A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle
Jasper F. Kok
备注：
Published in Proceedings of the National Academy of Sciences (PNAS)
发表信息：
Kok, J. F. (2011), A scaling theory for the size distribution of emitted dust aerosols suggests that climate models underestimate the size of the global dust cycle, Proc. Natl. Acad. Sci. USA, 108(3), 1016-1021
Mineral dust aerosols impact Earth's radiation budget through interactions with clouds, ecosystems, and radiation, which constitutes a substantial uncertainty in understanding past and predicting future climate changes. One of the causes of this large uncertainty is that the size distribution of emitted dust aerosols is poorly understood. The present study shows that regional and global circulation models (GCMs) overestimate the emitted fraction of clay aerosols (< 2 μm diameter) by a factor of ~2 - 8 relative to measurements. This discrepancy is resolved by deriving a simple theoretical expression of the emitted dust size distribution that is in excellent agreement with measurements. This expression is based on the physics of the scale-invariant fragmentation of brittle materials, which is shown to be applicable to dust emission. Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust. On local and regional scales, this affects the magnitude and possibly the sign of the dust radiative forcing, with implications for numerical weather forecasting and regional climate predictions in dusty regions. On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought.
Effective radiative forcing in the aerosol-climate model CAM5.3-MARC-ARG
利用气溶胶-气候模式CAM 5.3-MARC-ARG对人为气溶胶的有效辐射强迫进行了数值模拟。CAM5.3-MARC-ARG是CAM5.3的一个新结构，其中的气溶胶模块被MARC（二阶矩、多模态、混合状态分辨气溶胶气候研究模式）所取代。CAM5.3-MARC-ARG使用默认的ARG气溶胶激活方案，与CAM5.3的默认配置一致。我们计算使用1850年气溶胶排放模拟和使用2000年气溶胶排放模拟之间的差异，以评估人为气溶胶的辐射效应。我们比较了气溶胶柱负荷，云的属性，和辐射效应所产生的CAM 5.3-MARC-ARG与CAM 5.3的默认配置，它使用模态气溶胶模块与三个日志正交模（MAM 3）。与MAM 3相比，MARC通过直接辐射效应产生了更强的冷却，通过地面辐射效应产生了更强的冷却，通过云长波辐射效应产生了更强的增暖。MARC和MAM 3的全球平均云短波辐射效应相似，但区域分布不同。总体而言，MARC产生的全局平均净ERF为-1.75 $\pm$ 0.04 W m $^{-2}$，其强于MAM 3产生的全局平均净ERF-1.57 $\pm$ 0.04 W m $^{-2}$。在MARC和MAM 3之间，ERF的区域分布也不同，这主要是由于云短波辐射效应的区域分布不同。我们的结论是气溶胶在全球气候模式中的具体表现，包括气溶胶混合状态，对气候模拟有重要意义。
The Equilibrium Climate Response to Sulfur Dioxide and Carbonaceous Aerosol Emissions from East and Southeast Asia
我们调查了东亚和东南亚碳质气溶胶和二氧化硫（硫酸盐气溶胶的前体）排放的平衡气候响应。使用共同体地球系统模式，与共同体大气模式版本5.3，我们发现，来自东亚和东南亚的人为气溶胶排放产生的全球平均净辐射效应为-0.49 $\pm$ 0.04 W m $^{-2}$。大约一半的冷却效应可以归因于人为的二氧化硫排放。气溶胶的排放导致了北半球大范围的降温。东亚和东南亚地区降水受到强烈抑制，表明人为气溶胶排放可能影响当地的水资源。然而，与以前的研究相比，我们没有发现澳大利亚和西非降水的远程影响的明确证据。我们建议进一步调查可能的远程影响。
Sensitivity of the ECMWF seasonal forecast model to CO2 and anthropogenic aerosol forcings: Experimental design and impact on climate trends
ECMWF（欧洲中期天气预报中心）；Department of Meteorology and Geophysics, University of Vienna（维也纳大学气象与地球物理系）；NCAS, University of Oxford, Atmospheric, Oceanic and Planetary Physics（牛津大学大气、海洋和行星物理国家环境科学研究中心）
Aerosol-cloud interactions (ACI) include various effects that result from aerosols entering a cloud, and affecting cloud properties. In general, an increase in aerosol concentration results in smaller droplet sizes which leads to larger, brighter, longer-lasting clouds that reflect more sunlight and cool the Earth. The strength of the effect is however heterogeneous, meaning it depends on the surrounding environment, making ACI one of the most uncertain effects in our current climate models. In our work, we use causal machine learning to estimate ACI from satellite observations by reframing th…
Aerosols sourced from combustion such as black carbon (BC) are important short-lived climate forcers whose direct radiative forcing and atmospheric lifetime depend on their morphology. These aerosols' complex morphology makes modeling their optical properties difficult, contributing to uncertainty in both their direct and indirect climate effects. Accurate and fast calculations of BC optical properties are needed for remote sensing inversions and for radiative forcing calculations in atmospheric models, but current methods to accurately calculate the optical properties of these aerosols are co…
Aerosol-cloud interactions constitute the largest source of uncertainty in assessments of the anthropogenic climate change. This uncertainty arises in part from the difficulty in measuring the vertical distributions of aerosols, and only sporadic vertically resolved observations are available. We often have to settle for less informative vertically aggregated proxies such as aerosol optical depth (AOD). In this work, we develop a framework for the vertical disaggregation of AOD into extinction profiles, i.e. the measure of light extinction throughout an atmospheric column, using readily availa…
Dissipating the correlation smokescreen: Causal decomposition of the radiative effects of biomass burning aerosols over the South-East Atlantic
ETH Zurich（苏黎世联邦理工学院）；University of Colorado, Boulder（科罗拉多大学博尔德分校）；NOAA（美国国家海洋和大气管理局）；Colorado State University（科罗拉多州立大学）；University of Lausanne（洛桑大学）；GeoSphere Austria（奥地利地球科学研究所）
Unveiling the Shortwave Absorption Spectra of Alumina Aerosols: Implications for Solar Radiation Modification
Washington University in St. Louis（华盛顿大学圣路易斯分校）；Veterans Affairs Medical Center（退伍军人事务医疗中心）；ETH Zurich（苏黎世联邦理工学院）；Physikalisch-Meteorologisches Observatorium Davos and World Radiation Center（达沃斯物理气象观测站和世界辐射中心）；John A Paulson School of Engineering and Applied Sciences, Harvard University（哈佛大学约翰·A·保尔森工程与应用科学学院）；Center for Nanophase Materials Sciences, Oak Ridge National Laboratory（橡树岭国家实验室纳米材料科学中心）
Background Conditions Influence the Estimated Cloud Radiative Effects of Anthropogenic Aerosol Emissions from Different Source Regions
本文利用共同体地球系统模式，结合共同体大气模式5.3版，研究了不同源区和全球航运排放的人为气溶胶的云辐射效应。本文还分析了气溶胶负荷、云凝结核浓度、液态水路径和冰水路径。由于云对气溶胶响应的跨界传输和次线性，来自一个特定源区的排放的云辐射效应受到来自其他源区的排放的影响。例如，当存在其他人为排放源时（“当今背景”假设），航运的短波云辐射效应为$-0.39 \pm 0.03$ W m $^{-2}$，而当不存在其他人为排放源时（“自然背景"假设），航运的短波云辐射效应为$-0.60 \pm 0.03$ W m $^{-2}$。一般来说，云的辐射效应弱，如果假设现在的背景条件相比，如果假设自然背景条件。在调查特定源区气溶胶排放的气候影响时，应仔细考虑有关背景条件的假设。
Unsupervised Regionalization of Particle-resolved Aerosol Mixing State Indices on the Global Scale
University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Meteorological Research Institute（气象研究所）；Japan Meteorological Agency（日本气象厅）；Southern University of Science and Technology（南方科技大学）
Direct Radiative Impacts of Stratospheric Aerosols on the Tropical Troposphere: Clouds, Precipitation, and Circulation in Convection-Resolving and Global Simulations
Developing Global Aerosol Models based on the Analysis of 30-Year Ground Measurements by AERONET (AEROEX models) and Implication on Satellite based Aerosol Retrievals
Space Applications Centre, Indian Space Research Organization (ISRO)（空间应用中心，印度空间研究组织）；Indian Institute of Space Science and Technology（印度空间科学与技术学院）
Collaborative Neural Networks significantly Improve Global Aerosol Retrievals From Multi-Angle Polarimeters
SRON Space Research Organisation Netherlands（荷兰空间研究所）；NASA Goddard Space Flight Center Code 616（美国宇航局戈达德太空飞行中心616室）；Science Systems and Applications, Inc.（科学系统与应用程序公司）
Establishing a non-hydrostatic global atmospheric modeling system (iAMAS) at 3-km horizontal resolution with online integrated aerosol feedbacks on the Sunway supercomputer of China
Evaluating local climate in global storm-resolving models with the Köppen-Geiger classification
Wageningen University & Research（瓦赫宁根大学与研究）；University of Hamburg（汉堡大学）；University of Lausanne（洛桑大学）；University of Bern（伯尔尼大学）；Instituto Português do Mar e Atmosfera（葡萄牙海洋与大气研究所）；ETH Zurich（苏黎世联邦理工学院）；Seoul National University（首尔国立大学）；European Centre for Medium-Range Weather Forecasts (ECMWF)（欧洲中期天气预报中心）
Seasonal cycle of Precipitation over Major River Basins in South and Southeast Asia: A Review of the CMIP5 climate models data for present climate and future climate projections
