Sunday, January 23, 2011

Wyoming combined temperatures

As with New Mexico, Wyoming has 29 USHCN weather stations, however it has two GISS stations at Casper and Lander, WY, rather than just the one. (Should I hypothesize that there is only going to be one with a record before 1947?) Interesting that about a third lie along the interstates.

Well, bless my socks, I’m right! Casper has only data since 1947, while Lander has the full record from 1892. Another tug of the forelock to Chiefio, who first noticed this pattern.

GISS plot of temperatures for Casper WY

GISS plot of temperatures for Lander WY (GISS)

So with the temperatures, both homogenized mean and TOBS (Time of Observation corrected) data collected, and tabulated, it is time to get the station populations.

First question is as to whether Bates Creek is part of the 5,834 folk in Hell’s Half Acre, which citi-data suggests is the community. A quick glance at Google Earth, and the answer is no!

View of the location around the weather station at Bates Creek (Google Earth)

So there are maybe 3 houses? Say 20 folk.

Google would have me believe that Diversion Dam is in Kinnear (Pop 272). Checking with an aerial view, however there are only a couple of buildings, and it is right by the river – even the highway is on the other side. So I give it a population of 10.

View of Diversion Dam station (Google Earth)

I have to go to zip-codes to get that Moran has a population of 1.

There are two different values for Yellowstone and two sites, (Mammoth and Lake) with one population of 64, and the other (citi-data) 377, so I should check and see relative construction around both. As luck would have it there is a cloud over part of the Lake site, but I can see a few buildings so I give it the 64, and Mammoth – wow it has even more, so perhaps I will use 377 for this one. (But we don’t know the effects of the geothermal heat in either place).

Looking at the difference between the average of the GISS data and the USHCN homogenized average values over the years.

The trend lines seems to be stronger than the curves, so I checked it twice, and that is what the data shows.

Looking at the TOBS data and the trend in the state temperature over the years:

The temperature has increased at a rate of around 1.9 degrees per century.

In terms of its geography, Wyoming is 360 miles long by 280 miles wide, stretching from 104 to 111 deg W (sensibly) and 41 to 45 N. It has an average elevation of 2,042 m, the average USHCN station elevation is at 1,965 m, and the average GISS station is at 1,600 m. Since there is a linear inverse correlation with elevation, this suggests that the GISS station will, as it does, read high. But it is, on average, 1.74 deg F above the USHCN station average, homogenized which is less than the difference in elevation would suggest (3.2 degrees).

Looking at the impact of geography on the temperatures over the years:

There is a quite weak correlation with latitude (which given that we have moved North from looking at New Mexico last week, where the elevations weren’t on average that much different (ave 1,737 m) but the temperatures were about 54 deg F on average, rather than the 43 deg here, some roughly 10 degrees of latitude further North.

There is a stronger correlation with Longitude, but this is correlation without causation, as they say:

The real cause, as we have seen so often, is the changing elevation:

The population correlatiom had a smaller number of questions over individual station populations than in the recent past, and mainly used the citi-data populations. And it also leaves me wondering if the cabins at Lake Yellowstone were only occupied in the summer, and unheated the rest of the time.

And finally there is a little surprise, the trend line is actually negative, if only just so.


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