Examining the impact of mineral dust aerosol on photosynthetically active radiation and surface radiative balance in dryland ecosystems of Central and East Asia

The aerosol impact on the shortwave (SW) and longwave (LW) components of surface energy balance and photosynthetically active radiation (PAR, 0.4–0.7 μm) has been suggested to play an important role in land-atmosphere interactions. In particular, past studies reported reductions in plant primary production due to less incoming PAR as a result of aerosol attenuation. At the same time while reducing the total amount of PAR, aerosols can generate more diffuse sunlight. The diffuse component of PAR can penetrate through the plant canopy, enhancing the radiation use efficiency and total photosynthetic rate. This ‘diffuse radiation fertilization' effect may lead to more carbon uptake by the terrestrial biosphere despite the total PAR reduction. In this study, we investigate the impact of Asian dust on total and diffuse PAR and surface energy balance in dryland ecosystems in Central and East Asia. Using recent data on the dust size-resolved mineralogical composition and satellite multi-sensor aerosol and land products as model inputs, we assessed the range of the dust radiative impact and linkages between SW and total and diffuse PAR. We examined the role of the properties and loadings of dust, and the effect of the spectral surface albedo. In addition to modeling, radiative fluxes from CERES along with A-Train aerosol data products were used to constrain the dust impact from observations. A combination of modeled and observation-based assessments provides a better understanding of the relative importance of the involved factors. The results of the study will be presented with the focus on the role of radiative processes in the functioning of dryland ecosystems and overall land-atmosphere interactions.