Abstract. An accurate representation of aerosols in global numerical weather prediction
(NWP) models is important to predict major air pollution events and to also
understand aerosol effects on short-term weather forecasts. Recently the
global aerosol forecast model at NOAA, the NOAA Environmental Modeling System
(NEMS) GFS Aerosol Component (NGAC), was upgraded from its dust-only
version 1 to include five species of aerosols (black carbon, organic carbon,
sulfate, sea salt and dust). This latest upgrade, now called NGACv2, is an
in-line aerosol forecast system providing three-dimensional aerosol mixing
ratios along with aerosol optical properties, including aerosol optical
thickness (AOT), every 3 h up to 5 days at global
1∘×1∘ resolution. In this paper, we evaluated
nearly 1.5 years of model AOT at 550 nm with available satellite retrievals,
multi-model ensembles and surface observations over different aerosol
regimes. Evaluation results show that NGACv2 has high correlations and low
root mean square errors associated with African dust and also accurately
represented the seasonal shift in aerosol plumes from Africa. Also, the model
represented southern African and Canadian forest fires, dust from Asia, and
AOT within the US with some degree of success. We have identified model
underestimation for some of the aerosol regimes (particularly over Asia) and
will investigate this further to improve the model forecast. The addition of
a data assimilation capability to NGAC in the near future is expected to
provide a positive impact in aerosol forecast by the model.