Pan-Arctic surface ozone: modelling vs. measurements

Abstract

Abstract. Within the framework of the International Arctic Systems for Observing the Atmosphere (IASOA), we report a modelling-based study on surface ozone across the Arctic. We use surface ozone from six sites – Summit (Greenland), Pallas (Finland), Barrow (USA), Alert (Canada), Tiksi (Russia), and Villum Research Station (VRS) at Station Nord (North Greenland, Danish realm) – and ozone-sonde data from three Canadian sites: Resolute, Eureka, and Alert. Two global chemistry models – a global chemistry transport model (parallelised-Tropospheric Offline Model of Chemistry and Transport, p-TOMCAT) and a global chemistry climate model (United Kingdom Chemistry and Aerosol, UKCA) – are used for model data comparisons. Remotely sensed data of BrO from the GOME-2 satellite instrument and ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) at Eureka, Canada, are used for model validation. The observed climatology data show that spring surface ozone at coastal sites is heavily depleted, making ozone seasonality at Arctic coastal sites distinctly different from that at inland sites. Model simulations show that surface ozone can be greatly reduced by bromine chemistry. In April, bromine chemistry can cause a net ozone loss (monthly mean) of 10–20 ppbv, with almost half attributable to open-ocean-sourced bromine and the rest to sea-ice-sourced bromine. However, the open-ocean-sourced bromine, via sea spray bromide depletion, cannot by itself produce ozone depletion events (ODEs; defined as ozone volume mixing ratios, VMRs, < 10 ppbv). In contrast, sea-ice-sourced bromine, via sea salt aerosol (SSA) production from blowing snow, can produce ODEs even without bromine from sea spray, highlighting the importance of sea ice surface in polar boundary layer chemistry. Modelled total inorganic bromine (BrY) over the Arctic sea ice is sensitive to model configuration; e.g. under the same bromine loading, BrY in the Arctic spring boundary layer in the p-TOMCAT control run (i.e. with all bromine emissions) can be 2 times that in the UKCA control run. Despite the model differences, both model control runs can successfully reproduce large bromine explosion events (BEEs) and ODEs in polar spring. Model-integrated tropospheric-column BrO generally matches GOME-2 tropospheric columns within ∼ 50 % in UKCA and a factor of 2 in p-TOMCAT. The success of the models in reproducing both ODEs and BEEs in the Arctic indicates that the relevant parameterizations implemented in the models work reasonably well, which supports the proposed mechanism of SSA production and bromide release on sea ice. Given that sea ice is a large source of SSA and halogens, changes in sea ice type and extent in a warming climate will influence Arctic boundary layer chemistry, including the oxidation of atmospheric elemental mercury. Note that this work dose not necessary rule out other possibilities that may act as a source of reactive bromine from the sea ice zone.

Implementation and Impacts of Surface and Blowing Snow Sources of Arctic Bromine Activation Within WRF‐Chem 4.1.1

“…In agreement with previous work (Yang et al., 2019 ), we show that blowing snow has a strong impact on Arctic sea salt aerosol concentrations (supplementary Figure S1 ). However, in contradiction with previous work (Huang & Jaeglé, 2017 ; Huang et al., 2020 ; Yang et al., 2020 ), we find that blowing snow has little effect on Arctic ozone depletion, being responsible only for a few events and, regionally, at most for 10%–20% of the total depletion in a limited region along the Russian Coast. Here we explore some possible causes for these differences.…”

“…Model studies on polar aerosols also demonstrate an improved agreement compared to sea salt observations for winter and spring when blowing snow sourced sea salt aerosols are included (Huang et al., 2018 ; Rhodes et al., 2017 ). Further, this has been recently shown to improve model predictions of BrO and O 3 (Huang et al., 2020 ; Yang et al., 2020 ). Finally, observations show that aerosols can sustain bromine activation above the boundary layer (Peterson et al., 2017 ), but it has not yet been clearly demonstrated from measurements that blowing snow sourced sea salt aerosols trigger bromine explosion events.…”

Role of oceanic ozone deposition in explaining temporal variability in surface ozone at High Arctic sites

“…The simulation period is 8 August to 7 September 2008 including 3 d of spin-up. This end-of-summer 2008 period is chosen (1) to limit the role of active halogen chemistry during springtime (Pratt et al, 2013;Thompson et al, 2017;Yang et al, 2020) and (2) the additional availability of O 3 observations in the High Arctic over sea ice from the Arctic Summer Cloud Ocean Study (ASCOS) campaign (Paatero et al, 2009). The ECMWF ERA5 meteorology (0.25 • × 0.25 • ) (Hersbach et al, 2020) and CAMS reanalysis chemistry (0.75 • × 0.75 • ) (Inness et al, 2019) products are used for the initial and boundary conditions.…”

“…Its main sinks are chemical destruction and deposition to the Earth's surface Published by Copernicus Publications on behalf of the European Geosciences Union. (Young et al, 2018;Tarasick et al, 2019). Understanding the Arctic O 3 budget is of particular interest because its remote location implies that anthropogenic sources and sinks are generally absent.…”

Evaluation of the offline-coupled GFSv15–FV3–CMAQv5.0.2 in support of the next-generation National Air Quality Forecast Capability over the contiguous United States

“…The plume rise of the point source will be driven by the meteorology and allocated to the 35 elevated layers in the GFSv15-CMAQv5.0.2 system by the PREMAQ preprocessing system. Biogenic emissions are calculated inline by the Biogenic Emission Inventory System (BEIS) version (Binkowski et al, 2007) Gas-phase chemistry The Carbon Bond mechanism version 5 with active chlorine chemistry and updated toluene mechanism (CB05tucl) (Yarwood et al, 2005;Sarwar et al, 2012) Aqueous-phase chemistry AQCHEM (Sarwar et al, 2011) Aerosol module AERO6 with non-volatile POA (Carlton et al, 2010;Simon and Bhave, 2012;Appel et al, 2013) 3.14 (Schwede et al, 2005). Sea-salt emission is parameterized within CMAQv5.0.2.…”