A couple of days ago there was a guest post from Russ Steele citing a California study “Feeling the Heat” on global warming that just didn’t seem to add up. One of the stations cited as having climate change related warming was Reno, NV. So, I decided to do a field experiment to test this. The results show clearly that UHI exists in Reno.
Here is what Russ wrote a couple fo days ago:
Feeling the Heat was published by Environment California a non-profit group a few weeks ago, claiming 2007 was the tenth warmest year on record and that the mountain west was experiencing above-average temperatures. Full report here: Download feeling_the_heat_ca.pdf One of the examples given for the high western temperatures was Reno Nevada with a average temperature of 55.3 degrees in 2007, four degrees higher than the 30 years average temperatures from 1971 to 2000.
…Up front in the EC report the author dispatches UHI as having any influence on the climate change, citing studies by Easterling, PD Jones and Parker…
Well I decided to test this myself tonight, since I’m driving through Reno on my return home, I arranged an overnight stay. With me is my NIST calibrated data logger, NIST Calibrated temperature probe, a vehicle mounted Gill IR shield, my laptop computer, and my trusty vehicle. See my previous post “Road Kit”
I chose Virginia Street as the transect route, since it remains relatively straight, level, and crosses all of Reno, including the built up southern suburbs and downtown. It is the original “main street” for Reno.
Here is the result of my South to North transect driving Virgina Street overlaid on a Google Earth image oriented to match the timeline of the transect:
Click for larger image
The weather tonight was perfect. Light winds, clear skies.
Here is the data from the Reno airport ASOS, which also happens to be a USHCN climate station:
Time Temp Dew RH Wind Wind Vis WX Sea Level Altimeter Station
Point Dir Speed Pressure Setting Pressure
(PDT) (f) (f) (%) (mph) (miles) (mb) (inches) (inches)
1:55 am 44 25 47 CALM 10.00 CLR 1023.0 30.30 25.788
12:55 am 48 24 39 CALM 10.00 CLR 1023.4 30.31 25.797
11:55 pm 51 23 33 WSW 3 10.00 CLR 1023.7 30.31 25.797
10:55 pm 54 23 30 S 6 10.00 CLR 1024.1 30.32 25.805
For those interested, I have the raw source data from my datalogger in CSV form for the South to North Reno transect here. (PDF)
Note the placement of the airport, which has it’s ASOS weather station used in many climate studies essentially in the north end middle of the airport. The Reno UHI bubble does extend into this area.
Click for a larger image
I also did a reverse transect, driving the same route in reverse immediately. Plus a route near the airport. I’ll have more tomorrow, its 2AM and I’m tired.
UPDATE:
Jeff Id inquired in comments “how is it mounted to the car?” Here is the answer:
The temperature sensor (inside the Gill IR shield) mounted on the vehicle using an improvised window mount.
Also, the time of night that I made the transect (11:15PM to 11:39PM) allowed me to maintain a nearly constant speed during the transect due to the lack of traffic. Plus Virginia street has stoplights set for all green unless there is cross traffic. I was fortunate to have to stop only once during the entire drive, and that was in the downtown area. I kept an eye on the temperature reading during the stop, and no change was recorded.
I’ll have a complete post in the next day, still catching up from my trip.
Excellent stuff Anthony.
Up to 10 degrees F difference, quite amazing. And what does GISS most generously allow in their adjustments for UHI? less than 1 degree I believe.
Why oh why can’t there be a full blown study on UHI to put the facts out there clearly about the impact of UHI ? – wait, I think I know the answer!
Look forward to seeing your follow ups.
Neil
http://www.ncdc.noaa.gov/oa/climate/research/ushcn/#urbanization
Reno after homogenization
Even the BBC weather forecasters (and by extension the Met Office and Hadley Centre) accept large UHI effects. At least one of the BBC overnight forecasts earlier this year predicted a 4C temperature difference between rural areas and towns and cities in the UK. Rural areas where predicted to be -4C and town and cities 0C.
I wonder if they will sacrifice accuracy for AGW correctness and narrow that gap in their predictions this winter.
This is tremendous. This stuff cannot be refuted.
Thanks,
Mike
This brings up something I’ve been thinking about over the past week or two regarding GISS, which seems to be the ‘official’ dataset referred to by the media (and thence the rest of the world, since the media is supposed to be the public’s eyes and ears for what’s going on in the world while we’re living our daily lives).
The oceans have lost a huge amount of heat content in the el ninos of the past 10-15 years, which have sometimes come one right after another. The 2007 one may have wrung out the last of was accumulated since the 80’s, since temperatures dropped like a rock when then one was done.
IF Svensmark is right, the oceans will be slow to replenish that heat given the cosmic ray situation that NASA was on about a couple of weeks ago. The oceans might spend the next ?? number of years shaded by a lot more nice fluffy clouds than they’re used to.
Those clouds will also change the earth’s albedo, and not only will the oceans be slow to warm back up, everything else will be slower to gather heat as well.
IF there is anything to the what the solar guys are saying (sorry Leif, speculating here), and Solar Cycle 24 turns out to be a dud, if they’re right then that will contribute further to the general cooling.
A hockey stick may be a bad way to describe temperatures over the past 1000 years, but its not a bad representation of human population growth. That will demand land-use changes in the form of more agriculture land use, and in many parts of the world, that means fewer forests and urban areas.
This will also contribute to changes in earth’s albedo, not to mention how much extra wood will get burned for heating if things stay cool for an extended period.
People tend to migrate toward cities and suburbs, which will expand accordingly, and more and more of those nice rural temperature stations will become absorbed by expanding urban areas.
Which will have a direct impact on the GISS temperature set because thanks to its proponents’ continual “dispatching” of UHI as a factor, and its owner’s propensity for adjusting it in a way that matches his models, global temperatures might be dropping off a cliff for several years before the media, our window on the world, even notice that anything is happening.
They did a real good job noticing problems with the Reno’s UHI, right? Ha.
So thanks Anthony, for keeping UHI front and center for us. Without your work I don’t think anyone would know just how serious and widespread that issue is.
I see something similar every day I drive across Charlotte, NC. I start my commute in rural Kings Mountain, drive throught Charlotte, and wind up in rural Midlands, NC. I see, every day, at least a 5-6F increase in temperature as I drive through.
Oops, above I meant “…fewer forests and MORE urban areas…”
Could not make things much clearer than that — regarding the potential of the UHI effect to disturb a multi-decade temperature record.
If you watched the recent BBC ‘Climate Wars’ series you will recall that the presented did an excellent demonstration of UHI at Las Vegas. He simply measured the temperature, drove into the city and measured the temperature again. It was several degrees higher.
The really odd thing is that he did not refute this in any way. But what he failed to mention is that the IPCC gives a ludicrously low value for the UHI effect. If the UHI is far larger, as seems almost certain, then a very simple logical conclusion flows from that: the global temperature trend over the last few decades has been exaggerated. Last year Michaels and McKitrick demonstrated a very significant UHI effect. They concluded that if UHI were properly taken into account then the real warming over recent decades is only a half of the normally stated amount.
The presenter is a scientist and seemed a reasonable person. But it never seemed to occur to him that his own demonstration of UHI refuted his own arguments.
As I understand it, the main argument against strong UHI involves windy and windless days. It seems a bizarre argument, bearing in mind that all you have to do is grab a thermometer and measure the UHI yourself, as Anthony has done.
Chris
A couple comments, tongue in cheek:
1) You took measurements with a weather station mounted over a paved road? That’s as bad as a USHCN station in a parking lot, maybe worse!
2) “I also did a reverse transect, driving the same route in reverse immediately.” Next time, consider turning the car around. However, your actions would be considered normal in Boston on one-way streets, at least it is among taxi drivers.
A little more seriously, I don’t have hard data, but I’ve noticed that between my usual parking place at work (shaded in the afternoon, at the bottom of a short hill going up to self-storage place) and the Turnpike heading north, I’ll see a 2-3 F rise. Some of it may be from sun, the temperature sensor is in the exterior rearview mirror, but I think most is from the hillside and car being in the shade at work.
At the hour you were driving, the solar effects would be quite different.
What about altitude affecting the start and finish readings?
One month ago, the UK Met Office made this statement –
25 September 2008 The Met Office forecast for the coming winter suggests it is, once again, likely to be milder than average. It is also likely that the coming winter will be drier than last year.
http://www.metoffice.gov.uk/corporate/pressoffice/2008/pr20080925.html
How are they doing so far?
29th October 2008 Arctic blast turns large swathe of the UK white as London sees first October snowfall in 74 YEARS
http://www.dailymail.co.uk/news/article-1081135/Arctic-blast-turns-large-swathe-UK-white-London-sees-October-snowfall-74-YEARS.html
ASOS data, reformatted, minus date and max/min temps:
Time Temp Dew RH Wind Wind Vis WX Sea Level Altimeter Station
Point Dir Speed Pressure Setting Pressure
(PDT) (f) (f) (%) (mph) (miles) (mb) (inches) (inches)
1:55 am 44 25 47 CALM 10.00 CLR 1023.0 30.30 25.788
12:55 am 48 24 39 CALM 10.00 CLR 1023.4 30.31 25.797
11:55 pm 51 23 33 WSW 3 10.00 CLR 1023.7 30.31 25.797
10:55 pm 54 23 30 S 6 10.00 CLR 1024.1 30.32 25.805
ASOS data, reformatted, minus date and max/min temps, this time with spaces changed to :
Time Temp Dew RH Wind Wind Vis WX Sea Level Altimeter Station
Point Dir Speed Pressure Setting Pressure
(PDT) (f) (f) (%) (mph) (miles) (mb) (inches) (inches)
1:55 am 44 25 47 CALM 10.00 CLR 1023.0 30.30 25.788
12:55 am 48 24 39 CALM 10.00 CLR 1023.4 30.31 25.797
11:55 pm 51 23 33 WSW 3 10.00 CLR 1023.7 30.31 25.797
10:55 pm 54 23 30 S 6 10.00 CLR 1024.1 30.32 25.805
If that doesn’t work, I give up….
So, common then somebody, just when is Solar Cycle 24 going to start in earnest?
Dr Hathaway & the Solar Prediction Panels & others seem to be having little more than wild stabs at it. First it was Autumn 06 definitely & wild & furious to boot peaking in 2010-2011, Spring 07 for sure, probably Autumn 07, looks like Spring 08 now, well, Autumn 08 has come & we’re heading into the “gone” phase as winter overtakes us, speculation about Spring 09 has been dabbled with even less confidence than previous “Guessing Games”. With all that brain power & computer power I would have thought someone would hit the nail on the head.
And are the Arctic temperatures +5°C higher up there or are they lower?
Have clever & powerful people embarrassingly succumbed to being little more than Medieval prophets, adjusting dates when their “end of the world is nigh” prediction fails, rushing back to the crystal ball for anther check, perhaps it was a speck of dust on the other side of the glass that threw them out, then making another prediction to compensate!
Guess what, yet another UK University study has claimed with great accuracy that Solar variations have little or no impact on climate! I wonder which Sun they’re looking at. Hmmmm! and the band played “Believe it if you like!”, as my late father used to say.
The UHI is estimated to be just +0.05C on average across all temperature monitoring stations. I guess they are assuming that there are enough rural stations with no UHI to offset the urban stations which are impacted by UHI.
But let’s just do some basic math with that assumption. The Reno UHI looks to be 5F to 6F or 3C, which is pretty typical for a large city (Reno might be a little small to get into the large city category but Anthony’s measurements show the same impact none-the-less.)
If Urban stations have an average +3.0C UHI and the average UHI across all stations is only +0.05C, then the number of rural stations must be 98.3% of the total number of stations and the urban stations must be only 1.7% of all stations.
Change the UHI to just 1.5C for large cities and we still end up with 3.3% of stations are urban and 96.7% are rural.
Obviously, the math doesn’t work here because the number of urban stations is a large fraction, approaching half, of the total and the UHI average should be closer to 1.0C.
Anthony,
Thanks for providing first hand, the chance to see science in action…it’s fascinating to witness things like this unfold.
Jim
A simple question that perhaps Anthony can answer based on his meteorological experience.
Why don’t we calculate average surface temperature using the techniques meteorologists use to produce those nice temperature gradient maps (isobars? I am not sure of the exact term)?
Use the known temperature points to interpolate a temperature field for all lat/lons, and then sample that field at regular grid points. This corrects for UHI quite naturally, as the vast majority of grid points in a regular sampling grid would be rural. Sure, UHI would influence the overall average, but urbans areas would probably represent just a few percentage of the sample points. Lacking a good way to remove UHI from the temperature signal (other than ignoring urban areas altogether), this would seem to be the best way to handle it.
“I see something similar every day I drive across Charlotte, NC. I start my commute in rural Kings Mountain, drive throught Charlotte, and wind up in rural Midlands, NC. I see, every day, at least a 5-6F increase in temperature as I drive through.”
This mornings drive:
6:45 33F at the house
7:20 38F at the intersection of I85 and I77 in Charlotte (LOTS of concrete/asphalt)
7:50 29F in the parking lot at work.
I see this EVERY day. My commute covers 60 miles accros 3 counties. Those that refuse to acknowledge UHI effect are the true deniers.
Come on, guys. No one denies UHI is real. The question is: does urbanisation affect trends over large periods of time for a significant number of stations. In the case of the Reno airport, which probably started very rural in the thirties and is now in a very large area of concrete and asphalt, this is very likely. And there are sure to be many other stations like it, leading to the IPCC underestimating the effect on the trend.
But just driving through the city proves absolutely nothing about whether the Reno time series is compromised by urbanisation or not. It just proves that the Reno station is not measuring the temperature that would’ve been had the city not been there. But to say something meaningful from a climate perspective, you need to compare the Reno trend to the trend of a nearby station outside of the UHI-bubble. Or you’d need data from the same trip half a century ago, that would be informative as well.
REPLY: Ared do your research before spouting off. Parker and Petersen claim UHI is insignificant, clearly it is not. EC says Reno UHI is insignificant, clearly it is not. The National Weather Service uses Reno’s UHI in their own training manual, so clearly it impacts the sensor.
http://wattsupwiththat.com/2008/01/10/how-not-to-measure-temperature-part-46-renos-ushcn-station/
It shows up as a hot spot in USHCN contours done by Steve McIntyre.
http://www.climateaudit.org/?p=1748
Clearly UHI exists in Reno. I’m not interested in a long debate on this, as I’m on the road. – Anthony
Anthony, Helmut Landsberg would have been proud of you for illistratiog the urban climate so well.
“But just driving through the city proves absolutely nothing about whether the Reno time series is compromised by urbanisation or not.”
Okay…non-scientist here again, so humor me.
From my perspective, if you show me a graph that shows, in general, that things have increased over all, and I say “But what about this thing called UHI?”, and you say “We’ve accounted for that with a formula, and that effect is Xdeg, which we’ve used to adjust all the values.”, and someone goes and actually MEASURES it, and it turns out to be Z, not X, then it calls the whole graph into question, at least for me.
“Into question” being the operative term…
Jim
Near-record cold, and mountain snow
Snow is accumulating this afternoon in the North Carolina mountains, and the rest of the Carolinas is shivering in the first cold outbreak of the season.
http://www.charlotteobserver.com/local/story/283717.html
Right Ared,
It means nothing whatsoever. I was wondering how long it would take for someone to say that.
I wonder if the name A Red means anything.
Mike B.
A couple of thoughts. What was the day like in Reno? Was it clear and sunny with only a light wind? What about a cloudy day followed by a clear evening? Or a clear day followed by a cloudy evening? Or a foggy day or a high wind day? It is interesting to see that the UHI exists, but how often does it exist and to what magnitude? — John M Reynolds