Testing mean air temperature trends in southern Greece: A Bayesian approach

This study investigates the variability and trends of the mean annual and seasonal surface air temperature in southern Greece, namely in Crete and in the islands of the southern Aegean Sea. The climatic data used are the mean monthly homogenized air temperature values of seven meteorological stations of the Hellenic Meteorological Service, for the period 1960-2004. A Bayesian trend analysis is performed by fitting alternative stochastic-trend models based on the Log-normal, the Normal, the Generalized Extreme Value and the Gumbel distributions. Posterior simulations results based on the best fitting model reveal the locations and time-periods with the strongest and the weakest interannual trends for both mean and variance. Furthermore, a model comparison experiment based on Bayes Factors compares the above stochastic-trend models with the corresponding ones with no-time trends. The results are very significant since they reveal the locations and the seasons where interannual trends for both mean and variance have real grounds.