Solar activity and cosmic ray variations as a factor of intensity of cyclonic processes at midlatitudes

Abstract

It is widely known that the zone of middle and subpolar latitudes of the North Atlantic is of special interest for studying changes in weather and climate as a region of formation and development of cyclones. The solar activity effects in variations of atmospheric characteristics in this region were studied in many works. The number of cyclones in the western part of the North Atlantic was shown to decrease at a solar activity maximum (a minimum in the flux of galactic cosmic rays) in the years with the western phase of quasi-biennial oscillations (QBOs) of the atmosphere [Labitzke and van Loon, 1989]. Tinsley [1988] found a northward shift of the trajectories of the cyclone motion in the North Atlantic in solar activity minimum (the maximum in the GCR flux), the shift being more distinct at the western phase of QBO. The data presented by Tinsley and Deen [1991] indicate that there is a decrease in cyclonic vorticity (mainly in the ocean sector of middle latitudes) due to short-period changes (Forbush decreases) in the GCR flux. In this paper, variations in the surface pressure in the North Atlantic in the 1874‐ 1995 period (making it possible to estimate the intensity of cyclonic processes in the studied region) and comparison of these data to variations in solar and geomagnetic activity and GCR flux are presented.