Effects of Solar Proton Events of January 2005 on the middle atmosphere dynamics in the Northern hemisphere

Abstract

• The stratospheric polar vortex was strongly intensified in the course of Solar Proton Events in January 2005. • Intensification of the vortex seems to be associated with ionization increase. • The vortex state may be influenced by solar activity phenomena on a daily time scale. In January 2005, a series of strong Solar Proton Events (SPEs) associated with an enhancement of flare activity on the Sun occurred resulting in a considerable increase of ionization in the polar atmosphere. In this work an impact of these events on the middle atmosphere circulation in the Northern hemisphere is investigated on the base of daily values of western wind velocity at different stratospheric levels taken from NCEP-DOE reanalysis-2 archive. A noticeable increase of western wind velocity in the latitudinal belt 60–80°N at all the stratospheric levels was revealed in the course of SPEs under study. The detected effects provide evidence for intensification of the stratospheric polar vortex which plays an important part in the mechanism of solar-atmospheric links. It was shown that ionization changes associated with powerful SPEs and, possibly, auroral phenomena may influence the state of the stratospheric polar vortex on the day-to-day time scale. A possible reason for the polar vortex intensification seems to be temperature variations which may be associated with changes of chemical composition of the polar atmosphere caused by ionization increase, as well as with radiative forcing of cloud changes.