This study investigates the effects of aerosol-radiation interactions on subseasonal prediction using the Unified Forecast System, which includes atmosphere, ocean, sea ice, and wave components, coupled with an aerosol module. The aerosol module is from the current NOAA operational GEFSv12-Aerosols model, which is based on the WRF-Chem GOCART with updates to the dust scheme and the biomass burning plume rise module. It simulates five aerosol species: sulfate, dust, black carbon, organic carbon, and sea salt. The modeled aerosol optical depth (AOD) is compared to MERRA-2 reanalysis, MODIS satellite retrievals, and ATom aircraft measurements. Despite biases primarily in dust and sea salt, the AOD shows good agreement globally. The simulated radiative forcing (RF) at the top of the atmosphere (TOA) from the total aerosols is approximately -2.6 W/m2 or -16 W/m2 per unit AOD globally. In subsequent simulations, the prognostic aerosol module is replaced with climatological aerosol concentrations derived from the preceding experiments. While regional differences in RF at TOA between these two experiments are noticeable in specific events, the multi-year subseasonal simulations reveal consistent patterns in RF at TOA, surface temperature, geopotential height at 500 hPa, and precipitation. These results suggest that given the current capacities of aerosol modeling, adopting a climatology of aerosol concentrations as a cost-effective alternative to a complex aerosol module may be a practical approach for subseasonal applications.

Approximately 50% of the Earth's deserts are covered with stony surfaces, not dunes. The stony surfaces often block or diminish mineral dust aerosol emissions through area fraction and roughness element effects. Incorporating these stone coverage effects is crucial for climate and environmental modeling research. Based on our field observations, this study combined the stone coverage effects into a dust simulation model for East Asia using two regression formulas and some constants. The double regression scheme assumed that the stone roughness density could be derived from the coarse fragment fraction of the SoilGrids 2.0 data set. According to the data set, the stone coverage is higher in Western Mongolia and Dzungaria and lower in the Chinese Gobi Desert and the Loess Plateau. Consequently, the model reproduced fewer dust aerosols in the higher coverage areas and more in the lower coverage areas. This simulation result was consistent with the World Meteorological Organization's current weather reports and satellite aerosol observations. The improved model reproduced the diversity of soil erodibility and was well balanced in performance statistics. This study is the first successful investigation of stone coverage effects on dust storm simulation using a realistic stone coverage map to the authors' best knowledge. Plain Language Summary More than 50% of the Earth's deserts are covered with stones, not dunes. The stony surfaces suppress sand and dust storms in the deserts. Because the mineral dust particles globally influence climate change, investigating the stony surfaces is crucial to climate prediction research. Therefore, we developed a new simulation scheme for sand and dust storms to incorporate the stony surface effects. Formulating the stony surface effects was based on our field observations in East Asia. The global stone map we used was obtained from the SoilGrids 2.0 data set. Our simulation model reproduced fewer dust storms in higher stone coverage areas and more in lower areas. This simulation result was consistent with weather observatory observations in Mongolia and China. Satellite measurements for air pollution also backed up the simulation result. This study is the first successful investigation of the stony surface effects on dust storm simulations using a realistic stone coverage map to the authors' best knowledge.

Mechanisms of vertical transport of black carbon (BC) aerosols and their three-dimensional transport pathways over East Asia in spring were examined through numerical simulations for the Aerosol Radiative Forcing in East Asia (A-FORCE) aircraft campaign in March-April 2009 using a modified version of the Community Multiscale Air Quality (CMAQ) modeling system. The simulations reproduced the spatial distributions of mass concentration of BC and its transport efficiency observed by the A-FORCE campaign reasonably well, including its vertical and latitudinal gradients and dependency on precipitation amount that air parcels experienced during the transport. During the A-FORCE period, two types of pronounced upward BC mass fluxes from the planetary boundary layer (PBL) to the free troposphere were found over northeastern and inland-southern China. Over northeastern China, cyclones with modest precipitation were the primary uplifting mechanism of BC. Over inland-southern China, both cumulus convection and orographic uplifting along the slopes of the Tibetan Plateau played important roles in the upward transport of BC, despite its efficient wet deposition due to a large amount of precipitation supported by an abundant moisture supply by the low-level southerlies. In addition to the midlatitude (35-45 degrees N) eastward outflow within the PBL (21% BC removal by precipitation during transport), the uplifting of BC over northeastern and inland-southern China and the subsequent BC transport by the midlatitude lower tropospheric (50% BC removal) and subtropical (25-35 degrees N) midtropospheric westerlies (67% BC removal), respectively, provided the major transport pathways for BC export from continental East Asia to the Pacific.