English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

Marine-produced short-lived trace gases such as dibromomethane(CH2Br2), bromoform (CHBr3), methyliodide (CH3I) anddimethyl sulfide (DMS) significantly impact tropospheric and stratosphericchemistry. Describing their marine emissions in atmospheric chemistry modelsas accurately as possible is necessary to quantify their impact on ozonedepletion and Earth's radiative budget. So far, marine emissions oftrace gases have mainly been prescribed from emission climatologies, thuslacking the interaction between the actual state of the atmosphere and theocean. Here we present simulations with the chemistry climate model EMAC (ECHAM5/MESSyAtmospheric Chemistry)with online calculation of emissions based on surface water concentrations,in contrast to directly prescribed emissions. Considering the actual stateof the model atmosphere results in a concentration gradient consistent withmodel real-time conditions at the ocean surface and in the atmosphere, whichdetermine the direction and magnitude of the computed flux. This method hasa number of conceptual and practical benefits, as the modelled emission canrespond consistently to changes in sea surface temperature, surface windspeed, sea ice cover and especially atmospheric mixing ratio. This onlinecalculation could enhance, dampen or even invert the fluxes (i.e. depositioninstead of emissions) of very short-lived substances (VSLS). We show thatdifferences between prescribing emissions and prescribing concentrations(−28 % for CH2Br2 to +11 % for CHBr3) result mainlyfrom consideration of the actual, time-varying state of the atmosphere. Theabsolute magnitude of the differences depends mainly on the surface oceansaturation of each particular gas. Comparison to observations from aircraft,ships and ground stations reveals that computing the air–sea fluxinteractively leads in most of the cases to more accurate atmospheric mixingratios in the model compared to the computation from prescribed emissions.Calculating emissions online also enables effective testing of differentair–sea transfer velocity (k) parameterizations, which was performed here foreight different parameterizations. The testing of these different k values isof special interest for DMS, as recently published parameterizations derivedby direct flux measurements using eddy covariance measurements suggestdecreasing k values at high wind speeds or a linear relationship with windspeed. Implementing these parameterizations reduces discrepancies inmodelled DMS atmospheric mixing ratios and observations by a factor of 1.5compared to parameterizations with a quadratic or cubic relationship to windspeed

atmospheric chemistry and physics

Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions