Articles | Volume 4, issue 9/10
Atmos. Chem. Phys., 4, 2313–2336, 2004
https://doi.org/10.5194/acp-4-2313-2004
Atmos. Chem. Phys., 4, 2313–2336, 2004
https://doi.org/10.5194/acp-4-2313-2004

  26 Nov 2004

26 Nov 2004

Evaluation of archived and off-line diagnosed vertical diffusion coefficients from ERA-40 with 222Rn simulations

D. J. L. Olivié1,2, P. F. J. van Velthoven1, and A. C. M. Beljaars3 D. J. L. Olivié et al.
  • 1Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
  • 2Eindhoven University of Technology, Eindhoven, The Netherlands
  • 3European Centre for Medium-range Weather Forecasts, Reading, UK

Abstract. Boundary layer turbulence has a profound influence on the distribution of tracers with sources or sinks at the surface. The 40-year ERA-40 meteorological data set of the European Centre for Medium-range Weather Forecasts contains archived vertical diffusion coefficients. We evaluated the use of these archived diffusion coefficients versus off-line diagnosed coefficients based on other meteorological parameters archived during ERA-40 by examining the influence on the distribution of the radionuclide 222Rn in the chemistry transport model TM3. In total four different sets of vertical diffusion coefficients are compared: (i) 3-hourly vertical diffusion coefficients archived during the ERA-40 project, (ii) 3-hourly off-line diagnosed coefficients from a non-local scheme based on Holtslag and Boville (1993), Vogelezang and Holtslag (1996), and Beljaars and Viterbo (1999), (iii) 6-hourly coefficients archived during the ERA-40 project, and (iv) 6-hourly off-line diagnosed coefficients based on a local scheme described in Louis (1979) and Louis et al. (1982). The diffusion scheme to diagnose the coefficients off-line in (ii) is similar to the diffusion scheme used during the ERA-40 project (i and iii).

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