87th AMS Annual Meeting

Monday, 15 January 2007
Identifying Connections Between Temperature Trends and Station Changes in the United States
Exhibit Hall C (Henry B. Gonzalez Convention Center)
Rebecca A. Smith, Florida State Univ./COAPS, Tallahasssee, FL; and J. J. O'Brien
Decile plots are created using daily maximum and minimum temperature data from weather reporting stations in the United States for the time period 1948-2005. The temperatures are sorted, and 730 days of data are plotted for each year to remove annual variability. Each decile is comprised of 73 days with the cold extremes located in the first decile and the warm extremes located in the tenth decile.

Trendlines for each decile are plotted, using a linear least squares regression, and tested for significant warming or cooling using the Student T-test. The most significant stations (the top 5% and the bottom 5%) are then tested for significance using the bootstrapping method. These results will indicate stations in the United States which show significant warming or cooling over the past 57 years.

The second part of this study is to research station dynamics, where stations are categorized in one of three sections: 1) urban, 2) small urban, and 3) rural. As has been shown in previous work, the southeastern United States has experienced varying trends for different categories: rural stations tend to show cooling trends while stations undergoing urbanization show warming. Other station aspects are also investigated, including changes in station location (latitude, longitude, and elevation) and changes in instrumentation. Many different factors regarding the station could influence the temperature data being recorded, thus giving the false impression that major climate changes are occurring.

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