Coupling between the neutral atmosphere and the ionosphere during major stratospheric warming events
Abstract
The coupling of dynamical processes in the middle atmosphere and in the ionosphere over Nordic polar region during Sudden Stratospheric Warming (SSW) is investigated. For middle atmosphere dynamics analysis the databases of UK Met Office and MLS Aura temperature data were used. Ionosphere dynamics was investigated by using COSMIC data and data from ionosondes, at high-midlatitudes. Two events are considered in the study. First is the major SSW in January 2009 which appeared as one of most powerful events in the period of continuous Solar minimum in years 2005-2010. Second event is the major SSW in winter of years 2012-2013. The driver of SSW was the global circulation energy, which has been released in the stratosphere when circumpolar vortex divided by couples of cyclonic and anti-cyclonic vortexes. Maximal neutral atmosphere effect (heating) was observed on circulations borders with northward currents, and was caused by adiabatic dynamical compression of the gas on vortexes borders. Ionosondes network data showed SSW effects in the ionosphere and these effects highly depended on observational site positions relatively to circulation zones. Five high- ionosondes in Yekaterinburg, Novosibirsk, Irkutsk, Yakutsk and Paratunka are used as midlatitude chain with ~20 degrees longitudinal space apart. During both stratospheric warmings we observed quite different ionosphere responses on these ionosondes. When ionosonde is under stratospheric cyclone vortex we observed increasing of critical frequency lowering of ionosphere maximum height. When ionosonde is under heating area we observe reverse ionosphere dynamics. As mechanism of neutral atmosphere impact to the ionosphere above the cyclone we consider the lowering of molecular gas from the lower thermosphere in low pressure zone. Over the heating area we consider the uplifting of molecular gas due to turbulent processes in regions of dynamical compressing. Both processes significantly change chemical properties of lower thermosphere and, as the result, the recombination rate in the ionosphere. The work was done in the frame of joint Russian-Bulgarian project “Atmosphere-Ionosphere Coupling during Sudden Stratospheric Warming”. The work was supported by Russian Found of Basic Research (Grant RFBR 13-05-00292-a), and by the Integration Project of SB RAS No. 106.
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E3049S