometers, amazing but true!

I'm not really denying that big temperature changes can be experienced over small areas. I mean if you put one weather station out in the middle of a large flat field on a cold night, and then another 300 metres away beside a takeaway shop (just an example!), you're going to see some temperature variation. I guess I'm asking whether two official weather stations should be placed in an area where they're so at odds with each other?

As I write this, Dublin Airport is currently showing 0c whereas Casement is showing 7c! Is one area of Dublin really battling winter-like conditions and frost at the moment, whereas the other is still enjoying a relatively mild spring night?

Danno

And there in lies the question, which station is more representative of the area? I think that Dublin Airport would be more like North Rural Dublin County, whereas Casement Airport would be more like the suburbs and the city.

I think that Dublin county as a whole, is more surface covered by what one would class as rural, therefore Dublin Airport would should be regarded as the main county station.

Another case study, albeit brief, is Kilkenny. StratoQ runs this station since the MetE station closed and it shows a riverside city centre location compared to a rural site used by MetE.

Danno

http://kilkennyweather.com/index.php/about-us#ComparisonwithKKMet <<< forgot the link...

lucernarian

Here's my two pennies:

In conditions where there are no breezes or any air movement generated from pressure gradients across sea level, a given air mass will obviously remain static. Now, supposing on a cold clear night the atmosphere in a given area will lose heat equally whether the air is lying over a hill or in a valley or on a plain. But... The air on top of the hill will now have a small extra buoyancy force in play and this cooling air can take the path of least resistance down the hill. In the valley, cold air will pool. I assume anyone will agree with this so far.

This is the interesting bit. Supposing the land is flat over a few square miles. The air will cool near the surface as expected, but even though it's not a valley there isn't exactly a steep gradient where the colder air can flow to. Any given patch of cold air in the centre of a plain will have to wait for all the neighbouring "square miles" of cold air to shift itself somewhere... And overcoming that inertia is going to take a long time. Air on grass and air against air has a friction coefficient, small as it is, and it will not help. This is like the way a ball rolling down a gentle slope takes longer to do so than if it were to roll down the same height except on a steeper slope.

Mothman

octo wrote: »

Yes, but the wind is from the east....

Compare the mean daily max's and mins http://www.met.ie/climate-ireland/30year-averages.asp . Dublin Airport has lower average max's and higher average mins.

The data (averages) on the page you linked to is from a different site and has little or no relevance (there has been no homogenisation) to the current weather station site which has regularly recorded relatively low minimum temperatures.
This is what this thread is about.

Deep Easterly

octo wrote: »

Yes, but the wind is from the east....

But wouldn't that have had a moderating effect on the temperature at Dublin Airport at the time spoken of since the wind was coming in off the sea?

Although having said that, I notice that the airport's temperature tends to be lower than surrounding areas when there is a more northerly componant to the wind direction on the reports, and I recall this was the case last night on one of the reports. Not knowing the geography of the area that well though I have no idea as to why that would be case.

compsys

Just to confuse things further, another issue I've noticed is that Dublin Airport's temperature seems to drop extremely rapidly on some nights after dark. However, on the majority of these nights, the absolute minimum temp recorded at the station is often not much lower than other nearby stations such as Mullingar or Casement. The unusual thing is simply that Dublin Airport reaches its minimum temperature for the night as early as 9pm or so, whereas other stations won't reach their minimum until 3 or 4am (as one would usually expect). If you look at yesterday's temperature readings from Met Eireann, you'll see that Dublin Airport's minimum temperature wasn't too out of synch with a few other stations. However, it reached that temperature very early in the night.

And then another strange occurance is that once the temperature has plummeted after dark, it will sometimes begin to increase again after midnight or so. Again, a bit strange.

compsys

octo wrote: »

Yes, but the wind is from the east....

Compare the mean daily max's and mins http://www.met.ie/climate-ireland/30year-averages.asp . Dublin Airport has lower average max's and higher average mins.

Octo, if the wind is coming from the East, this should actually help keep the temperature warmer at night (but cooler than the day) as the sea has a moderating effect on the temps like Elmer says. Sea keeps its heat longer than land at night.

Danno

http://maps.google.ie/?ie=UTF8&ll=53.420991,-6.280918&spn=0,0.087547&z=14&layer=c&cbll=53.421025,-6.29779&panoid=frXkgP4j_q1GpzqQrO5eVw&cbp=12,348.57,,1,0.74

Seems to be in a bit of a shallow hollow...

Elmer Blooker

Here we go again! At the moment Dub Airport 9c and Casement 12c.

Mothman

and 6C with me.

Now 8 and 10C at Dublin AP and Casement
2300 reading

Sponge Bob

Maybe the Northside is a cold place and maybe them Southsiders were right all along.

Su Campu

I've been keeping a daily watch on Dublin and Casement for the past 6 months or so to see if there is a trend, and I can confirm that there is actually none. Some nights Dublin's colder, others Casement is. Most of the time though Mullingar is the coldest, such as yesterday morning, for example.

Grass minimum temperatures are around the same most of the time, but I think Dublin Airport may just be a degree or so colder on the odd night.

Take the last two nights (minimum air / grass temperatures)

Tuesday Night
Dublin 4.8 / 2 °C
Casement 4.8 / 2 °C
Mullingar 3.9 / 0 °C

Last Night
Dublin 5.6 / 3 °C
Casement 7.7 / 3 °C
Mullingar 10.8 / 10 °C

Yes Dublin was a bit cooler last night, but it was also cooler during the day yesterday with the cool northeasterly, reaching 16.7 °C, compared to Casement's 18.1 °C. Swings and roundabouts!

compsys

Su Campu wrote: »

I've been keeping a daily watch on Dublin and Casement for the past 6 months or so to see if there is a trend, and I can confirm that there is actually none. Some nights Dublin's colder, others Casement is. Most of the time though Mullingar is the coldest, such as yesterday morning, for example.

Grass minimum temperatures are around the same most of the time, but I think Dublin Airport may just be a degree or so colder on the odd night.

Take the last two nights (minimum air / grass temperatures)

Tuesday Night
Dublin 4.8 / 2 °C
Casement 4.8 / 2 °C
Mullingar 3.9 / 0 °C

Last Night
Dublin 5.6 / 3 °C
Casement 7.7 / 3 °C
Mullingar 10.8 / 10 °C

Yes Dublin was a bit cooler last night, but it was also cooler during the day yesterday with the cool northeasterly, reaching 16.7 °C, compared to Casement's 18.1 °C. Swings and roundabouts!

I dunno SU. On clear nights when there's little wind there can be a big difference in temps between D.A. and Casement, let alone the rest of the country. Perhaps over the course of an entire year the whole thing averages out somewhat but you still wouldn't expect to see the extremes which you sometimes do.

Also, D.A. has shown frequent below average monthly temps for around 18 months and it's mainly to do with the ridiculously low overnight readings that are recorded there sometimes. Just last month D.A.'s average temp according to ME was 13.8, lower than anywhere else except Malin Head - and then only by .1 degree. In 2010 every month was below average apart from 2!

If you go back to my post on 24/3 on that at night at around 11pm D.A. was showing 0 whereas Casement was 7 degrees. That's a big difference!

octo

I'm neutral. Here's some data: (how do you paste tables into posts?)

Mean temperature in degrees Celsius for Casement

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
2011 3.6 7.0 6.3 10.9 11.4 12.4 14.1 14.5 9.8
2010 1.4 2.3 5.4 8.3 10.2 14.8 15.9 13.9 13.4 10.1 4.9 -0.5 8.4
mean 4.6 4.6 5.9 7.4 10.1 13.1 14.9 14.5 12.6 10.2 6.5 5.4 9.2



Mean temperature in degrees Celsius for Dublin_Airport

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
2011 3.6 7.0 5.8 10.1 11.4 12.0 13.8 14.4 9.5
2010 1.7 2.3 4.9 7.7 9.6 14.1 16.0 13.9 13.1 10.1 5.2 -0.1 8.2
mean 5.0 5.0 6.3 7.9 10.5 13.4 15.1 14.9 13.1 10.6 7.0 5.9 9.6

Danno

LOL Lads, what is the problem with DA appearing so cold? If the mercury can dip that low then it can read that low!

I'd be more worried with mercury readings coming in too high due to tarmac, buildings etc... or God forbid a bumping of figures to massage the Global Warming Tax scam.

Deep Easterly

Danno wrote: »

LOL Lads, what is the problem with DA appearing so cold? If the mercury can dip that low then it can read that low!

I don't think has anyone has a problem with the actual temperature readings at Dublin Airport as doubtlessly they are accurate for the location. Just seems a little odd though that headlines such as 'Coldest month at Dublin Airport in 40/50/60 years' are becoming more and more frequent; all the more odd when nearby stations such as Casement don't record such.

I think Mothman mentioned before that the weather station at the airport has changed location more than once in recent years and I think this is beginning to reflect in the data. Might be worth doing some research into this though.


Octo, don't know how to make a table in a post but if you use Excel you can highlight the cells containing the data, then right click: click copy and paste into Paint or similar graphic program, save as image file and just upload.


PS, does anyone know when the weather station at Dublin Airport changed location? as might be worth looking at the Airport's data before and after to compare and contrast.

compsys

Deep Easterly wrote: »

I don't think has anyone has a problem with the actual temperature readings at Dublin Airport as doubtlessly they are accurate for the location. Just seems a little odd though that headlines such as 'Coldest month at Dublin Airport in 40/50/60 years' are becoming more and more frequent; all the more odd when nearby stations such as Casement don't record such.

I think Mothman mentioned before that the weather station at the airport has changed location more than once in recent years and I think this is beginning to reflect in the data. Might be worth doing some research into this though.


Octo, don't know how to make a table in a post but if you use Excel you can highlight the cells containing the data, then right click: click copy and paste into Paint or similar graphic program, save as image file and just upload.


PS, does anyone know when the weather station at Dublin Airport changed location? as might be worth looking at the Airport's data before and after to compare and contrast.

Yeah, I pretty much agree with what you're saying. It's also the fact that it's the main station in the capital. If it were a station somewhere less important you mightn't mind as much but it should be more representative of the city, and even country, as a whole.

I mean last March the weather was fairly seasonal and every station in the country recorded an average monthly temperature of around .3 to .5 degrees above average - apart from D.A. which recorded a temp of 0.5 below average and was the only station in the country to record a below average temp. That's just strange. It's like it has its own micro climate as times.

Deep Easterly

Been looking and taking data for Dublin Airport and Casement Aerodrome from the Met Eireann monthly bulletins between Jan 2007 and May 2011:

http://www.met.ie/climate/monthly-weather-bulletin.asp

Jotted down both mean maxima and mean minima at both for the period (Excel file attached, and if anyone spots any mistakes please let me know. Will triple check again tomorrow)

Just focusing on the monthly mean minima, and particularly the difference in the monthly deviation values for the monthly mean minima at both stations, there seems to be an interesting trend emerging:



Spaced over an average year, the mean minima at Dublin Airport works out about 1.0c higher than that of Casement, and which, up the first half of 2010, the chart shows nicely. It is interesting to see though that during the 2nd half of 2010, this difference changes drastically.

I am not sure I totally understand what all this means myself at the moment as I am totally jacked and seeing 4 of everything at this stage so will continue this tomorrow!

Mothman

DE, there is a fundamental issue.

The weather station has been recently moved and the averages you are using refer to a different site. This site is not even the previous one, but the original station.

I have referred to this issue in #5 AND #21

You may as well be comparing apples and oranges!

I don't know when the latest site came into operation, but it was well before mid 2010, so there may be still an anomaly to discuss.

You may be interested to having the mean mins for my own site. My site shares characteristics with DA. I suggest comparing the actual figures between the 3 stations.

Sponge Bob

I looked for where Casement is located. The Location is given by Met Eireann Here....and looks suspiciously rounded.

I translated that Met co ordinate and it landed me at a location on top of a jet exhaust blocking berm HERE . Lucky we only got small jets in Ireland, what! Nothing Met like at that spot though.

I would be delighted were anyone to confirm I did the TRANSLATION correctly.

I think I see it slightly west of there and that it has been there for years looking at OSI maps.

thetonynator

Sponge Bob wrote: »

I think I see it slightly west of there and that it has been there for years looking at OSI maps.

40m from tarmac and about 20m from a building.


I'd say Dublin is more accurate!!!

Deep Easterly

Mothman wrote: »

DE, there is a fundamental issue.

The weather station has been recently moved and the averages you are using refer to a different site. This site is not even the previous one, but the original station.

I have referred to this issue in #5 AND #21

You may as well be comparing apples and oranges!

I don't know when the latest site came into operation, but it was well before mid 2010, so there may be still an anomaly to discuss.

Your absolutely right MM which begs the question why the 61-90 temperature average for Dublin Airport is still being used to compare current data with. M.E still seem to use it YET, as you know, the DA climatological average is not listed or used in the monthly Met Bulletins which makes the whole thing all the more confusing.

Deep Easterly

The 61-90 average dictates that mean minima at Dublin Airport during the month of January is 0.69c higher than that of Casement Aerodrome.

This was more or less the case until 1995:


The 1995-2011 average dictates that the mean minima during the month of January at Dublin Airport is now 0.6c lower than that of Casement Aerodrome.

Incredible!

Mothman

Not incredible, I believe the station moved in May 94, ties in nicely.

And has been moved again in recent years and this latest site appears to be recording relatively lower mins.

Sponge Bob

They really should look at the siting of the Rome Ciampino Airport weather station for some top tips.

NIALL D

Sponge Bob wrote: »

They really should look at the siting of the Rome Ciampino Airport weather station for some top tips.

they must get some funny readings

the video is mad , the car flying through the air as it passes the engine , jus goes to show the power of one of those engines !!

Su Campu

If you look back to my original post and my photos you'll see that the current Dublin site is pretty much perfect, as regards the standards set down by the WMO. It's in total contrast to the Ciampino example above, which is an all-too-common feature nowadays.

While taxiing into Charles de Gaulle recently I laughed at the Meteo France building with its weather station sited just outside it, and a few steps from the huge concrete apron on one side, two massive carparks just to the west and south...and of course the multi-story MeteoFrance building itself shielding the station from northerly winds! :rolleyes:

Su Campu

The Met Office at Dublin Airport is located between Piers D and A. It's the curved building in this IAA Aircraft Docking Chart, and also in this map. You walk right by it when walking along that long corridor to Pier D. It's on the left hand side, and has a "control tower" type lookout, along with various instruments (radiation sensors, Campbell-Stokes, etc) on its roof.

I'm not sure exactly where the original met instruments (screen, etc.) themselves were located before the airport built up around it. I'm sure they wouldn't have been on the roof.

http://www.flickr.com/photos/38016434@N05/5755841317

Elmer Blooker

Casement 9c and D.Airport 5c now.
I make it 9c too and I'm about 5km from the Airport. 5c for a location quite near the coast just doesn't seem right to me considering sea temps are at their highest in late summer?

Mothman

Elmer Blooker wrote: »

Casement 9c and D.Airport 5c now.
I make it 9c too and I'm about 5km from the Airport. 5c for a location quite near the coast just doesn't seem right to me considering sea temps are at their highest in late summer?

I recorded less than 6C 4 times this month and I'm only 1.5km from sea.
My min last night was 6.6C with 2.0C recorded 1.2m below on the grass.

I've been taking daily obs for nearly 10 years and I have no issue with the temps recorded at Dublin AP.

Neither do I have an issue with 5C+ difference across 5km. I've experienced this difference across a matter of 200 metres!

Elmer Blooker

Mothman wrote: »

I recorded less than 6C 4 times this month and I'm only 1.5km from sea.
My min last night was 6.6C with 2.0C recorded 1.2m below on the grass.

I've been taking daily obs for nearly 10 years and I have no issue with the temps recorded at Dublin AP.

Neither do I have an issue with 5C+ difference across 5km. I've experienced this difference across a matter of 200 metres!

Your low temps this month could due to your location, the air over the Wicklow Mts cools quickly on clear calm nights and because cold air is heavier it will flow towards the warm sea - a katabatic wind which is the exact opposite to a daytime sea breeze.
The terrain at D. Airport is as flat as a pancake (which is why the airport is there :rolleyes: ) so I cannot think of any reason for this micro climate.
The 5c difference over 200m is due to temperature inversion surely?

Mothman

Elmer Blooker wrote: »

Your low temps this month could due to your location, the air over the Wicklow Mts cools quickly on clear calm nights and because cold air is heavier it will flow towards the warm sea - a katabatic wind which is the exact opposite to a daytime sea breeze.
The terrain at D. Airport is as flat as a pancake (which is why the airport is there :rolleyes: ) so I cannot think of any reason for this micro climate.
The 5c difference over 200m is due to temperature inversion surely?

I do get katabatic breezes here which actually warm up the air by shifting the local inversion. Much more prevalent in winter than in summer. Soil conditions play a part as well with the light soil leading quicker cooling as well. But it is true to point out the mtns having an influence, a significant one, with my site. It was one of my main motivations to in getting a climate station here.

I'm not familiar with the Dublin AP site but perhaps not as flat as a pancake. Judging by my site it doesn't take much of a hollow to trap the cool air on calm nights.

Danno

Having a good look at the sites in question and to me it would be down to soil type.

There are 2 quarrys to the west of the site which suggests very sandy soil in the vicinity of the location, alot of grain fields to the west of the airport would support this theory.

Another hint is the townsland called "Coldwinters" about 1km SW of the new site!

Finally, the new site is roughly 12 to 15 metres higher up and a further 2km inland.

Mothman

I think you're on to something Danno.

Have a look at 6" map on OSI site and see all the gravel pits mentioned.

I can't help thinking that coldwinters is simply a coincidence.....but my mind is open