Aerosol Species in the Air Quality Forecasting System of FMI: Possibilities for Coupling with NWP Models

Abstract

This note outlines the current status of the regional air quality forecasting system (AQFS) of Finnish Meteorological Institute (FMI) and considers the means of bi-directional coupling of the current off-line system with meteorological models.

Current FMI regional AQFS is based on off-line coupled multi-model structure where the default meteorological driver is the reference HIgh Resolution Limited Area Model (HIRLAM), with a possibility to bypass it directly accepting the forcing of global data of European Centre of Medium-range Weather Forecast (ECMWF). The meso-to-regional scale chemistry transport model SILAM (Air Quality and Emergency Modelling System) is the atmospheric composition model, which is forced by the above meteorological fields, as well as by anthropogenic, biomass-burning, and natural emissions. The forecasting system evaluates several aerosol components: primary and secondary inorganic aerosols, sea salt, and biogenic pollen.

Options for closer coupling of the atmospheric chemical transport model (ACTM) and meteorological driver are based on bi-directional interfacing the SILAM and HIRLAM models, so that the chemical composition data are made available to meteorological model with a time lag or during the next forecasting cycle. However, the main obstacle on the way is the limitations of the HIRLAM physics, which do not allow any external aerosol fields – neither in radiative nor in cloud microphysics modules. Solution of these problems or accepting another model with higher flexibility, such as AROME, would pave the way for consideration of feedbacks.