| ABSTRACT | Since impacts caused by temperature extremes are of considerable relevance especially for societies, it is crucial to estimate potential changes in the occurrence and magnitude of these events. The present contribution analyses extreme maximum temperatures and their relationships with different atmospheric variables in the Mediterranean region in the observational period 1950-2012. Subsequently, validated relationships are used to project extreme temperatures under future climate change conditions in the framework of statistical downscaling.
Gridded maximum temperature data from the daily E-OBS dataset (Haylock et al., 2008) with a spatial resolution of 0.25° x 0.25° from January 1950 until December 2012 serves as predictand for the analyses. A s-mode principal component analysis (PCA) was performed in order to reduce data dimension and to retain different regions of similar maximum temperature variability. The representative grid box, i.e. the grid box with the highest PC-loading, is selected for each principal component. A central part of the analyses is the model development for temperature extremes under the use of extreme value statistics. In this context, a statistical model which contains a quantile regression for the estimation of thresholds is developed. Then, the quantile estimates are used as location parameters for the Generalized Pareto Distribution (GPD) and a further model is derived to assess the dependence of the GPD scale parameter under the influence of various predictor variables. The latter include atmospheric variables, like sea level pressure, geopotential heights, atmospheric temperatures, and relative humidity. Based on the best-performing predictor set the resulting statistical model will be used to project changes in the extreme value distribution of the maximum temperatures in the Mediterranean area under future climate change conditions.
Haylock, M. R., N. Hofstra, A. M. G. Klein Tank, E. J. Klok, P. D. Jones, and M. New (2008), A European daily high-resolution gridded data set of surface temperature and precipitation for 1950 – 2006, J. Geophys. Res., 113, D20119, doi:10.1029/2008JD010201. |