Technical note: Evaluation of the simultaneous measurements of mesospheric OH, HO<sub>2</sub>, and O<sub>3</sub> under a photochemical equilibrium assumption – a statistical approach

Abstract

Abstract. This Technical Note presents a statistical approach to evaluating simultaneous measurements of several atmospheric components under the assumption of photochemical equilibrium. We consider simultaneous measurements of OH, HO 2 , and O 3 at the altitudes of the mesosphere as a specific example and their daytime photochemical equilibrium as an evaluating relationship. A simplified algebraic equation relating local concentrations of these components in the 50-100 km altitude range has been derived. The parameters of the equation are temperature, neutral density, local zenith angle, and the rates of eight reactions. We have performed a one-year simulation of the mesosphere and lower thermosphere using a 3-D chemical-transport model. The simulation shows that the discrepancy between the calculated evolution of the components and the equilibrium value given by the equation does not exceed 3-4 % in the full range of altitudes independent of season or latitude. We have developed a statistical Bayesian evaluation technique for simultaneous measurements of OH, HO 2 , and O 3 based on the equilibrium equation taking into account the measurement error. The first results of the application of the technique to MLS/Aura data (Microwave Limb Sounder) are presented in this Technical Note. It has been found that the satellite data of the HO 2 distribution regularly demonstrate lower altitudes of this component's mesospheric maximum. This has also been confirmed by model HO 2 distributions and comparison with offline retrieval of HO 2 from the daily zonal means MLS radiance.

Inferring the absorption properties of organic aerosol in Siberian biomass burning plumes from remote optical observations

“…( 9) is performed numerically using a Monte Carlo algorithm (Press et al, 1992). Monte Carlo algorithms, which have frequently been used in the atmospheric sciences to solve optimization problems within probabilistic frameworks (e.g., Beekmann and Derognat, 2003;Konovalov et al, 2006;Lu et al, 2015;Kulikov et al, 2018), involve running multiple model calculations with randomly varied parameters. In this study, our Monte Carlo calculations included the following steps: (1) sampling of x from the corresponding a priori PDFs, (2) Mie theory simulations of z m as a function of the given x, and (3) summation over the values of the product of f (x) with P p (x|z o ).…”

“…The discussion above emphasizes the need for additional observational constraints on the BrC absorption. To address this need, multiple studies (e.g., Arola et al, 2011;Bahadur et al, 2012;Chung et al, 2012b;Cazorla et al, 2013;Lack and Langridge, 2013;Wang et al, 2016;Xie et al, 2017;Kim et al, 2021) have employed different methods to estimate the contribution of BrC to the total aerosol absorption using retrievals from the Aerosol Robotic Network (AERONET), which comprises numerous sun photometers located worldwide (Holben et al, 1998). Most of these studies have exploited the fact that the BrC absorption rapidly decreases with an increase in the wavelength.…”

Retrieval of daytime O and H distributions at the altitudes of the mesosphere - lower thermosphere from satellite measurement data

“…In the second case, we used the values of parameters presented in the forth column of Table 2. Local daytime concentrations of OH and HO 2 were found from retrieved O and H data with the use of the chemical equilibrium conditions of OH and HO 2 (see, for example, [2]): ,…”

“…The photochemical equilibrium assumption of trace gases with relatively short lifetime gives us unique algebraic connections to derive unmeasured gases from available data, evaluate data of simultaneous measurements, estimate reaction rates usually known with significant uncertainty (see, e.g., the short review in [2] and references therein), and etc. Nevertheless, to avoid significant systematic errors in application, these connections and their parameters should be justified.…”

The 2‐Day Photochemical Oscillations in the Mesopause Region: The First Experimental Evidence?

“…Second, we use the 3‐D chemical‐transport model of the middle atmosphere developed by the Leibniz Institute of Atmospheric Physics (e.g., Grygalashvyly et al., 2009; Hartogh et al., 2004, 2011; Körner & Sonnemann, 2001; Sonnemann et al., 1998) with the fields of temperature and winds adopted by Kulikov, Nechaev et al. (2018) from the Canadian Middle Atmosphere Model (Scinocca et al., 2008). The grid of the model includes 354 pressure‐height levels (0–135 km), 32 latitudinal, and 64 longitudinal levels.…”