A simple method using climatic variables to estimate canopy temperature,sensible and latent heat fluxes in a winter wheat field on the North China Plain     

L. Li  Q. Yu  Z. Su  C. van der Tol 《水文研究》2009,23(5):665-674

Estimation of evapotranspiration from a crop field is of great importance for detecting crop water status and proper irrigation scheduling. The Penman–Monteith equation is widely viewed as the best method to estimate evapotranspiration but it requires canopy resistance, which is very difficult to determine in practice. This paper presents a simple method simplified from the Penman–Monteith equation for estimating canopy temperature (T_c). The proposed method is a biophysically‐sound extended version of that proposed by Todorovic. The estimated canopy temperature is used to calculate sensible heat flux, and then latent heat flux is calculated as the residual of the surface energy balance. An eddy covariance (EC) system and an infrared thermometer (IRT) were installed in an irrigated winter wheat field on the North China Plain in 2004 and 2005, to measure T_c, and sensible and latent heat fluxes were used to test the modified Todorovic model (MTD). The results indicate that the original Todorovic model (TD) severely underestimates T_c and sensible heat flux, and hence severely overestimates the latent heat flux. However, the MTD model has good capability for estimating T_c, and gives acceptable results for latent heat flux at both half‐hourly and daily scales. The MTD model results also agreed well with the evapotranspiration calculated from the measured T_c. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Effects of topography on the spatial distribution of evapotranspiration over a complex terrain using two‐source energy balance model with ASTER data     

H. K. Kafle  Y. Yamaguchi 《水文研究》2009,23(16):2295-2306

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梯度扩散理论在能量和物质输送计算中的若干问题     

陈发祖 《地理研究》1990,9(2):76-84

本文用近年来的大量观测结果,揭示了被长期使用的梯度扩散理论的问题和局限性。讨论了它的成立条件:只有当湍流的涡旋尺度远小于梯度变化的空间尺度时,梯度扩散理论才可以正确使用。对于几种典型的近地层条件,计算了它们的湍流的涡旋尺度,从而说明了梯度扩散理论在这些条件下失败的原因。  相似文献   

“一带一路”区域可持续发展生态环境遥感监测   总被引：2，自引：1，他引：1  

柳钦火  吴俊君  李丽  俞乐  李静  辛晓洲  贾立  仲波  牛铮  徐新良  孟庆岩  赵静  张海龙  胡光成  郑超磊 《遥感学报》2018,22(4):686-708

2013年9月和10月,习近平主席在出访中亚和东南亚国家期间,先后提出了共建"丝绸之路经济带"和"21世纪海上丝绸之路"(简称"一带一路")的重大倡议。要全面保护"一带一路"区域生态环境,实现2030年可持续发展目标,是一个具有挑战性的问题。遥感技术对生态环境监测与评价发挥着十分重要的作用。本研究利用多尺度、多源遥感数据,对2015年"一带一路"区域的生态环境状况进行监测和分析,旨在提供可持续发展目标生态环境遥感监测的本底。本文选取了几个重要的生态环境方面开展监测与分析,主要包括宏观生态系统结构和植被状况、太阳能资源分布、水资源平衡、主要生态环境限制因素对经济走廊建设的影响、主要城市生态环境质量等。监测区域覆盖亚洲、非洲、欧洲和大洋洲的陆上区域。研究结果为生态环境评价与保护提供了有效的决策依据,有助于"一带一路"建设积极推进。  相似文献   

Long-term performance evaluation of zero-valent iron amended permeable reactive barriers for groundwater remediation – A mechanistic approach     

《地学前缘(英文版)》2023,14(2):101494

Permeable reactive barriers (PRBs) are used for groundwater remediation at contaminated sites worldwide. This technology has been efficient at appropriate sites for treating organic and inorganic contaminants using zero-valent iron (ZVI) as a reductant and as a reactive material. Continued development of the technology over the years suggests that a robust understanding of PRB performance and the mechanisms involved is still lacking. Conflicting information in the scientific literature downplays the critical role of ZVI corrosion in the remediation of various organic and inorganic pollutants. Additionally, there is a lack of information on how different mechanisms act in tandem to affect ZVI-groundwater systems through time. In this review paper, we describe the underlying mechanisms of PRB performance and remove isolated misconceptions. We discuss the primary mechanisms of ZVI transformation and aging in PRBs and the role of iron corrosion products. We review numerous sites to reinforce our understanding of the interactions between groundwater contaminants and ZVI and the authigenic minerals that form within PRBs. Our findings show that ZVI corrosion products and mineral precipitates play critical roles in the long-term performance of PRBs by influencing the reactivity of ZVI. Pore occlusion by mineral precipitates occurs at the influent side of PRBs and is enhanced by dissolved oxygen and groundwater rich in dissolved solids and high alkalinity, which negatively impacts hydraulic conductivity, allowing contaminants to potentially bypass the treatment zone. Further development of site characterization tools and models is needed to support effective PRB designs for groundwater remediation.  相似文献   

赣西石竹山硅灰石矿床石榴子石特征及其地质意义     

张鹏浩  王先广  丁枫  范宇航  王骏怡  邹婧  孙培均  李文韬 《岩石矿物学杂志》2023,42(4):521-540

江西省石竹山硅灰石矿床位于钦杭成矿带东段的萍乐坳陷带内,是世界资源储量规模最大的硅灰石矿床。为了厘清区内成矿流体性质及进一步找矿潜力,本文根据矿物间的穿插关系和光学特征,将该矿床的石榴子石分为早(GrtⅠ)、晚(GrtⅡ)两个世代,在详细的野外工作基础上,利用电子探针(EMPA)和LA-ICP-MS原位微区分析技术,对石竹山矿床中的石榴子石开展了系统研究。结果表明,石竹山硅灰石矿床石榴子石属于钙铝榴石-钙铁榴石固溶体系列,早期形成的石榴子石(GrtⅠ)Fe含量更高,且震荡环带发育,而晚期形成的石榴子石(GrtⅡ)则发育复杂环带。石榴子石GrtⅠ和GrtⅡ都亏损大离子亲石元素K、Rb、Ba、Sr等,而Nb、Ta、Zr等高场强元素相对含量较高,U含量与∑REE成正比。GrtⅡ的∑REE较低(12.92×10^-6~21.12×10^-6),具有较平坦的稀土元素配分模式,轻微富集轻稀土元素(Ce、Pr、Nd、Sm),微弱负铕异常;GrtⅠ的∑REE相对较高(13.78×10^-6~73.52×10^-6),更富集轻稀土元素(Ce、Pr、Nd、Sm),呈右倾的稀土元素配分模式,负铕异常明显。推测石榴子石GrtⅠ形成于相对开放、水岩比值较高、高氧逸度的酸性体系中,GrtⅡ则形成于相对封闭、水岩比值较低、高氧逸度的中酸性体系中。此外,将石榴子石的端员组分和微量元素特征与国内外不同矿种的接触交代型金属矿床进行对比,结果显示该矿床存在成Cu、Fe、Mo矿体的潜力。  相似文献   

持续开挖效应下结构面剪切力学性质与能量特征研究     

郭佳奇  程立攀  朱斌忠  田永超  黄鑫 《岩土力学》2023,44(1):131-143

基于地下岩体工程开挖扰动的实际情况,开展考虑持续开挖效应,充分反映岩体结构面应力调整过程的结构面剪切试验更具理论意义和工程应用价值。采用人工劈裂方法制备岩体结构面,开展了常规应力路径和持续开挖效应下的结构面剪切试验,系统研究了两种条件下结构面剪切力学性质、声发射特征和能量的演化规律。研究结果表明：开挖扰动荷载强度越大,结构面发生剪切破坏时的剪应力降整体上越大,但持续开挖效应下的剪应力降最大值仅为常规应力路径下剪应力降的48.57%;考虑持续开挖效应的结构面剪切过程中声发射活动主要集中于结构面受剪破坏和剪应力降产生时,且声发射活动强度与开挖扰动强度正相关,声发射振铃计数变化率极值明显小于常规应力路径下的相应值;持续开挖效应下试样裂纹发育密集度、结构面磨损区域及破坏程度均随开挖扰动强度增加而增加,但试样裂纹发育的密集程度和结构面破坏程度相对常规应力路径下的情况轻;考虑持续开挖效应的结构面发生剪切破坏时弹性应变能随扰动荷载增大而增大,均低于常规应力路径条件下的弹性应变能值,持续开挖效应降低了结构面剪切破坏的强度,但更易引发结构面发生剪切破坏。  相似文献   

Abiotic Methane Reservoirs in the Western Tianshan HP–UHP Metamorphic Belt,China     

ZHANG Lijuan  ZHANG Lifei  LI Xiaowei  WANG Xiao 《《地质学报》英文版》2023,97(1):337-349

Natural gas, consisting primarily of methane(CH₄), has become a major source of clean energy in modern society in many parts of the globe. Recent experimental observations and discoveries of deep-sourced abiotic CH₄ in cold subduction zones indicate the important ability of cold subducted slabs to generate natural gas reservoirs. However, most CH₄ flux and reservoirs remain unknown and their potential is overlooked in global carbon flux estimations. Massive abiot...  相似文献   

中深层套管式换热器可持续供热性能及优化设计研究     

刘俊  张育平  王沣浩  周聪  张代磊  刘博洋  薛宇泽  张英琛 《地球学报》2023,44(1):230-238

中深层套管式换热器的热提取具有“取热不取水”的特点,是我国北方地区稳妥推进中深层地热能供暖的重要技术之一。针对当前中深层套管式换热器在长期热提取期间供热性能不明的问题,本文基于可持续供热的运行特点,建立数值换热模型分析换热器水温、性能系数随运行年份的变化规律,并针对性地开展设计优化研究。结果表明:在可持续供热过程中,换热器水温在前5年的下降程度较为明显,运行至20年以后,基本不发生变化。换热器季节性能系数的下降程度受岩土体导热系数的影响较大,在1.5 W/(m·K)条件下的SPF₁、SPF₂分别下降11.50%和10.56%,在3.0 W/(m·K)条件下的SPF₁、SPF₂则分别下降4.73%和4.23%。岩土体导热系数越小,换热器供热性能的下降程度越明显。基于可持续供热性能的变化规律,提出以“准稳态特征年”的供热性能为基准进行设计,并综合考虑运行要求与节能性要求优化换热器的运行条件,明确了在不同地热特征参数、埋管深度下的最优运行流速与最佳供热负荷的分布情况,对中深层套管式换热器的高效可持续供热设...  相似文献   

滇西地区稀有金属宝石矿床成矿系列成矿规律与找矿方向     

施玉北  曾妍  李蓉  程胜辉  邹积林 《地球学报》2023,44(4):707-722

本文按矿床成矿系列理论研究方法, 初步厘定了滇西地区与燕山期—喜马拉雅期伟晶岩有关的稀有金属宝石矿床成矿系列及亚系列, 与第四纪表生作用有关的稀有金属矿床成矿系列及亚系列, 研究结果表明本地区在燕山期—喜马拉雅期发生了大规模的中-酸性岩浆侵入活动, 并形成众多的伟晶岩, 发生了重要的岩浆-热液成矿事件, 稀有金属铍、铌、钽、锂、铷、铯等矿产成矿主要与其有关, 构成了特定的稀有金属矿产矿床成矿系列。本文初步总结了滇西地区稀有金属矿产资源及其特征、矿床成矿系列及成矿规律, 分析了找矿潜力, 划分出找矿远景区, 深化了该区稀有金属矿产成矿规律认识。  相似文献