Saturday, July 10, 2010

State temperatures - Missouri corrected for observation time

The data that I have been correlating in regard to the temperatures of the different recording stations in the different states of the Union, now comes in three flavors, rather than the one that I started with. The three are the Raw data, data that has been adjusted for the time of day of observation (TOBS), and that which has been homogenized to account for the urban heat island effect, among other things.

However the little data that I have massaged from about 8 states suggests that those massaging the data who ignored town sizes below 10,000 folk were neglecting a sensitivity that the data was beginning to repetitively indicate. Thus it does not seem appropriate to continue with using the “homogenized” data of the set that was the only one available at the U.S. Historical Climate Network (USHCN) when I started . On the other hand, a strong case can be made that the adjustment that the USHCN has made to correct for the varying time of days at which the readings were taken is a legitimate one. If one goes to the USHCN website and selects the time of day corrected data (under the listing TOBS for time of observation) then one can, in the same way as I did last week create a table of information using this simple correction to the Raw data. And so, I will see, this week, whether making that change will affect the trends in the data.

Using the procedures that I have outlined, therefore, I have just done that, and will now continue to work back through the states I have already covered (marking the list with either RAW or TOBS) and beyond using this less manipulated data. For Missouri, you may recall that my original concern was for the difference between the GISS stations and the USHCN. Last week I posted the comparison of the Raw data and it showed that changing the data and the measuring stations both made a difference.

The blue line is for the homogenized data, the red is for the raw.

And if I now look at the difference using the TOBS data I get:

A slight upward trend, but not that significant. As for the temperatures in Missouri, over the past 100 years, with the correction – really there is no trend, it has been relatively stable:

I do note that the highest temperatures were some decades ago.

Actually a little surprise in looking at the changes in standard deviation. They had been reducing over time, with both the raw and homogenized data, but when the TOBS values are used, then there is a slight increase over time.

And for the four parameters that had started to appear to have an impact on relative temperature across the states. First there is latitude:

For which there is not much change. Then there is longitude:

And though the state is relatively flat though it rises toward the west, the change due to elevation:

Which gives a better correlation (and one more logically based) than longitude.

And finally that of population, which I have shown both with log and normal scales, but for tonight – because it emphasizes the effect of towns below 10,000 in size, I’ll use the normal one again.

And so, starting with this as the new baseline of a mid-western state, let’s head off West again, and see what the TOBS data will show.


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