Methane, Ozone & Other Trace Gases

Wednesday, January 4, 2017 -
09:00 to 10:00


-          Roll call (5min)


-          Presentation from Xin Yang: Modelling polar spring ozone losses via bromine chemistry (20min)


-          Discussion (10min)


-          Presentation on CATCH program: Jennie Thomas (15min)

Here is a bit about CATCH:


IASOA Ozone/Trace Gases Working Group

January 4, 2017


Attendees: Sara Crepinsek, Taneil Uttal, Irina Petropavlovskikh, Audra McClure, Xin Yang, Jennie Thomas, Jen Murphy, Markus Fiebig, Bahramvash Shima, Sverre Solberg, Rebecca Sheesley, Xiaoyi Zhao, Kim Strong, Nicholas Spada, Andreas Massling, Detlev Helmig, David Tarasick, Eija Asmi


Roll Call of group members

Modelling Spring Ozone Losses in Arctic Boundary Layer presentation by Xin Yang – pTOMCAT is an offline global chemistry transport model (CTM) with the following key features: forcing meteorological fields, photolysis, horizontal resolutions with top layer, tropospheric bromine chemistry scheme, and updates to model setups (mainly in sea ice sourced SSA and bromine) including new snow salinity based on the Weddell Sea collections; dry/wet depositions for SSA and Bry, previous publication: A sea-ice sourced bromine: from sea-salt aerosol production from bowing snow (Yang et al. 2008), Through a sublimation process sea salt aerosols can be formed and through heterogeneous reactions on SSA bromide will be liberated, the updated version gives reasonable well results in both SSA and Bry simulations comparing to observations at two Antarctic sites: DDU and Concordia stations, Observations in the Arctic shows large boundary layer ozone drops in Spring (March – May) though with exceptions at Summit and Pallas, model simulations indicate that the sea ice-sourced Br (flowing the formation of SST and the subsequent bromide depletion) can cause significant ozone depletions in spring, net differences for surface ozone and BrO (with-without): in spring, the sea ice sourced Br can cause BrO increase by a few pptvs; which results in ozone losses by more than 10 ppbv, the first large ozone depletion observed in Arctic spring can be well explained by the sea ice sourced bromine chemistry, surface differences for ozone and BrO concentrations between runs with and without sea ice sourced bromine: surface ozone losses in March can be up to 20 ppbv; BrO increases up to 10 pptv, zonal mean differences for ozone and BrO between runs with and without sea ice sourced bromine (March): effects can reach the whole boundary layer >1-2km, Summit likely does not have ozone depletion due to altitude being above boundary layer, Tiksi observations show depletion events occurring later in Spring whereas model does not replicate this, could be due to monthly average of model, suggest doing a scatter plot with model and observation results by month to see where months do not relate, further analysis by individual months and years to see pattern, this model output is only year 2000, whereas observation plots are several years data, model uses surface layer so no interpolation applied, how would like observed data to be packaged to better compare to model: break observations into individual year plots, look into more detailed time series like hourly averages to see individual events


CATCH: The Cryosphere and ATmostpheric CHemistry presentation by Jenny Thomas and Jen Murphy – IGAC & SOLAS emerging activity, scientists engaged in helping to plan CATCH, IGAC core activities and sustainability connections, past activities sponsored by IGAC: Air Ice Chemical Interactions (AICI) and Ocean Atmosphere Sea Ice Snowpack (OASiS) and Halogens in the Troposphere (HitT), the CATCH mission: to facilitate atmospheric chemistry research within the international community with a focus on natural processes specific to the cryosphere and cold regions of the Earth and how these processes are linked to global environmental change, research in cold and Polar regions is inherently international requiring cooperation among researchers and programs across national boundaries to achieve science objectives, CATCH focuses on processes occurring at snow and ice interfaces, oceanic surfaces, as well as aerosol and clouds in cold regions, as well as other to be determined areas of research, shared activities: IASOA, PACES, PAGES, CLiC, SOLAS, BEPSII, can learn more about CATCH:, link to CATCH mission and vision statements also available on IASOA webpage, CATCH is currently seeking community input, attend the first CATCH community workshop on April 19-20 near Paris, France, some financial aid for participants (early career scientists), workshop science themes to be put on IASOA webpage, CATCH newsletter available, two CATCH sessions at EGU 2017

CATCH (find out more):



Community meeting:

Community input survey:

Draft mission & vision:


Action Items:

  • Continue email conversation among working group member to re-define and focus key science questions (Crepinsek)
  • Define clean air sector for climatology publication (Uttal, Petropavlovskikh, Crepinsek)
  • Xin Yang to run model for specific year of hourly averages that correspond to specific year of observations (McClure, Crepinsek)
  • Create yearly and hourly observation plots (McClure)
  • Put CATCH info and workshop info on IASOA science pages (Crepinsek)
  • IASOA overview and highlights at CATCH workshop to avoid duplication (Uttal)