Atomic oxygen retrievals in the MLT region from SCIAMACHY nightglow limb measurements

Abstract

Abstract. Vertical distributions of atomic oxygen concentration ([O]) in the mesosphere and lower thermosphere (MLT) region were retrieved from sun-synchronous SCIAMACHY/Envisat (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY on board the Environmental Satellite) limb measurements of the oxygen 557.7 nm green line emission in the terrestrial nightglow. A band pass filter was applied to eliminate contributions from other emissions, the impact of measurement noise and auroral activity. Vertical volume emission rate profiles were retrieved from integrated limb-emission rate profiles under the assumption that each atmospheric layer is horizontally homogeneous and absorption and scattering can be neglected. The radiative transfer problem was solved using regularized total least squares minimization in the inversion procedure. Atomic oxygen concentration profiles were retrieved from data collected for altitudes in the range 85–105 km with approximately 4 km vertical resolution during the time period from August 2002 to April 2012 at approximately 22:00 local time. The retrieval of [O] profiles was based on the generally accepted two-step Barth transfer scheme including consideration of quenching processes and the use of different available sources of temperature and atmospheric density profiles. A sensitivity analysis was performed for the retrieved [O] profiles to estimate maximum uncertainties assuming independent contributions of uncertainty components. Errors in photochemical model parameters depending on temperature uncertainties and random errors of model parameters contribute less than 50% to the overall [O] retrieval error. The retrieved [O] profiles were compared with reference [O] profiles provided by SABER/TIMED (Sounding of the Atmosphere using Broadband Emission Radiometry instrument on board the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics satellite) or by the NRLMSISE-00 (Naval Research Laboratory Mass Spectrometer and Incoherent Scatter radar Extended model, year: 2000) and SD-WACCM4 (Whole Atmosphere Community Climate Model with Specified Dynamics, version 4). A comparison of the retrieved [O] profiles with the reference [O] profiles led to the conclusion that the photochemical model taking into account quenching of O(1S) by O2, O(3P), and N2 and the SABER/TIMED model as a source of temperature and density profiles are the most appropriate choices for our case. The retrieved [O] profile time series exhibits characteristic seasonal variations in agreement with satellite observations based on analysis of OH Meinel band emissions and atmospheric models. A pronounced 11-year solar cycle variation can also be identified in the retrieved atomic oxygen concentration time series.

First mesopause Na retrievals from satellite Na D‐line nightglow observations

“…All retrievals use SCIAMACHY level 1c data version 7.0x calibrated with the scialc tool [Deutsches Zentrum für Luft-und Raumfahrt, 2015] with all calibration flags applied. Orbital data affected by instrumental or platform anomalies were screened the same way as in the case of the MLT atomic oxygen profile retrievals from SCIAMACHY oxygen green line observations described by Lednyts'kyy et al [2015]. Figure 1a shows monthly averaged Na D-line emission spectra for November 2008 and different tangent heights.…”

Updated SABER Night Atomic Oxygen and Implications for SABER Ozone and Atomic Hydrogen

“…As shown in Figure 15 of M1, SABER global mean O concentrations were larger than those from the empirical NRLMSIS-00 model (hereafter "MSIS"), although the two nearly agreed to within the uncertainty of the SABER O concentrations. Subsequently, Kaufmann et al (2014) and Lednyts'kyy et al (2015) noted that SABER atomic oxygen may be too large. Smith et al (2013) also noted that daytime upper mesospheric ozone from SABER (derived from 9.6 μm emission) was likely too large, which implies that SABER daytime atomic oxygen is also too large.…”

Nighttime atomic oxygen in the mesopause region retrieved from SCIAMACHY O(1S) green line measurements and its response to solar cycle variation

“…OH * emissions were measured by the WINDII instrument, the OSIRIS instrument, and the SABER instrument on the TIMED (Thermosphere Ionosphere Mesosphere Energetics Dynamics) A O * 2 3.0 (s −1 ) Khomich et al [2008] k OOM 4.7 × 10 −33 × ( 300 T ) 2 (cm 6 mol −2 s −1 ) Campbell and Gray [1973] k ′ O * 2 O 1.0 × 10 −12 (cm 3 mol −1 s −1 ) Khomich et al [2008] k O 1S O (5.0 ± 0.533) × 10 −11 × exp( −305 T ) (cm 3 mol −1 s −1 ) Slanger [1976] k O 1S O 2 (2.32 ± 0.94) × 10 −12 × exp( −812+1.82×10 −3 T 2 T ) (cm 3 mol −1 s −1 ) Capetanakis et al [1993] k O 1S N 2 5.0 × 10 −17 (cm 3 mol −1 s −1 ) Gobbi et al [1992] k O * 2 O 5.9 × 10 −12 (cm 3 mol −1 s −1 ) Khomich et al [2008] k O * 2 O 2 3.0 × 10 −14 (cm 3 mol −1 s −1 ) Khomich et al [2008] et al [1986] satellite [Mlynczak et al, 2013]. Recently, Two long-term atomic oxygen data sets were derived from SCIAMACHY O( 1 S) green line measurements [Kaufmann et al, 2014;Lednyts'kyy et al, 2015].…”

“…The Khomich model has never been utilized to retrieve atomic oxygen from global green line measurements. The third model was introduced by von Savigny and Lednyts'kyy [2013] and Lednyts'kyy et al [2015] (the "Lednyts'kyy model," hereinafter also referred to as "led"). This model is based on the ETON model but with significantly enhanced quenching by atomic oxygen.…”