Effects of two large solar energetic particle events on middle atmosphere nighttime odd hydrogen and ozone content: Aura/MLS and TIMED/SABER measurements

Abstract

It is well established that large solar energetic particle (SEP) events affect ozone in the middle atmosphere through chemical reactions involving odd hydrogen (HO x ) species. We analyze global middle atmospheric effects at local nighttime for two large SEP events during the 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. Temporal dynamics and latitudinal distribution of HO x and ozone densities inferred from measurements by the Aura/MLS (Microwave Limb Sounder) instrument are analyzed. We show statistically significant increases of nighttime hydroxyl (OH) density in the middle atmosphere up to 5°10 6 cm À3 in the latitude range from 70°down to 50°latitude in northern and to À40°latitude in southern hemispheres in connection with peaks in proton fluxes of >10 MeV energy range measured by GOES spacecraft. During the storm main phases, the nighttime OH density increases were observed around ±50°in southern and northern hemispheres in the altitude range of 65-80 km. There is a correspondence between averaged nighttime OH partial column density (in 0.005 to 0.1 hPa pressure range) in the polar latitudes and energetic proton (>10 MeV) fluxes. Corresponding statistically significant nighttime ozone destructions up to 45% are observed from 70°down to 60°latitude in the northern and southern hemispheres. The SEP impulsive phases correspond to onsets of ozone density depletions. Larger relative ozone destructions are observed in the northern hemisphere in November and in the southern hemisphere in August. Simultaneous measurements of ozone density by the Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER) instrument independently confirm the MLS results.

Impact of M‐solar flare‐induced solar proton event on mesospheric Na layer over Utah (41.8°N,112°W)

“…Ozone has a secondary peak in the mesospheric altitude and it significantly affects sodium concentration. The atmospheric ozone concentration undergoes depletion during solar proton event (SPE) as well established from modeling and observations [ Jackman et al , , , , , ; Seppälä et al , ; Degenstein et al , ; Rohen et al , ; Verronen et al , ; Krivolutsky et al , ; Friederich et al , ; Verkhoglyadova et al , , and references therein]. Krivolutsky et al [] and Jackman et al [] reported depletion in ozone concentration during SEPs in 23rd solar cycle using models.…”

Response of Mesospheric HO2and O3to Large Solar Proton Events

“…The high reactivity makes the hydrogen radical of particular importance in atmospheric chemistry. During the SPEs, the increases in mesospheric OH have been observed (Damiani et al, ; Jackman et al, ; Verkhoglyadova et al, , ; Verronen et al, ). Jackman et al () compared the observations and model predictions and showed a good simulation of hydrogen radical and ozone during large SPEs.…”

“…Few of them explored the general influence on the atmospheric compositions and of the SPEs during the solar cycle 24 and the correlation between variations of the neutral components after the SPEs. Verkhoglyadova et al, 2015Verkhoglyadova et al, , 2016Verronen et al, 2006). Jackman et al (2014) compared the observations and model predictions and showed a good simulation of hydrogen radical and ozone during large SPEs.…”

Nighttime mesospheric hydroxyl enhancements during SEP events and accompanying geomagnetic storms: Ionization rate modeling and Aura satellite observations

“…In our previous paper [ Verkhoglyadova et al ., , hereafter Paper I] we reported observations of changes in nighttime hydroxyl and ozone during two SEP events of 7–17 November 2004 and 20–30 August 2005 based on global measurements by two satellites. We showed a correspondence between the energetic proton flux (>10 MeV) measured at the Earth's orbit and the nighttime zonal average OH partial column density enhancements between 0.005 and 0.1 hPa (approximately from 65 km to 85 km in altitude).…”

“…The main mechanism is through ionization by precipitating high-energy particles, e.g., protons with~5 MeV deposit their maximum energy at~75 km altitude, which leads to an efficient ionization of atmosphere at this altitude [Turunen et al, 2009;Wissing and Kallenrode, 2009]. Among other effects, SEPs create odd hydrogen (HO x , primarily hydroxyl OH and HO 2 ) species through ion chemistry and cause ozone (O 3 ) destruction in the mesosphere [Solomon et al, 1981[Solomon et al, , 1983Jackman et al, 2005Jackman et al, , 2006Jackman et al, , 2011Verronen et al, 2006Verronen et al, , 2007Damiani et al, 2008Damiani et al, , 2010Verkhoglyadova et al, 2015]. For example, tertiary ozone maximum observed in wintertime high-latitude mesosphere around that altitude range [Marsh et al, 2001] is strongly affected by SEPs [Seppälä et al, 2006;Sofieva et al, 2009].…”