In this study, a global variable-resolution modeling framework of atmospheric dust and its radiative feedback is established and evaluated. In this model, atmospheric dust is simulated simultaneously with meteorological fields, and dust-radiation interactions are included. Five configurations of global mesh with refinement at different resolutions and over different regions are used to explore the impacts of regional refinement on modeling dust lifecycle at regional and global scales. The model reasonably produces the overall magnitudes and spatial variabilities of global dust metrics such as surface mass concentration, deposition, aerosol optical depth, and radiative forcing compared to observations and previous modeling results. Two global variable-resolution simulations with mesh refinement over major deserts of North Africa (V16 km-NA) and East Asia (V16 km-EA) simulate less dust emissions and smaller dry deposition rates inside the refined regions due to the weakened near-surface wind speed caused by better resolved topographic complexity at higher resolution. The dust mass loadings over North Africa are close to each other between V16 km-NA and the quasi-uniform resolution (similar to 120 km) (U120 km), while over East Asia, V16 km-EA simulates higher dust mass loading. Over the non-refined areas with the same resolution, the difference between global variable-resolution and uniform-resolution experiments also exists, which is partly related to their difference in dynamic time-step and the coefficient for horizontal diffusion. Refinement at convection-permitting resolution around the Tibetan Plateau (TP) simulates less dust due to its more efficient wet scavenging from resolved convective precipitation around the TP against coarse resolution. Mineral dust plays an important role in Earth's climate system. Numerical simulation of dust and its impacts on a regional scale still has large uncertainties, partly due to the relatively coarse horizontal resolution. Limited-area simulation at relatively high resolution can generally better characterize dust and its impacts on a regional scale; however, lateral boundary conditions may introduce some numerical issues and constrain regional feedback, such as dust-cloud and dust-radiation interactions, to large-scale circulation. In this study, a novel modeling framework of atmospheric dust and its climatic feedbacks with the capability of global variable-resolution simulation is established and evaluated. The model produces reasonable global spatial distributions of dust compared to observations and previous studies. The difference between the simulations at global quasi-uniform resolution and global variable resolution with regional refinement over East Asia and North Africa is significant, particularly with refinement at convection-permitting resolution. This model may be used in the future to provide new insights into the impacts of dust on regional and global climate systems. A modeling framework of atmospheric dust with the capability of global variable-resolution simulation is introduced and evaluatedExperiments with regional refinement produce less dust emissions and mass loading and smaller dry deposition due to weaker surface windRefinement at convection-permitting resolution simulates stronger wet scavenging and less dust mass compared to coarse resolution

The Aerosol Optical Depth (AOD) and aerosol-induced radiative forcing trends inferred for the period 1995-2019 over the Arabian Peninsula region (APR) are extensively studied using the state-of-the-art Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis data. We examine the long-term AOD change for five major aerosol species: Dust (DU), Sea Salt (SS), Sulfate (SU), Black Carbon (BC), and Organic Carbon (OC) over the APR. The MERRA-2 AOD comparisons with surface measurements show that it is capable to reproduce the AOD features over APR. The total AOD over the region shows a high value in JJA with the combined effect of DU and SU being major contributors. The total AOD over APR shows an increasing trend at a rate of similar to 0.05/decade. Along with an incline in DU AOD , the anthropogenic signature on total AOD also hikes contributed mainly by the SU and OC. The increase in AOD also results in a surge in aerosol-induced atmospheric forcing (ATM) with a trend of 0.13 Wm(-2) year and 0.15 Wm(-2) year during MAM and JJA respectively. Overall, the study gives a comprehensive picture of the capability of the MERRA-2 in long-term aerosol monitoring over APR, primarily situated in the dust-belt region.

East Asian dust (EAD) exerts considerable impacts on the energy balance and climate/climate change of the earth system through its influence on solar and terrestrial radiation, cloud properties, and precipitation efficiency. Providing an accurate description of the life cycle and climate effects of EAD is therefore critical to better understanding of climate change and socioeconomic development in East Asia and even worldwide. Dust modeling has undergone substantial development since the late 1990s, associated with improved understanding of the role of EAD in the earth system. Here, we review the achievements and progress made in recent decades in terms of dust modeling research, including dust emissions, long-range transport, radiative forcing (RF), and climate effects of dust particles over East Asia. Numerous efforts in dust/EAD modeling have been directed towards furnishing more sophisticated physical and chemical processes into the models on higher spatial resolutions. Meanwhile, more systematic observations and more advanced retrieval methods for instruments that address EAD related science issues have made it possible to evaluate model results and quantify the role of EAD in the earth system, and to further reduce the uncertainties in EAD simulations. Though much progress has been made, large discrepancies and knowledge gaps still exist among EAD simulations. The deficiencies and limitations that pertain to the performance of the EAD simulations referred to in the present study are also discussed.

A synergistic use of satellite and ground based remote sensing data has been utilized to analyze recent changes in the aerosol column loading over the Indo Gangetic Plain (IGP). Despite an overall statistically significant increase in the trend of annual mean aerosol optical depth (AOD) over the past decade, a prominent difference within seasons was observed. Summer and monsoon seasons have a slight decreasing trend, while post monsoon and winter have significant increasing trend. The optically equivalent composition inferred from ground based long term measurements of aerosol size and absorption characteristics reveals that summer and monsoon season are mostly dust dominated. Whereas, post monsoon and winter seasons are dominated by black carbon (BC) and/or other absorbing aerosols. We find that the observed decrease in AOD is associated with decrease in dust loading in the atmosphere with a large spatial extent covering the whole of North-Western part of India and IGP. Similar changes are associated with absorbing carbonaceous aerosol species during the periods showing an increasing trend. The decreasing dust loading over Indian region during summer along with increase in absorbing black carbon aerosols during the pre-monsoon and the monsoon period may have significant impact on aerosol radiative forcing and hence Indian summer monsoon rainfall.

Mineral dust aerosols, the tiny soil particles suspended in the atmosphere, have a key role in the atmospheric radiation budget and hydrological cycle through their radiative and cloud condensation nucleus effects. Current understanding of spatial and temporal variations of mineral dust, as well as its impacts on the climate system and cloud properties is outlined. Mineral dust aerosols are blown into the atmosphere mainly from arid and semi-arid regions where annual rainfall is extremely low and substantial amounts of alluvial sediment have been accumulated over long periods. They are subject to long-range transport of an intercontinental scale, including North African dust plumes over the Atlantic Ocean, summer dust plumes from the Arabian Peninsula over the Arabian Sea and Indian Ocean and spring dust plumes from East Asia over the Pacific Ocean. Mineral dust aerosols influence the climate system and cloud microphysics in multiple ways. They disturb the climate system directly by scattering and partly absorbing shortwave and longwave radiation, semi-directly by changing the atmospheric cloud cover through evaporation of cloud droplets (i.e. the cloud burning effect), and indirectly by acting as cloud and ice condensation nuclei, which changes the optical properties of clouds (i.e. the first indirect effect), and may decrease or increase precipitation formation (i.e. the second indirect effect). Radiative forcing by mineral dust is associated with changes in atmospheric dynamics that may change the vertical profile of temperature and wind speed, through which a feedback effect on dust emission can be established. (C) 2013 Elsevier B.V. All rights reserved.