Sahin, S. & Türkeş, M. Theor Appl Climatol (2013) 113: 337. doi:10.1007/s00704-012-0789-5
The aim of this study was to examine the climatological characteristics of boundary layer gradient winds in Turkey in detail. In the study, monthly average wind speed (Vm) data measured at 267 stations for the 16 directions, prevailing wind direction (Vp), and station pressure (Ps) data measured at 174 stations during the period 1970–2008 by the Turkish Meteorological Service (TMS) were used. The data were provided by the TMS. To attain the aim of the study, wind patterns of midseason months representing the seasonal wind distributions were used, and surface wind formations were examined through calculation of divergent and rotational components of the average wind rate. Besides, it was aimed at explaining the relationships between sea level pressure (SLP) patterns and wind formations. The patterns of midseason months were examined via the Principal Component Analysis (PCA). In accordance with Vm data, it is seen that air flows in Turkey generally tend to orientate radially from west to east. Climatologically, the strongest prevailing winds in Turkey blow during the summer months, while the weakest winds blow during the autumn months. Vm and Vp distributions show a parallelism (i.e., wind gradient) in the months during which temperature differences between land and sea are high due to the differences in their specific heat values. The distributions of Vm and Vp values vary considerably in spring and autumn months during which temperature differences are relatively lower. According to the PCA results, the first two components represent the strong wind areas in Turkey. These components presumably explain the existence of coherent wind formation areas, which display different characteristics due to regional physical geographical factors and processes (e.g., orography, altitude, exposure, land–sea distribution, surface mechanical and thermodynamic modifications of the air masses and air flows, etc.) in addition to the direct effect of different synoptic-scale pressure and circulation conditions.