A three-dimensional variational data assimilation system for a size-resolved aerosol model: Implementation and application for particulate matter and gaseous pollutant forecasts across China     

Wang  Daichun  You  Wei  Zang  Zengliang  Pan  Xiaobin  He  Hongrang  Liang  Yanfei 《中国科学:地球科学(英文版)》2020,63(9):1366-1380

A three-dimensional variational(3DVAR) data assimilation(DA) system is presented here based on a size-resolved sectional aerosol model, the Model for Simulating Aerosol Interactions and Chemistry(MOSAIC) within the Weather Research and Forecasting model coupled to Chemistry(WRF-Chem) model. The use of this approach means that both gaseous pollutants such as SO_2, NO_2, CO, and O_3 as well as particulate matter(PM_(2.5), PM_(10)) observational data can be assimilated simultaneously.Two one-month parallel simulation experiments were conducted, one with the assimilation of surface hourly concentration observations of the above six pollutants released by the China National Environmental Monitoring Centre(CNEMC) and one without assimilation in order to verify the impact of assimilation on initial chemical fields and subsequent forecasts. Results show that, in the first place, use of the DA system can provide a more accurate model initial field. The root-mean-square error of PM_(2.5), PM_(10), SO_2, NO_2, CO, and O_3 mass concentrations in analysis field fell by 29.27 μg m~(-3)(53.5%), 34.5 μg m~(-3)(50.9%),30.36 μg m~(-3)(64.2%), 8.91 μg m~(-3)(39.5%), 0.46 mg m~(-3)(47.4%), and 15.11 μg m~(-3)(51.0%), respectively, compared to a background field without assimilation. At the same time, mean fraction error was reduced by 42.6%, 53.1%, 45.2%, 43.1%,69.9%, and 48.8%, respectively, while the correlation coefficient increased by 0.51, 0.55, 0.48, 0.38, 0.47, 0.65, respectively.Secondly, the results of this analysis reveal variable benefits from assimilation on different pollutants. DA significantly improves PM_(2.5), PM_(10), and CO forecasts leading to positive effects that last more than 48 h. The positive effects of DA on SO_2 and O_3 forecasts last up to 8 h but that remains relatively poor for NO_2 forecasts. Thirdly, the influence of assimilation varies in different areas. It is possible that the positive effects of DA on PM_(2.5) and PM_(10) forecasts can last more than 48 h across most regions of China. Indeed, DA significantly improves SO_2 forecasts within 48 h over north China, and much longer CO assimilation benefits(48 h) are found in most regions apart from north and east China and across the Sichuan Basin. DA is able to improve O_3 forecasts within 48 h across China with the exception of southwest and northwest regions and the O_3 DA benefits in southern China are more evident, while from a spatial distribution perspective, NO_2 DA benefits remain relatively poor.  相似文献   

高温加速度传感器关键技术研究     

丁莉莎  朱小毅  薛兵  李建飞  张金川  臧宾 《地震地磁观测与研究》2014,35(5)

为了满足深井和核电站强震动观测需求,研制一种能在100℃ 130℃环境下有效连续工作的力平衡反馈加速度计,并重新设计其电路方案,主要利用高温分立元件重新设计检波及前后级放大电路,并对其余电路进行升级改造.样机实验结果表明:设计方案满足要求,具有一定的实用性.  相似文献   

Modeling urban land use conversion of Daqing City,China: a comparative analysis of “top-down” and “bottom-up” approaches   总被引：3，自引：1，他引：2  

Wenliang Li  Changshan Wu  Shuying Zang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(4):817-828

During the past decades, Daqing City, China has experienced unprecedented urban expansion due to the rapid development of petroleum industry. With rapid urbanization and lack of strategic planning, Daqing is facing many socio-economic and environmental problems, and it is essential to examine the process of urbanization, and to develop policy recommendations for sustainable development. To address this problem, this paper examined the urbanization process of Daqing City through developing two multi-level models: an integrated system dynamic (SD) and CLUE-S model (SD-CLUES), and an integrated SD and stochastic cellular automata model (SD-CA). Analysis of results suggests that these two models generate significantly different results. With the SD-CLUES model, new urban developments are clustered in the downtown area or along major transportation networks, indicating exogenous driving forces playing an important role in shaping urban spatial dynamics. With the SD-CA model, on the contrary, the resultant new urban cells are spread over the entire study area, and associated with existing urban areas. Further, visual comparisons and validations indicate that the SD-CA model is a better alternative in explaining the urbanization mechanism of Daqing City. In addition, analysis of results suggests that the stochastic factor in the CA model has significant impact on the modeling accuracy.  相似文献   

Forward induced seismic hazard assessment: application to a synthetic seismicity catalogue from hydraulic stimulation modelling     

Amir Hossein Hakimhashemi  Jeoung Seok Yoon  Oliver Heidbach  Arno Zang  Gottfried Grünthal 《Journal of Seismology》2014,18(3):671-680

The M _w 3.2-induced seismic event in 2006 due to fluid injection at the Basel geothermal site in Switzerland was the starting point for an ongoing discussion in Europe on the potential risk of hydraulic stimulation in general. In particular, further development of mitigation strategies of induced seismic events of economic concern became a hot topic in geosciences and geoengineering. Here, we present a workflow to assess the hazard of induced seismicity in terms of occurrence rate of induced seismic events. The workflow is called Forward Induced Seismic Hazard Assessment (FISHA) as it combines the results of forward hydromechanical-numerical models with methods of time-dependent probabilistic seismic hazard assessment. To exemplify FISHA, we use simulations of four different fluid injection types with various injection parameters, i.e. injection rate, duration and style of injection. The hydromechanical-numerical model applied in this study represents a geothermal reservoir with preexisting fractures where a routine of viscous fluid flow in porous media is implemented from which flow and pressure driven failures of rock matrix and preexisting fractures are simulated, and corresponding seismic moment magnitudes are computed. The resulting synthetic catalogues of induced seismicity, including event location, occurrence time and magnitude, are used to calibrate the magnitude completeness M _c and the parameters a and b of the frequency-magnitude relation. These are used to estimate the time-dependent occurrence rate of induced seismic events for each fluid injection scenario. In contrast to other mitigation strategies that rely on real-time data or already obtained catalogues, we can perform various synthetic experiments with the same initial conditions. Thus, the advantage of FISHA is that it can quantify hazard from numerical experiments and recommend a priori a stimulation type that lowers the occurrence rate of induced seismic events. The FISHA workflow is rather general and not limited to the hydromechanical-numerical model used in this study and can therefore be applied to other fluid injection models.  相似文献   

云南水氡群体异常特征     

李琼  秦嘉政  石绍先 《地震地磁观测与研究》2012,33(5):152-159

采用非均匀度方法,分别提取滇西北、滇中北、滇西南、滇东南和滇东北地区水氡观测资料的地震前兆群体异常。结果表明,该方法能满足水氡观测点所在地区成组中强地震的中、短临预报要求;且该方法能自动识别异常,排除人为主观影响,便于在其他震区进行预报效能检验。  相似文献   

秦皇岛地质环境综述     

臧文学  张希中  贡长青  孙娟 《地质灾害与环境保护》2012,23(2):32-35,43

通过大量野外调查和对已有成果的分析,发现该地区地质环境破坏严重,并有恶化的趋势.该地区主要地质环境问题包括地质灾害、水环境污染、海水入侵和海岸蚀退,多数为人为因素引发,自然灾害是次要灾害.最后针对不同的地质环境问题提出综合保护建议.  相似文献   

World Stress Map Database as a Resource for Rock Mechanics and Rock Engineering     

Arno Zang  Ove Stephansson  Oliver Heidbach  Silke Janouschkowetz 《Geotechnical and Geological Engineering》2012,30(3):625-646

Knowledge of the in situ stress state is of key importance for rock engineering. We inform the reader about the World Stress Map (WSM) database and its application to rock mechanics and rock engineering purpose, and in particular the orientation of maximum horizontal stress. We discuss the WSM and the quality ranking system of stress orientation data. We show one example of discrete-measured and computed-smoothed stress orientations from central and northern Europe with respect to relative plate velocity trajectories. We give first insights into ongoing development of a second, more Quantitative World Stress Map database which compiles globally rock-type specific stress magnitudes versus depth. We discuss the vertical stress component, and the lateral stress coefficient versus depth for different rock types. We display stress magnitudes in 2D and 3D stress space, and investigate stress ratios in relation to depth, lithology and tectonic faulting regime.  相似文献   

Stabilization of extracellular polymeric substances (Bacillus subtilis) by adsorption to and coprecipitation with Al forms     

Robert Mikutta  Ulrich Zang  Ludwig Haumaier 《Geochimica et cosmochimica acta》2011,75(11):3135-3154

Extracellular polymeric substances (EPS) are continuously produced by bacteria during their growth and metabolism. In soils, EPS are bound to cell surfaces, associated with biofilms, or released into solution where they can react with other solutes and soil particle surfaces. If such reaction results in a decrease in EPS bioaccessibility, it may contribute to stabilization of microbial-derived organic carbon (OC) in soil. Here we examined: (i) the chemical fractionation of EPS produced by a common Gram positive soil bacterial strain (Bacillus subtilis) during reaction with dissolved and colloidal Al species and (ii) the resulting stabilization against desorption and microbial decay by the respective coprecipitation (with dissolved Al) and adsorption (with Al(OH)_3(am)) processes. Coprecipitates and adsorption complexes obtained following EPS-Al reaction as a function of pH and ionic strength were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stability of adsorbed and coprecipitated EPS against biodegradation was assessed by mineralization experiments for 1100 h. Up to 60% of the initial 100 mg/L EPS-C was adsorbed at the highest initial molar Al:C ratio (1.86), but this still resulted only in a moderate OC mass fraction in the solid phase (17 mg/g Al(OH)_3(am)). In contrast, while coprecipitation by Al was less efficient in removing EPS from solution (maximum values of 33% at molar Al:C ratios of 0.1-0.2), the OC mass fraction in the solid product was substantially larger than that in adsorption complexes. Organic P compounds were preferentially bound during both adsorption and coprecipitation. Data are consistent with strong ligand exchange of EPS phosphoryl groups during adsorption to Al(OH)_3(am), whereas for coprecipitation weaker sorption mechanisms are also involved. X-ray photoelectron analyses indicate an intimate mixing of EPS with Al in the coprecipitates, which is not observed in the case of EPS adsorption complexes. The incubation experiments showed that both processes result in overall stabilization of EPS against microbial decay. Stabilization of adsorbed or coprecipitated EPS increased with increasing molar Al:C ratio and biodegradation was correlated with EPS desorption, implying that detachment of EPS from surface sites is a prerequisite for microbial utilization. Results indicate that the mechanisms transferring EPS into Al-organic associations may significantly affect the composition and stability of biomolecular C, N and P in soils. The observed efficient stabilization of EPS might explain the strong microbial character of organic matter in subsoils.  相似文献   

深层地下水开采引起的生态环境问题及其治理   总被引：2，自引：0，他引：2  

赵秀兰  陈宁生  臧逸中 《地下水》2005,27(1):46-49

在分析河北平原深层地下水资源的构成与开发利用问题的基础上,论述了深层地下水严重超采引起的生态环境问题,通过建立深层地下水开发利用管理模型,探求深层地下水可开采量,提出了深层地下水开发利用的对策以及防治生态环境继续恶化的措施.  相似文献   

震源应力场与构造应力场          下载免费PDF全文

魏柏林  藏绍先 《地震工程学报》1983,5(3):48-56

每个地震按照双力偶模型所得到的震源应力场,有的反映构造应力场,有的反映转换应力场。凡是在已存在的活动断裂上由粘滑发震的震源机制解而得出的P、B和T轴与构造应力场的最大、中等、最小的压力主轴是对应的,只是略有偏离。分析了岩块相对滑动产生的转换应力场,证明由转换应力场所产生的脆性剪切破裂而发震的震源机制解得出的P、B、T轴则与构造应力场三个主轴方向可以完全不符。通过对具体震例分析表明,当考虑了转换应力场之后可对几个地震区的应力场得到统一的解释。因此,在一个地区根据震源机制解来恢复构造应力场时必须先判明:是构造应力的直接作用下的粘滑或剪切破裂,还是转换应力场所形成的、共轭剪切破裂,前者可直接恢复构造应力场,后者则应经过转换寸能恢复构造应力场。  相似文献