Pollution trace gases C<sub>2</sub>H<sub>6</sub>, C<sub>2</sub>H<sub>2</sub>, HCOOH, and PAN in the North Atlantic UTLS: observations and simulations

Abstract

Abstract. Measurements of the pollution trace gases ethane (C2H6), ethyne (C2H2), formic acid (HCOOH), and peroxyacetyl nitrate (PAN) were performed in the North Atlantic upper troposphere and lowermost stratosphere (UTLS) region with the airborne limb imager GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) with high spatial resolution down to cloud top. Observations were made during flights with the German research aircraft HALO (High Altitude and LOng Range Research Aircraft) in the frame of the WISE (Wave-driven ISentropic Exchange) campaign, which was carried out in autumn 2017 from Shannon (Ireland) and Oberpfaffenhofen (Germany). Enhanced volume mixing ratios (VMRs) of up to 2.2 ppbv C2H6, 0.2 ppbv C2H2, 0.9 ppbv HCOOH, and 0.4 ppbv PAN were detected during the flight on 13 September 2017 in the upper troposphere and around the tropopause above the British Isles. Elevated quantities of PAN were measured even in the lowermost stratosphere (locally up to 14 km), likely reflecting the fact that this molecule has the longest lifetime of the four species discussed herein. Backward trajectory calculations as well as global three-dimensional Chemical Lagrangian Model of the Stratosphere (CLaMS) simulations with artificial tracers of air mass origin have shown that the main sources of the observed pollutant species are forest fires in North America and anthropogenic pollution in South Asia and Southeast Asia uplifted and moved within the Asian monsoon anticyclone (AMA) circulation system. After release from the AMA, these species or their precursor substances are transported by strong tropospheric winds over large distances, depending on their particular atmospheric lifetime of up to months. Observations are compared to simulations with the atmospheric models EMAC (ECHAM5/MESSy Atmospheric Chemistry) and CAMS (Copernicus Atmosphere Monitoring Service). These models are qualitatively able to reproduce the measured VMR enhancements but underestimate the absolute amount of the increase. Increasing the emissions in EMAC by a factor of 2 reduces the disagreement between simulated and measured results and illustrates the importance of the quality of emission databases used in chemical models.

Impact of typhoon Soudelor on ozone and water vapor in the Asian monsoon anticyclone western Pacific mode

“…The western Pacific mode of the ASMA dominated by eastward shedding is strongly impacted by the background mid‐latitude dynamics such as the subtropical jet (Rupp & Haynes, 2021). Aerosol and other tracer gases within the ASMA will be partially transported to the lower northern extra‐tropical stratosphere via the western Pacific mode of the ASMA (Fujiwara et al, 2021; Lauther et al, 2022; Vogel et al, 2016; Wetzel et al, 2021).…”

“…Deep convection penetrated the stratosphere and injected ice particles, which will hydrate the lower stratosphere (Corti et al, 2008;Khaykin et al, 2009Khaykin et al, , 2022. Measurements have proved that water vapor and air pollutants within the ASMA during boreal summer are transported from the subtropics to high latitudes in the lower stratosphere (Bian et al, 2020;Fujiwara et al, 2021;Ploeger et al, 2013;Vogel et al, 2016;Wetzel et al, 2021). Enhanced stratospheric water vapor has further potential to cause ozone loss in the stratosphere (Robrecht et al, 2019;Tian et al, 2009;Vogel et al, 2011), which will contribute to change in the rate of global warming (Randel & Jensen, 2013).…”

Non‐Orographic Gravity Waves and Turbulence Caused by Merging Jet Streams

“…The GLORIA observations during SouthTRAC are characterized by instrumental gain and offset errors as low as 1% and 30 nW cm −2 sr −1 cm, respectively (Ungermann et al., 2022). From the GLORIA observations, vertical profiles and 3D distributions of temperature, trace gas volume mixing ratios, and clouds are retrieved (e.g., Johansson et al., 2018; Krasauskas et al., 2021; Krisch et al., 2017; Wetzel et al., 2021).…”

Retrieval of Water Vapour Profiles from GLORIA Nadir Observations

“…A state-of-the-art airborne mid-infrared imaging Fourier transform spectrometer is the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) instrument [17,18]. Up to now, GLORIA has mostly been used for measurements in the limb configuration aboard the high-flying aircraft Geophysica [19,20] and during several campaigns of the German research aircraft HALO [21][22][23]. Depending on cloud top height, GLORIA can measure in limb mode down to 5-6 km.…”