ABSTRACT:The present study explores the spatial variability of the continentality, oceanity and aridity indices in Turkey. Climatic indices are diagnostic tools used to describe climatic conditions and the state of a climate system. In this study, four indices were calculated using the climatic data from 229 meteorological stations in Turkey. The nature of the indices expresses general climatic features such as continentality, marine influences and aridity. The climatic indices used here are the Johansson Continentality (JC) Index, the Kerner Oceanity Index (KOI), the De Martonne Aridity Index (I DM ) and the Pinna Combinative (PV) Index. Furthermore, aridity characteristics in Turkey have been examined using the two separate periods (1960-1990 and 1991-2006). To assess the temperature and precipitation patterns in Turkey, the climatic indices were calculated by using monthly temperature and precipitation for the period 1960-2006. According to the results of the KOI, marine climates characteristics were dominant in the Black Sea region than in its Aegean and Mediterranean region. The JC index is used for the climatic classification between continental and oceanic climates. The continental effect was found across 25% of the country. The maximum continentality with a score of 71.5 has been found in the eastern Anatolia. Furthermore, semi-dry areas were increasing in the 1991-2006 period compared to 1960-1990. A significant correlation was found between the values of the JC index and the KOI. The JC index gives reasonable results for Turkey. The continental effect was found across 25% of the country. This analysis may be of benefit for the explanation of landscape characteristics and the rational utilization of water resources, agriculture and energy scenarios for the region in many areas of Turkey.

No abstract

No abstract

ABSTRACT:In the present study, annual, wet and dry seasons precipitation records for the period 1961-2008 from 271 stations in Turkey were analysed using the rotated empirical orthogonal function (REOF), the Mann-Kendall trend test and the continuous wavelet transform (WT) method. Additionally, relationships between time variability of the significant spatial patterns and North Atlantic Oscillation (NAO), Arctic Oscillation (AO), and North-Sea Caspian Pattern (NCP) are examined. The REOF method was used to analyse the annual, dry, and wet season variability of precipitation patterns over Turkey. The Mann-Kendall method was used to detect the temporal trend of the rotated principal components (RPCs) time series, and the continuous wavelet method was used to explore the periodicity of precipitation changes. Continuous WT results indicate that the significant 3-4 year, 6-10 year, and 12-16 year bands are the major period components. Precipitation in Turkey is uneven in space and time, and its complex temporal structure and spatial variations are different in each dry and wet season. The Mann-Kendall test results show that decreasing annual precipitation is the dominating trend throughout Anatolia, including west, and southwest sections. Increasing annual precipitation can be observed in only northeast Black Sea region of Turkey. Decreasing wet/dry season precipitation that we observe throughout the country, except northeast coasts and eastern parts of Turkey, is expected to have a strong impact on the economic livelihood of the region, especially on agricultural production, drinking water supply, and hydroelectricity production.

No abstract

No abstract

In this study a set of cyclone frequency statistics is developed and the prevailing tracks of cyclones are derived for a region of the world that has not been previously investigated in detail. Analysis reveals that Turkey experiences the effects of five dominant cyclone trajectories. Investigation of the seasonal variability of the cyclone frequencies shows that the highest number of cyclones occurs during winter. The variability of the subtropical jetstream latitude is analysed by multi-variable regression involving cyclone numbers, the numbers of occurrences of the Mediterranean Persistence High Pressure (MPHP), which is an extension of the Azore High Pressure and their periods. This analysis revealed that the most important factor among the three factors chosen is the number of observed blocking cases over Turkey. Although the northern parts of Turkey are accepted as having a transitional type climate between the Mediterranean and temperate regions, our results showed that they are more influenced by cyclones of Mediterranean origin.

No abstract