edu.ucar.opensky::articles:22175 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-25T15:44:38.383207 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7zs30hm https://doi.org/10.5067/Aircraft/ATom/TraceGas_Aerosol_Global_Distribution https Related Dataset #1 AToM EVS2 airborne mission https://doi.org/10.3334/ORNLDAAC/1581 https Related Dataset #2 ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols https://doi.org/10.3334/ORNLDAAC/1651 https Related Dataset #3 Atom: Global Modeled and CAFS Measured Cloudy and Clear Sky Photolysis Rates, 2016 Cloud impacts on photochemistry: building a climatology of photolysis rates from the Atmospheric Tomography mission 2018-11-28T00:00:00Z publication https://n2t.org/ark:/85065/d7zs30hm https://doi.org/10.5194/acp-18-16809-2018 Hall, Samuel R. author Ullmann, Kirk author Prather, M. J. author Flynn, C. M. author Murray, L. T. author Fiore, A. M. author Correa, G. author Strode, S. A. author Steenrod, S. D. author Lamarque, Jean-François author Guth, J. author Josse, B. author Flemming, J. author Huijnen, V. author Abraham, N. L. author Archibald, A. T. author UCAR/NCAR - Library publisher Measurements from actinic flux spectroradiometers on board the NASA DC-8 during the Atmospheric Tomography (ATom) mission provide an extensive set of statistics on how clouds alter photolysis rates (J values) throughout the remote Pacific and Atlantic Ocean basins. J values control tropospheric ozone and methane abundances, and thus clouds have been included for more than three decades in tropospheric chemistry modeling. ATom made four profiling circumnavigations of the troposphere capturing each of the seasons during 2016-2018. This work examines J values from the Pacific Ocean flights of the first deployment, but publishes the complete Atom-1 data set (29 July to 23 August 2016). We compare the observed J values (every 3 s along flight track) with those calculated by nine global chemistry-climate/transport models (globally gridded, hourly, for a mid-August day). To compare these disparate data sets, we build a commensurate statistical picture of the impact of clouds on J values using the ratio of J-cloudy (standard, sometimes cloudy conditions) to J-clear (artificially cleared of clouds). The range of modeled cloud effects is inconsistently large but they fall into two distinct classes: (1) models with large cloud effects showing mostly enhanced J values aloft and or diminished at the surface and (2) models with small effects having nearly clear-sky J values much of the time. The ATom-1 measurements generally favor large cloud effects but are not precise or robust enough to point out the best cloud-modeling approach. The models here have resolutions of 50-200 km and thus reduce the occurrence of clear sky when averaging over grid cells. In situ measurements also average scattered sunlight over a mixed cloud field, but only out to scales of tens of kilometers. A primary uncertainty remains in the role of clouds in chemistry, in particular, how models average over cloud fields, and how such averages can simulate measurements. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2018 Author(s). This work is licensed under a Creative Commons Attribution 4.0 International license. None eng geoscientificInformation