Effects of inorganic seed aerosols on the growth and chemical composition of secondary organic aerosol formed from OH-initiated oxidation of toluene

(NH₄)₂SO₄, CaCl₂, Na₂SiO₃ and NaNO₃ were selected as surrogates of inorganic seed aerosols of ambient atmosphere of Chinese urban areas, respectively, to study their effects on the formation of secondary organic aerosol (SOA) in the toluene/CH₃ONO/NO_x photooxidation system. The SMPS and aerosol laser time-of-flight mass spectrometer (ALTOFMS) was used to measure the aerodynamic size and chemical composition of individual SOA particles in real-time. Experimental results indicate that either the growth or products of SOA is affected by the presence of inorganic seed aerosol. Inorganic seed aerosols would promote growth rates of SOA formation at the start of the reaction and inhibits its formation rate with prolonging the reaction time. In the case of about 100 μg m^?3 seed aerosol load, the addition of Na₂SiO₃ induced a same growth rate of SOA formation as NaNO₃. The influence of four individual seed aerosols on the generation of SOA decreased in the order of CaCl₂ > (NH₄)₂SO₄ > NaNO₃, Na₂SiO₃. The presence of Na₂SiO₃ or NaNO₃ has no obvious effect on the growth rates of SOA formation, but it does increase the yield of organic acid and nitrogen-containing organic compounds, respectively. Besides the significantly effect on the growth rate of SOA formation, the presence of CaCl₂ or (NH₄)₂SO₄ can lead to the formation of high-molecular weight species which is found to be positively correlated with the hygroscopic behavior of seed aerosols. The CaCl₂ shows the strongest hygroscopic behavior among the four individual seed aerosols, and the most significant promotion effect on the formation of the high-molecular weight species. It is proposed that the SOA generation enhancement and high-molecular weight products are achieved by particle-phase heterogeneous reactions induced and catalyzed by the acidity of CaCl₂ and (NH₄)₂SO₄ seed aerosols.     

FIO-ESM v2.0 Outputs for the CMIP6 Global Monsoons Model Intercomparison Project Experiments

Three tiers of experiments in the Global Monsoons Model Intercomparison Project(GMMIP), one of the endorsed model intercomparison projects of phase 6 of the Coupled Model Intercomparison Project(CMIP6), are implemented by the First Institute of Oceanography Earth System Model version 2(FIO-ESM v2.0), following the GMMIP protocols.Evaluation of global mean surface air temperature from 1870 to 2014 and climatological precipitation(1979–2014) in tier-1 shows that the atmosphere model of FIO-ESM v2.0 can reproduce the basic observed atmospheric features. In tier-2, the internal variability is captured by the coupled model, with the SST restoring to the model climatology plus the observed anomalies in the tropical Pacific and North Atlantic. Simulation of the Northern Hemisphere summer monsoon circulation is significantly improved by the SST restoration in the North Atlantic. In tier-3, five orographic perturbation experiments are conducted covering the period 1979–2014 by modifying the surface elevation or vertical heating in the prescribed region. In particular, the strength of the South Asian summer monsoon is reduced by removing the topography or thermal forcing above 500 m over the Asian continent. Monthly and daily simulated outputs of FIO-ESM v2.0 are provided through the Earth System Grid Federation(ESGF) node to contribute to a better understanding of the global monsoon system.     

Prospective scenarios of the saltwater intrusion in an estuary under climate change context using Bayesian neural networks

In recent decades, saltwater intrusion over some low-lying coastal regions was deteriorated by rising sea-level and decreasing streamflow in the context of climate change. Though physically-based hydrodynamic models are the most detailed means to simulate salinity processes, they are commonly restricted by data insufficiency issues both in spatial resolution and temporal lasting. This motivates us to build a statistical model enable simulation and scenario analysis for coastal salinity change with limited observations. A Bayesian neural network (BNN) model is built hereby to simulate salinity. It offers more precise estimation compared with the conventional artificial neural network. Meanwhile, the model gives the uncertainty behaviors of the final salinity simulation which is not available for other methods. Future scenarios of salinity change are constructed and analyzed in different time periods on the basis of the validated BNN model. Results indicate that the water quality over lower Pearl River is degrading along with more significant uncertainties. Further analysis suggests that streamflow alteration has a more direct impact on salinity variations than the sea-level change does. The method allows a profound analysis of the potential influence on water quality degradation in coastal and low-lying regions in support of water management and adaptation toward global climate change.     

蓄水初期三峡水库草堂河水-气界面CO2和CH4通量日变化特征及其影响因素

为查明三峡水库蓄水初期典型支流水-气界面CO_2和CH_4通量的日变化特征,采用LGR在线分析仪-通量箱法,于2015年9月初在库腹一级支流草堂河回水区开展连续24 h的定位观测.结果表明,24 h监测期内,支流库湾水-气界面CO_2通量变幅为-81.642~180.991 mg/(m~2·h),呈"昼吸夜放"特征,均值为17.346 mg/(m~2·h),总体为释放特征;CH_4全天均表现为释放状态,释放通量均值为0.064 mg/(m~2·h),呈"昼弱夜强"变化.相关分析结果表明,CH_4和CO_2释放通量与风速呈正相关,与表层水温、溶解氧浓度、叶绿素a浓度呈负相关,说明风速物理扰动、浮游植物光合作用是控制草堂河水-气界面气体通量最重要的环境因素.同时,干-支流相互作用形成的特殊水环境(如异重流、水温分层)也与水-气界面温室气体通量过程密切相关,但是其作用机制更为复杂,应开展进一步系统观测和深入研究.     

Arctic sea ice concentration and thickness data assimilation in the FIO-ESM climate forecast system

To improve the Arctic sea ice forecast skill of the First Institute of Oceanography-Earth System Model (FIO-ESM) climate forecast system, satellite-derived sea ice concentration and sea ice thickness from the Pan-Arctic Ice-Ocean Modeling and Assimilation System (PIOMAS) are assimilated into this system, using the method of localized error subspace transform ensemble Kalman ?lter (LESTKF). Five-year (2014–2018) Arctic sea ice assimilation experiments and a 2-month near-real-time forecast in August 2018 were conducted to study the roles of ice data assimilation. Assimilation experiment results show that ice concentration assimilation can help to get better modeled ice concentration and ice extent. All the biases of ice concentration, ice cover, ice volume, and ice thickness can be reduced dramatically through ice concentration and thickness assimilation. The near-real-time forecast results indicate that ice data assimilation can improve the forecast skill significantly in the FIO-ESM climate forecast system. The forecasted Arctic integrated ice edge error is reduced by around 1/3 by sea ice data assimilation. Compared with the six near-real-time Arctic sea ice forecast results from the subseasonal-to-seasonal (S2S) Prediction Project, FIO-ESM climate forecast system with LESTKF ice data assimilation has relatively high Arctic sea ice forecast skill in 2018 summer sea ice forecast. Since sea ice thickness in the PIOMAS is updated in time, it is a good choice for data assimilation to improve sea ice prediction skills in the near-real-time Arctic sea ice seasonal prediction.     

Laser desorption/ionization mass spectrometric study of secondary organic aerosol formed from the photooxidation of aromatics

Five aromatic hydrocarbons – benzene, toluene, ethylbenzene, p-xylene and 1,2,4-trimethylbenzene – were selected to investigate the laser desorption/ionization mass spectra of secondary organic aerosols (SOA) resulting from OH-initiated photooxidation of aromatic compounds. The experiments were conducted by irradiating aromatic hydrocarbon/CH₃ONO/NO _X mixtures in a home-made smog chamber. The aerosol time-of-flight mass spectrometer (ATOFMS) was used to measure the aerodynamic size and chemical composition of individual secondary organic aerosol particles in real-time. Experimental results showed that aerosol created by aromatics photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and different aromatic hydrocarbons SOA mass spectra have eight same positive laser desorption/ionization mass spectra peaks: m/z = 18, 29, 43, 44, 46, 57, 67, 77. These mass spectra peaks may come from the fragment ions of the SOA products: oxo-carboxylic acids, aldehydes and ketones, nitrogenated organic compounds, furanoid and aromatic compounds. The possible reaction mechanisms leading to these products were also discussed.     

甘肃永登5.8级地震前兆异常特征及天祝-古浪5.4级地震中短期预报

综合分析了 1 995年 7月 2 2日甘肃永登 5 .8级地震前兆异常时空分布特征 ,主要表现为异常数量多、分布广、密度大、震后响应性异常显著 ,且时空分布具有成组性、空间分布具有相对稳定性。这可能与该区中强震成丛活动方式有关。此研究结果在 1 996年 6月 1日甘肃天祝 -古浪 5 .4级地震中短期预报中发挥了作用     

基于高分辨率遥感影像的建筑物轮廓信息提取

针对许多领域对建筑物信息更新的迫切要求,提出并发展了一套完整的基于高分辨率遥感影像的建筑物二维轮廓快速提取流程。首先介绍一种利用数学形态学理论进行边缘检测和边缘连接的新方法,然后利用了模式识别和图像分析领域的相关技术(区域标识和特征量测等)进行建筑物二维信息的提取。最后通过Quickbird影像进行了方法验证,试验证明该流程可以快速有效的提取建筑物轮廓信息。     

人造地震动反应谱的非线性拟合

为了进一步提高人造地震动时程对目标反应谱的拟合精度和效率,本文提出了一种人造地震动反应谱非线性拟合方法.在人造地震动反应谱非线性拟合过程中,认为Fouricr幅值谱与反应谱调整项之间满足非线性(幂指数)关系.通过比例拉伸和折叠等数值技巧以促使模拟加速度向目标加速度逼近.算例分析结果表明,人造地震动反应谱非线性拟合方法具...     

Removal of phosphorus from water using scallop shell synthesized ceramic biomaterials

This study describes the development of scallop shell synthesized ceramic biomaterial for phosphorus removal from water. The synthesized biomaterial was characterized by scanning electron microscope, Brunauer–Emmett–Teller and X-ray diffractometer methods. The influences of contact time, initial phosphate concentration, initial solution pH, co-existing ions and temperature for phosphorus removal were investigated by batch experiments. The results indicated that the equilibrium data can be fitted by the Langmuir isotherm model at temperatures ranging from 15 to 55 °C, with the maximum sorption capacity of 13.6 mg/g. Sorption kinetics followed a pseudo-second-order kinetic equation model. The sorption process was optimal at a wide range of solution pH (above 2.4), with a relatively high sorption capacity level. Phosphorus sorption was slightly impeded by the presence of F^?, HCO₃ ^? and NH₄ ⁺ ions, and significantly inhibited by Cl^?, SO₄ ^2? and NO₃ ^? ions. Sorption process appeared to be controlled by a chemical precipitation processes. The mechanism may be attributed to ion complexation during subsequent sorption of phosphorus on scallop shell synthesized ceramic biomaterial.