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Greenler, 1980). Computations of angular scattering patterns forhexagonal crystals were first reported by Jacobowitz(1971) assuming infinitely long hexagonal columns.Wendling et al. (1979) and Liou and Coleman (1980)undertook a more comprehensive ray-tracing analysisto evaluate the scattering phase functions for finitehexagonal columns and plates. More recently, Cai andLiou (1982) developed a scattering model involvingcomplete polarization information for arbitrarily oriented hexagonal columns and
Greenler, 1980). Computations of angular scattering patterns forhexagonal crystals were first reported by Jacobowitz(1971) assuming infinitely long hexagonal columns.Wendling et al. (1979) and Liou and Coleman (1980)undertook a more comprehensive ray-tracing analysisto evaluate the scattering phase functions for finitehexagonal columns and plates. More recently, Cai andLiou (1982) developed a scattering model involvingcomplete polarization information for arbitrarily oriented hexagonal columns and
al. 2006 ). e. Model evaluations The current uncertainties in the prediction of convective rainfall, in general, and CI, in particular, and the importance of prediction of CI at boundaries over the SGP led to the examination of how well numerical operational and high-resolution research models predict the onset of convection. IHOP_2002 included a significant modeling component that allowed researchers to investigate convective triggering in these models and to evaluate the model prediction
al. 2006 ). e. Model evaluations The current uncertainties in the prediction of convective rainfall, in general, and CI, in particular, and the importance of prediction of CI at boundaries over the SGP led to the examination of how well numerical operational and high-resolution research models predict the onset of convection. IHOP_2002 included a significant modeling component that allowed researchers to investigate convective triggering in these models and to evaluate the model prediction
in this experimental data scatter. Future experiments must provide detailed measurements of theseparameters and of the wave structure, with carefulconsideration given to instrumental performance, ifsuch effects are to be resolved. Over land, vertical momentum transfer over largeareas can probably be evaluated realistically usingeffective drag coefficients or roughness parameters.These must account for both the frictional drag (dueto vegetation, etc.) and form drag introduced by perturbation of
in this experimental data scatter. Future experiments must provide detailed measurements of theseparameters and of the wave structure, with carefulconsideration given to instrumental performance, ifsuch effects are to be resolved. Over land, vertical momentum transfer over largeareas can probably be evaluated realistically usingeffective drag coefficients or roughness parameters.These must account for both the frictional drag (dueto vegetation, etc.) and form drag introduced by perturbation of
the background error covariances. Such an issue can be raised both for ensemble-based and innovation-based variance estimates. Evaluating and improving the accuracy of these two kinds of variance estimates is all the more important as innovation-based estimates can be used to represent model error contributions, by calibrating additive model perturbations (e.g., Houtekamer et al. 2009 ) or ensemble inflation factors (e.g., Li et al. 2009 ). Moreover, other approaches than Schur filter techniques
the background error covariances. Such an issue can be raised both for ensemble-based and innovation-based variance estimates. Evaluating and improving the accuracy of these two kinds of variance estimates is all the more important as innovation-based estimates can be used to represent model error contributions, by calibrating additive model perturbations (e.g., Houtekamer et al. 2009 ) or ensemble inflation factors (e.g., Li et al. 2009 ). Moreover, other approaches than Schur filter techniques
disturbances as observed during Phase III of GATE. Mon. Wea. Rev. , 105 , 317 – 333 . Reed , R. J. , A. Hollingsworth , W. A. Heckley , and F. Delsol , 1988 : An evaluation of the performance of the ECMWF operational system in analyzing and forecasting easterly wave disturbances over Africa and the tropical Atlantic. Mon. Wea. Rev. , 116 , 824 – 865 . Riehl , H. , and J. S. Malkus , 1958 : On the heat balance in the equatorial trough zone. Geophysica , 6 , 503 – 538 . Ritchie
disturbances as observed during Phase III of GATE. Mon. Wea. Rev. , 105 , 317 – 333 . Reed , R. J. , A. Hollingsworth , W. A. Heckley , and F. Delsol , 1988 : An evaluation of the performance of the ECMWF operational system in analyzing and forecasting easterly wave disturbances over Africa and the tropical Atlantic. Mon. Wea. Rev. , 116 , 824 – 865 . Riehl , H. , and J. S. Malkus , 1958 : On the heat balance in the equatorial trough zone. Geophysica , 6 , 503 – 538 . Ritchie
; moreover, the forecast became rather poor after a lead time of as little as 5 days. The latter result seems to be at odds with the commonly held view that large-scale phenomena such as RWPs should be predictable on a rather long time scale. However, this evaluation was for a single case only involving a single forecast model; further systematic studies are required to possibly generalize these results. Regarding the waveguide, several operational forecast models are fraught with a spurious decrease of
; moreover, the forecast became rather poor after a lead time of as little as 5 days. The latter result seems to be at odds with the commonly held view that large-scale phenomena such as RWPs should be predictable on a rather long time scale. However, this evaluation was for a single case only involving a single forecast model; further systematic studies are required to possibly generalize these results. Regarding the waveguide, several operational forecast models are fraught with a spurious decrease of
