Cyclone regeneration in the North Atlantic intensified by energetic solar proton events

Atmospheric effects of energetic Solar Proton Events (SPEs) were studied in the North Atlantic region, for particle energies above 90 MeV, using NCEP/NCAR reanalysis data and weather charts. A significant lowering of the pressure levels in the troposphere accompanied by an increase of the cyclonic vorticity was found near the south-eastern coast of Greenland on the days following the event onsets. According to the weather charts, the detected effects are caused by the re-deepening (the regeneration) of well developed cyclones that seem to be intensified during the SPEs under study. A joint analysis of the pressure and temperature variations showed a noticeable decrease of the temperature in the rear of the deepening cyclones that may be due to the cold advection increase. The results obtained suggest the influence of energetic SPEs on the cyclone development as well as the importance of the frontal zone situated near the Greenland coast for this influence. A physical mechanism of the detected effects may involve the increase of the cold advection due to changes in the temperature gradients in this region resulting from the radiative forcing and/or the latent heat release related to the cloudiness variations.