Thursday, August 9, 2012

Temperature drop with elevation

This morning I visited Watts Up with That and read a post on the accuracy of the new set of temperature stations around the country. It points out that the new set of stations show, on average, a lower temperature than the record claimed by Jim Hansen.

In his rebuttal to this Nick Stokes points out that the average elevation of the two sets of stations is different and that when that is taken into account, allowing a temperature drop of 6 degC/km then the difference between the two sets of data is explained.

However the original network had an average elevation of 1,681 ft (512 m) and the new network has an average of 2,223 ft (667.6 m) giving a difference of 155.6 m or an anticipated temperature difference of 0.1556 x 6 = 0.93 deg C.

Well, in the state data that I calculated some time ago I plotted the temperature against elevation and so I quickly (too quickly as I found out) went through the various posts for the different states shown undeer the Follower pictures on the right hand side of the page, and listed them with the average slopes of the graphs I had plotted. Ran an average, and posted the result on WUMT.

Turns out I made a slight error since I plotted the temperature in deg F and the elevation in meters, so that the correlation I got was in bastard units. And I mis-entered one of the data points into the table. It translates, when done correctly into an average decrease of 0.016 deg F per meter, or 0.0089 deg C per m, 8.9 deg C per km, 50% higher than that quoted by Nick.

For those interested I have tabulated the average slope against average state elevation and then plotted it, just for grins.


Figure 1. Temperature trend with average elevation for each of the Contiguous United States

What is interesting (apart from the two negative values for North and South Dakota) is how the trend shifts as one gets closer to sea level. I did not plot this relative to their actual distance from the sea, but it reinforces my conclusion that the sea temperatures have more of an influence than we are giving them credit for.


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10 comments:

  1. When I was followoing your posts on this issue it seemed to me that temperatures were rising, and that they backed up the scienitific studies, the latest of which is funded by Kock industries, which show that there is global warming, and that it is caused by industrial pollution in the form of CO2 and related poisons. Do you agree? I never saw a overall summary

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  2. I think that you have to differentiate two things: firstly there is reasonable agreement that since the end of the Little Ice Age (an event that is now generally accepted as occurring in around 1850), the globe has been warming. By far the greatest retreat of the glaciers happened before 1970, when the influence of greenhouse gases is projected to have started. And then you have to include the effect of those gases. The relative proportions of the warming that can be assigned to the natural cycle as opposed to the GHG is something that is in serious debate.
    The difficulty in having an open discussion is exacerbated by those who exaggerate the ongoing climate changes or events - and the current situation where there is a rush to avow last month's temperatures as being truly extra-ordinary when they are not is only one highlight of this.
    If you have been reading this site that long you will remember that I predicted some months ago, based on this being a winter La Nina year, that the drought would last until at least the end of this month.
    But "nothing extra-ordinary" does not sell newspapers, bring viewers to television, or research grants to university scientists.

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