Biomass burning aerosols in most climate models are too absorbing.

Uncertainty in the representation of biomass burning (BB) aerosol composition and optical properties in climate models contributes to a range in modeled aerosol effects on incoming solar radiation. Depending on the model, the top-of-the-atmosphere BB aerosol effect can range from cooling to warming. By relating aerosol absorption relative to extinction and carbonaceous aerosol composition from 12 observational datasets to nine state-of-the-art Earth system models/chemical transport models, we identify varying degrees of overestimation in BB aerosol absorptivity by these models.

Seasonal influences on surface ozone variability in continental South Africa and implications for air quality.

Although elevated surface ozone (O) concentrations are observed in many areas within southern Africa, few studies have investigated the regional atmospheric chemistry and dominant atmospheric processes driving surface O formation in this region. Therefore, an assessment of comprehensive continuous surface O measurements performed at four sites in continental South Africa was conducted. The regional O problem was evident, with O concentrations regularly exceeding the South African air quality standard limit, while O levels were higher compared to other background sites in the Southern Hemisphere.