Links between geomagnetic activity and atmospheric cold fronts passage over the Belgrade region, Serbia.

The suggestion that variations in solar irradiance affect Earth's weather and climate is based on correlations between solar and meteorological parameters. Solar activity influences the Earth's magnetic field. The geomagnetic activity index (GAI) is one of the indexes that measure this influence. In this paper, we researched the link between GAI and the passage of atmospheric cold fronts (CFs) over the Belgrade region, Serbia. Three years of daily data for solar (coronal holes, protons velocity and density), geomagnetic (GAI, electrical potential of Earth's atmosphere) and meteorological (air temperature, wind and precipitation) parameters were analysed. We developed a methodology that established pairs of GAI peaks and CFs and found the time interval (TI) between them. In 88.5% of cases, we were able to pair a GAI and a CF, while in 11.44% pairing could not be established. The number of GAI peaks without assigned CFs increased as mean values of GAI decreased. Most frequently, following an increase in the GAI, a CF passed after 7 days (relative frequency 22.8%), followed by 6 days (19.9%) and 8 days (18.5%). These three TIs covered, in sum, 61.3% of cases. Mean TI value was 6.82 days. The warm part of the year had the same TI distribution but the cold part of the year produced a bimodal frequency, with a maximum of 8 days (21.6%), followed by 5 (18.3%) and 6 days (17.6%). The most frequent CFs passing over Belgrade are from WNW‐N (67.1%) and SSW‐W (27.6%) quadrants. [ABSTRACT FROM AUTHOR]