By Steven Mosher.
In his august draft of Hansen2010, Dr. Hansen makes the following claim:
“We present evidence here that the urban warming has little effect on our standard global temperature analysis. However, in the Appendix we carry out an even more rigorous test.
We show there that there are a sufficient number of stations located in “pitch black” regions, i.e., regions with brightness below the satellite’s detectability limit (~1 µW/m2/sr/µm), o allow global analysis with only the stations in pitch black regions defining long-term trends. The effect of this more stringent definition of rural areas on analyzed global temperature change is immeasurably small (<0.01°C per century). The finding of a negligible effect in this test (using only stations in pitch black areas) also addresses, to a substantial degree, the question of whether movement of weather stations to airports has an important effect on analyzed global temperature change. The pitch black requirement eliminates not only urban and peri-urban stations but also three-quarters of the stations in the more than
500 GHCN records that are identified as airports in the station name. (The fact that one-quarter of the airports are pitch black suggests that they are in extreme rural areas and are shut down during the night.) Station location in the meteorological data records is provided with a resolution of 0.01 degrees of latitude and longitude, corresponding to a distance of about 1 km. This resolution is useful for investigating urban effects on regional atmospheric temperature.”
The are several claims here but I will only narrowly examine a few of them. I do not assess the claim about the role of UHI in the global record. That claim, in my mind cannot be assessed until the categorization of rural/urban is settled. So, my observations here have nothing to do with the effect of the issues that the case of Middlesboro will raise. In short, I still believe the world is warming and that man is the principal cause. Instead I will focus on Dr. Hansen’s methodology. In particular, the assumption that the station locations are accurate to .01 degrees or 1 km ( at the equator) and his assumption that selecting “pitchblack stations” gives you a rural sample. Very simply, the station locations are not accurate to .01 degrees as we have seen repeatedly in this series.
To understand this problem in detail requires focusing on individual stations. That focus should neither convince people that the problem is widespread nor should it convince them that it is rare. What it should do is motivate those concerned to be more comprehensive and diligent in their work and their criticism. The conclusions I draw then are most narrow. First, station location data is too inaccurate to use with a simple look up into nightlights, second, a pitch black requirement does not eliminate the issue, and third nightlights is not a reliable indicator of the actual physical processes that cause UHI.
We will start with the GISS inventory data for this station: found here
42572326006 MIDDLESBORO 36.60 -83.73 358 469S 11HIxxno-9x-9COOL FOR./FIELD C2 0
decoding: the latitude is 36.60, longitude is -83.73. The “S” indicates it is a small town, 11 indicates a population of 11,000 and finally the last value 0, indicates that the station is pitch black by nightlights. In H2010 this last value is apparently the one used to determine if a station is dark. Lets look what our replicated inventory shows. it shows that Nightlights is 0, but it also indicates that there is a light with value 54 within 55km of the site. More importantly, the expanded inventory shows that within 3km of the station location there is a light with a value more than 35 DN. Simply, there are urban lights very close to the proported station location. Because I process all the pixels within a radius of every station I can locate these cases automatically. I merely sort for all the pitch dark stations and then sort for those with urban pixels within 3, 5, 10 20 km all the way out to the 1degree cell boundary. Having identified this station as a possible issue the program then outputs the relevant google map with an overlay of nightlights contours. Like so: look at the pale blue cross. So, my algorithm works.
The program also outputs a kml file which then I can bring
up in Google earth and tour all the stations.
Not seeing anything that looks like a weather station at the location, perhaps at the airport? Well, if we check source data at NCDC we find the actual location(s)
And we can map all four which are all north of 36.60. In the bright zone
Checking close to the airport 36.61 -83.74 E
cellFromXY(hiResLights,c(-83.74,36.61))
[1] 276750752
The Nightlights value value at that location? not zero. its 33.
cellValues(hiResLights,cell=276750752) 33
To repeat. GISS have the station at 36.60,-83.73. The “lights at that location are Zero. But the actual station location is north of that in the bright zone .The lights at the airport are 33, which qualifies as Periurban, periurban type2. There are lights as high as 56 within the region. That qualifies as urban, urban type2 by Imhoff’s criteria.
The lights in the area near to the station suggest something btween periurban type2 or urban type 2. Urban type 1 is roughly 680 people per square km. The town in fact has 20 square km which translates into roughly 13K people. Checking back with the GISS inventory:
469S 11
11K people . You can check wikipedia. So Imhoffs nightlights did a good job of guessing the population, but if the station location is wrong you look up a dark pixel as opposed to the bright picels right next to them.
Hansen’s screen of pitch black stations is not adequate. A tighter screen, such as no dark pixels within the area of station location uncertainty would be better. We will work our way through that as we improve the tools here.
And in case you wondered about the temps?
Now there is one last thing I had to check. Hansen speaks of stations in pitch black “areas” Looking at his charts however it appears he picked stations at pitch black pixels. To check this the only think I can do is compare his view of USA stations with my view. They match fairly well ( he shows fewer which may mean the stations drop for other reasons like short records), so I’ll assume that he picked stations at pitch black “pixels”. As we have seen the value at the “pixel” of a station can be misleading because of very very minor location errors.
hansens graphic and then mine
For one final check, I produce a graphic of stations with periurban pixels within 3km ( marked by a cross) and those with periurban pixels within 5km of the site. Confirming the supposition that hansen has picked stations at pitch black pixels. he does not consider potential station location errors
Steve, have you contacted Hansen with this information?
MattE says:
October 20, 2010 at 2:55 am (Edit)
Steven,
I’m perplexed by your belief that the world is warming and that man is the root cause. We’re on the rebound from the LIA (oceans have risen at a consistent pace for 150 years) and you’re obviously a bit skeptical of UHI (and cautious in believing in those who discount it). Unjust wonder what is convincing that man is the root of any observed warming?
1.known physics. more ghg’s cause warming, not cooling.
2.’on a rebound from “LIA” is a meaningless restatement of observation .
its getting warmer. the cause is not “a rebound”. thats circular reasoning.
“Will it happen? Not a chance. With UHI properly accounted for, the measured amount of global warming would probably be cut in half. That would be Hansen’s worst dream come true.
Chris”
not physically possible. land is only 30% of the total. UHI might contribute .1-.15C
The number of data stations is not overly large, especially post 1990. Is it not reasonable to have half a dozen NASA smart guys look at individual stations on Google-Earth or NASA satellite imagery, plus the temp profiles, pre- and post-adjustments, and make a rural/urban call (and suspicious adjustment call)? Then follow up? Or are human brains not up to the task that computer programs do?
You know, all that is needed to refute Hansen’s ridiculous analysis is some back-of-the-envelope stuff Roy Spencer posted here not long ago. Have you published yet, Roy? Might be a good time, finishing your paper with a thorough evisceration of Hansen’s claims.
Spencer shows, for those who don’t recollect his analysis, that MOST of the UHI effect takes place below 100 persons/km^2, and the effect is strongest (about 3x the rate for larger densities) under 20 persons/km^2.
Wondering what the luminosity rating for populations under 100 persons/km^2 is? I imagine in most cases it is “pitch black”. In other words, simple analysis of UHI shows that the interesting distinction between UHI and non-UHI stations will occur BENEATH the pitch black threshold. Hansen’s analysis is akin to denying that water freezes when it gets cold because he tried cooling it all the way to 35 degrees F, and “that’s damn cold for swimmin’ ” but it didn’t freeze.
Dr Hansen really needs to get out of the office and out in the real world to check if his assumptions have merit. If he did this his papers would have a lot more value as science. “The result is what I wanted” is not science.
Steven Mosher says:
October 20, 2010 at 8:24 am
“2.’on a rebound from “LIA” is a meaningless restatement of observation .
its getting warmer. the cause is not “a rebound”. thats circular reasoning.”
I can’t believe you put that in print as an argument.
What CO2 or GHG increase accounts for the rise in temperatues since the last Ice Age let alone the the LIA?
Or does that not somehow count?
So why is it a “meaningless restatement”, I always thought that Science was based on Observations?
http://blogan.net/blog/wp-content/2006/10/korea2.jpg
North Korea must be the coldest country in the world is guess, and it must be true since Japan (the bright islands just east of it) that i have visited several times now is blistering hot (just don’t vist the westcoast and Hokkaido during the wintermonths and stay away from the mountainregions as well during those months).
I always wonder how someone like Mr. Mosher can be so astute about the scientific process and data analysis and not be able to recognize that CO2 emissions cannot warm the climate more than a probably undetectable amount. Water vapor is the dominant relevant gas and part of a massive global heat engine which convects heat upwards where it is lost to space. Only be specifically ignoring this huge elephant in the room can CO2 have any effect – and, even so. it s still small. Unless he has some other mechanism by which he thinks we are warming the climate, this is about the only supposed factor.
Has anyone thought to check Hansen’s stations against Surfacestations results? If Hansen’s list has both well and poorly sited stations it would be possible to compare the temp increase of the 2 lists and quantify the validity of his work.
I thought I would have a go att analyzing the 19 weather stations in Sweden on the GISS list.
Two of them have zero nightlights:
64502142000 JOKKMOKK 66.63 19.65 264 313R -9HIFOLA-9x-9WOODED TUNDRA A 0
64502456001 KREUZBURG SWEDEN 60.00 18.20 621 19R -9HIFOCO25x-9COOL MIXED A 0
The position for Jokkmokk is way off. The position given is in the middle of a large lake, so it is not strange that there are no nightlights. The actual weather station is at Jokkmokk airfield at 66.49 N, 20.17 E, 25 km to the SE, on the other side of Jokkmokk town. By the way the vegetation in the area is taiga (coniferous forest), not wooded tundra.
The case of Kreuzburg is even odder. There is no such place in Sweden. The altitude is absurd, the closest mountains that high are some 300 km to the northwest. The actual altitude at 60.00, 18.20 is about 40 meters. The position is in the middle of a large forest with no houses nearby, thus explaining the zero nightlights. There is a Kreuzburg (romanian name Teliu) near Brasov in Romania that is at approximately the right altitude. Perhaps that’s the place? The station number seems to indicate that the station might actually be Films Kyrkby, a small village at 60.23 N, 17.90 E, i. e. ca 30 km NW. Whether the actual weather record is for Films Kyrkby or Kreuzburg I don’t know. The difference in altitude would probably mean that the figures would not be obviously absurd.
So that is the two “dead black” sites in Sweden, both obvious errors. So let us take a look at how valid Hansens claim of 0.01 degree accuracy is at the other Swedish sites:
64502080000 KARESUANDO 68.45 22.50 327 371R -9FLFOno-9x-9WOODED TUNDRA B 12
I don’t know exactly where the weather station in Karesuando is, but it is definitely not in the position given, which is not even in Sweden, but rather about a kilometre inside Finland.
64502128001 STENSELE 65.10 17.20 327 380R -9HIFOLA-9x-9MAIN TAIGA B 12
The position given is in the middle of Rackojaure lake c. 4 km NE of Stensele village.
64502183001 LULEA FLYGPLATS SWEDEN 65.60 22.10 17 23S 42FLxxCO 1A 3MAIN TAIGA C 71
The indicated position is about 6 kilometres north of Lulea airport (flygplats=airport), inside Luleå town and in the middle of Luleaelv river
64502196000 HAPARANDA 65.83 24.15 6 5R -9FLxxCO 3x-9COASTAL EDGES C 41
The position given is also in the middle of a River (Torneaelv), but otherwise it seems likely to be within a kilometre of the correct position.
64502226000 OSTERSUND/FRO 63.18 14.50 370 317S 14HIxxLA-9A 8MAIN TAIGA B 22
The weather station is at Oestersund/Froesoen airport. The indicated position is on a golf course about a kilometre south of the airport.
64502361001 HARNOSAND SWEDEN 62.60 18.00 8 18S 19HIxxCO 5x-9WATER A 7
I don’t know exactly where the Haernoesand weather station is either, but is very unlikely to be in the indicated position on overgrown former farmland on Haernoe island, 4 km SE of Haernoesand.
64502418000 KARLSTAD FLYG 59.37 13.47 55 55U 51HIxxLA-9A 1WATER C 38
Also an airport. This position is pretty good. It is in a suburb about 500 meters NE of the airport
64502439001 OREBO SWEDEN 59.30 15.20 33 42U 171HIxxLA-9x-9MAIN TAIGA C 95
Also pretty good, probably within a kilometre of the correct position. Not in a taiga area though.
64502458000 UPPSALA 59.88 17.60 41 29U 157HIxxno-9A 2COOL MIXED C 80
Another airport. The position given is in a suburb of Uppsala town about 1.5 kilometers south of the airport.
64502464000 STOCKHOLM 59.33 18.05 52 13U 1357FLxxCO10x-9WATER C 120
This is the site at the old observatory in the middle of the city, which incidentally has a continuous temperature series since 1756. The position given is about 1.5 km SSW of the true one.
64502512000 GOTEBORG/SAVE 57.78 11.88 53 41U 691FLxxCO 7A 2WATER C 36
Also an airport. An excellent position, only about 300 m NW of the actual weather station.
64502512001 TORSLANDA 57.72 11.78 3 11U 691FLxxCO 1A 3WATER C 37
Classed as an aiport but isn’t. Torslanda airport closed in 1977. The position given is in a suburb about a kilometre north of the old airport.
64502550000 JONKOPING FLY 57.77 14.08 232 183U 131HIxxno-9A 5COOL MIXED C 24
Also an airport. A good position within a few hundred meters from the airport.
64502576001 VASTERVIK SWEDEN 57.80 16.60 9 7S 21FLxxCO 3x-9WATER C 36
I don’t know exactly where the weather station in Vaestervik is, but is not likely to be very close to the position given
64502590000 VISBY AIRPORT SWEDEN 57.67 18.35 47 18S 20FLxxCO 1x-9WATER B 17
This is NOT classed as an airport, despite “airport” being part of the name, and it most certainly is an airport. The position is excellent, being the only one except Goteborg/Säve to be within the actual airport area.
64502620001 HALMSTAD SWEDEN 56.70 12.90 64 37U 50HIxxCO 5x-9WARM CROPS C 37
This also is not classed as an airport, though it is one. The position is also badly off, being in mixed forest/farmland about 5 km east of the airport.
64502627001 LUND SWEDEN 55.70 13.20 73 40U 55HIxxCO 8x-9WARM CROPS C 41
Also an old station with a record going back to 1753, and now in the center of a major town. The position is within a kilometre of the correct one.
So that is it, folks. The two stations with zero nightlights have completely muddled positions, and would almost certainly not be “pitch black” if the positions were correct. At least half of the remaining stations are not within 0.01 degrees of their true positions. Airport/Non Airport data are unreliable. Population data are out of date (Lund has 110,000 inhabitants, not 40,000) and habitat data are shaky.
So what, this is climate science!
Wherever century-long small-town records are found intact, they manifest (as a statistical rule) far less, if any, warming during the 20th century than cities of modest size. Although Middlesboro is fragmented into four pieces, it shows that eastern Kentucky is no exception to that rule. Direct comparison with the records from Knoxville TN and Lexington KY (the two nearest urban stations) reveals that urban growth has added ~0.6K per century to current readings at the latter stations. This is very much in line with what is found by such comparisons throughout the globe.
The basic problem is that century-long small-town records are seldom found in GHCN for stations outside the US. China and Mongolia have none (as does all of equatorial Africa), Brazil has exactly one, and even Europe offers precious few (none in France, Ukraine, or European Russia. ) Thus records from cities of modest size (pop. of a few hundred thousand) serve in lieu of small towns as the de facto benchmark for “homogenization” of records from major cities. It requires a naiivete to which no one should aspire to accept the global station averages from GISS or CRU as having been corrected in any credible way for UHI. If anything, independent compilations show that these results differ little from an indiscriminate average of ALL unadjusted data records.
It’s only blind belief that sustains the premise that we know the century-long global temperature trend to within <0.1K. The ad hoc night-light criterion is totally misleading in undeveloped countries , where electricity is in short supply. It only serves as a distraction from patent corruptive effects of urban growth upon temperature records found routinely in GHCN.
tty says:
October 20, 2010 at 2:01 pm
Great analysis, thanks.