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1. Harmonized Emissions Component (HEMCO) 3.0 as a versatile emissions component for atmospheric models: application in the GEOS-Chem, NASA GEOS, WRF-GC, CESM2, NOAA GEFS-Aerosol, and NOAA UFS models

   https://doi.org/10.5194/gmd-14-5487-2021  

   Lin, Haipeng ; Jacob, Daniel J. ; Lundgren, Elizabeth W. ; Sulprizio, Melissa P. ; Keller, Christoph A. ; Fritz, Thibaud M. ; Eastham, Sebastian D. ; Emmons, Louisa K. ; Campbell, Patrick C. ; Baker, Barry ; et al ( January 2021 , Geoscientific Model Development)

   Abstract. Emissions are a central component of atmosphericchemistry models. The Harmonized Emissions Component (HEMCO) is a softwarecomponent for computing emissions from a user-selected ensemble of emissioninventories and algorithms. It allows users to re-grid, combine, overwrite,subset, and scale emissions from different inventories through aconfiguration file and with no change to the model source code. Theconfiguration file also maps emissions to model species with appropriateunits. HEMCO can operate in offline stand-alone mode, but more importantlyit provides an online facility for models to compute emissions at runtime.HEMCO complies with the Earth System Modeling Framework (ESMF) forportability across models. We present a new version here, HEMCO 3.0, thatfeatures an improved three-layer architecture to facilitate implementationinto any atmospheric model and improved capability for calculatingemissions at any model resolution including multiscale and unstructuredgrids. The three-layer architecture of HEMCO 3.0 includes (1) the Data InputLayer that reads the configuration file and accesses the HEMCO library ofemission inventories and other environmental data, (2) the HEMCO Core thatcomputes emissions on the user-selected HEMCO grid, and (3) the ModelInterface Layer that re-grids (if needed) and serves the data to theatmospheric model and also serves model data to the HEMCO Core forcomputing emissions dependent on model state (such as from dust or vegetation). The HEMCO Core is common to the implementation in all models, whilethe Data Input Layer and the Model Interface Layer are adaptable to themodel environment. Default versions of the Data Input Layer and ModelInterface Layer enable straightforward implementation of HEMCO in any simplemodel architecture, and options are available to disable features such asre-gridding that may be done by independent couplers in more complexarchitectures. The HEMCO library of emission inventories and algorithms iscontinuously enriched through user contributions so that new inventoriescan be immediately shared across models. HEMCO can also serve as a generaldata broker for models to process input data not only for emissions but forany gridded environmental datasets. We describe existing implementations ofHEMCO 3.0 in (1) the GEOS-Chem “Classic” chemical transport model withshared-memory infrastructure, (2) the high-performance GEOS-Chem (GCHP)model with distributed-memory architecture, (3) the NASA GEOS Earth SystemModel (GEOS ESM), (4) the Weather Research and Forecasting model withGEOS-Chem (WRF-GC), (5) the Community Earth System Model Version 2 (CESM2),and (6) the NOAA Global Ensemble Forecast System – Aerosols(GEFS-Aerosols), as well as the planned implementation in the NOAA Unified ForecastSystem (UFS). Implementation of HEMCO in CESM2 contributes to theMulti-Scale Infrastructure for Chemistry and Aerosols (MUSICA) by providinga common emissions infrastructure to support different simulations ofatmospheric chemistry across scales. 

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2. Implementation and evaluation of the GEOS-Chem chemistry module version 13.1.2 within the Community Earth System Model v2.1

   https://doi.org/10.5194/gmd-15-8669-2022  

   Fritz, Thibaud M. ; Eastham, Sebastian D. ; Emmons, Louisa K. ; Lin, Haipeng ; Lundgren, Elizabeth W. ; Goldhaber, Steve ; Barrett, Steven R. ; Jacob, Daniel J. ( January 2022 , Geoscientific Model Development)

   Abstract. We implement the GEOS-Chem chemistry module as a chemical mechanism in version 2 of the Community Earth System Model (CESM). Our implementation allowsthe state-of-the-science GEOS-Chem chemistry module to be used with identical emissions, meteorology, and climate feedbacks as the CAM-chemchemistry module within CESM. We use coupling interfaces to allow GEOS-Chem to operate almost unchanged within CESM. Aerosols are converted at eachtime step between the GEOS-Chem bulk representation and the size-resolved representation of CESM's Modal Aerosol Model (MAM4). Land-type informationneeded for dry-deposition calculations in GEOS-Chem is communicated through a coupler, allowing online land–atmosphere interactions. Wet scavengingin GEOS-Chem is replaced with the Neu and Prather scheme, and a common emissions approach is developed for both CAM-chem and GEOS-Chem in CESM. We compare how GEOS-Chem embedded in CESM (C-GC) compares to the existing CAM-chem chemistry option (C-CC) when used to simulate atmosphericchemistry in 2016, with identical meteorology and emissions. We compare the atmospheric composition and deposition tendencies between the twosimulations and evaluate the residual differences between C-GC and its use as a stand-alone chemistry transport model in the GEOS-Chem HighPerformance configuration (S-GC). We find that stratospheric ozone agrees well between the three models, with differences of less than 10 % inthe core of the ozone layer, but that ozone in the troposphere is generally lower in C-GC than in either C-CC or S-GC. This is likely due to greatertropospheric concentrations of bromine, although other factors such as water vapor may contribute to lesser or greater extents depending on theregion. This difference in tropospheric ozone is not uniform, with tropospheric ozone in C-GC being 30 % lower in the Southern Hemisphere whencompared with S-GC but within 10 % in the Northern Hemisphere. This suggests differences in the effects of anthropogenic emissions. Aerosolconcentrations in C-GC agree with those in S-GC at low altitudes in the tropics but are over 100 % greater in the upper troposphere due todifferences in the representation of convective scavenging. We also find that water vapor concentrations vary substantially between the stand-aloneand CESM-implemented version of GEOS-Chem, as the simulated hydrological cycle in CESM diverges from that represented in the source NASA Modern-Era Retrospective analysis for Research and Applications (Version 2; MERRA-2)reanalysis meteorology which is used directly in the GEOS-Chem chemistrytransport model (CTM). Our implementation of GEOS-Chem as a chemistry option in CESM (including full chemistry–climate feedback) is publicly available and is beingconsidered for inclusion in the CESM main code repository. This work is a significant step in the MUlti-Scale Infrastructure for Chemistry andAerosols (MUSICA) project, enabling two communities of atmospheric researchers (CESM and GEOS-Chem) to share expertise through a common modelingframework, thereby accelerating progress in atmospheric science. 

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3. Comparison of Urban Air Quality Simulations During the KORUS‐AQ Campaign With Regionally Refined Versus Global Uniform Grids in the Multi‐Scale Infrastructure for Chemistry and Aerosols (MUSICA) Version 0

   https://doi.org/10.1029/2022MS003458  

   Jo, Duseong S. ; Emmons, Louisa K. ; Callaghan, Patrick ; Tilmes, Simone ; Woo, Jung‐Hun ; Kim, Younha ; Kim, Jinseok ; Granier, Claire ; Soulié, Antonin ; Doumbia, Thierno ; et al ( July 2023 , Journal of Advances in Modeling Earth Systems)

   Model intercomparison studies often report a large spread in simulation results, but quantifying the causes of these differences is hindered by the fact that several processes contribute to the model spread simultaneously. Here we use the Multi‐Scale Infrastructure for Chemistry and Aerosols (MUSICA) version 0 to investigate the model resolution dependencies of simulated chemical species, with a focus on the differences between global uniform grid and regional refinement grid simulations with the same modeling framework. We construct two global (ne30 [∼112 km] and ne60 [∼56 km]) and two regional refinement grids over Korea (ne30x8 [∼14 km] and ne30x16 [∼7 km]). The grid resolution can change chemical concentrations by an order of magnitude in the boundary layer, and the importance increases as the species' reactivity increases (e.g., up to 50% and 1,000% changes for ethane and xylenes, respectively). The diurnal cycle of oxidants (OH, O₃, and NO₃) also varies with the grid resolution, which leads to different oxidation pathways of volatile organic compounds (e.g., the fraction of monoterpenes reacting with NO₃in Seoul around midnight is 90% for ne30, but 65% for ne30x16). The models with high‐resolution grids usually do a better job at reproducing aircraft observations during the KORUS‐AQ campaign, but not always, implying compensating errors in the coarse grid simulations. For example, ozone is better reproduced by the coarse grid due to the artificial mixing of NO_x. When developing new chemical mechanisms and evaluating models over urban areas, the uncertainties associated with model resolution should be considered.

    

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4. Effects of Fire Diurnal Variation and Plume Rise on U.S. Air Quality During FIREX‐AQ and WE‐CAN Based on the Multi‐Scale Infrastructure for Chemistry and Aerosols (MUSICAv0)

   https://doi.org/10.1029/2022JD036650  

   Tang, Wenfu ; Emmons, Louisa K. ; Buchholz, Rebecca R. ; Wiedinmyer, Christine ; Schwantes, Rebecca H. ; He, Cenlin ; Kumar, Rajesh ; Pfister, Gabriele G. ; Worden, Helen M. ; Hornbrook, Rebecca S. ; et al ( August 2022 , Journal of Geophysical Research: Atmospheres)

   We analyze the effects of the diurnal cycle of fire emissions (DCFE) and plume rise on U.S. air quality using the MUSICAv0 (Multi‐Scale Infrastructure for Chemistry and Aerosols Version 0) model during the FIREX‐AQ (Fire Influence on Regional to Global Environments and Air Quality) and WE‐CAN (Western wildfire Experiment for Cloud chemistry, Aerosol absorption and Nitrogen) field campaigns. To include DCFE in the model, we employ two approaches: a DCFE climatology and DCFE derived from a satellite fire radiative power product. We also implemented two sets of plume‐rise climatologies, and two plume‐rise parameterizations. We evaluate the model performance with airborne measurements, U.S. EPA Air Quality System surface measurements, and satellite products. Overall, including plume rise improves model agreement with observations such as aircraft observations of CO and NO_xfor FIREX‐AQ and WE‐CAN. Applying DCFE also improves model performance, such as for surface PM_2.5in fire‐impacted regions. The impact of plume rise is larger than the impact of DCFE. Plume rise can greatly enhance modeled long‐range transport of fire‐emitted pollutants. The simulations with plume‐rise parameterizations generally perform better than the simulations with plume‐rise climatologies during FIREX‐AQ, but not for WE‐CAN. The 2019 Williams Flats Fire case study demonstrates that DCFE and plume rise change fire impacts because fire emissions are subject to different meteorology and chemistry when emitted at different times of a day and altitudes. Moreover, DCFE and plume rise also impact local‐to‐regional meteorology and chemical reaction rates. DCFE and plume rise will be included in future MUSICA versions.

    

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5. Evaluating the Impact of Chemical Complexity and Horizontal Resolution on Tropospheric Ozone Over the Conterminous US With a Global Variable Resolution Chemistry Model

   https://doi.org/10.1029/2021MS002889  

   Schwantes, Rebecca H. ; Lacey, Forrest G. ; Tilmes, Simone ; Emmons, Louisa K. ; Lauritzen, Peter H. ; Walters, Stacy ; Callaghan, Patrick ; Zarzycki, Colin M. ; Barth, Mary C. ; Jo, Duseong S. ; et al ( June 2022 , Journal of Advances in Modeling Earth Systems)

   A new configuration of the Community Earth System Model (CESM)/Community Atmosphere Model with full chemistry (CAM‐chem) supporting the capability of horizontal mesh refinement through the use of the spectral element (SE) dynamical core is developed and called CESM/CAM‐chem‐SE. Horizontal mesh refinement in CESM/CAM‐chem‐SE is unique and novel in that pollutants such as ozone are accurately represented at human exposure relevant scales while also directly including global feedbacks. CESM/CAM‐chem‐SE with mesh refinement down to ∼14 km over the conterminous US (CONUS) is the beginning of the Multi‐Scale Infrastructure for Chemistry and Aerosols (MUSICAv0). Here, MUSICAv0 is evaluated and used to better understand how horizontal resolution and chemical complexity impact ozone and ozone precursors over CONUS as compared to measurements from five aircraft campaigns, which occurred in 2013. This field campaign analysis demonstrates the importance of using finer horizontal resolution to accurately simulate ozone precursors such as nitrogen oxides and carbon monoxide. In general, the impact of using more complex chemistry on ozone and other oxidation products is more pronounced when using finer horizontal resolution where a larger number of chemical regimes are resolved. Large model biases for ozone near the surface remain in the Southeast US as compared to the aircraft observations even with updated chemistry and finer horizontal resolution. This suggests a need for adding the capability of replacing sections of global emission inventories with regional inventories, increasing the vertical resolution in the planetary boundary layer, and reducing model biases in meteorological variables such as temperature and clouds.

    

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