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Globally Uniform Mineral Dust Aerosols (Tegen et al. 1994-1996)

Results from a global mineral dust transport model are available here.

Spatial, temporal, and size distributions of mineral dust with sizes of less than 10 µm radius were calculated with a global dust model (Tegen and Fung 1994, see References below) based on the GISS three-dimensional atmospheric tracer transport model (Russell and Lerner 1981). The total dust load as well as the part that is deflated from disturbed soils was calculated (Tegen and Fung 1995). The contribution from disturbed soils should be taken into account in climate change studies (Tegen et al. 1996). As dust particle size information is important for calculations of the dust radiative effect, we provide concentrations for 8 particle size classes with effective radii between 0.1 µm and 10 µm which were transported independently in the model.

Optical Thickness Plots

Spatial, Temporal, and Size Distribution Datasets

Monthly mean concentrations of dust distribution, with 4°×5° horizontal resolution and in nine vertical layers, are available in binary form.

These files were created using FORTRAN on an AIX workstation. The following snippet of code can be used to read the data:

      PARAMETER (LON=72, LAT=46, LAYERS=9, NSIZES=8)
      REAL*4 ARRAY(LON,LAT,LAYERS,NSIZES)
      CHARACTER*80 TITLE
      OPEN (10, FILE='dust.natural.72x46x9x8.monthly.bin',
     *                                    FORM='UNFORMATTED')

      DO MONTH = 1,12
      READ (10) TITLE, ARRAY
      WRITE (6,*) TITLE
      ENDDO

      STOP
      END

Dust Deposition Datasets

The modeled soil dust deposition (Tegen and Fung 1995) is available for two size classes: clay size fraction (less than 1 µm radius) and small silt size fraction (1 - 10 µm radius). Units in these datasets are kg/m2/month.

These files are in plain ASCII text. The following FORTRAN snippet provides an example of how to read one.

      DIMENSION  depo(72,46)
      open (10, file='depo_4x5_12m_1-10u.txt')
      do m=1,nm
         read(10,1000)depo
      enddo
 1000 format (12(e10.3,1x))

Explanation of Data Arrays

The horizontal dimensions of each cell are 4° latitude by 5° longitude, with the following orientation:

  • LON = 1 is centered at 180°W longitude
  • LON increases eastward
  • LAT = 1 is centered at 90°S latitude
  • LAT increases northward
  • Note: Polar grid boxes only span 2° of latitude

The dust concentration binary datasets use sigma as the vertical coordinate (Philips 1957). The boundaries of the vertical layers are:

  • Layer 1 extends from 984 to 934 mbar
  • Layer 2 extends from 934 to 854 mbar
  • Layer 3 extends from 854 to 720 mbar
  • Layer 4 extends from 720 to 550 mbar
  • Layer 5 extends from 550 to 390 mbar
  • Layer 6 extends from 390 to 255 mbar
  • Layer 7 extends from 255 to 150 mbar
  • Layer 8 extends from 150 to 70 mbar
  • Layer 9 extends from 70 to 10 mbar

Note: These values are global means. The actual pressure levels follow the topography.

The effective radii of the eight particle size bins are: 0.1 µm, 0.2 µm, 0.4 µm, 0.8 µm, 1 µm, 2 µm, 4 µm, 8 µm.

Units are kgdust / kgair.

Contact

If you are interested in obtaining copies of the monthly dust source files or if you have any questions regarding these datasets, please contact Dr. Ina Tegen, presently at Leibniz Institute for Tropospheric Research.

References

Philips, N.A. 1957. A coordinate system having some special advantages for numerical forecasting. J. Meterol. 14, 184-185.

Russell, G.L. and J. Lerner 1981. A new finite differencing scheme for the tracer transport equation. J. Appl. Meteorol. 20, 1483-1498.

Tegen, I. and I. Fung 1994. Modeling of mineral dust in the atmosphere: Sources, transport and optical thickness. J. Geophys. Res. 99, 22897-22914.

Tegen, I. and I. Fung 1995. Contribution to the atmospheric mineral aerosol load from land surface modification. J. Geophys. Res. 100, 18707-18726.

Tegen, I. and A.A. Lacis 1994. Parameterization of mineral dust particle sizes and their radiative properties for climate impact studies. In Aerosols and Atmospheric Optics: Radiative Balance and Visual Air Quality, Proceedings of the International Specialty Conference, Snowbird, Utah 293-305.

Tegen I., A.A. Lacis, and I. Fung 1996. The influence of mineral aerosol from disturbed soils on the global radiation budget. Nature 380, 419-422.

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