Statistical Distributions and Climate Change

Climate is often understood as the characteristics of the Earth system observed year after year: the average state, the range of variability and the frequency of occurrence of extreme events. When these characteristics change over the long term (i.e. decades or longer), we perceive it as a change in the climate. In detail, climate change involves the long-term change in the probability distribution of the short-term (e.g. daily) state. Detecting such a detailed change would necessitate first understanding the underlying statistical distribution and its governing statistical parameters. Insight is gained when the set of parameters describing the distribution is smaller than or equal to the set of characteristics describing the climate and when the variations of these parameters can be explained theoretically. We focus on the atmosphere in particular here and use wind speed as a specific illustration of this paradigm. We investigate the statistical distribution of wind speed observed at tropical radiosonde stations, examine the underlying dynamics and speculate on what possible changes could occur as climate changes.