Urban Heat Island Effect

[IanC]

Many people believe in CO2 warming because there are known physics mechanisms involved. I also believe in CO2 warming but I disagree with the magnitude.

UHI also has known physics mechanisms. Albedo changes, concrete and asphalt heat sinks, water drainage, waste heat, etc. Yet UHI is dismissed as negligable in most global datasets and even considered negative in BEST.

the paradigm was set in place by Jones1990, a paper so flawed that it actually spawned a fraud investigation. gardeners and the plants that grow in the gardens have known about about UHI for a long time. likewise the UHI effect at airports is well known and increases as the amount of tarmac expands.

it is easy to see how a powerful case could be made for UHI explaining a significant portion of the warming trend over the last 100 years. as it stands now, rural stations are brought into line with urban ones rather than the other way around.

this is yet another example of how the climate science community wears blinders when it comes to exploring other factors besides CO2. it is becoming obvious natural conditions are overwhelming the trivial effect of CO2. even the other man made changes like land use or soot may be as strong or stronger than CO2.

 

[flacaltenn]

UHI can be detected and measured because it perturbs the night-time lows. There is heat storage that can be detected by a closer Tmax/Tmin ratio..

Recently ran into an interesting article on UHI, that discussed some of errors and biases associated with measuring it.. The High and Low for that solar cycle does not occur on the same day !!!

If heat is being stored during the day -- the LOW on the clock for that cycle occurs in the morning of the NEXT day. And believe it or not -- many diurnal studies on UHI and heat storage have gotten this wrong.
Someones' got to get it wrong -- before someone else gets it right..

Your observation about equalizing the rural areas to agree with the city centers is simply because that favors their argument.
THe math is simple.. If 10% of stations read 1deg high --- then you've added a 0.1deg upward bias to the data mean. So just manipulating the urban/rural selection process is within significance for resolution that you are seeking.. Maybe captain --- that answer your question about those "average yearly" GISS adjustments and where they are getting the revisions from..

 

[IanC]

Last summer there was a thread on a NASA project that was studying measurement effects such as max/min thermometers etc. One interesting finding was that even a single building near the station increased the temp.

I haven't seen any update but I think I will search for the thread and bump it.

 

[orogenicman]

The problem with the UHI effect hypothesis supposedly explaining global warming is that even rural areas that aren't affected by the UHI effect see increased temperatures and increased rate of change. This has been discussed ad nauseam.

 

[flacaltenn]

The problem with the UHI effect hypothesis supposedly explaining global warming is that even rural areas that aren't affected by the UHI effect see increased temperatures and increased rate of change. This has been discussed ad nauseam.

I can give you DOZENS of stations all over the US that show NOTHING of a 0.4degC trend over the past 60 years.

IT's the exceptions that need and REQUIRE explanation.. But you should know that.
You should also know that you would FIND an UHI effect by inspecting the rural/urban data.

Or are you saying it doesn't exist and shouldn't be properly quantified and corrected?

 

[orogenicman]

The problem with the UHI effect hypothesis supposedly explaining global warming is that even rural areas that aren't affected by the UHI effect see increased temperatures and increased rate of change. This has been discussed ad nauseam.

I can give you DOZENS of stations all over the US that show NOTHING of a 0.4degC trend over the past 60 years.

Dozens of stations in one country as opposed to thousands located worldwide. And this is supposed to mean, what, exactly? Okay, show me ALL of them.

 

[flacaltenn]

The problem with the UHI effect hypothesis supposedly explaining global warming is that even rural areas that aren't affected by the UHI effect see increased temperatures and increased rate of change. This has been discussed ad nauseam.

I can give you DOZENS of stations all over the US that show NOTHING of a 0.4degC trend over the past 60 years.

Dozens of stations in one country as opposed to thousands located worldwide. And this is supposed to mean, what, exactly? Okay, show me ALL of them.

You really didn't answer my question... And you clipped it out as well...

Or are you saying it [UHI] doesn't exist and/or shouldn't be properly quantified and corrected?

Also -- do you even understand this science thingy we speak of? That you DON'T spend time amassing THOUSANDS of COMPLIANT points to pummel your questioners with --- That what you're supposed to do is to seek out EXCEPTIONS to your theory and explain those??

Kinda fundamental science thingy there chief....

 

[orogenicman]

I can give you DOZENS of stations all over the US that show NOTHING of a 0.4degC trend over the past 60 years.

Dozens of stations in one country as opposed to thousands located worldwide. And this is supposed to mean, what, exactly? Okay, show me ALL of them.

You really didn't answer my question... And you clipped it out as well...

Or are you saying it [UHI] doesn't exist and/or shouldn't be properly quantified and corrected?

Also -- do you even understand this science thingy we speak of? That you DON'T spend time amassing THOUSANDS of COMPLIANT points to pummel your questioners with --- That what you're supposed to do is to seek out EXCEPTIONS to your theory and explain those??

Kinda fundamental science thingy there chief....

Did you not read my earlier post where I pointed out that this has been discussed and analyzed ad nauseum by the climate science community? Or are you saying that your brain cannot process simple, to the point responses?

 

[edthecynic]

The fact that satellites confirm the ground station data proves that the UHI effect is negligible.

How about this, instead of you deniers whining about the ground stations, why don't you set up your own and collect your own data? You won't because from the satellite data you know that your own ground stations would simply confirm the data we already have.

 

[Old Rocks]

So many here, when Muller stated he was going to do this study, crowed about those of us that followed this subject for decades getting our just deserts. But when the study confirmed what the scientists had been stating all along, immediatly either ignored the study, or stated that it was flawed, but never identified the flaws. Just like when they are stating natural causes, yet fail to identify even one natural cause.

http://www.nytimes.com/2012/07/30/o...imate-change-skeptic.html?pagewanted=all&_r=0

CALL me a converted skeptic. Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming. Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause.

My total turnaround, in such a short time, is the result of careful and objective analysis by the Berkeley Earth Surface Temperature project, which I founded with my daughter Elizabeth. Our results show that the average temperature of the earth’s land has risen by two and a half degrees Fahrenheit over the past 250 years, including an increase of one and a half degrees over the most recent 50 years. Moreover, it appears likely that essentially all of this increase results from the human emission of greenhouse gases.

 

[flacaltenn]

The fact that satellites confirm the ground station data proves that the UHI effect is negligible.

How about this, instead of you deniers whining about the ground stations, why don't you set up your own and collect your own data? You won't because you from the satellite data you know that your own ground stations would simply confirm the data we already have.

Isn't a cynic a chronic skeptic??

Yes -- I worry less about the surface temp record since the mid 70s because of sat data. But only because it's controlled by folks who are not vested in altering it for their advantage. What I worry about NOW is the data from the 30s and 40s that is STILL being changed on a yearly basis.

There is STILL an UHI effect in the sat data because they are reading lower tropo temps and those are influenced by urban areas. The correction is probably similiar and accurate if you just base the correction on mere population density. See for instance....

http://www.utsa.edu/lrsg/Teaching/EES5093/UHI-houston.pdf
Satellite-measured growth of the urban heat island of Houston, Texas

Over the course of 12 years, between 1987 and 1999, the
mean nighttime surface temperature heat island of Houston
increased 0.82F0.10 K in magnitude. It increased in area
170F30 km2 using the Gaussian method of area determination,
and 650F60 km2 using the 1 K threshold method. It
is curious to note that the growth of UHI, both in magnitude
and spatial extent (using the Gaussian method of determination),
scales roughly with the increase in population
(extrapolated to 1987 levels), at approximately 30%. Also
of interest is the large amount of variation shown in the UHI
measurements, particularly in the UHI spatial extents. The
UHI magnitudes varied over several degrees K, while the
spatial extents varied over nearly an order of magnitude in
area. It is well known that UHI magnitude depends on
environmental variables such as wind speed, cloud cover,
and atmospheric aerosol and water vapor content.

Interesting ain't it?? Over 12 years --- this particular Heat Island INCREASED by 0.8deg..
You only need 10% of your readings to be 1 deg high to bias the mean by 0.1deg....

 

[orogenicman]

RealClimate: Urban Heat Islands and U.S. Temperature Trends

Homogenization of the monthly temperature data via NCDC’s Pairwise Homogenization Algorithm (PHA) removes the majority of this apparent urban bias, especially over the last 50 to 80 years. Moreover, results from the PHA using all available station data and using only data from stations classified as rural are broadly consistent, which provides strong evidence that the reduction of the urban warming signal by homogenization is a consequence of the real elimination of an urban warming bias present in the raw data rather than a consequence of simply forcing agreement between urban and rural station trends through a ‘spreading’ of the urban signal to series from nearby stations.

 

[flacaltenn]

RealClimate: Urban Heat Islands and U.S. Temperature Trends

Homogenization of the monthly temperature data via NCDC’s Pairwise Homogenization Algorithm (PHA) removes the majority of this apparent urban bias, especially over the last 50 to 80 years. Moreover, results from the PHA using all available station data and using only data from stations classified as rural are broadly consistent, which provides strong evidence that the reduction of the urban warming signal by homogenization is a consequence of the real elimination of an urban warming bias present in the raw data rather than a consequence of simply forcing agreement between urban and rural station trends through a ‘spreading’ of the urban signal to series from nearby stations.

Not to be trusted.. to wit....

In our paper (Hausfather et al, 2013) (pdf, alt. site), we found that urban-correlated biases account for between 14 and 21% of the rise in unadjusted minimum temperatures since 1895 and 6 to 9% since 1960.

The paper I referenced above found that urban Houston had increased 0.8degC in just 12 years... That's no "14 to 21%" of unadjusted anything. That's more than FIVE TIMES the unadjusted rise we're trying to measure..

Maybe --- they are calling any city with the lights on after 2AM --- urban.. Or maybe they're drowning the problem with an entire national average minimum temp. Don't know what their gigue is.. But statements like that --- indicate their bias to MINIMIZE the issue...

FIRST --- you read HOUSTON correctly ---

THEN --- you go and see what the effect on the national average is...

 

[Abraham3]

Isn't it amazing that every issue you come up with biases the data in the same direction? What are the odds...?

 

[mamooth]

If you're hellbent on finding a conspiracy, you can always find one. All you have to do is make cherrypicking your chosen alternative lifestyle.