Use of four-dimensional data assimilation in a limited-area mesoscale model Part II: effects of data assimilation within the planetary boundary layer

The data used for assimilation include conventional synoptic-scale rawinsonde data and mesoalpha-scale surface data. The main objective of this study is to determine how to effectively utilize the combined strength of these two simple data systems while avoiding their individual weaknesses. Ten experiments, which use a 15-layer version of the model, are evaluated for two midlatitude, real-data cases. Overall, the best dynamic analyses of precipitation, PBL depth, surface layer temperature, and tropospheric mass and wind fields were obtained by nudging to analyses of rawinsonde wind, temperature, and moisture above the model PBL and to analyses of surface-layer wind and moisture within the model PBL -from Authors