Consistent estimates from satellites and models for the first aerosol indirect forcing

Authors

  • Joyce E. Penner,

    Corresponding author
    1. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA
    • Corresponding author: J. E. Penner, Department of Atmospheric, Oceanic, and Space Sciences, Space Research Building, University of Michigan, 2455 Hayward St., Ann Arbor, MI 48109-2143, USA. (penner@umich.edu)

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  • Cheng Zhou,

    1. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA
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  • Li Xu

    1. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA
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Abstract

[1] Satellite-based estimates for the aerosol indirect forcing are consistently smaller than those from models due, in part, to the use of present-day results that do not capture the temporal changes between present day and pre-industrial conditions. Here, we use results from a coupled aerosol-climate model to pick regions and seasons that are sufficiently pristine to represent pre-industrial conditions. Then we use results from MODIS and CERES to estimate the forcing between present and pre-industrial conditions. The estimated forcing in the North Pacific Ocean region ranges from −1.8 to −2.2 Wm−2 from observations. This range is similar to our modeled forcing for this region, −2.65 Wm−2, but is smaller than the modeled forcing using the same methodology as that used with the satellite observations, −3.6 W/m2. Nevertheless, a previous estimate based on satellite observations was a factor of 10 smaller, −0.2 to −0.5 Wm−2. Results demonstrate that while the estimated forcing from models may be somewhat larger than estimates based on satellite data, a judicious choice of analysis methods, yields results that are much closer than previous satellite and model-based comparisons.

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