Description and evaluation of the tropospheric aerosol scheme in the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS-AER, cycle 45R1)

Abstract

Abstract. This article describes the IFS-AER aerosol module used operationally in the Integrated Forecasting System (IFS) cycle 45R1, operated by the European Centre for Medium-Range Weather Forecasts (ECMWF) in the framework of the Copernicus Atmospheric Monitoring Services (CAMS). We describe the different parameterizations for aerosol sources, sinks, and its chemical production in IFS-AER, as well as how the aerosols are integrated in the larger atmospheric composition forecasting system. The focus is on the entire 45R1 code base, including some components that are not used operationally, in which case this will be clearly specified. This paper is an update to the Morcrette et al. (2009) article that described aerosol forecasts at the ECMWF using cycle 32R2 of the IFS. Between cycles 32R2 and 45R1, a number of source and sink processes have been reviewed and/or added, notably increasing the complexity of IFS-AER. A greater integration with the tropospheric chemistry scheme of the IFS has been achieved for the sulfur cycle and for nitrate production. Two new species, nitrate and ammonium, have also been included in the forecasting system. Global budgets and aerosol optical depth (AOD) fields are shown, as is an evaluation of the simulated particulate matter (PM) and AOD against observations, showing an increase in skill from cycle 40R2, used in the CAMS interim ReAnalysis (CAMSiRA), to cycle 45R1.

An aerosol climatology for global models based on the tropospheric aerosol scheme in the Integrated Forecasting System of ECMWF

“…Moreover, extra difficulties arise when assimilating real time observations to constrain the initialisation of the prognostic aerosol field because some species require an accurate prediction of their sources, as in the case of anthropogenic and natural fires. A realistic representation of the mean climatological distribution of the most important aerosols can already improve the forecast skill both on a regional scale and globally (Rodwell and Jung, 2008).…”

“…The IFS has employed since 2003 a monthly-mean climatology of five main aerosol species based on one of the first multiaerosol model simulations by Tegen et al (1997) (TG97 hereinafter), and this substituted an earlier, simpler annual mean distribution based on Tanré et al (1984) (Table 1). When the more-detailed TG97 climatology was introduced, it improved the model forecast skills mainly on a regional scale, but, thanks to teleconnection feedbacks, it also affected the large-scale mean flow (Rodwell and Jung, 2008). The tropical regions and in particular the monsoon areas of western Africa and India showed the largest sensitivity to the change in aerosol radiative forcing, resulting in improvements in the precipitation bias (Tompkins et al, 2005).…”

Multi-model evaluation of aerosol optical properties in the AeroCom phase III Control experiment, using ground and space based columnar observations from AERONET, MODIS, AATSR and a merged satellite product as well as surface in-situ observations from GAW sites

“…The aerosol component is described in Rémy et al (2019) and based on the earlier work of Morcrette et al (2009). This is an externally-mixed hybrid bin/bulk scheme, consisting of three size bins each for desert dust (up to 20µm dry radius) and sea salt (up to 20µm radius at 80% relative humidity), and bulk tracers for organic matter, black carbon and sulphate aerosol.…”

Evaluation of ECMWF IFS-AER (CAMS) operational forecasts during cycle 41r1 - 46r1 with calibrated ceilometer profiles over Germany

“…The CAMS aerosol model system IFS-AER is described in Benedetti et al (2009); Morcrette et al (2009); Rémy et al (2019). Further information as well as analyses, forecasts, evaluation re-145 sults and other products can be found on the web page https://atmosphere.copernicus.eu/.…”