The 11th Conference on Applied Climatology

6.6
THE RELATIONSHIP BETWEEN RECORD DAILY TEMPERATURE EXTREMES AND ANNUAL MEAN TEMPERATURE

Glen Conner, Western Kentucky Univ, Bowling Green, KY; and B. Brunson and S. J. Richter

The behavior of the occurrence of extreme events as a result of climatic variation could be a tool for evaluating the nature of the variation. In temperature, a day's record highest, lowest high, highest low, and lowest temperatures, are examples of extremes over a single day. Each element exists for each day of the year and collectively they offer at least 1460 record breaking opportunities each year at each station. In a previous study, we found that an observing station's all-time record daily temperature extremes are dependable artifacts that represent trends in temperature extremes. This paper uses the same 1896 through 1995 period and the same forty-seven stations used in that 1997 study. The stations, each with fewer than four percent missing days, were selected from the National Climatic Data Center's Historical Climate Network. The relationship of national mean annual temperature to the number of record daily extreme temperature events at the 47 stations was analyzed. Re-enacting the chronology of daily extremes for each station, the number of new record daily highest, lowest high, highest low and lowest temperature events were calculated for each month and year. This actual number of new record events was compared to the number that would be expected in the absence of trends. Following the 1954 work of Foster and Stuart, the chronology was then reversed and the data examined from 1995 back through 1896 using the otherwise identical procedure. This round-trip analysis produced the extreme event data set. The annual mean temperature data set was produced by the National Climatic Data Center. These two data sets were statistically compared. For an observed variation in the annual mean temperature, the number of daily record extreme temperature events can be anticipated. Three periods were examined. The 1915-1934 period was used as an example of how a two-decade warming period would appear. The 1954-1973 period was used for a cooling period example. The annual mean temperatures for entire 1896-1995 period were compared to each of the extreme elements: daily highest, lowest high, highest low and lowest. Each element exhibited the expected relationship of more highest and highest low and fewer lowest high and lowest events when mean temperature rises. The results suggest that this relationship can be useful in determining the nature of changes in mean annual temperature and whether they are accompanied by changes in the frequency of record extremes

The 11th Conference on Applied Climatology