Implementing convection into Lorenz’s global cycle. Part II. A new estimate of the conversion rate into kinetic energy

Article English OPEN
Haimberger, Leopold ; Hantel, Michael (2011)

The global conversion rates into available potential and kinetic energy (Lorenz’s quantities Gand C) have been traditionally evaluated on the gridscale (Ggrid, Cgrid#+2.5±0.4 W/m2).Convective phenomena acting on the sub-gridscale ( like, e.g., thunderstorms) have been treatedas molecular. In Part I of this study it has been outlined how Lorenz’s energy cycle may beextended to include sub-gridscale processes. For this purpose new fluxes, particularly the globalmean conversion rate into kinetic energy on the sub-gridscale (Csub), have been defined.Evaluating them is the purpose of the present Part II. Csub is closely related to the buoyancyproduction term of turbulence kinetic energy which can be expressed through the vertical subgridscalefluxes of moisture and heat. A thermodynamic diagnostic model (DIAMOD) thatestimates these fluxes indirectly from gridscale analyses is applied. In this way the conversionrate has been calculated for three months using global reanalysis data from ECMWF and fromNCEP/NCAR. The errors of our results are caused by the analysis data used, by the specificationof the ratio between moisture and heat fluxes (the main closure assumption in DIAMOD)and by uncertainties in the radiative heating field; they are given here at the 95% level.We find Csub=+2.2±1.7W/m2. The new complete conversion rate C=Cgrid+Csub is+4.7±2.0W/m2. This figure is the main result of this study, presented here for the first time:Lorenz’s energy cycle, if extended to the sub-gridscale, is about twice as intense as in thetraditional approximations. In contrast to Csub the sub-gridscale generation rate Gsub andtherefore the complete G cannot be evaluated. All one can do is to improve the estimate of Ggrid by improving the estimates of the net heating. For Ggrid we find the new value of+3.1±0.5W/m2.DOI: 10.1034/j.1600-0870.2000.520106.x
  • References (31)
    31 references, page 1 of 4

    Emanuel, K. A. 1994. Atmospheric convection. Oxford University Press, 580 pp.

    Fortelius, C. 1995. Inferring the diabatic heat and moisture forcing of the atmosphere from assimilated data. J. Climate 8, 224-239.

    Garratt, J. R. 1992. T he atmospheric boundary layer. Cambridge University Press, 316 pp.

    Gibson, J. K., Ka˚lberg, P. and Uppala, S. 1996. The ECMWF re-analysis (ERA) project. ECMW F Newsletter 73, 7-17.

    Haimberger, L. 1998. Estimating the conversion rate into kinetic energy of sub-gridscale motions. Phys. Chem. Earth 23, 623-628.

    Haimberger, L. and Hantel, M. 1996. Extension of Lorenz's energy cycle to the sub-gridscale. In: Preprint Volume of the Second International Scientific Conference on the Global energy and water cycle, 17-21 June 1996, Washington DC, USA, pp. 308-309. GEWEXWCRP.

    Haimberger, L., Hantel, M. and Dorninger, M. 1995. A thermodynamic diagnostic model for the atmosphere. Part III: DIAMOD with orography and new error model. Meteorol. Z., N.F. 4, 162-182.

    Hantel, M. 1987. Subsynoptic vertical heat fluxes from high resolution synoptic budgets. Meteorol. Atmos. Phys. 36, 24-44.

    Hantel, M. and Baader, H. R. 1978. Diabatic heating climatology of the zonal atmosphere. J. Atmos. Sci. 35, 1180-1189.

    Hantel, M., Ehrendorfer, M. and Haimberger, L. 1993. A thermodynamic diagnostic model for the atmosphere. Part II: The general theory and its consequences. Meteorol. Z., N.F. 2, 255-271.

  • Metrics
    No metrics available
Share - Bookmark