TY - JOUR
T1 - Using TIMED/SABER nightglow observations to investigate hydroxyl emission mechanisms in the mesopause region
AU - Xu, Jiyao
AU - Gao, Hong
AU - Smith, Anne K.
AU - Zhu, Yajun
PY - 2012
Y1 - 2012
N2 - Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) observations of vertical profiles of the OH nightglow emission rates, temperature, and ozone are used along with a theoretical model of the OH nightglow to distinguish the dominant mechanism for the nightglow. From the comparison between the model fit and the observations we conclude that the chemical reaction O3+H→OH(v≤9)+O2 leads to population distributions of vibrationally excited states that are consistent with the measurements. The contribution of the reaction HO2+O→ OH(v≤6)+O2 to the nightglow is not needed to reproduce the measurements above 80km, at least for the emissions originating from vibrational transitions with v≥4. The analysis also determines the best fits for quenching of OH(v) by O2 and O. The results show that the quenching rate of OH(v) by O2 is smaller and that the removal by O is larger than currently used for the analysis of SABER data. The rate constant for OH(v) quenching by O2 decreases with temperature in the mesopause region. The vertical profiles of atomic oxygen and hydrogen retrieved using both 2.0 and 1.6μm channels of Meinel band emission of the OH nightglow and the new quenching rates are slightly smaller than the profiles retrieved using only the 2.0μm channel and the quenching rate coefficients currently used for the analysis of SABER data. The fits of the model to the observations were also used to evaluate two other assumptions. The assumption of sudden death quenching of OH by O2 and N2 (i.e., quenching to the ground state rather than to intermediate vibrational levels) leads to poorer agreement with the SABER observations. The question of whether the reaction with or quenching by atomic oxygen depends on the OH vibrational level could not be resolved; assumptions of vibrational level dependence and independence both gave good fits to the observed emissions.
AB - Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) observations of vertical profiles of the OH nightglow emission rates, temperature, and ozone are used along with a theoretical model of the OH nightglow to distinguish the dominant mechanism for the nightglow. From the comparison between the model fit and the observations we conclude that the chemical reaction O3+H→OH(v≤9)+O2 leads to population distributions of vibrationally excited states that are consistent with the measurements. The contribution of the reaction HO2+O→ OH(v≤6)+O2 to the nightglow is not needed to reproduce the measurements above 80km, at least for the emissions originating from vibrational transitions with v≥4. The analysis also determines the best fits for quenching of OH(v) by O2 and O. The results show that the quenching rate of OH(v) by O2 is smaller and that the removal by O is larger than currently used for the analysis of SABER data. The rate constant for OH(v) quenching by O2 decreases with temperature in the mesopause region. The vertical profiles of atomic oxygen and hydrogen retrieved using both 2.0 and 1.6μm channels of Meinel band emission of the OH nightglow and the new quenching rates are slightly smaller than the profiles retrieved using only the 2.0μm channel and the quenching rate coefficients currently used for the analysis of SABER data. The fits of the model to the observations were also used to evaluate two other assumptions. The assumption of sudden death quenching of OH by O2 and N2 (i.e., quenching to the ground state rather than to intermediate vibrational levels) leads to poorer agreement with the SABER observations. The question of whether the reaction with or quenching by atomic oxygen depends on the OH vibrational level could not be resolved; assumptions of vibrational level dependence and independence both gave good fits to the observed emissions.
UR - https://www.scopus.com/pages/publications/84863012333
U2 - 10.1029/2011JD016342
DO - 10.1029/2011JD016342
M3 - Article
AN - SCOPUS:84863012333
SN - 0148-0227
VL - 117
JO - Journal of Geophysical Research
JF - Journal of Geophysical Research
IS - 2
M1 - D02301
ER -