Statistical complexity in daily precipitation of NCEP/NCAR reanalysis over the Mediterranean Basin

摘要

This study investigates a deterministic index (I _D) for shaping regular coherent structures in meteorological and climatic variables. The developed I _D was applied to the large-scale daily precipitation series derived from the data sets of the reanalysis available from National Centres for Environmental Prediction/National Centre for Atmospheric Research for the period of 1950-2011 over the Mediterranean Basin. In order to show advantages and disadvantages of I _D, its results were compared with two other persistence indexes known in the literature. One of persistence index is estimated by using autocorrelation function (I _(ACF)), and the other is based on conditional probability (I _(CP)). Following the patterns of I _D, the low values are obtained over the countries facing the sea including Greece, Italy, Turkey, Syria, Lebanon, Cyprus, Macedonia, Albania, Serbia, Slovenia, France, Portugal, Spain, Morocco and Tunisia, almost all of which are characterized with dry summer subtropical Mediterranean climate. On the other hand, the meaningful climatic patterns of I _(ACF) are observed only over the Mediterranean Sea. At the same time as employing I _(CP) to wet state of the precipitation series, the same patterns are obtained as I _(ACF). However, for dry state, I _(CP) produces noticeable similar patterns to I _D, generally in arid and semi-arid areas. The major results show that the patterns estimated by I _D could be better understandable in point of view of its representing traditional spatio-temporal meteorological features. That is, the patterns of I _D correspond to wellknown climatic and weather features for large-scale daily precipitation values associated with influences of the atmospheric disturbances and physical geographical features such as topography and land-sea distribution over the Mediterranean Basin.