An Observing System Simulation Experiment (OSSE) for Aerosols

摘要

The hope to obtain real-time comprehensive two-dimensional or three dimensional analysis or forecasts of air quality pollutants may be fulfilled by combination of model simulations and observations. Space-borne observations can be of particular interest for e.g. aerosols. Following consultation with representatives of the operational meteorological and air chemistry/air quality community, requirements have been documentted for Aerosol Optical Depth (AOD) derived from space borne observations used for operational air quality applications. The users requested an AOD product in two broad layers (planetary boundary layer and free troposphere) with a time and horizontal space resolution of 0.25-1 hour and 0.5-5 km respectively. The objective of this study is to determine whether these requirements are necessary to have an impact on the forecast and analysis of PM_(2.5) levels over Europe and to investigate if AOD measurements with more relaxed requirements in time and space will lead to noticeably less impact. To this end, an Observing System Simulation Experiment (OSSE) has been designed. OSSEs are commonly used to quantify the impact of observations from future observation systems such as satellite instruments or groundbased networks on e.g. weather forecasts. In this study we apply such an OSSE to AOD measurements from two future satellite instruments using the LOTOS-EUROS chemistry transport model and the ensemble Kalman filter data assimilation method. Assimilation of synthetic AOD measurements from an imager type instrument providing total AOD in some cases improves the analysis of PM_(2.5) concentrations. The level of improvement depends on a.o. the vicinity of simultaneously assimilated groundbased measurements. In this paper the set-up of the study is explained and some first results are shown.