我国大气透明度系数的时间变化     

方先金  翁笃铭 《地理学报》1988,(1)

作者在文献[1]中探讨了我国大气透明度系数的空间分布及其主要影响因子。本文则探讨大气透明度系数的时间变化,特别是它的长期变化及其成因。结果发现:火山爆发可使大气透明度系数明显减小;由于人类活动影响,冬季大气透明度系数P_2、P_d有明显的减小趋势,P_2、P_d与用煤量等污染指标有很好的负相关。文中还对大气可降水含量的气候学推算方法进行了探讨。本文应用1820—1983年的地球自转变化率资料,分析出地球自转变化存在准44个月、准11年、准24年和准49年的周期。南方涛动指数的变化,大气活动中心位置的移动,赤道东太平洋海温的异常等,都能从地球自转速度变化思期中找到关系。已经发现,在地转长期(准24年和准49年周期)加(减)速时,南方涛动指数减弱(增强),大气活动中心向西北(东南)移动,非洲干旱区降水偏多(偏少);同时发现:在地转短期(准44个月周期)加(减)速时,赤道东太平洋海温降低(升高)。  相似文献   

前兆地电阻率资料处理的剥皮法   总被引：2，自引：1，他引：2       下载免费PDF全文

毛先进  钱家栋 《地震学报》2001,24(6):645-650

在台址下电阻率分层均匀的前提下，针对我国绝大多数前兆地电台单极距观测的事实与现状，提出一种试图从这种观测所获得的视电阻率时间序列中识别电阻率表层变化和深部变化的等效模型方法．分析表明，在保持布极方式和观测结果不变的前提下，任意多层的地电结构都可以视为一个二层地电结构——等效模型．本文中，等效模型上层的地电参数（电阻率和厚度）与实际模型第一层相同，下层的地电参数（电阻率）则根据等效要求，由实际模型第二层及其以下各层的地电参数经计算得到，因此，等效模型的下层包含了实际模型第二层及其以下各层的综合影响．初步研究表明，这种方法是可行的．   相似文献   

Spectral and anisotropic corrections for GMS satellite data     

Fang Xianjin 《大气科学进展》1992,9(3):287-298

Using the radiative transfer simulation, the sampling study about the spectral and anisotropic corrections for GMS satellite data is carried out. The conversion factor and the anisotropic reflectance factor in inversion process of broadband radiation fluxes have been obtained for various underlying surface scenes in clear sky and for the case of overcast sky. The results demonstrate that the consideration of spectral and anisotropic corrections is essential for the earth radiation budget research using satellite data. The mean conversion factors for GMS are between 2.54 and 5.30. The values of the conversion factor are different for various observation angles, especially in cases of ocean, vegeta-tion cover and wet soil surface. The error of retrieving broadband radiance without considering the difference of ob-servation geometry is about 5.5%-15% for ocean, 4.5%-10% for various land surfaces. The calculated anisotropic factors for ocean and cloud scenes are in good agreement with those estimated from Nimbus-7. For Land, desert and snow scenes, the calculated values in backward scattering direction are smaller than the measured.  相似文献   

Spatial variation in annual actual evapotranspiration of terrestrial ecosystems in China: Results from eddy covariance measurements     

Han Zheng  Guirui Yu  Qiufeng Wang  Xianjin Zhu  Honglin He  Yanfen Wang  Junhui Zhang  Yingnian Li  Liang Zhao  Fenghua Zhao  Peili Shi  Huimin Wang  Junhua Yan  Yiping Zhang 《地理学报(英文版)》2016,26(10):1391-1411

Understanding the spatial variation in annual actual evapotranspiration (AET) and its influencing factors is crucial for a better understanding of hydrological processes and water resources management. By synthesizing ecosystem-level observations of eddy-covariance flux sites in China (a total of 61 sites), we constructed the most complete AET dataset in China up to now. Based on this dataset, we quantified the statistic characteristics of AET and water budgets (defined as the ratio of AET to annual mean precipitation (MAP), AET/MAP) of terrestrial ecosystems in China. Results showed that AET differed significantly among both different vegetation types and climate types in China, with overall mean AET of 534.7±232.8 mm yr^-1. AET/MAP also differed significantly among different climate types, but there were no distinct differences in AET/MAP values across vegetation types, with mean AET/MAP of 0.82±0.28 for non-irrigated ecosystems. We further investigated how the main climatic factors and vegetation attributes control the spatial variation in AET. Our findings revealed that the spatial variation of AET in China was closely correlated with the geographical patterns of climate and vegetation, in which the effects of total annual net radiation (R _n), MAP and mean annual air temperature (MAT) were dominant. Thus, we proposed an empirical equation to describe the spatial patterns of AET in China, which could explain about 84% of the spatial variation in AET of terrestrial ecosystems in China. Based on the constructed dataset, we also evaluated the uncertainties of five published global evapotranspiration products in simulating site-specific AET in China. Results showed that large biases in site-specific AET values existed for all five global evapotranspiration products, which indicated that it is necessary to involve more observation data of China in their parameterization or validation, while our AET dataset would provide a data source for it.  相似文献   

Carbon Emission of Regional Land Use and Its Decomposition Analysis: Case Study of Nanjing City,China   总被引：1，自引：0，他引：1  

ZHAO Rongqin  HUANG Xianjin  LIU Ying  ZHONG Taiyang  DING Minglei  CHUAI Xiaowei 《中国地理科学(英文版)》2015,(2):198-212

Through the matching relationship between land use types and carbon emission items, this paper estimated carbon emissions of different land use types in Nanjing City, China and analyzed the influencing factors of carbon emissions by Logarithmic Mean Divisia Index(LMDI) model. The main conclusions are as follows: 1) Total anthropogenic carbon emission of Nanjing increased from 1.22928 x 107 t in 2000 to 3.06939 x 107 t in 2009, in which the carbon emission of Inhabitation, mining & manufacturing land accounted for 93% of the total. 2) The average land use carbon emission intensity of Nanjing in 2009 was 46.63 t/ha, in which carbon emission intensity of Inhabitation, mining & manufacturing land was the highest(200.52 t/ha), which was much higher than that of other land use types. 3) The average carbon source intensity in Nanjing was 16 times of the average carbon sink intensity(2.83 t/ha) in 2009, indicating that Nanjing was confronted with serious carbon deficit and huge carbon cycle pressure. 4) Land use area per unit GDP was an inhibitory factor for the increase of carbon emissions, while the other factors were all contributing factors. 5) Carbon emission effect evaluation should be introduced into land use activities to formulate low-carbon land use strategies in regional development.  相似文献   

Temporospatial changes of carbon footprint based on energy consumption in China     

CHUAI Xiaowei  LAI Li  HUANG Xianjin  ZHAO Rongqin  WANG Wanjing  CHEN Zhigang 《地理学报》2012,22(1):110-124

Study on regional carbon emission is one of the hot topics under the background of global climate change and low-carbon economic development, and also help to establish different low-carbon strategies for different regions. On the basis of energy consumption and land use data of different regions in China from 1999 to 2008, this paper established carbon emission and carbon footprint models based on total energy consumption, and calculated the amount of carbon emissions and carbon footprint in different regions of China from 1999 to 2008. The author also analyzed carbon emission density and per unit area carbon footprint for each region. Finally, advices for decreasing carbon footprint were put forward. The main conclusions are as follows: (1) Carbon emissions from total energy consumption increased 129% from 1999 to 2008 in China, but its spatial distribution pattern among different regions just slightly changed, the sorting of carbon emission amount was: Eastern China > Northern China > Central and Southern China > Southwest China > Northwest China. (2) The sorting of carbon emission density was: Eastern China > Northeast China > Central and Southern China > Northern China > Southwest China > Northwest China from 1999 to 2003, but from 2004 Central and Southern China began to have higher carbon emission density than Northeast China, the order of other regions did not change. (3) Carbon footprint increased significantly since the rapid increasing of carbon emissions and less increasing area of productive land in different regions of China from 1999 to 2008. Northern China had the largest carbon footprint, and Northwest China, Eastern China, Northern China, Central and Southern China followed in turn, while Southwest China presented the lowest area of carbon footprint and the highest percentage of carbon absorption. (4) Mainly influenced by regional land area, Northern China presented the highest per unit area carbon footprint and followed by Eastern China, and Northeast China; Central and Southern China, and Northwest China had a similar medium per unit area carbon footprint; Southwest China always had the lowest per unit area carbon footprint. (5) China faced great ecological pressure brought by carbon emission. Some measures should be taken both from reducing carbon emission and increasing carbon absorption.  相似文献   

非开挖穿河管道工程对堤基渗流稳定的影响评价     

周贤金  邓正东 《岩土工程技术》2010,24(4):171-175

非开挖穿河管道工程在河流与堤基下的地层中形成一条隐蔽、弯曲的扰动带,为了评价该扰动带诱发渗透破坏的可能性,结合工程实例建立了相应的地下水流数值模拟模型。利用该模型,在极端不利的水文、气象条件下,计算地下水流场中最大水力坡度;依据临界水力梯度法,定量评价工程诱发渗透破坏的可能性。实例研究表明,最大水力坡度值随河水位上升而逐渐增大,但增速逐渐变缓;河道底部厚度不大但渗透系数很小的淤泥层,对最大水力坡度值的影响十分明显。  相似文献   

模糊聚类分析在有机质演化阶段划分上的应用     

师先进 《上海国土资源》1993,(3):16-21

本文概述了模糊聚类分析的方法,并使用此法对有机质演化阶段的划分进行了初探,这个方法有利于油田的勘探和开采。  相似文献   

水平电偶极子在三层媒质中激发的电磁场特征的数值研究     

毛燕  毛先进  陈顺云  王彬  周光全 《地震研究》2003,26(4):343-349

将空气及地面以下两层视为三层有耗散的线性媒质，求出第三层中的水平偶极子激发的电磁场在地表处的积分形式解，进行数值计算，分析其频谱特征。结果表明电磁辐射异常的优势频率为0～2Hz，与实际观测资料相吻合，在超低频或甚低频，有比较明显的电磁场异常。并讨论其对地震电磁辐射监测的指导意义。  相似文献   

国外地理学对公共卫生问题的研究与启示   总被引：1，自引：0，他引：1  

徐云帆  黄贤金 《地理研究》2021,40(9):2638-2656

在工业化、城镇化、信息化持续发展,全球变化和全球事件轮番冲击的背景下,公共卫生研究不断深化,已发展为全球性的跨学科议程及研究热点。回顾相关文献发现,国内外地理学对公共卫生问题的研究在数量上均经历了缓慢上升、加速上升和当前的快速上升阶段,但切入角度和关注议题存在差异。本文通过梳理国外地理学对公共卫生问题的研究,对这一领域概念、理论、方法的发展及热点进行归纳总结和综合评述,探讨健康老龄化、健康不平等、融合健康考量的城市规划等议题下现有研究的主要争议、前景及其对国内研究的启示,尤其指出气候变化和传染病大流行等外部压力下暴露出的地理学研究契机,以期拓展视野、聚焦问题,为国内地理学者参与公共卫生研究提供参考。  相似文献