Analysis and evaluation of the global aerosol optical properties simulated by an online aerosol-coupled non-hydrostatic icosahedral atmospheric model

Abstract

Aerosol optical properties are simulated using the Spectral Radiation Transport Model for Aerosol Species (SPRINTARS) coupled with the Non-hydrostatic ICosahedral Atmospheric Model (NICAM). The 3-year global mean all-sky aerosol optical thickness (AOT) at 550 nm, theÅngström Exponent (AE) based on AOTs at 440 and 870 nm, and the single scattering albedo (SSA) at 550 nm are estimated at 0.123, 0.657 and 0.944, respectively. For each aerosol species, the mean AOT is within the range of the AeroCom models. Both the modeled all-sky and clear-sky results are compared with observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic Network (AERONET). The simulated spatiotemporal distributions of all-sky AOTs can generally reproduce the MODIS retrievals, and the correlation and model skill can be slightly improved using the clear-sky results over most land regions. The differences between clear-sky and all-sky AOTs are larger over polluted regions. Compared with observations from AERONET, the modeled and observed all-sky AOTs and AEs are generally in reasonable agreement, whereas the SSA variation is not well captured. Although the spatiotemporal distributions of all-sky and clear-sky results are similar, the clear-sky results are generally better correlated with the observations. The clear-sky AOT and SSA are generally lower than the all-sky results, especially in those regions where the aerosol chemical composition is contributed to mostly by sulfate aerosol. The modeled clear-sky AE is larger than the all-sky AE over those regions dominated by hydrophilic aerosol, while the opposite is found over regions dominated by hydrophobic aerosol.Key words: aerosol optical properties, non-hydrostatic icosahedral atmospheric model, Moderate Resolution Imaging Spectroradiometer, Aerosol Robotic Network Citation: Dai, T., G. Y. Shi, and T. Nakajima, 2015: Analysis and evaluation of the global aerosol optical properties simulated by an online aerosol-coupled non-hydrostatic icosahedral atmospheric model.

Key factors affecting single scattering albedo calculation: Implications for aerosol climate forcing

“…As a result, the input parameters used for aerosol SSA calculations are variable and depend on the corresponding measurements, which can cause a wide range of calculated aerosol SSAs. For example, some 5 previous global modeling studies found that no significant bias existed between calculated SSAs versus Aerosol Robotic Network (AERONET) observations (Chin et al, 2009;Dai et al, 2015), while other studies showed positive biases in the estimates (Feng et al, 2013;Jo et al, 2016;Lin et al, 2014;Myhre et al, 2009). We surmised that the SSA bias could be reduced when models use relatively high BC emissions and a low BC density.…”

“…3. The modelled SSA calculations from previous studies were mostly evaluated between 440 -550 nm (Dai et al, 2015;Jo et al, 2016;Lin et al, 2014). However, SSAs at both shorter and longer wavelengths should be evaluated together for the model evaluation.…”

Hourly Aerosol Assimilation of Himawari‐8 AOT Using the Four‐Dimensional Local Ensemble Transform Kalman Filter

“…The large positive BIAS and RMSE of the CONTROL experiment over Australia, which are mainly caused by the overestimation of dust aerosol, are also removed by the assimilation of the Himawari‐8 AOTs. The CONTROL experiment tends to underestimate the AOTs over India and most of the ocean regions (Dai et al, ), and all of the analyses correctly increase the AOTs to better match the observations. In Figure , we further plot the straightforward comparisons of the simulated monthly mean hourly AOTs in the experiments of the CONTROL, 4D‐LETKF‐6H, and 4D‐LETKF‐24H to those in the LETKF, respectively.…”

“…The highest anthropogenic and biomass burning emissions are found over the North China Plain (NCP) and North Australia, respectively. The emission fluxes of dust and sea salt are both calculated online (Dai, Goto, et al, ; Dai et al, ; Dai et al, ; Takemura et al, ) and are mainly dependent on the near‐surface wind speed.…”

Dependence of Backscattering Coefficients of Atmospheric Particles on their Concentration and Constitution under Dry and Humid Conditions at Southwestern Japanese Coast in Spring

“…In numerical models, the extinction of light is usually quantified with the integration of scattering and absorbing effects of the particles (e.g., Takemura et al, 2002;Goto et al, 2011;Dai et al, 2015). Major aerosol types included in the models are carbonaceous, sulfate, soil dust, and sea salt (e.g., Takemura et al, 2002).…”