HR: 1340h
AN: SA23A-1133    [Abstracts]
TI: NO_x Enhancements in the Middle Atmosphere: The Relative Significance of Solar Proton Events and the Aurora as a Source
AU: * Seppälä, A
EM: annika.seppala@fmi.fi
AF: Finnish Meteorological Institute, P.O.Box 503 (Erik Palmenin aukio 1), Helsinki, FI-00101, Finland
AU: Clilverd, M A
EM: macl@bas.ac.uk
AF: British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom
AU: Rodger, C J
EM: crodger@physics.otago.ac.nz
AF: University of Otago, P.O.Box 56, Dunedin, 9054, New Zealand
AB: In this study we combine odd nitrogen (NO_x) observations from the satellite instruments with a radio wave ionisation index to provide a detailed description of the generation and descent of polar NO_x into the upper stratosphere during the Northern Hemisphere winter of 2003-2004. The measurements are used to study the relative contributions of ionization due to solar proton events, energetic electron precipitation, and auroral precipitation on NO_x production, and its subsequent downward transport to the upper stratosphere. We show that NO_x generated from the large solar proton storm in October/November 2003 was transported into the upper stratosphere in agreement with model calculations, but that aurorally generated NO_x also descended later in the winter. Both periods were highly significant and produced large long-lived decreases in stratospheric ozone. The observations made by GOMOS/Envisat deep into the nighttime polar vortex prove critical in differentiating between the stratospheric effects of these two events.
DE: 0341 Middle atmosphere: constituent transport and chemistry (3334)
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2455 Particle precipitation
DE: 7974 Solar effects
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting