Cyclone-induced surface ozone and HDO depletion in the Arctic

Abstract

Abstract. Ground-based, satellite, and reanalysis datasets were used to identify two similar cyclone-induced surface ozone depletion events at Eureka, Canada (80.1 • N, 86.4 • W), in March 2007 and April 2011. These two events were coincident with observations of hydrogen deuterium oxide (HDO) depletion, indicating that condensation and sublimation occurred during the transport of the ozonedepleted air masses. Ice clouds (vapour and crystals) and aerosols were detected by lidar and radar when the ozoneand HDO-depleted air masses arrived over Eureka. For the 2007 event, an ice cloud layer was coincident with an aloft ozone depletion layer at 870 m altitude on 2-3 March, indicating this ice cloud layer contained bromine-enriched blowing-snow particles. Over the following 3 days, a shallow surface ozone depletion event (ODE) was observed at Eureka after the precipitation of bromine-enriched particles onto the local snowpack. A chemistry-climate model (UKCA) and a chemical transport model (pTOMCAT) were used to simulate the surface ozone depletion events. Incorporating the latest surface snow salinity data obtained for the Weddell Sea into the models resulted in improved agreement between the modelled and measured BrO concentrations above Eureka. MERRA-2 global reanalysis data and the FLEXPART particle dispersion model were used to study the link between the ozone and HDO depletion. In general, the modelled ozone and BrO showed good agreement with the ground-based observations; however, the modelled BrO and ozone in the nearsurface layer are quite sensitive to the snow salinity. HDO depletion observed during these two blowing-snow ODEs was found to be weaker than pure Rayleigh fractionation. This work provides evidence of a blowing-snow sublimation process, which is a key step in producing bromine-enriched seasalt aerosol.

Pan-Arctic surface ozone: modelling vs measurements

“…Below are some specific parameters applied in this study for the Arctic SSA simulation, which are slightly different from previous runs. For instance, a full distribution of surface snow salinity taken from the Weddell Sea cruise data (Frey et al, 2019) is used, instead of a constant value (=0.3 psu, practical salinity unit) that was used in Legrand et al (2016) and Zhao et al (2017). For the Arctic, snow salinity is assumed to be 3.5 times the Weddell Sea salinity, rather than 2 times as used in https://doi.org/10.5194/acp-2019-984 Preprint.…”

Arctic Reactive Bromine Events Occur in Two Distinct Sets of Environmental Conditions: A Statistical Analysis of 6 Years of Observations

“…The end of the reactive bromine recycling season is also associated with rainfall (Burd et al, ). Other meteorological processes have also been shown to increase bromide conversion to BrO, such as high wind speeds (Choi et al, ; Jones et al, ; Zhao et al, ), surface inversions (Frieß et al, ; Koo et al, ; Peterson et al, ), conditions with high aerosol extinction (Frieβ et al, ), cold temperatures (Pöhler et al, ), and increased contact time between air masses and sea ice (Peterson et al, ; Simpson et al, ). There are potentially several physical and chemical processes that could explain these associations.…”

The world Brewer reference triad – updated performance assessment and new double triad

“…From October 2004, MERRA-2 assimilates ozone profiles and total column data from the Microwave Limb Sounder (MLS) and the OMI, respectively (Wargan et al, 2017). MERRA-2 column ozone data has been found to be of good quality when compared with satellite and ground-based observations (e.g., Rienecker et al, 2011;Wargan et al, 2017;Zhao et al, 2017Zhao et al, , 2019. In this work, the MERRA-2 total column ozone (0.5° × 0.625°, version 5.12.4) with 1hour temporal resolution is used as an input in the third-party comparison model (see Section 4 for more details).…”