Abstract. Dust aerosols affect the radiative and energy balance at local and global scales by scattering and absorbing sunlight and infrared light. A previous study suggests that dust size distribution is one of the major sources of uncertainty in modeling the dust global distribution. Climate models overestimate the fine dust (≤5 µm) by an order of magnitude, while underestimates of the coarse dust (≥5 µm) range between 0.5 to 1.5 orders of magnitude compared with the global observations. Here we improved the simulated size distribution of dust aerosol using a sectional aerosol model (Community Aerosol and Radiation Model for Atmospheres) coupled with the Community Earth System Model (CESM1/CARMA). Simulated dust mass size distributions peak at around 2–3 µm in diameter and increase by 4 orders of magnitude from 0.1 to 2 µm. Our model demonstrates that North African, Middle Eastern, and Asian dust accounts for ∼ 59.7 %, 12.5 %, and 13.3 % of the global annual mean dust emissions, with the remaining 14.5 % originating from scattered smaller dust sources. The model dust vertical distributions are validated against the NASA Atmospheric Tomography (ATom) field campaign datasets. Both simulations and ATom in situ measurements during the ATom field campaign suggest that dust mass concentrations over the remote ocean drop by 2 to 3 orders of magnitude from the surface to the upper troposphere (200 hPa). Our model suggests that Asian dust contributes to more than 40 % of annual mean dust mass abundances in the global upper troposphere and lower stratosphere (UTLS). The model suggests that Asian dust dominates the dust mass budget in the UTLS of the Asian summer monsoon (ASM) region, with a relative contribution 1–2 orders of magnitude higher than the dust originating from the North African and Middle Eastern deserts.

Abstract. Dust aerosols affect the radiative and energy balance at local and global scales by scattering and absorbing sunlight and infrared light. Parameterizations of dust lifting, microphysics, as well as physical and radiative properties of dust in climate models are still subject to large uncertainty. Here we use a sectional aerosol model (CARMA) coupled with a climate model (CESM1) to investigate the global distribution of dust aerosols, with an emphasis on the vertical distribution of dust. Consistent with observations at locations remote from source regions, simulated dust mass size distributions peak at around 2–3 micrometres in diameter and increase by 4 orders of magnitude from 0.1 μm to 2 µm. The size distribution above 2 µm is highly variable depending on distance from the source, and subject to uncertainty due to possible size dependent changes in physical properties such as shape and density. Simulated annual mean dust mass concentrations are within one order of magnitude of those found by the surface measurement network around the globe. Simulated annual mean aerosol optical depths are ~10 % lower than AERONET observations near the dust source regions. Both simulations and in-situ measurements during the NASA ATom field campaign suggest that dust mass concentrations over the remote ocean drop by two to three orders of magnitude from the surface to the upper troposphere (200 hPa). The model suggests that Saharan, Middle Eastern, and Asian dust accounts for ~59.7 %, 12.5 %, and 13.3 % of the global annual mean dust emissions, with the remaining 14.5 % originating from scattered smaller dust sources. Although Saharan dust dominates global dust mass loading at the surface, the relative contribution of Asian dust increases with altitude and becomes dominant in the upper troposphere. The simulations show that Asian dust contributes ~60.9 % to the global and annual mean dust concentration between 266 hPa and 160 hPa. Asian dust is mostly lifted in the spring by mid-latitude frontal systems. However, deep convection during the Asian summer monsoon (ASM) favours the vertical transport of local dust to the upper atmosphere. Simulated dust accumulates in the ASM anticyclone and forms a local maximum; however, the simulated dust mass concentration is only ~0.04 % of the total aerosols in the Asian Tropopause Aerosol Layer (ATAL), which are dominated by organics, sulfates and nitrates.

The landfill leachate was treated by catalytic wet oxidation. The catalysts was prepared by impregnation method, and FSC was used as catalyst carrier. Fe and Co were used as catalyst active components and Ce was used as catalyst auxiliary, and noble metal ruthenium was added to prepare supported multi-component composite catalyst of Fe-Co-Ru-Ce/γ-Al2O3. The water sample pH, decolorization rate, COD removal rate and turbidity removal rate were used as evaluation indexes of catalyst activity. The catalysts were prepared under the conditions of calcination temperature of 450 °C and calcination time of 3 h. Under the same conditions, for the Landfill Leachate, the COD removal rate, decolorization rate, turbidity removal rate of the water samples reached 78.1%, 60.4% and 92.7%, respectively.

The tropospheric and stratospheric nitrate aerosol is simulated by a sectional aerosol model coupled to the Community Earth System Model. The simulated nitrate mass fractional contribution to aerosols is significantly higher in the upper troposphere and lower stratosphere (UTLS) than that at the surface. Both in situ measurements and simulations show that nitrate aerosol accounts for about 30%–40% of the aerosol mass at the tropopause of the Asian summer monsoon (ASM) region. Furthermore, simulated condensed nitric acid particles account for ∼20% of the annual mean aerosol mass at the tropical tropopause, and over 95% in the UTLS at the South Pole in June‐July‐August. Our study suggests that the extremely cold ambient conditions in the UTLS of the tropics, ASM and polar regions thermodynamically favor the condensation of ammonia and nitric acid. The widely distributed nitrate aerosol in the global UTLS may be overlooked by climate models.