SA41D-05:
Effects of Two Large Solar Energetic Particle Events on Middle Atmosphere Nighttime Odd Hydrogen and Ozone Content
Thursday, 18 December 2014: 9:10 AM
Mark Butala1, Olga P Verkhoglyadova1, Shuhui Wang2, Martin G Mlynczak3, Linda A Hunt4 and Gary Paul Zank5, (1)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (2)Jet Propulsion Laboratory, Pasadena, CA, United States, (3)NASA Langley Research Ctr, Hampton, VA, United States, (4)SSAI, Hampton, VA, United States, (5)University of Alabama in Huntsville, Huntsville, AL, United States
Abstract:
We analyze global middle atmospheric (~60 to 90 km) effects at local nighttime for two large Solar Energetic Particle (SEP) events that occurred during intervals of 7-17 November 2004 and 20-30 August 2005. Properties of the SEP events and concomitant geomagnetic storms are discussed using in situ measurements at 1 AU. Temporal dynamics and latitudinal distribution of odd hydrogen and ozone densities inferred from measurements by the AURA/MLS (Microwave Limb Sounder) instrument are analyzed. We show statistically significant increases of nightime hydroxyl (OH) density in the middle atmosphere up to 5∙106 cm-3 in the latitude range from 70° down to 50° latitude in both northern and southern hemispheres in connection with peaks in proton fluxes of >10 MeV energy range measured by the GOES spacecraft. During storm main phases the nighttime hydroxyl density increases were observed at ±50° and above. The altitude range where these effects are observed (65-80 km) is consistent with precipitating protons of >4 MeV energy range. There is a correspondence between averaged nighttime OH density in the polar latitudes and 65-85 km altitude range, and energetic proton (>10 MeV) fluxes. Corresponding statistically significant nighttime ozone depletions up to 40% relative to the background values are observed from 70° down to 60° latitude in northern and southern hemispheres. Simultaneous measurements of ozone density by TIMED/SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) instrument independently confirm that major nighttime ozone density depletions occurred in the altitude range of 65-75 km and down to ±50° latitude during strong geomagnetic storms. The SEP impulsive phases on November 8-9th 2004 and August 23rd -25th 2005 correspond to onsets of ozone density depletions. Larger relative ozone depletions are observed in the northern hemisphere in November and in the southern hemisphere in August.
