Energy Fluxes of an Open Water Area in a mid-Latitude Prairie Wetland     

G. G. Burba  S. B. Verma  J. Kim 《Boundary-Layer Meteorology》1999,91(3):495-504

Concurrent measurements of the surface energy balance components (net radiation, heat storage, and sensible and latent heat fluxes) were made in three communities (open water, Phragmites australis, Scirpus acutus) in a wetland in north-central Nebraska, U.S.A., during May-October, 1994. The Bowen ratio – energy balance method was used to calculate latent and sensible heat fluxes. This paper presents results from the open water area. The heat stored in water (G) was found to play a major role in the energy exchange over the water surface. During daytime, G consumed 45–60% of R _n , the net radiation (seasonally averaged daytime G was about 127 W m^–2). At night, G was a significant source of energy (seasonally averaged nighttime G was about -135 Wm^–). The diurnal pattern of latent heat flux ( E) did not follow that of R _n . On some days, E was near zero during midday periods with large R _n . The diurnal variability in E seemed to be significantly affected by temperature inversions formed over the cool water surface. The daily evaporation rate (E) ranged from 2 to 8 mm during the measurement period, and was generally between 70 and 135% of the equilibrium rate.  相似文献   

近实时中高空间分辨率森林火灾监测系统展望     

孙福洋  李晓松  李增元  覃先林 《遥感学报》2020,24(5):543-549

森林火灾是最为常见的灾害之一,严重危及人类生命安全。及时准确监测森林火灾的发生及火场状况,对应对火灾及减少损失至关重要。当前,森林火灾卫星遥感监测主要以低空间分辨率的卫星遥感为主,空间分辨率过低导致无法探测规模较小火灾及掌握详细火场态势。针对这一问题,结合近些年中高空间分辨率卫星观测、共享及处理能力的发展,本文从森林火灾卫星遥感监测的基本原理、当前可用中高空间分辨率卫星数据及其特点、中高分辨率森林着火区监测算法,以及数据共享与云端存储与计算等4个技术环节,对森林火灾中高分辨率卫星遥感监测当前研究现状与存在问题进行了总结,阐述了近实时中高空间分辨率森林火灾监测系统的可行性。近实时中高空间分辨率森林火灾监测系统可对已有低空间分辨率森林火灾监测体系形成重要补充,依托其空间分辨率的优势有助于及早、准确发现小规模火情,进而为森林火灾的防治与管理提供更好支撑。  相似文献   

新疆呼图壁地下储气库断层气体地球化学特征研究     

蒋雨函  高小其  张磊  许秋龙  汪成国  陈其峰  范雪芳 《中国地震》2021,37(4):749-766

Rn、CO₂、Hg、H₂等断层气体被广泛应用于断层活动性以及断层结构特征的研究。当前，研究介质中压力变化与断层气间的关系是断层气映震研究的主要技术方法之一。新疆呼图壁地下储气库自建成以来，每年以周期性循环“注入/采出”模式运行，该运行模式带来的储气库气压变化会影响周围地区的地震活动。同时，这一定期加压存储与减压释放气体的过程为研究应力变化引起的断层气变化提供了天然的实验场。通过对呼图壁储气库开展断层气定期流动测量以及定点连续观测，获取反复加载、卸载气体过程中储气库及周边区域断层气体Rn、CO₂、Hg、H₂浓度的变化特征，在储气库区域内观测到明显的Hg、H₂浓度高值现象，其最大值分别为190ng/m³和725.40ppm，且其空间分布特征表现为在储气库加压存储过程中，储气库区域内注采井附近的气体浓度高于储气库区域外；此外，长期连续观测结果表明，断层气H₂与储气库的压力变化存在一定的关系，H₂对储气库内压力变化的响应更为灵敏。对呼图壁储气库应力变化引起的断层气变化特征进行分析，可以认识不同应力状态下断层气变化特征，为地震台站勘选与建设、震情跟踪以及异常落实等提供地球化学科技支撑。  相似文献   

大型地下停车库结构防漏施工技术     

计国 《上海国土资源》2002,(3):25-26

锦乡天第地下停车库是一个高等级的大型车库,位于高水位软土地基中,施工时处于高温季节,由于采取了有效的技术和措施,未产生任何裂缝和渗漏现象。  相似文献   

地下水库调蓄能力分析   总被引：20，自引：4，他引：20  

戴长雷  迟宝明 《水文地质工程地质》2003,30(2):37-40

在解析地下水库功能特征的基础上,结合实例给出一种地下水库调蓄能力分析的思路,并对各分析要素进行定性描述和定量刻画。地下水库调蓄能力分析可以从调蓄目标、调蓄方案、蓄水能力和调水能力四个方面着手,其中,调蓄目标和调蓄方案对调蓄能力的构建及人工干预的方式、程度有直接的约束和规范;蓄水能力和调水能力则从蓄、导、出、纳等角度全方位标示一座既成地下水库的调蓄能力。  相似文献   

国家卫星气象中心气象卫星资料存档系统   总被引：5，自引：4，他引：5  

钱建梅  郑旭东 《应用气象学报》2003,14(6):756-762

论述了国家卫星气象中心的气象卫星资料存档系统构成、存储数据的编目组织、应用软件的逻辑关联结构、层次框架结构及组织结构，介绍了应用软件主要功能和流程图，对存档系统建设中的经验进行了总结。  相似文献   

Methane and CO₂ sorption and desorption measurements on dry Argonne premium coals: pure components and mixtures     

Andreas Busch  Yves Gensterblum  Bernhard M. Krooss 《International Journal of Coal Geology》2003,55(2-4):205-224

Sorption and desorption behaviour of methane, carbon dioxide, and mixtures of the two gases has been studied on a set of well-characterised coals from the Argonne Premium Coal Programme. The coal samples cover a maturity range from 0.25% to 1.68% vitrinite reflectance. The maceral compositions were dominated by vitrinite (85% to 91%). Inertinite contents ranged from 8% to 11% and liptinite contents around 1% with one exception (Illinois coal, 5%). All sorption experiments were performed on powdered (−100 mesh), dry coal samples.Single component sorption/desorption measurements were carried out at 22 °C up to final pressures around 51 bar (5.1 MPa) for CO₂ (subcritical state) and 110 bar (11 MPa) for methane.The ratios of the final sorption capacities for pure CO₂ and methane (in molar units) on the five coal samples vary between 1.15 and 3.16. The lowest ratio (1.15) was found for the North Dakota Beulah-Zap lignite (VR_r=0.25%) and the highest ratios (2.7 and 3.16) were encountered for the low-rank coals (VR_r 0.32% and 0.48%) while the ratio decreases to 1.6–1.7 for the highest rank coals in this series.Desorption isotherms for CH₄ and CO₂ were measured immediately after the corresponding sorption isotherms. They generally lie above the sorption isotherms. The degree of hysteresis, i.e. deviation of sorption and desorption isotherms, varies and shows no dependence on coal rank.Adsorption tests with CH₄/CO₂ mixtures were conducted to study the degree of preferential sorption of these two gases on coals of different rank. These experiments were performed on dry coals at 45 °C and pressures up to 180 bar (18 MPa). For the highest rank samples of this sequence preferential sorption behaviour was “as expected”, i.e. preferential adsorption of CO₂ and preferential desorption of CH₄ were observed. For the low rank samples, however, preferential adsorption of CH₄ was found in the low pressure range and preferential desorption of CO₂ over the entire pressure range.Follow-up tests for single gas CO₂ sorption measurements consistently showed a significant increase in sorption capacity for re-runs on the same sample. This phenomenon could be due to extraction of volatile coal components by CO₂ in the first experiment. Reproducibility tests with methane and CO₂ using fresh sample material in each experiment did not show this effect.  相似文献   

Stream water infiltration, bank storage, and storage zone changes due to stream-stage fluctuations   总被引：3，自引：0，他引：3  

Xi Chen  Xunhong Chen   《Journal of Hydrology》2003,280(1-4):246-264

During a flood period, stream-stage increases induce infiltration of stream water into an aquifer; subsequent declines in stream stage cause a reverse motion of the infiltrated water. This paper presents the results of the water exchange rate between a stream and aquifer, the storage volume of the infiltrated stream water in the surrounding aquifer (bank storage), and the storage zone. The storage zone is the part of aquifer where groundwater is replaced by stream water during the flood. MODFLOW was used to simulate stream–aquifer interactions and to quantify rates of stream infiltration and return flow. MODPATH was used to trace the pathlines of the infiltrated stream water and to determine the size of the storage zone. Simulations were focused on the analyses of the effects of the stream-stage fluctuation, aquifer properties, the hydraulic conductivity of streambed sediments, regional hydraulic gradients, and recharge and evapotranspiration (ET) rates on stream–aquifer interactions. Generally, for a given stream–aquifer system, larger flow rates result from larger stream-stage fluctuations; larger storage volumes and storage zones are produced by larger and longer-lasting fluctuations. For a given stream-stage hydrograph, a lower-permeable streambed, an aquitard, or an anisotropic aquifer of low vertical hydraulic conductivity can significantly reduce the rate of infiltration and limit the size of the storage zone. The bank storage solely caused by the stage fluctuation differs slightly between gaining and losing streams. Short-term rainfall recharge and ET loss in the shallow groundwater slightly influence on the flow rate, but their effects on bank storage in a larger area for a longer period can be considerable.  相似文献   

利用实验资料检验扁椭球形雨滴和冰粒后向散射DDA算法   总被引：1，自引：2，他引：1  

许小永  王振会  王庆安  巢增明 《高原气象》2002,21(1):31-36

简要介绍了DDA法理论，并根据后向散射截面测量实验所选用的扁椭球形粒子，运用DDA法计算了它们在微波段，电磁波垂直于粒子旋转轴入射情况下的后向散射截面。经过对比，DDA法计算结果与实验测量资料一致性较好。同时评价了DDA算法计算的特点，分析了扁椭球雨滴和冰粒的后向散射特性并描述了实验测量技术。  相似文献   

论三峡库区地质灾害防治工程综合效益   总被引：1，自引：0，他引：1  

任幼蓉 《地质灾害与环境保护》2002,13(2):70-74

从防治地质灾害的角度，探讨防治工程如何结合三峡库区经济、社会、人口、资源、环境全面协调发展，力求近期与远期的目标利益为最佳兼顾，从单纯的地质灾害工程防治综合向解决社会经济和环境保护问题转变，坚持防治效益与生态效益、经济效益和社会效益并重，将治理保护与开发利用相结合，力求获得库区整体的最大综合实效。  相似文献