Joe D’Aleo suggested earlier today that I take a look at some of the data from NCDC’s web page called “US climate at a glance“. This page allows comparisons of the actual data not anomalies used in the NCDC USHCN Surface temperature network. The NCDC web page allows you to compare and not only the nation but states and cities as well using the actual USHCN data. Joe’s interest was the urban heat island effect (UHI) in cities in Texas. First let’s take a look at the state of Texas itself for the last 100 years:
Source: http://www.ncdc.noaa.gov/oa/climate/research/cag3/tx.html
As you can see the trend is essentially flat, with the trend equaling 0.01F Per decade over the last 100 years. That trend by itself is interesting, but there’s a lot more of interest when you look at the cities individually.
Here is a list of cities in Texas based on population size, this table is from Wikipedia:
| Rank | Population | Place name |
|---|---|---|
| 1 | 2,099,451 | Houston |
| 2 | 1,327,407 | San Antonio |
| 3 | 1,197,816 | Dallas |
| 4 | 790,390 | Austin |
| 5 | 741,206 | Fort Worth |
| 6 | 649,121 | El Paso |
| 7 | 365,438 | Arlington |
| 8 | 305,215 | Corpus Christi |
| 9 | 259,841 | Plano |
| 10 | 236,091 | Laredo |
| 11 | 229,573 | Lubbock |
| 12 | 226,876 | Garland |
| 13 | 216,290 | Irving |
| 14 | 190,695 | Amarillo |
The third largest city in Texas by population is of course Dallas. Unfortunately, Dallas only has data going back to 1948 according to the NCDC pages that allow selection. So will use 1948 as a starting point for comparison, here then is the statewide trend since 1948:
The Decadal scale trend from 1948 to 2011 is 10 times larger than that of the last 100 years at 0.10 Fahrenheit per decade.
Now let’s look at major cities in Texas available from the NCDC cities page, first Dallas:
Source: http://www.ncdc.noaa.gov/oa/climate/research/cag3/city.html
The decadal-scale trend in Dallas is almost three times larger than that of the state of Texas at 0.28 Fahrenheit per decade.
Now let’s have a look at the largest city in Texas, Houston:
Being the largest city, one might expect that Houston would have a larger trend than Dallas, however it should be noted that Houston has a strong ocean influence from the Gulf of Mexico. So, one would expect that it’s trend would be muted compared to an inland city.
Corpus Christi is another Texas city that has an ocean influence. It’s decadal-scale trend is also somewhat muted by comparison:
It is also a significantly smaller city with less growth:
San Antonio however being the second largest city is well inland away from the ocean – look at its trend:
At 0.41 Fahrenheit per decade, it is four times larger than the statewide trend from 1948 to 2011. The population of San Antonio looks like a hockey stick, especially after 1940:
According to the Wikipedia entry on San Antonio: “It was the fastest growing of the top 10 largest cities in the United States from 2000-2010, and the second from 1990-2000.”. So I suppose it is no surprise to find it having such a large temperature trend compared to other Texas cities and the state itself.
El Paso, TX:
Like Corpus Christi, El Paso didn’t grow quickly either.
Amarillo:
Amarillo didn’t see wild growth like San Antonio.
So what can we conclude from all of these comparisons? First, I’d like to point out that this is not a definitive comparison, as it is lacking many of the cities in Texas but these are the cities that were available from the NCDC page.
But, what we can conclude with certainty is that all of the (available) cities plotted from NCDC Data at “US climate at a glance” show a decadal-scale trend that is larger than the decadal-scale trend for entire state of Texas for the same period. Of course, Texas being composed of wide open range has many USHCN stations that are not in populated areas. Thus, it is not surprising to see that the state of Texas has very little trend while Texas cities have a significantly greater trend.
Dr. Roy Spencer has found more UHI examples in Roy Spencer’s ISH population adjusted discoveries. He writes:
The bottom line is that there is still clear evidence of an urban heat island effect on temperature trends in the U.S. surface station network. Now, I should point out that most of these are not co-op stations, but National Weather Service and FAA stations. How these results might compare to the GHCN network of stations used by NOAA for climate monitoring over the U.SA., I have no idea at this point.
The city graphs all seem to show the common v- shaped pattern centered on the 1970s.
This pattern appears in the global average record as well suggesting the composite analysis is fine.
Obviously if you trend a v with a linear fit you are going to get zero trend. So doing that is misleading.
The higher temps in the 1930s might reflect the dustbowl droughts, or might not. Similar dust bowl conditions in Australia in the same time period might reflect [SNIP: LT, I’m not picking on you, but it would be nice to see commenters in general rise above excretory adjectives. This is a family blog. Think of the children! -REP] agricultural practices.
KevinUK,
My map is certainly not misleading. Firstly, it’s not anomalized. It shows station trends on the unadjusted data. You can display the stations and click on them to get the numerical values.
It is billed as a station trend map, and the shading is my equivalent of your color coding. The methodology is transparent – you can display the triangular mesh used and see the color interpolation scheme, which is what is provided by HTML 5. So anyone curious about the Canada red can clearly see what stations are producing it.
And it uses a spherical projection, so the Arctic areas are not inflated.
I must say that my coloring scheme is not to commercial CFD standards. It is not meant to represent a continuum, and is not a finite element solution of anything. And, of course, it has to be done with what HTML 5 provides, so as to have interactivity.
The Google maps approach that you have used has merits too. However, you say that it represents trends from 1880 to 2010, but you seem to have a trend for almost every GHCN station. Some of those must be for quite short sub-periods. How can we tell? At least the labels should say what the period is. And the colors will be also misleading where they represent a trend over a shorter period.
That’s the reason my display of trend periods is limited. The trends I show are actually of the periods stated.
Larry in Texas says on June 28, 2012 at 10:10 pm:
An interesting study. Which is why I’ve fled to Wisconsin for most of the summer this year! Although, today the temperature/heat index in Milwaukee was around 105 degrees Fahrenheit. Yuck! But it is supposed to be much less humid tomorrow.
Vancouver’s best kept secret: No mosquitos in Summertime!!! All the young ladies wear tank tops, short shorts and flip-flops. They all are practically na-a-a-a-ked.!!!
Present temp and RH: 22 deg C and 75 %.
Come visit in August when the salmon start running up the mighty Fraser river.
After sleeping on it, I’ve reconsidered the idea that increasing population will increase the UHI. Since an increasing Population in a Sunbelt city will translate into increased sprawl, the density at the recording station should stay the same, and the heat content in, say, Joules, should be more or less stable.
Since 1990, the populations of the Texas metros has increased anywhere from 60% to 110%, but the settled area of the metro has just expanded.
One exception, would be the energy intensity of the downtowns, which should increase to an extent. but it would not increase linearly with population, since offices, as well as residential areas, have migrated to suburbs.
Houston’s downtown has grown upwards, however, massively, but on the other hand Dallas’s downtown has not appreciably increased upward, but has expanded to the north, due to height restrictions from a nearby airport. So the apparent UHI at a fixed point in Dallas’ old downtown should show a lower increase than Houston’s.
The basic problem with falsifying this hypothesis is the same as the basic problem in evaluating AGW in general… The quality and extent of the data is insufficient. Unless we can measure the physical world, we cannot know it. And the one location that would validate or invalidate AGW in Texas just doesn’t have a history of measured data behind it. In the 1950’s and onward, no one knew of a need to make accurate temperature measurements of Texas downtowns.
A couple of points;
–never forget that the “contribution” to global temperatures of cities is nugatory, trivial, except insofar as they corrupt the measurements and averages;
–the population of Houston in 1948 eyeballs to 600K. Dallas lagged by about 10 yrs., San Antonio by about 15, etc. The start point of measurement comparisons could be rejigged to match pop. levels instead of date, with interesting results, I think.