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Dust shortwave absorbability suffers from significant uncertainties. We investigated the radiative effects of dust aerosols from the circum‐Tibet region using four shortwave absorbability schemes and examined their impacts on the East Asian summer monsoon by using the Community Earth System Model (CESM). We adopted superspheroidal models to compute dust aerosol optical properties and found that more absorptive particles have larger asymmetry factor and lower single‐scattering albedo. Meiyu precipitation, as a part of the East Asian summer monsoon, is weakened by dust aerosols, particularly for the convective precipitation. The mechanism is that dust aerosols transported mainly from the Gobi desert radiatively heat the lower atmosphere to the north of the Meiyu rainband and decrease the meridional temperature gradient, leading to the weakening of the midtropospheric westerly jet over the Meiyu rainband, which is important for convection. More absorptive dust aerosols with a stronger radiative heating effect inhibit more convective Meiyu precipitation. Plain Language Summary: The circum‐Tibet region including the Taklimakan and Gobi deserts is the major source region of dust aerosols in East Asia particularly during the spring and summer seasons. Meiyu, as a part of the East Asian summer monsoon, generally occurs from mid‐June to mid‐July and often shows a tilt rain band extending from southwest to east China. The Letter reports on our finding about the relationship between dust shortwave absorbability (the amount of solar radiation absorbed by dust) and Meiyu precipitation. For weakly absorptive dust aerosols, convective Meiyu precipitation is rarely changed by dust aerosols; however, for strongly absorptive dust aerosols, convective Meiyu precipitation is significantly decreased. The impact of dust absorbability on Meiyu precipitation is explained through atmospheric heating rate, temperature, and wind field changes. This Letter emphasizes the urgent need of a more accurate knowledge of dust shortwave absorbability for climate modeling since significant uncertainties of refractive indices exist and new evidences show that Asian dust could be less absorptive than previously believed. Key Points: Dust shortwave absorbability affects single‐scattering albedo and asymmetry factorDust aerosols inhibit convective Meiyu precipitation depending on absorbabilityMidtropospheric westerly jet is weakened by dust aerosols causing decreased convective precipitation [ABSTRACT FROM AUTHOR]

Sea salt aerosols were assumed to be homogeneous spheres in most climate models. However, observations show that sea salt particles are inhomogeneous during the deliquesce and crystallization processes. Using a two‐layer sphere model, we found that backscattering of solar radiation associated with sea salts is underestimated in homogeneous sea salt models. The Community Earth System Model is used to assess the inhomogeneity effect on direct radiative forcing. For global climate model simulation, the inhomogeneity effect on radiative transfer is found to be small as high RHs over widespread oceans suppress the impact of inhomogeneity. On the other hand, in coastal regions, the inhomogeneity effect can cause up to 10% radiative forcing difference of sea salt aerosols. The inhomogeneity effect of sea salt aerosols has to be considered over coastal regions, especially in the Mediterranean, Australia, and the eastern coast of South America. Plain Language Summary: In a humid environment, solid sea salt particles can be coated with water. Sea salt aerosol has a cooling effect on the Earth, but coated sea salt has even stronger cooling effect. However, in most climate models, coated sea salt is not considered. This study confirms that coated sea salt aerosols may not significantly affect the global radiation budget, but they should definitely be considered in the coastal climate where large changes in relative humidity are evident. Key Points: For some range of relative humidity (50‐80%), sea salt is assumed to be an inhomogeneous two‐layer sphereThe inhomogeneity of sea salt decreases the asymmetry factor and increases backscattering of solar radiationInhomogeneity has a relatively large impact (up to 10%) on sea salt radiative forcing over coastal waters [ABSTRACT FROM AUTHOR]

Abstract: The nonsphericity and inhomogeneity of marine aerosols (sea salts) have not been addressed in pertinent radiative transfer calculations and remote sensing studies. This study investigates the optical properties of nonspherical and inhomogeneous sea salts using invariant imbedding T‐matrix simulations. Dry sea salt aerosols are modeled based on superellipsoidal geometries with a prescribed aspect ratio and roundness parameter. Wet sea salt particles are modeled as coated superellipsoids, as spherical particles with a superellipsoidal core, and as homogeneous spheres depending on the level of relative humidity. Aspect ratio and roundness parameters are found to be critical to interpreting the linear depolarization ratios (LDRs) of NaCl crystals from laboratory measurements. The optimal morphology parameters of NaCl necessary to reproduce the measurements are found to be consistent with data gleaned from an electron micrograph. The LDRs of wet sea salts are computed based on inhomogeneous models and compared with the measured data from ground‐based LiDAR. The dependence of the LDR on relative humidity is explicitly considered. The increase in the LDR with relative humidity at the initial phase of deliquescence is attributed to both the size increase and the inhomogeneity effect. For large humidity values, the LDR substantially decreases because the overall particle shape becomes more spherical and the inhomogeneity effect in a particle on the LDR is suppressed for submicron sea salts. However, the effect of inhomogeneity on optical properties is pronounced for coarse‐mode sea salts. These findings have important implications for atmospheric radiative transfer and remote sensing involving sea salt aerosols. [ABSTRACT FROM AUTHOR]

The soil state (e.g., temperature and moisture) in a mesoscale numerical prediction model is typically initialized by reanalysis or analysis data that may be subject to large bias. Such bias may lead to unrealistic land-atmosphere interactions. This study shows that the Climate Forecast System Reanalysis (CFSR) dramatically underestimates soil temperature and overestimates soil moisture over most parts of China in the first (0-10 cm) and second (10-25 cm) soil layers compared to in situ observations in July 2013. A correction based on the global optimal dual kriging is employed to correct CFSR bias in soil temperature and moisture using in situ observations. To investigate the impacts of the corrected soil state on model forecasts, two numerical model simulations-a control run with CFSR soil state and a disturbed run with the corrected soil state-were conducted using the Weather Research and Forecasting model. All the simulations are initiated 4 times per day and run 48 h. Model results show that the corrected soil state, for example, warmer and drier surface over the most parts of China, can enhance evaporation over wet regions, which changes the overlying atmospheric temperature and moisture. The changes of the lifting condensation level, level of free convection, and water transport due to corrected soil state favor precipitation over wet regions, while prohibiting precipitation over dry regions. Moreover, diagnoses indicate that the remote moisture flux convergence plays a dominant role in the precipitation changes over the wet regions. [ABSTRACT FROM AUTHOR]