Statistical Procedures for Making Inferences about Climate Variability

Abstract

A statistical procedure is described for making inferences about changes in climate variability. The fundamental question of how to define climate variability is first addressed, and a definition of intrinsic climate variability based on a ?prewhitening? of the data is advocated. A test for changes in variability that is not sensitive to departures from the assumption of a Gaussian distribution for the data is outlined. In addition to establishing whether observed differences in variability are statistically significant, the procedure provides confidence intervals for the ratio of variability. The technique is applied to time series of daily mean surface air temperature generated by the Oregon State University atmospheric general circulation model. The test application provides estimates of the magnitude of change in variability that the procedure should be likely to detect.