This study analyzes the relationship between large-scale relative vorticity fields, a key variable in synoptic movements in mid-latitude regions, and rainfall in Syria. The main elements are analyzed using S-mode Principal Component Analysis (PCA), employing statistical methods such as Canonical Correlation Analysis (CCA) to investigate the relationships between the variables under study. This involves studying the patterns of relative vorticity at different pressure levels (such as hPa 850 and hPa 500) and rainfall data over Syria. The application of relative vorticity activity centers and rainfall was conducted, alongside analyzing the common relationships based on factor results related to these centers to determine any significant correlations.
The analysis relied on relative vorticity fields at pressure levels of hPa 850 and hPa 500 at grid points 10°-70° and 10°-70° with a spacing of 2.5°. Monthly relative vorticity values were obtained from the NCEP-DOE reanalysis databases (1981–2020), alongside rainfall data from 14 major stations in Syria. Major patterns from canonical regression analysis indicated changes in relative vorticity at the hPa 500 pressure level throughout the Eastern Mediterranean region and Iraq, connected with rainfall in Syria. An inverse relationship was found between relative vorticity over Eastern Europe and rainfall on the southern shores of the Caspian Sea, as well as a connection between changes in relative vorticity over Turkey and Cyprus and rainfall in Syria. The study also examined the relationship between changes in relative vorticity at hPa 850 over the Arabian Sea and rainfall in Syria.