| In this work, we have considered several aspects of the McGill radar assimilation system. Currently, information other than radar observations is included in the assimilation system: the forecast of a high-resolution numerical weather prediction model. Besides, the structure of errors of this background term has been improved using a recursive filter.;Errors in forecasts, frequently referred to as background errors, result from errors in the initial conditions that grow through non-linear model equations with imperfect physical parameterizations. However, estimating forecast errors is not straightforward since the true atmospheric state is never exactly known. Ensemble forecasting is a feasible way to characterize the structure of forecasting errors and represent the probability distribution of plausible atmospheric states.;In our work, an ensemble scheme has been applied to understand the structure of background errors at convective scale. The analysis has consisted in perturbing radar observations with two sets of simulated errors: one that neglects the spatial correlation of radar errors, and another where their spatial correlation is prescribed. The sensitivity of the system to such perturbations has been studied over a convective case. The results demonstrated that neglecting the correlation of radar errors badly limits the spread of ensembles and underestimates the model error correlation. In addition, further studies on the cross-correlations between different control variables illustrated the strong connection between the dynamics and the microphysical processes as depicted by the model. Our work also included the analysis of the different features of the background error within and outside the precipitation regions.;With single-Doppler S-band radar observations, the analyses from the assimilation system proved to successfully generate convection in a rainfall-free background. Furthermore, the system successfully simulated the evolution of a convective storm for more than 30 minutes. To account for the rapid evolution of the convective storms and to correct the forecast errors with time, a cycling process has also been applied. The cycling process helps to maintain the intensity of storm cells for a longer period of time. However, a comparison of radar observations with the 90-min simulation indicated an error in the position of the convective cells. |
