Saturday, September 5, 2009

The Anatomy of Biased temperatures

I always want to start out by pointing out that two closeby towns should, by all considerations, have very similar temperature records. But, as I have found over the past few months, this is not the case. I am taking a second look at Columbus and Seymour, Indiana tonight. Tonight I am looking in detail at the bias between the two towns.

Below is a chart of the temperature difference between Columbus and Seymour (Columbus minus Seymour) for the years 1992-1994.

You can see both wild differences in temperature between the two towns, but you can also see that for the 3 years shown here, in general, Columbus is much hotter than Seymour--by 3 degrees.

Let's look at 1992-1993.

You can see that in the winter of 1992-1993 the bias decreased a bit and then rose again in the spring.

1992 looks like this:

Now, all the above biases are positive. During 1971-1972 the bias was the other direction.

One sees a long stretch of negative biases from 1958 to 1964. Such things do not give great confidence that the temperature is being measured properly.


  1. I can't believe it's been so long since I looked you up. You have a blog now! I use your page as a reference somewhat regularly.

    We exchanged some emails years ago. I'm working on my own web site at the moment, linking to your story and your Pathway Papers, which I hope are being used by many people. Can't wait to read through your blog posts, though it will probably have to wait for tomorrow.

  2. Hi Shammah, Thanks for the kind words. The Pathway Papers were a failure, but that is ok, a life is filled with more failure than success, at least for most people.