Improvements to the representation of BVOC chemistry-climate interactions in UKCA (v11.5) with the CRI-Strat 2 mechanism: incorporation and evaluation

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Weber, James ^[1] ; Archer-Nicholls, Scott ^[1] ; Abraham, Nathan Luke ^{[1, 2]} ; Shin, Youngsub M. ^[1] ; Bannan, Thomas J. ^[3] ; Percival, Carl J. ^[4] ; Bacak, Asan ^[5] ; Artaxo, Paulo ^[6] ; Jenkin, Michael ^[7] ; Khan, M. Anwar H. ^[8] ; Shallcross, Dudley E. ^[8] ; Schwantes, Rebecca H. ^{[9, 10]} ; Williams, Jonathan ^{[11, 12]} ; Archibald, Alex T. ^{[1, 2]}

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^[1] Univ Cambridge, Ctr Atmospher Sci, Dept Chem, Cambridge CB2 1EW - England

^[2] Univ Cambridge, Natl Ctr Atmospher Sci, Dept Chem, Cambridge CB2 1EW - England

^[3] Univ Manchester, Sch Earth & Environm Sci, Manchester M13 9PL, Lancs - England

^[4] CALTECH, NASA, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 - USA

^[5] Ankara Univ, Inst Accelerator Technol, Turkish Accelerator & Radiat Lab, Golbasi Campus, TR-06830 Ankara - Turkey

^[6] Univ Sao Paulo, Phys Inst, Rua Matao 1371, BR-05351015 Sao Paulo - Brazil

^[7] Atmospher Chem Serv, Okehampton EX20 4BQ, Devon - England

^[8] Univ Bristol, Sch Chem, Biogeochem Res Ctr, Bristol BS8 1TS, Avon - England

^[9] Univ Colorado, Cooperat Inst Res Environm Sci, Boulder, CO 80309 - USA

^[10] NOAA, Chem Sci Lab, Boulder, CO 80305 - USA

^[11] Max Planck Inst Chem, Dept Atmospher Chem, D-55128 Mainz - Germany

^[12] Cyprus Inst, Energy Environm & Water Res Ctr, Nicosia - Cyprus

• Tipo de documento: Artigo Científico
• Fonte: Geoscientific Model Development; v. 14, n. 8, p. 5239-5268, AUG 20 2021.
• Citações Web of Science: 0

Resumo

We present the first incorporation of the Common Representative Intermediates version 2.2 tropospheric chemistry mechanism, CRI v2.2, combined with stratospheric chemistry, into the global chemistry-climate United Kingdom Chemistry and Aerosols (UKCA) model to give the CRI-Strat 2 mechanism. A rigorous comparison of CRI-Strat 2 with the earlier version, CRI-Strat, is performed in UKCA in addition to an evaluation of three mechanisms, CRI-Strat 2, CRI-Strat and the standard UKCA chemical mechanism, StratTrop v1.0, against a wide array of surface and airborne chemical data. CRI-Strat 2 comprises a state-of-the-art isoprene scheme, optimized against the Master Chemical Mechanism v3.3.1, which includes isoprene peroxy radical isomerization, HOx recycling through the addition of photolabile hydroperoxy aldehydes (HPALDs), and isoprene epoxy diol (IEPOX) formation. CRI-Strat 2 also features updates to several rate constants for the inorganic chemistry, including the reactions of inorganic nitrogen and O(D-1). The update to the isoprene chemistry in CRI-Strat 2 increases OH over the lowest 500m in tropical forested regions by 30%-50% relative to CRI-Strat, leading to an improvement in model-observation comparisons for surface OH and isoprene relative to CRI-Strat and StratTrop. Enhanced oxidants also cause a 25% reduction in isoprene burden and an increase in oxidation fluxes of isoprene and other biogenic volatile organic compounds (BVOCs) at low altitudes with likely impacts on subsequent aerosol formation, atmospheric lifetime, and climate. By contrast, updates to the rate constants of O(D-1) with its main reactants relative to CRI-Strat reduces OH in much of the free troposphere, producing a 2% increase in the methane lifetime, and increases the tropospheric ozone burden by 8 %, primarily from reduced loss via O(D-1) + H2O. The changes to inorganic nitrogen reaction rate constants increase the NOx burden by 4% and shift the distribution of nitrated species closer to that simulated by StratTrop. CRI-Strat 2 is suitable for multi-decadal model integrations and the improved representation of isoprene chemistry provides an opportunity to explore the consequences of HOx recycling in the United Kingdom Earth System Model (UKESM1). This new mechanism will enable a re-evaluation of the impact of BVOCs on the chemical composition of the atmosphere and further probe the feedback between the biosphere and the climate. (AU)

• Processo FAPESP: 17/17047-0 - O ciclo de vida de aerossóis e nuvens na Amazônia: emissões biogênicas, emissões de queimadas e impactos no ecossistema
• Beneficiário: Paulo Eduardo Artaxo Netto
• Modalidade de apoio: Auxílio à Pesquisa - Programa de Pesquisa sobre Mudanças Climáticas Globais - Temático