The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in the Community Atmosphere Model with chemistry and Whole Atmosphere Community Climate Model configurations. These model configurations use the Model for Ozone and Related chemical Tracers (MOZART) family of chemical mechanisms, covering the troposphere, stratosphere, mesosphere, and lower thermosphere. The new MOZART tropospheric chemistry scheme (T1) has a number of updates over the previous version (MOZART‐4) in CESM, including improvements to the oxidation of isoprene and terpenes, organic nitrate speciation, and aromatic speciation and oxidation and thus improved representation of ozone and secondary organic aerosol precursors. An evaluation of the present‐day simulations of CESM2 being provided for Climate Model Intercomparison Project round 6 (CMIP6) is presented. These simulations, using the anthropogenic and biomass burning emissions from the inventories specified for CMIP6, as well as online calculation of emissions of biogenic compounds, lightning NO, dust, and sea salt, indicate an underestimate of anthropogenic emissions of a variety of compounds, including carbon monoxide and hydrocarbons. The simulation of surface ozone in the southeast United States is improved over previous model versions, largely due to the improved representation of reactive nitrogen and organic nitrate compounds resulting in a lower ozone production rate than in CESM1 but still overestimates observations in summer. The simulation of tropospheric ozone agrees well with ozonesonde observations in many parts of the globe. The comparison of NO_x and PAN to aircraft observations indicates the model simulates the nitrogen budget well.

中文翻译：

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社区地球系统模型版本2（CESM2）中的化学机制

社区地球系统模型版本2（CESM2）在社区大气模型中使用化学和整个大气社区气候模型配置详细表示了整个大气中的化学物质。这些模型配置使用“臭氧和相关化学示踪剂模型”（MOZART）系列的化学机理，涵盖对流层，平流层，中层和低热层。新的MOZART对流层化学方案（T1）在CESM的先前版本（MOZART-4）上进行了许多更新，包括改进了异戊二烯和萜烯的氧化，有机硝酸盐的形成以及芳香族的形成和氧化，从而改善了臭氧和有机气溶胶的前体。提出了对当前为第六轮气候模型比对项目（CMIP6）提供的CESM2模拟的评估。这些模拟使用针对CMIP6指定的清单的人为排放量和生物量燃烧排放量，以及在线计算生物源化合物，雷电NO，粉尘和海盐的排放量，表明低估了各种化合物的人为排放量，包括一氧化碳和碳氢化合物。美国东南部的表面臭氧模拟比以前的模型版本有所改进，这在很大程度上是由于活性氮和有机硝酸盐化合物的表示有所改善，导致臭氧生成率低于CESM1，但仍高估了夏季的观测值。对流层臭氧的模拟与全球许多地方的臭氧探空仪观测结果非常吻合。NO的比较飞机观测值的_x和PAN表示该模型很好地模拟了氮预算。