| 總結: | Current climate models cannot resolve individual convective clouds and hence parameterizations are needed. The primary goal of convective parameterization is to represent the bulk impact of convection on the gridbox-scale variables. Spectral convective parameterizations also aim to represent the key features of the subgrid-scale convective cloud field such as cloud top height distribution and in-cloud vertical velocities, in addition to precipitation rates. Ground-based radar retrievals of these quantities have been made available at Darwin, Australia, permitting direct comparisons of internal parameterization variables and providing new observational references for further model development. <p>A spectral convective parameterization (the convective cloud field model, CCFM) is discussed, and its internal equation of motion is improved. Results from the ECHAM-HAM model in single column mode using CCFM and the bulk mass-flux Tiedtke-Nordeng scheme are compared with the radar retrievals at Darwin. CCFM is found to outperform the Tiedtke-Nordeng scheme for cloud top height and precipitation rate distributions. Radar observations are further used to propose a modified CCFM configuration with aerodynamic drag and reduced entrainment parameter, further improving both the convective cloud top height distribution (important for large-scale impact of convection) and the in-cloud vertical velocities (important for aerosol activation). <p>This study provides new development in CCFM improving the representation of convective cloud spectrum characteristics observed in Darwin. This is a new step towards an improved representation of convection and ultimately of aerosol effects on convection. It also shows how long-term radar observations of convective cloud properties can help constrain parameters of convective parameterization schemes.</p></p>
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