Influence of energetic Solar Proton Events on the development of cyclonic processes at extratropical latitudes

Abstract

Effects of energetic Solar Proton Events (SPEs), with energies above 90 MeV, on the development of cyclonic processes at extratropical latitudes of the Northern and Southern hemispheres were studied, using NCEP/NCAR reanalysis data. The study revealed that these events are accompanied by a noticeable intensification of cyclonic activity at middle latitudes, mainly over oceans. In the Northern hemisphere this effect is observed for the SPEs occurring in October-March, whereas in the Southern hemisphere it is most pronounced for the events in April-September. In the Northern hemisphere the largest cyclone deepening takes place in the North Atlantic near the south-eastern coasts of Greenland, this area being characterized by high temperature contrasts and low geomagnetic cutoff rigidities. In the Southern hemisphere most appreciable cyclone intensification was found over the Southern Ocean near the Antarctic coasts next to the South Magnetic Pole, the region is characterized by low geomagnetic cutoff rigidities and high temperature contrasts, too. The results obtained show an importance of ionization changes produced by cosmic ray variations for the mechanism of solar activity influence on the lower atmosphere circulation.