Earth System Model Aerosol–Cloud Diagnostics Package v1.0

  • August 21, 2022
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  • FIgure 1. Aircraft (black) and ship (red) tracks for the six field campaigns included in the current version of ESMAC Diags. The red stars in the enlarged map indicate two Atmospheric Radiation Measurement user facility fixed sites where ground-based measurements are available for model diagnostics: the Southern Great Plains (SGP) and Eastern North Atlantic (ENA). The map overlay is aerosol optical depth at 550nm averaged from 2014–2018 and simulated by the Energy Exascale Earth System Model (E3SM).

    The Science

    Earth system model representations of aerosols and their interactions with clouds and radiation are subject to large uncertainties. Model simulations need to be evaluated against real-world measurements to ensure their fidelity in representing the observed properties. Existing climate model diagnostics packages are typically used for evaluating climatology, so a detailed evaluation toolkit for aerosol properties is needed. Researchers (Tang et al., 2022) developed a new diagnostics package that specifically focuses on evaluating aerosol properties with aircraft, ship, and surface measurements.

    The Impact

    The Earth System Model Aerosol-Cloud Diagnostics (ESMAC Diags) package provides a range of diagnostics and metrics, including time series, diurnal cycles, mean aerosol size distribution, pie charts of aerosol composition, percentiles by height, percentiles by latitude, mean statistics of aerosol number concentration, and more. This allows researchers to quantify model performance in predicting aerosol number, size, composition, vertical distribution, spatial distribution (along ship or aircraft tracks), and new particle formation events. ESMAC Diags is continually extended to include clouds and aerosol-cloud interactions and is being applied to evaluate the performances of newly developed physical components in the Energy Exascale Earth System Model (E3SM).

    Summary

    ESMAC Diags package is a Python-based open-source package to quantify the performance of the Department of Energy’s E3SM atmospheric model using Atmospheric Radiation Measurement (ARM) user facility and U.S. National Center for Atmospheric Research field campaign measurements. The first version of this diagnostics package focuses on the aerosol properties, including aerosol number, size distribution, chemical composition, and cloud condensation nuclei collected from surface, aircraft, and ship platforms needed to assess how well a model represents the aerosols across spatial and temporal scales. ESMAC Diags provides various types of diagnostics and metrics, including time series, diurnal cycles, mean aerosol size distribution, pie charts for aerosol composition, percentiles by height, percentiles by latitude, mean statistics of aerosol number concentration, and more. Currently, the diagnostics package includes six field campaigns over the Northeastern Atlantic, Continental U.S., Northeastern Pacific, and the Southern Ocean, respectively. These regions produce frequent liquid- or mixed-phase clouds, with extensive measurements available from the ARM program and other agencies. The code structure is designed to be flexible and modular to allow for future extension to other field campaigns or the incorporation of additional datasets.

    Publication

    • Shuaiqi Tang, et al., “Earth System Model Aerosol–Cloud Diagnostics (ESMAC Diags) package, version 1: assessing E3SM aerosol predictions using aircraft, ship, and surface measurements”, Geosci. Model Dev., 15, 4055–4076, (2022). [DOI: 10.5194/gmd-15-4055-2022]

    Funding

    • This study was supported by the Enabling Aerosol-cloud interactions at GLobal convection-permitting scalES (EAGLES) project, funded by the Department of Energy, Office of Science, Biological and Environmental Research program, Earth System Model Development program area.

    Contact

    • Po-Lun Ma, Pacific Northwest National Laboratory

     

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