Synoptic analysis of atmospheric circulation mechanisms in the formation of very wet months in Syria

The aim of the study was to investigate the conditions of atmospheric circulation patterns in the very wet months of Syria. By calculating the standard precipitation index (SPI) and using the precipitation data of 16 Syrian synoptic stations in the statistical period of 2016-2017, very wet months were identified. Then, combined maps of sea level pressure parameters, geopotential height and wind components at 850, 700, 500 and 250 hpa levels, as well as specific humidity at 850 level and 700 hpa level omega from NCEP-NCAR gridded reanalysis data were produced and were used to study the synoptic atmospheric patterns of very wet months. The findings show that formation of a deep trough is the most important model for creating very humid Syrian months, which is centred almost between eastern Turkey and western Egypt, and Syria is located in front of this trough. This trough, especially in the middle and upper atmospheric levels, causes to falling cold air on the eastern Mediterranean. The moving polar trough pattern at 700 and 500 hpa levels towards lower latitudes had caused the aforementioned advections. Formation of negative values of omega and rising air currents, along with southwest winds at sea level and other levels over Syria, have caused above-average rainfalls.