Hudman et al 2012 soil NOx emissions algorithm

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This page describes the Hudman et al 2012 soil NOx emissions algorithm, which is being used in GEOS-Chem v9-02 and newer versions.


Rynda Hudman developed a new soil NOx emissions scheme, based on the work of Neil Moore (formerly of Dalhousie University). This work was published in Hudman et al (2012).

Bram Maasakkers (Eindhoven) further updated the Hudman et al (2012) soil NOx emissions scheme, as follows:

Bram Maasakkers wrote:

The most important changes in the submitted version are:
  • Minor changes originating from the update from GEOS-Chem v8-02-02 to GEOS-Chem v9-01-03. Furthermore, to allow the parametrization to work with non-local planetary-boundary layer (PBL) mixing, a soil NOx section has been added to the non-local PBL mixing module. This was required to report the deposition of N to the soil NOx module.
  • The Jacob and Bakwin (1991) reduction factor has been implemented, representing the deposition of emitted NOx in the canopy. Implementation leads to a decrease of annual soil NOx emissions from 10.7 to 9.5 Tg N yr-1. The largest impact occurs over the tropical rain-forests in South America and central Africa.
  • To allow the model to work at all resolutions (the provided code only worked at 2x2.5), online regridding has been implemented using new high resolution input files.

Bram Maasakker's updates to the Hudman et al (2012) emissions scheme were implemented into the GEOS-Chem v9-02 public release. The older Yienger and Levy (1995) soil NOx emissions algorithm has since been removed from GEOS-Chem.

--Bob Y. 14:54, 5 January 2015 (EST)


See this validation document by Rynda Hudman.

--Bob Y. 16:45, 9 March 2011 (EST)

Source code and data

These data files


are read and regridded by the Harmonized Emissions Component (HEMCO). These data files are contained in the HEMCO data directories path.

For detailed instructions on how to download these data files to your disk server, please see the [ Download input data section of

--Bob Yantosca (talk) 19:53, 16 September 2022 (UTC)


  1. Bey I., D. J. Jacob, R. M. Yantosca, J. A. Logan, B. Field, A. M. Fiore, Q. Li, H. Liu, L. J. Mickley, and M. Schultz, Global modeling of tropospheric chemistry with assimilated meteorology: Model description and evaluation, J. Geophys. Res., 106, 23,073-23,096, 2001. PDF
  2. Hudman, R.C., N.E. Moore, R.V. Martin, A.R. Russell, A.K. Mebust, L.C. Valin, and R.C. Cohen, A mechanistic model of global soil nitric oxide emissions: implementation and space based-constraints, Atm. Chem. Phys., 12, 7779-7795, doi:10.5194/acp-12-7779-2012. HTML
  3. Jacob, D.J., and P.S. Bakwin, Cycling of NOx in tropical forest canopies and its implications for the global source of biogenic NOx to the atmosphere, in Microbial Production and Consumption of Greenhouse Gases, edited by W.B. Whitman, American Society of Microbiology, Washington DC, 1991.
  4. Olson, J. World Ecosystems (WEI.4): Digital raster data on a 10 minute geographic 1080 x 2160 grid, in Global ecosystems database, version 1.0: Disc A, edited by NOAA Natl. Geophys. Data Center, Boulder, Colorado, 1992.
  5. Yienger, J.J, and H. Levy, Empirical model of global soil-biogenic NOx emissions, J. Geophys. Res., 100, D6, 11,447-11464, June 20, 1995.
  6. Wang, Y., D.J. Jacob, and J.A. Logan, Global Simulation of tropospheric O3-NOx-hydrocarbon chemistry: 1. Model formulation, J. Geophys. Res., 103, pp. 10713-10725, 1998. PDF

--Bob Y. 14:20, 19 February 2010 (EST)