Jacobians of an Operational Prognostic Cloud Scheme

Fillion, Luc; Mahfouf, Jean-Fran├žois
November 2003
Monthly Weather Review;Nov2003, Vol. 131 Issue 11, p2838
Academic Journal
A detailed examination of the Jacobian matrix of sensitivities of the prognostic cloud scheme operational at the European Centre for Medium-Range Weather Forecasts (ECMWF) is presented. These Jacobians exhibit sensitivities of output variables (e.g., cloud condensate) to small input perturbations on temperature and moisture. The coupling of the cloud scheme with the ECMWF convective mass-flux scheme is considered. The sensitivity of the cloud scheme is split into all its contributing parts in order to extract the dominant terms. A selection of contrasted convective cases normally present in a regular operational forecast is considered. Some comparisons are made with a simpler diagnostic cloud scheme. It is shown that the main contributing terms to the sensitivity in cloud condensate l are the following for cases of deep convection: detrainment from moist convection, evaporation processes, and conversion of cloud water into rain. The structure of the Jacobians in terms of temperature and moisture perturbations in such cases is strongly dominated by the structure of the Jacobians of the convective mass flux at cloud base. Because of this dominance, the Jacobians from a simpler diagnostic cloud scheme have similarities in shape with those produced by the prognostic scheme. For shallow convection cases, the same terms as for deep convective cases are important (convective effects still dominate), but now erosion of clouds becomes significant. Jacobians of integrated l produced by the diagnostic and prognostic cloud schemes here are also similar, still because of the dominance of convective effects. When moist convection plays a negligible role, the dominant terms are the condensation/evaporation effects and the conversion of cloud water into rain. Larger differences are found then between the Jacobians of the prognostic and diagnostic cloud schemes. In such situations, the sensitivity of l with respect to vertical motion plays an equally important role compared to temperature and humidity.


Related Articles

  • Circulation characteristics over the Himalayas during winter season. Rao, P. L. S. // Meteorology & Atmospheric Physics;Mar2003, Vol. 83 Issue 1/2, p19 

    During winter season, atmospheric systems, which traverse from west to east interact with the Himalayan massif and produce widespread rainfall over North India. In this study, we made an endeavor to examine the mean circulation features and large-scale budgets of kinetic energy, heat and...

  • Impact of environmental moisture on tropical cyclone intensification. Wu, L.; Su, H.; Fovell, R. G.; Dunkerton, T. J.; Wang, Z.; Kahn, B. H. // Atmospheric Chemistry & Physics Discussions;2015, Vol. 15 Issue 11, p16111 

    The impacts of environmental moisture on the intensification of a tropical cyclone (TC) are investigated in the Weather Research and Forecasting (WRF) model, with a focus on the azimuthal asymmetry of the moisture impacts. A series of sensitivity experiments with varying moisture perturbations...

  • Evaluation of Trigger Functions for Convective Parameterization Schemes Using Observations. Suhas, E.; Zhang, Guang J. // Journal of Climate;Oct2014, Vol. 27 Issue 20, p7647 

    Realistic simulation of different modes of atmospheric variability ranging from diurnal cycle to interannual variation in global climate models (GCMs) depends crucially on the convection trigger criteria. In this study, using the data from constrained variational analysis by the Atmospheric...

  • Improving aerosol interaction with clouds and precipitation in a regional chemical weather modeling system. Zhou, C.; Zhang, X.; Gong, S.; Wang, Y.; Xue, M. // Atmospheric Chemistry & Physics;2016, Vol. 16 Issue 1, p145 

    A comprehensive aerosol-cloud-precipitation interaction (ACI) scheme has been developed under a China Meteorological Administration (CMA) chemical weather modeling system, GRAPES/CUACE (Global/Regional Assimilation and PrEdiction System, CMA Unified Atmospheric Chemistry Environment). Calculated...

  • Satellite Data Assimilation in Numerical Weather Prediction Models. Part I: Forward Radiative Transfer and Jacobian Modeling in Cloudy Atmospheres. Weng, Fuzhong; Liu, Quanhija // Journal of the Atmospheric Sciences;11/1/2003, Vol. 60 Issue 21, p2633 

    Satellite data assimilation requires rapid and accurate radiative transfer and radiance gradient models. For a vertically stratified scattering and emitting atmosphere, the vector discrete-ordinate radiative transfer model (VDISORT) was developed to derive all Stokes radiance components at the...

  • Improvement in Determination of Ice Water Content from Two-Dimensional Particle Imagery. Part II: Applications to Collected Data. Lawson, R. Paul; Baker, Brad A. // Journal of Applied Meteorology & Climatology;Sep2006, Vol. 45 Issue 9, p1291 

    In Part I of this two-part series, a new relationship for ice particle mass M was derived based on an expanded dataset of photographed ice particles and melted drops. The new relationship resulted in a reduction of nearly 50% in the rms error in M. In this paper, new relationships for computing...

  • Estimations of Mass Fluxes for Cumulus Parameterizations from High-Resolution Spatial Data. Emanuel, Kerry; DesAutels, Christopher; Holloway, Christopher; Korty, And Robert // Journal of the Atmospheric Sciences;4/1/2004, Vol. 61 Issue 7, p829 

    The core of the mass flux formulation, on which the majority of the current cumulus parameterizations are based, is to transport physical variables by the so-called mass flux for individual physical components, such as convective updrafts, downdrafts, and environment. These parameterizations use...

  • Model-Generated Predictions of Dry Thunderstorm Potential. Rorig, Miriam L.; McKay, Steven J.; Ferguson, Sue A.; Werth, Paul // Journal of Applied Meteorology & Climatology;May2007, Vol. 46 Issue 5, p605 

    Dry thunderstorms (those that occur without significant rainfall at the ground) are common in the interior western United States. Moisture drawn into the area from the Gulfs of Mexico and California is sufficient to form high-based thunderstorms. Rain often evaporates before reaching the ground,...

  • A hydrological onset and withdrawal index for the West African monsoon. Dalu, G. A.; Gaetani, M.; Baldi, M. // Theoretical & Applied Climatology;2009, Vol. 96 Issue 1/2, p179 

    We have developed a hydrological prognostic index, HOWI (hydrological onset and withdrawal index), for the onset and the withdrawal of the West African monsoon (WAM), based on the vertically integrated moisture transport ( VIMT). The regions of West Africa with the same climatological onset...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics