期刊文献+
共找到54篇文章
< 1 2 3 >
每页显示 20 50 100
Parameterization, sensitivity, and uncertainty of 1-D thermodynamic thin-ice thickness retrieval
1
作者 Tianyu Zhang Mohammed Shokr +5 位作者 Zhida Zhang Fengming Hui Xiao Cheng Zhilun Zhang Jiechen Zhao Chunlei Mi 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2024年第7期93-111,共19页
Retrieval of Thin-Ice Thickness(TIT)using thermodynamic modeling is sensitive to the parameterization of the independent variables(coded in the model)and the uncertainty of the measured input variables.This article ex... Retrieval of Thin-Ice Thickness(TIT)using thermodynamic modeling is sensitive to the parameterization of the independent variables(coded in the model)and the uncertainty of the measured input variables.This article examines the deviation of the classical model’s TIT output when using different parameterization schemes and the sensitivity of the output to the ice thickness.Moreover,it estimates the uncertainty of the output in response to the uncertainties of the input variables.The parameterized independent variables include atmospheric longwave emissivity,air density,specific heat of air,latent heat of ice,conductivity of ice,snow depth,and snow conductivity.Measured input parameters include air temperature,ice surface temperature,and wind speed.Among the independent variables,the results show that the highest deviation is caused by adjusting the parameterization of snow conductivity and depth,followed ice conductivity.The sensitivity of the output TIT to ice thickness is highest when using parameterization of ice conductivity,atmospheric emissivity,and snow conductivity and depth.The retrieved TIT obtained using each parameterization scheme is validated using in situ measurements and satellite-retrieved data.From in situ measurements,the uncertainties of the measured air temperature and surface temperature are found to be high.The resulting uncertainties of TIT are evaluated using perturbations of the input data selected based on the probability distribution of the measurement error.The results show that the overall uncertainty of TIT to air temperature,surface temperature,and wind speed uncertainty is around 0.09 m,0.049 m,and−0.005 m,respectively. 展开更多
关键词 Arctic sea ice 1-D thermodynamic ice model thin-ice thickness sea ice parameterization
下载PDF
Levels, distributions, and source identification of organochlorine pesticides in the topsoils in Northeastern China 被引量:15
2
作者 WANG Xu REN Nanqi +2 位作者 QI Hong MA Wanli LI Yifan 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2009年第10期1386-1392,共7页
Seventeen topsoil samples (9 urban, 4 suburban, 3 rural and 1 background) were collected in/around Harbin, a typical city in northeast of China, to measure concentration levels of organocholrine pesticides (OCPs) ... Seventeen topsoil samples (9 urban, 4 suburban, 3 rural and 1 background) were collected in/around Harbin, a typical city in northeast of China, to measure concentration levels of organocholrine pesticides (OCPs) in topsoil of Northeastern China in 2006. Hexachlorohexanes (HCH), dichlorodiphenyltrichloroethane (DDT), and hexachlorobenzene (HCB) were detected in soil samples with mean concentrations (in pg/g dry weight (dw)) of 7120, 5425, and 1039, respectively. The mean concentrations for other OCPs were very low, 4.8 pg/g dw for chlordane and 3.3 pg/g dw for endosulfan. Source identification analysis reveals that all OCPs found in soil samples were due to historical use of these chemicals or from other source regions through long- and short-range atmospheric transport. DDT was mainly used in the rural sites, whereas the sources of HCB, chlordane and endosulfan were mainly in the urban area. HCH was found almost equally in both urban and rural area. Soil concentrations of all detected OCPs, except HCHs, in and around Harbin were much lower than those in the southeast of China, which is expected since the use of these OCPs in the former was much lower than that in the latter, however higher HCH concentrations in and around Harbin than those found in most places of the Southeast China is not expected. It is suggested that high HCH concentration in soil of Northeast China was most likely due to long-range atmospheric transport (LRAT) from Southeast China and the cold condensation process. 展开更多
关键词 organocholrine pesticides (OCPs) soil RESIDUE
下载PDF
Temporal Variability in Fine Carbonaceous Aerosol over Two Years in Two Megacities:Beijing and Toronto 被引量:3
3
作者 杨复沫 Jeffrey BROOK +2 位作者 贺克斌 段凤魁 马永亮 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第3期705-714,共10页
Time-series of weekly total carbon (TC) concentrations of fine aerosol particles (PM2.5) in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August... Time-series of weekly total carbon (TC) concentrations of fine aerosol particles (PM2.5) in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August 2001 through July 2003. In addition to this comparison, differences in the factors contributing to the observed concentrations and their temporal variations are discussed. Based upon past knowledge about the two megacities with highly contrasting air pollutant levels, it is not surprising that the average TC concentration in Belling (31.5 μg C m^-3) was greater than that in Toronto by a factor of 8.3. Despite their large concentration differences, in both cities TC comprised a similarly large component of PM2.5. TC concentrations exhibited very different seasonal patterns between the two cities. In Beijing, TC experienced higher levels and greater weekly fluctuations in winter whereas in Toronto this behavior was seen in summer. As a result, the greatest gap in TC concentrations between Beijing and Toronto (by a factor of 12.7) occurred in winter, while the smallest gap (a factor of 4.6) was in summer. In Beijing, seasonal variations in the emissions probably played a greater role than meteorology in influencing the TC seasonality, while in Toronto during the warm months more than 80% of the hourly winds were recorded from the south, along with many potential anthropogenic sources for the days with high TC concentrations. This comparison of the differences provides insight into the major factors affecting carbonaceous aerosol in each city. 展开更多
关键词 total carbon PM2.5 temporal variation carbonaceous aerosol BEIJING TORONTO
下载PDF
Trends in sunshine duration and atmospheric visibility in the Yunnan-Guizhou Plateau,1961-2005 被引量:4
4
作者 XiaoBo Zheng TianLiang Zhao +2 位作者 YuXiang Luo ChangChun Duan Juan Chen 《Research in Cold and Arid Regions》 2011年第2期179-184,共6页
Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over... Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between -12.2 and -173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols (including air pollutants) resulting from increased energy consumption over the YGP could be a major Factor influencing the reductions of sunshine duration and atmospheric visibility. 展开更多
关键词 Yunnan-Guizhou Plateau climatic change sunshine duration VISIBILITY cloudy cover
下载PDF
Morphology, crystal structure and hydration of calcined and modified anhydrite 被引量:1
5
作者 Xiao-qing Niu Ji-chun Chen 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第10期1028-1032,共5页
The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100℃ causes anhydrite to disintegra... The effects of calcination and modification on the morphology (shapes and textures) and crystal structure of anhydrite powders were studied. The results show that, calcination at 100℃ causes anhydrite to disintegrate into smaller crystals, accompanied by a slight in- crease in d-spacing. Without calcination and modification, the solidification time and curing time of anhydrite are 15 and 77 h, respectively. After the treatment, however, the solidification time and curing time are shortened significantly to 9.5 and 14 rain, respectively. The com- pressive and flexural strengths of hydration products made from the treated anhydrite reach 10.2 and 2.0 MPa, respectively. The much shorter solidification and curing time make it possible to use anhydrite as a building and construction material. 展开更多
关键词 ANHYDRITE MORPHOLOGY crystal structure curing HYDRATION CALCINATION modification
下载PDF
How can the forest sector mitigate climate change in a changing climate? Case studies of boreal and northern temperate forests in eastern Canada 被引量:1
6
作者 Lucas Moreau Evelyne Thiffault +2 位作者 Dominic Cyr Yan Boulanger Robert Beauregard 《Forest Ecosystems》 SCIE CSCD 2022年第2期267-287,共21页
Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and... Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and compare the cumulative effects on carbon dynamics of forest management and climate change on boreal and northern temperate forest sector in eastern Canada for the 2020–2100 period.Methods:We used the spatially explicit forest landscape model LANDIS-II and its extension Forest Carbon Suc-cession,in conjunction with the Carbon Budget Model for Harvested Wood Products framework.We simulated the dynamics of forest composition and carbon flows from forest ecosystems to wood products and their substitution effect on markets under increasing climate forcing,according to a tonne-year approach.Simulations were con-ducted for a series of forest management scenarios based on realistic practices principally by clearcut in the boreal territory and continuous-cover forestry in the northern temperate one.These scenarios included:i)a business-as-usual scenario(BaU),representing the current management strategy,ii)increased harvesting by 6.3%to 13.9%,iii)increased conservation(i.e.reduced harvesting by 11.1%to 49.8%),iiii)and a scenario representing the natural evolution of the forest landscape(i.e.without any management activity).Results:Our study revealed that increasing harvesting levels had contrasting effects on the mitigation potential in northern temperate(enhance net sequestration)and boreal forest sector(enhance net emissions)in comparison to the BaU from 2040 onwards,regardless of the future climate.Carbon storage in wood products and the substi-tution effect were not sufficient to offset carbon emissions from ecosystems.Moreover,climate change had a strong impact on the capacity of both landscapes to act as carbon sinks.Northern temperate landscapes became a net source of carbon over time due to their greater vulnerability to climate change than boreal landscapes.Conclusions:Our study highlights the need to consider the initial landscape characteristics in simulations to maximize the mitigation potential of alternative forest management strategies.The optimal management solution can be very different according to the characteristics of forest ecosystems.This opens the possibility of optimizing management for specific forest stands,with the objective of maximizing the mitigation potential of a given landscape. 展开更多
关键词 Climate change Carbon Forest sector Forest management Boreal landscapes Northern temperate landscape Mitigation potential
下载PDF
Possible Impacts of Climate Change on Daily Streamflow and Extremes at Local Scale in Ontario, Canada. Part II: Future Projection 被引量:2
7
作者 Chad Shouquan Cheng Qian Li +1 位作者 Guilong Li Heather Auld 《Atmospheric and Climate Sciences》 2012年第4期427-440,共14页
The paper forms the second part of an introduction to possible impacts of climate change on daily streamflow and extremes in the Province of Ontario, Canada. Daily streamflow simulation models developed in the compani... The paper forms the second part of an introduction to possible impacts of climate change on daily streamflow and extremes in the Province of Ontario, Canada. Daily streamflow simulation models developed in the companion paper (Part I) were used to project changes in frequency of future daily streamflow events. To achieve this goal, future climate information (including rainfall) at a local scale is needed. A regression-based downscaling method was employed to downscale eight global climate model (GCM) simulations (scenarios A2 and B1) to selected weather stations for various meteorological variables (except rainfall). Future daily rainfall quantities were projected using daily rainfall simulation models with downscaled future climate information. Following these projections, future daily streamflow volumes can be projected by applying daily streamflow simulation models. The frequency of future daily high-streamflow events in the warm season (May–November) was projected to increase by about 45%-55% late this century from the current condition, on average of eight-GCM A2 projections and four selected river basins. The corresponding increases for future daily low-streamflow events and future daily mean streamflow volume could be about 25%-90% and 10%-20%, respectively. In addition, the return values of annual one-day maximum streamflow volume for various return periods were projected to increase by 20%-40%, 20%-50%, and 30%-80%, respectively for the periods 2001-50, 2026-75, and 2051-2100. Inter-GCM and interscenario uncertainties of future streamflow projections were quantitatively assessed. On average, the projected percentage increases in frequency of future daily high-streamflow events are about 1.4-2.2 times greater than inter-GCM and interscenario uncertainties. 展开更多
关键词 Rainfall-Related Streamflow FUTURE PROJECTION DOWNSCALING Statistic Methods ONTARIO CANADA
下载PDF
Possible Impacts of Climate Change on Daily Streamflow and Extremes at Local Scale in Ontario, Canada. Part I: Historical Simulation 被引量:2
8
作者 Chad Shouquan Cheng Qian Li +1 位作者 Guilong Li Heather Auld 《Atmospheric and Climate Sciences》 2012年第4期416-426,共11页
The paper forms the first part of an introduction to possible impacts of climate change on daily streamflow and extremes in the Province of Ontario, Canada. In this study, both conceptual and statistical streamflow si... The paper forms the first part of an introduction to possible impacts of climate change on daily streamflow and extremes in the Province of Ontario, Canada. In this study, both conceptual and statistical streamflow simulation modeling theories were collectively applied to simulate daily streamflow volumes. Based on conceptual rainfall-runoff modeling principle, the predictors were selected to take into account several physical factors that affect streamflow, such as (1) current and previous quantities of rainfall over the watershed, (2) an index of pre-storm moisture conditions, (3) an index of pre-storm evapotranspiration capacities, and (4) a seasonal factor representing seasonal variation of streamflow volume. These rainfall-runoff conceptual factors were applied to an autocorrelation correction regression procedure to develop a daily streamflow simulation model for each of the four selected river basins. The streamflow simulation models were validated using a leave-one-year-out cross-validation scheme. The simulation models identified that the explanatory predictors are consistent with the physical processes typically associated with high-streamflow events. Daily streamflow simulation models show that there are significant correlations between daily streamflow observations and model validations, with model R2s of 0.68-0.71, 0.61-0.62, 0.71-0.74, and 0.95 for Grand, Humber, Upper Thames, and Rideau River Basins, respectively. The major reason for the model performance varying across the basins might be that rainfall-runoff response time and physical characteristics differ significantly among the selected river basins. The results suggest that streamflow simulation models can be used to assess possible impacts of climate change on daily streamflow and extremes at a local scale, which is major objective of a companion paper (Part II). 展开更多
关键词 Rainfall-Related Streamflow Simualtion Statistic Methods ONTARIO CANADA
下载PDF
Women's repression, rebellion and quest for the "true self": Theyellow wallpaper as the epitome of the female Gothic novel
9
作者 YIN Cai-qiao 《Sino-US English Teaching》 2008年第11期49-53,64,共6页
As a genre that expressed women's dark protests, fantasies and the fear, female Gothic was not theorized until the late 1960s, and before its theorization, this convention was adopted by many women writers in their w... As a genre that expressed women's dark protests, fantasies and the fear, female Gothic was not theorized until the late 1960s, and before its theorization, this convention was adopted by many women writers in their works. Charlotte Perkins Gilman's The yellow wallpaper is one of the many examples. As the epitome of female gothic, The yellow wallpaper utilized the female gothic conventions--the grotesque symbol of yellow wallpaper, the hysteric narrative format and the archetype image of madwoman, to express women's status of her time--their repression, rebellion and quest for the "true self". 展开更多
关键词 female Gothic REPRESSION REBELLION quest for "true self"
下载PDF
The Relationship between Interchangeability Standards and Precision Design in Teaching a Course on Interchangeability and Measurement Techniques
10
作者 Ren Xiu 《China Standardization》 2007年第4期19-24,共6页
This article discusses some views on the relationship between carrying out and applying standards and precision design and the teaching of a course on interchangeability and measurement techniques. It points out that ... This article discusses some views on the relationship between carrying out and applying standards and precision design and the teaching of a course on interchangeability and measurement techniques. It points out that while emphasizing precision design, we should not underrate the significance of interchangeability and standardization. Although there are presently many teaching models available for such courses, each course should be designed separately to preserve its systematic character and integrality. As well, the development of students' abilities in precision design and the application of standards should be strengthened in experimental lessons within each course. 展开更多
关键词 INTERCHANGEABILITY STANDARDIZATION precision design teaching mode
下载PDF
Tracking PCB Contamination in Ontario Great Lakes Tributaries: Development of Methodologies and Lessons Learned for Watershed Based Investigations
11
作者 Nadine Benoit Alice Dove +1 位作者 Debbie Burniston Duncan Boyd 《Journal of Environmental Protection》 2016年第3期390-409,共20页
Project Trackdown is an investigative environmental program aimed at tracking sources of polychlorinated biphenyl (PCB) contamination in Great Lakes tributaries. The program uses a multimedia weight of evidence approa... Project Trackdown is an investigative environmental program aimed at tracking sources of polychlorinated biphenyl (PCB) contamination in Great Lakes tributaries. The program uses a multimedia weight of evidence approach for identifying sources of PCBs to the environment. PCB concentrations in environmental media (sediment, water, suspended sediment and soil), passive samplers and/or exposed biota (mussels, young-of-the-year fish and benthic invertebrates) are used in combination to evaluate bioavailability and identify local anomalies within a tributary. These lines of evidence can be assessed with simple chemometric techniques and fingerprinting of PCB congener profiles, and, combined with anecdotal information such as land use history and tributary alterations, may be used to identify ongoing and locally controllable sources of PCBs to the Great Lakes. The program was successful at developing environmental triggers to differentiate potential source areas from background PCB conditions in urban areas, allowing efforts to focus on identifying active ongoing sources of PCB contamination. Project Trackdown has been carried out in three tributaries to Lake Ontario (Cataraqui River, Etobicoke Creek and Twelve Mile Creek) and two tributaries that flow into the Detroit River (Turkey Creek and Little River). Local ongoing PCB sources have been identified in four projects, leading to abatement or remediation measures. As a collaborative initiative between the Ontario Ministry of the Environment and Environment Canada, Project Trackdown has successfully identified several PCB sources leading to substantial cleanup efforts aimed ultimately at reducing PCB contamination to the Great Lakes. 展开更多
关键词 Source Tracking PCBS Great Lakes Tributaries
下载PDF
Modeling West Nile Virus transmission in birds and humans:Advantages of using a cellular automata approach
12
作者 Baki Cissé David R.Lapen +2 位作者 K.Chalvet-Monfray Nicholas H.Ogden Antoinette Ludwig 《Infectious Disease Modelling》 CSCD 2024年第1期278-297,共20页
In Canada,the periodic circulation of West Nile Virus(WNV)is difficult to predict and,beyond climatic factors,appears to be related to the migratory movements of infected birds from the southern United States.This hyp... In Canada,the periodic circulation of West Nile Virus(WNV)is difficult to predict and,beyond climatic factors,appears to be related to the migratory movements of infected birds from the southern United States.This hypothesis has not yet been explored in a spatially distributed model.The main objective of this work was to develop a spatially explicit dynamic model for the transmission of WNV in Canada,that allows us to explore non-climate related hypotheses associated with WNV transmission.A Cellular Automata(CA)approach for multiple hosts(birds and humans)is used for a test region in eastern Ontario,Canada.The tool is designed to explore the role of host and vector spatial heterogeneity,host migration,and vector feeding preferences.We developed a spatialized compartmental SEIRDS-SEI model for WNV transmission with a study region divided into 4 rectangular cells.We used 2010–2021 bird data from the eBird project and 2010–2019 mosquito data collected by Ontario Public Health to mimic bird and mosquito seasonal variation.We considered heterogeneous bird densities(high and low suitability areas)and homogeneous mosquito and human densities.In high suitability areas for birds,we identified 5 entry points for WNV-infected birds.We compared our simulations with pools of WNV-infected field collected mosquitoes.Simulations and sensitivity analyses were performed using MATLAB software.The results showed good correspondence between simulated and observed epidemics,supporting the validity of our model assumptions and calibration.Sensitivity analysis showed that a 5%increase or decrease in each parameter of our model except for the biting rate of bird by mosquito(c^(B,M)and mosquito natural mortality rate(d^(M)),had a very limited effect on the total number of cases(newly infected birds and humans),prevalence peak,or date of occurrence.We demonstrate the utility of the CA approach for studying WNV transmission in a heterogeneous landscape with multiple hosts. 展开更多
关键词 Cellular automata Mosquito-borne diseases SEIRDS-SEI modeling West Nile Virus
原文传递
中国气溶胶分布的地理学和气候学特征 被引量:42
13
作者 郑小波 罗宇翔 +2 位作者 赵天良 陈娟 康为民 《地理科学》 CSCD 北大核心 2012年第3期265-272,共8页
中国人口地理分界线——胡焕庸线根据人口、地理,气候和经济等特点把中国(不包括港、澳、台地区)分为东、西两部分。用2000~2010年MODIS大气气溶胶光学厚度(AOD)资料,分析气溶胶分布的地理学和气候学特征后发现,胡焕庸线还可被视为... 中国人口地理分界线——胡焕庸线根据人口、地理,气候和经济等特点把中国(不包括港、澳、台地区)分为东、西两部分。用2000~2010年MODIS大气气溶胶光学厚度(AOD)资料,分析气溶胶分布的地理学和气候学特征后发现,胡焕庸线还可被视为中国气溶胶地理学的分界线,在其两侧气溶胶的性质和浓度都有明显差别。在人口稠密和海拔较低的东部,由人类活动产生的气溶胶为主,年平均AOD约为0.45;在西部,自然过程释放的气溶胶主导的AOD约为0.25。近10 a来东部AOD的年际间变化呈现增加趋势,西部AOD出现微弱减少的趋势。东部人为气溶胶年际间变化受亚洲季风影响。西部自然气溶胶年际间变化主要受沙漠地区沙尘气溶胶排放源的影响,沙尘天气过程主要控制其气溶胶的释放。 展开更多
关键词 大气气溶胶光学厚度 MODIS 胡焕庸线 地理 气候
下载PDF
国产变压器油中多氯联苯及其异构体分布特征 被引量:41
14
作者 降巧龙 周海燕 +2 位作者 徐殿斗 柴之芳 李一凡 《中国环境科学》 EI CAS CSCD 北大核心 2007年第5期608-612,共5页
利用气相色谱质谱联用法(GC-MS)分析我国变压器油样品中84种PCB的异构体并计算其毒性当量值(TEQ).结果表明,国产变压器油所含PCBs主要是以三氯联苯为主,其含量高达63%,其次是四氯和二氯代联苯,分别占24%和9%,其含氯量约为42.9%,与美国产... 利用气相色谱质谱联用法(GC-MS)分析我国变压器油样品中84种PCB的异构体并计算其毒性当量值(TEQ).结果表明,国产变压器油所含PCBs主要是以三氯联苯为主,其含量高达63%,其次是四氯和二氯代联苯,分别占24%和9%,其含氯量约为42.9%,与美国产Aroclor1242(氯含量约为40%~42%)的含氯量极为相似.国产PCBs中,共平面PCBs含量仅占测定总量的1.6%,其中以CB-77的含量最高,对TEQ的贡献最大,占6种PCBs的72%,其次是CB-105和毒性最强的CB-126,分别占15%和8%;国产PCBs的TEQ值仅相当于美国产Aroclor1242的15%. 展开更多
关键词 变压器油 气相色谱质谱(GC-MS) 多氯联苯(PCBs) 毒性当量值(TEQ)
下载PDF
全球沙尘气溶胶源汇分布及其变化特征的模拟分析 被引量:20
15
作者 刘建慧 赵天良 +2 位作者 韩永翔 Gong S L 熊洁 《中国环境科学》 EI CAS CSCD 北大核心 2013年第10期1741-1750,共10页
根据全球沙尘气溶胶气候模式GEM-AQ/EC模拟的1995~2004年的沙尘起沙量和干湿沉降量,分析了沙尘气溶胶源汇的全球时空变化特征.全球沙尘起沙量集中在各个主要沙漠地区,北非对全球沙尘气溶胶贡献最大为66.6%.沙尘气溶胶沉降的高值区分布... 根据全球沙尘气溶胶气候模式GEM-AQ/EC模拟的1995~2004年的沙尘起沙量和干湿沉降量,分析了沙尘气溶胶源汇的全球时空变化特征.全球沙尘起沙量集中在各个主要沙漠地区,北非对全球沙尘气溶胶贡献最大为66.6%.沙尘气溶胶沉降的高值区分布在沙漠源区及其紧临的下风地区.最大净沙尘气溶胶接收主要分布在沙漠周围地区并形成净接收量大于10t/(km2·a)的位于0°N^60°N之间的北非、欧亚大陆、西太平洋、北印度洋、北美和大西洋的带状分布.在北非、阿拉伯半岛、中亚、东亚和澳大利亚5个主要沙漠地区中,起沙量和沉降量都存在明显的季节变化,除中亚其他4个区域干湿沉降量和起沙的季节变化基本一致;东亚地区沙尘气溶胶起沙量和总沉降量的季节变化最为明显,而北非沙漠起沙量和总沉降量的季节变化最小,其他3个区域的季节变化幅度基本相同.中亚起沙峰值和阿拉伯半岛起沙次峰值出现在夏季,其他区域的峰值均出现在春季.10年间全球陆地年平均起沙量为(1500±94)Mt,保持略微上升趋势.以北非沙漠起沙量年际变化率最低(6.3%),而以东亚(28.3%)和澳大利亚(45.0%)起沙量年际变化最为明显;全球陆地的沙尘气溶胶沉降量以约9.9Mt/a的速率递减,全球海洋的沙尘气溶胶沉降递增. 展开更多
关键词 沙尘气溶胶 起沙量 干湿沉降量 模拟分析
下载PDF
中国各省区近10年遥感气溶胶光学厚度和变化 被引量:31
16
作者 郑小波 周成霞 +2 位作者 罗宇翔 陈娟 Tianliang ZHAO 《生态环境学报》 CSCD 北大核心 2011年第4期595-599,共5页
用2000—2009年MODIS大气气溶胶光学厚度(AOD))资料,分析中国29个省(区、市)AOD多年平均值和年际间变化趋势。中国10年平均AOD高值区主要集中在华北、华中、华南和新疆,低值区主要在青藏高原、西北(除新疆外)、东北和西南地区。中国有1... 用2000—2009年MODIS大气气溶胶光学厚度(AOD))资料,分析中国29个省(区、市)AOD多年平均值和年际间变化趋势。中国10年平均AOD高值区主要集中在华北、华中、华南和新疆,低值区主要在青藏高原、西北(除新疆外)、东北和西南地区。中国有13个省(市、区)多年平均AOD超过0.4。最高为0.735(江苏)。只有西藏和黑龙江的AOD小于0.2,其余15个省区市的AOD在0.2至0.3之间。除新疆外,中国的AOD高值区全部集中在工业发达和人口密集的地区。中国年际间AOD的变化为上升趋势。近10 a来AOD增长的倾向率为0.019/10a,即增加了4.3%。其中在2000—2007年间的上升最为明显,在2007年达到近10 a来的最高峰(0.437 6),2008年以后中国的AOD开始出现下降趋势,2009年达到近10 a来最低值(0.372 0)。有17个省区市AOD气候学变化倾向率为正值,变化的范围为0.006~0.099/10a。有12个为负值,变化的范围为-0.037^-0.003/10a。出现AOD增加和减少趋势的区域两极分化,即高排放地区继续增加,低排放地区持续减少。 展开更多
关键词 中国 各省区 MODIS 气溶胶光学厚度(AOD) 变化趋势
下载PDF
1995~2004年东亚沙尘气溶胶的模拟源汇分布及垂直结构 被引量:15
17
作者 熊洁 赵天良 +1 位作者 韩永翔 Gong S L 《中国环境科学》 EI CAS CSCD 北大核心 2013年第6期961-968,共8页
利用全球气溶胶模式GEM-AQ/EC的1995-2004年10年沙尘气溶胶模拟,探讨了东亚地区沙尘气溶胶源汇分布和垂直结构特征.结果表明,东亚大陆沙尘气溶胶源区主要集中在东亚的沙漠地区,有两大沙尘主要源区:覆盖蒙古国南部及中国内蒙中西部的沙... 利用全球气溶胶模式GEM-AQ/EC的1995-2004年10年沙尘气溶胶模拟,探讨了东亚地区沙尘气溶胶源汇分布和垂直结构特征.结果表明,东亚大陆沙尘气溶胶源区主要集中在东亚的沙漠地区,有两大沙尘主要源区:覆盖蒙古国南部及中国内蒙中西部的沙漠地区和南疆的塔克拉玛干沙漠.东亚沙尘排放量春季最大,占全年排放总量的66.81%,四月份达15.29Mt,夏季下降,秋季小幅度回升,冬季最小;东亚沙尘排放量呈现明显的年际变化及增强的趋势.东亚沙尘沉降高值区与源区一致,源区及附近以干沉降为主,远距离传输到中国东北、长江以南及西太平洋包括日本、朝鲜半岛,湿沉降占主导地位;沙尘沉降具有季节变化,其趋势与东亚沙尘排放量的季节变化大致相同,且模拟的10年沉降量呈上升趋势.东亚沙漠地区排放的沙尘主导了东亚沙尘气溶胶的变化,最大的净沙尘汇区集中在紧邻净沙尘源区的黄土高原及华北平原西部.东亚地区春夏秋3个季节均是沙尘的净源区,而冬季强西风急流输入东亚以外的沙尘使东亚整体上为沙尘净接收区.东亚大陆大部分地区,沙尘垂直分布主要集中在对流层低层3km高度以下,在西太平洋地区包括日本、朝鲜半岛沙尘高值中心位于在对流层中层5km高度上下,在沙漠以北地区沙尘垂直廓线的高值出现在对流层中上层6-8km高度. 展开更多
关键词 东亚沙漠 沙尘气溶胶 气溶胶模式 垂直结构
下载PDF
中国825个基准、基本站地面气压系统误差的检验与订正 被引量:7
18
作者 远芳 曹丽娟 +1 位作者 唐国利 Xiaolan L.Wang 《气候变化研究进展》 CSCD 北大核心 2015年第5期331-336,共6页
使用RHtest均一化方法结合元数据信息对中国825个基准、基本站的地面气压月值数据进行均一性检验与订正,结果发现有400个站的气压数据均一,425个站存在系统误差。对于后者,使用静力模式订正可消除255个站的系统误差,另外170个站采用均... 使用RHtest均一化方法结合元数据信息对中国825个基准、基本站的地面气压月值数据进行均一性检验与订正,结果发现有400个站的气压数据均一,425个站存在系统误差。对于后者,使用静力模式订正可消除255个站的系统误差,另外170个站采用均值订正,均值订正的断点共245个。对气候趋势和个例的分析表明,上述方法对气压数据均一化订正效果明显。均一化之后站点气压长期趋势的空间一致性更好,中国东南沿海和西北部的新疆地区气压表现出下降趋势,中部地区主要表现出上升趋势。 展开更多
关键词 均一性 气压 中国825站 RHtest
下载PDF
亚暴等待时间的统计学分析:IMAGE卫星观测
19
作者 王慧 杨冰 +1 位作者 华滢 Liu William 《极地研究》 CAS CSCD 北大核心 2011年第4期259-263,共5页
利用IMAGE卫星FUV极光图像数据,对北半球极光椭圆带2760个亚暴事件进行统计分析,得到亚暴等待时间的统计分布,并利用简单的数学模型对卫星轨道的影响进行了讨论,得到以下结论:(1)亚暴等待时间在2—3 h附近有一个峰值,较低纬度(MLat<6... 利用IMAGE卫星FUV极光图像数据,对北半球极光椭圆带2760个亚暴事件进行统计分析,得到亚暴等待时间的统计分布,并利用简单的数学模型对卫星轨道的影响进行了讨论,得到以下结论:(1)亚暴等待时间在2—3 h附近有一个峰值,较低纬度(MLat<65°)发生的亚暴事件,其等待时间略长于较高纬度(MLat≥65°)发生的亚暴事件;(2)较近磁尾(L<6 RE)发生的亚暴事件,其等待时间分布主要是高斯分布,较远磁尾(L≥6 RE)发生的亚暴事件,其等待时间分布是高斯和泊松分布的叠加,表明较近磁尾发生的亚暴事件比较远磁尾的亚暴事件更具有周期性;(3)卫星轨道的影响主要在10 h以后,对较近磁尾发生的亚暴事件的影响更大,造成8.5 h处伪峰值的出现。 展开更多
关键词 亚暴 等待时间 IMAGE 卫星轨道
下载PDF
中国北方大气中有机卤素污染物的污染水平 被引量:3
20
作者 于丽娜 降巧龙 +4 位作者 张志 徐殿斗 李一凡 柴之芳 高大文 《核化学与放射化学》 EI CAS CSCD 北大核心 2008年第3期146-151,共6页
应用仪器中子活化分析(INAA)及气相色谱质谱联用技术(GC/MS)研究了PUF大气被动采样器采自全国31个点的大气样品中的可萃取有机氯/溴/碘(EOCl/Br/I)和多氯联苯(PCBs)。结果表明,大气中卤素污染物质量浓度最高的点大部分分布在城区,且呈... 应用仪器中子活化分析(INAA)及气相色谱质谱联用技术(GC/MS)研究了PUF大气被动采样器采自全国31个点的大气样品中的可萃取有机氯/溴/碘(EOCl/Br/I)和多氯联苯(PCBs)。结果表明,大气中卤素污染物质量浓度最高的点大部分分布在城区,且呈现沿城市到乡村的下降趋势;在交通枢纽地区大气中EOCl的质量浓度要高于远离交通枢纽的采样点,机动车尾气的排放是大气中有机氯污染物的重要来源之一;工业也是大气中有机氯污染物的主要来源。84种PCBs异构体分析结果表明,大气中PCBs主要以低氯代PCBs为主,Cl2-CB占总PCBs的41%,Cl3-CB含量最高,占总量的43%,其余异构体含量随取代氯原子的增加而下降,这种异构体的分布特征与我国所生产和使用的PCBs"指纹谱"非常相近,且PCBs异构体的分布特征没有地域差异,这表明大气环境中PCBs主要来自工业污染,且城市地区是我国大气中PCBs的主要来源。在所有已测定的样品中已知PCBs的氯在总EOCl中的比例不足1.0%,大气中绝大部分的有机氯为未知化合物。 展开更多
关键词 中子活化分析(NAA) 可萃取有机卤素污染物(EOX) 多氯联苯(PCBs) 大气 被动采样器
下载PDF
上一页 1 2 3 下一页 到第
使用帮助 返回顶部