A comparison of mixed-layer evolution as inferred from lidar, balloon observations and MM5 simulations in Milan (Italy)

摘要

In the framework of the QUITSAT project, several days of balloon-borne Optical Particle Counter and continuous lidar measurements were carried out in the Milan urban area. Aerosol vertical profiles by both lidar and optical counter (OPC) onboard a tethered balloon were collected during summer 2007 and winter 2008. Using the aerosol concentration as a tracer, these measurements allowed to investigate the daily and monthly evolution of the mixing layer height (MH). MH observations were then compared, in spatial-temporal matching, with the hourly evolution of the planetary boundary layer (PBL) as predicted by the PSU/NCAR mesoscale model (MM5, v3 r3-6) with four-dimensional data assimilation (FDDA), using two different schemes for the boundary layer parameterization: the Gayno-Seaman (GS) and non-local Medium Range Forecast (MRF). The differences between observations and model output are analyzed. Overall, the GS scheme is found to perform better than the MRF in determining the mixing layer height.