Browsing by Author "Millet, Dylan B"

Now showing 1 - 4 of 4
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    Code Updates of GEOS-Chem Adjoint v35 for TROPOMI Methane 4D-Var Inversion
    (2021-07-22) Yu, Xueying; Millet, Dylan B; Henze, Daven K; yxying1993@gmail.com; Yu, Xueying; University of Minnesota Atmospheric Chemistry Group
    The archive contains updated GEOS-Chem adjoint v35 code for TROPOMI methane 4D-Var inversion.
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    CrIS ROCR Isoprene Retrievals used for Mapping Atmospheric Oxidation
    (2024-03-21) Millet, Dylan B; Shutter, Joshua D; Wells, Kelley C; dbm@umn.edu; Millet, Dylan B
    This archive contains satellite-based observations of isoprene that are used in the reference cited below for mapping atmospheric oxidation rates from space.
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    Ecosystem-atmosphere fluxes of reactive carbon from the 2021 Flux Closure Study (FluCS) at Manitou Experimental Forest
    (2023-06-15) Vermeuel, Michael P; Millet, Dylan B; Farmer, Delphine K; Pothier, Matson A; Link, Michael F; dbm@umn.edu; Millet, Dylan B; University of Minnesota Atmospheric Chemistry Group
    This archive contains hourly observed and modeled fluxes of ambient volatile organic compounds (VOCs) over Manitou Experimental Forest in Woodland Park, CO during the FluCS 2021 study throughout August and September 2021. Observations were collected via the eddy covariance method using mass spectrometry for VOC concentrations and a sonic anemometer for vertical windspeed. Model fluxes were simulated using the GEOS-Chem (v13.3) model. Also included are observed and simulated meteorology during this time period.
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    Global nitrogen deposition (2°×2.5° grid resolution) simulated with GEOS-Chem for 1984-1986, 1994-1996, 2004-2006, and 2014-2016
    (2018-05-31) Ackerman, Daniel E; Chen, Xin; Millet, Dylan B; dackerma@umn.edu; Ackerman, Daniel E; Ecology, Evolution, and Behavior Department, University of Minnesota
    Atmospheric deposition of inorganic nitrogen is critical to the function of ecosystems and elemental cycles. During the industrial period, humans have doubled the amount of inorganic nitrogen in the biosphere and radically altered rates of atmospheric nitrogen deposition. Despite this rapid change, estimates of global nitrogen deposition patterns generally have low, centennial-scale temporal resolution. Lack of information on annual- to decadal-scale changes in global nitrogen deposition makes it difficult for scientists researching questions on these finer timescales to contextualize their work within the global nitrogen cycle. Here we use the GEOS-Chem Chemical Transport Model to estimate wet and dry deposition of inorganic nitrogen globally at a spatial resolution of 2°×2.5° for 12 individual years in the period from 1984 to 2016. During this time, we found an 8% increase in global inorganic nitrogen deposition from 86.6 TgN yr-1 to 93.6 TgN yr-1, a trend that comprised a balance of variable regional patterns. For example, inorganic nitrogen deposition increased in areas including east Asia and Southern Brazil, while inorganic nitrogen deposition declined in areas including Europe. Further, we found a global increase in the percentage of inorganic nitrogen deposited in chemically reduced forms from 30% to 35%, and this trend was largely driven by strong regional increases in the proportion of chemically reduced nitrogen deposited over the United States. This study provides spatially explicit estimates of inorganic nitrogen deposition over the last four decades and improves our understanding of short-term human impacts on the global nitrogen cycle. We provide all output from these GEOS-Chem simulations related to atmospheric deposition. We provide all output from these GEOS-Chem simulations related to atmospheric deposition.