表面增暖形态决定了全球水汽加温度直减率反馈的不确定性   总被引：1，自引：0，他引：1  

张静纯  马建  车婧  周震强  高郭平 《海洋学报(英文版)》2020,39(3):81-89

气候反馈通常是利用与全球平均表面温度升高相关的辐射效应变化来评估的。但是反馈的不确定性不仅仅是全球平均表面温度升高的函数。全球气候模式的预测表明，海表面温度变化的地域不同，给区域尺度上的大气环流和降水响应带来了重大不确定性。在本文中我们证明了表面增暖的空间格局是造成水汽-直减率综合反馈的不确定性的主要因素。基于运用辐射核理论计算的31个气候模型中，气温和相对湿度变化的全球平均辐射效应证明了这一观点。我们的结果突出了区域气候变化对气候反馈不确定性的重要贡献，并确定了世界上限制表面增暖形态对提高气候预测能力最有效的区域。  相似文献   

Distribution of ductile deformation around the Main Central Thrust zone at the frontal part of nappe in southeastern Nepal Himalaya     

Katsushi Sato  Harutaka Sakai  Tetsuo Kawakami 《Island Arc》2020,29(1)

A geological survey and morphological analysis of quartz grains were performed to investigate the distribution of ductile deformation caused by the Himalayan Main Central Thrust (MCT) around Dhankuta, southeastern Nepal. The MCT was mapped as the lithological boundary between the gneiss of the Higher Himalayan Crystalline (HHC) as the hanging wall and the inverted metamorphic sequence of the Lesser Himalayan Sediments (LHS) as the footwall. The MCT was found to truncate various stratigraphic levels of LHS and cuts a map‐scale gentle fold developed in the LHS. Ductile deformation was quantified by fractal dimension between size and perimeter of dynamically recrystallized quartz grains in bedded metaquartzite intercalated in both HHC and LHS. Serrate and polygonal shapes of quartz indicate large and small strain rates, respectively, when the temperature during ductile deformation was assumed to be uniform. A peak of strain rate was found at the lithological boundary with the peak width of ca. 500 m. Such a thin shear zone is favorable for producing frictional heat to promote the inverted metamorphism in LHS.  相似文献   

Minimum geocoding match rates: an international study of the impact of data and areal unit sizes     

Martin A. Andresen  Nick Malleson  Wouter Steenbeek  Michael Townsley  Christophe Vandeviver 《International journal of geographical information science》2020,34(7):1306-1322

ABSTRACT

The analysis of geographically referenced data, specifically point data, is predicated on the accurate geocoding of those data. Geocoding refers to the process in which geographically referenced data (addresses, for example) are placed on a map. This process may lead to issues with positional accuracy or the inability to geocode an address. In this paper, we conduct an international investigation into the impact of the (in)ability to geocode an address on the resulting spatial pattern. We use a variety of point data sets of crime events (varying numbers of events and types of crime), a variety of areal units of analysis (varying the number and size of areal units), from a variety of countries (varying underlying administrative systems), and a locally-based spatial point pattern test to find the levels of geocoding match rates to maintain the spatial patterns of the original data when addresses are missing at random. We find that the level of geocoding success depends on the number of points and the number of areal units under analysis, but generally show that the necessary levels of geocoding success are lower than found in previous research. This finding is consistent across different national contexts.  相似文献   

中国大陆西部GNSS变形特征及其与M≥7.0强震孕育的关系     

武艳强  江在森  朱爽  赵静旸 《中国地震》2020,36(4):756-766

基于中国大陆地壳运动观测网络GNSS速度场结果，通过最小二乘配置建模、速度残差检验、应变率场分析等，研究了西部地区地壳变形特征及其与M≥7.0强震孕育的关系。主要认识包括：①GNSS应变率场结果显示青藏高原西部地区（92.5°E以西）呈现明显的EW向拉张变形特征，青藏高原东部（92.5°E～100°E）则表现为显著的EW向挤压应变积累。②GNSS旋转率场显示中国大陆西部呈现由南向北逐渐衰减的交替旋转变形现象，藏南地区为大范围顺时针旋转变形特征，旋转率极值达4.5×10^-8rad/a；柴达木地块表现为逆时针旋转变形特征，极值达-1.0×10^-8rad/a；塔里木地块表现为顺时针旋转变形特征，极值达1.0×10^-8rad/a。③2001～2018年中国大陆西部的7次M≥7.0强震均发生在与其构造背景一致的应变积累高值区边缘，呈现一定的孕震晚期特征。因此，最大剪应变率高值区边缘和大型走滑断裂交界部位、张应变率高值区边缘与大型正断层的交界部位、压应变率高值区边缘与大型逆断层交界部位是未来强震需要关注的地点。④2001年昆仑山口西地震导致了青藏高原东部地区较大尺度EW向挤压应变增强现象，在一定程度上反映了巴颜喀拉地块东向运动增强引起的变形调整过程，有利于汶川地震、芦山地震的孕育发生。  相似文献   

Micromechanical modeling for rate‐dependent behavior of salt rock under cyclic loading     

Xianda Shen  Jihui Ding  Chlo Arson  Judith S. Chester  Frederick M. Chester 《国际地质力学数值与分析法杂志》2021,45(1):28-44

The dependence of rock behavior on the deformation rate is still not well understood. In salt rock, the fundamental mechanisms that drive the accumulation of irreversible deformation, the reduction of stiffness, and the development of hysteresis during cyclic loading are usually attributed to intracrystalline plasticity and diffusion. We hypothesize that at low pressure and low temperature, the rate‐dependent behavior of salt rock is governed by water‐assisted diffusion along grain boundaries. Accordingly, a chemo‐mechanical homogenization framework is proposed in which the representative elementary volume (REV) is viewed as a homogeneous polycrystalline matrix that contains sliding grain‐boundary cracks. The slip is related to the mass of salt ions that diffuse along the crack surface. The relationship between fluid inclusion‐scale and REV‐scale stresses and strains is established by using the Mori–Tanaka homogenization scheme. It is noted from the model that a lower strain rate and a larger number of sliding cracks enhance stiffness reduction and hysteresis. Thinner sliding cracks (i.e., thinner brine films) promote stiffness reduction and accelerate stress redistributions. The larger the volume fraction of the crack inclusions, the larger the REV deformation and the larger the hysteresis. Results presented in this study shed light on the mechanical behavior of salt rock that is pertinent to the design of geological storage facilities that undergo cyclic unloading, which could help optimize the energy production cycle with low carbon emissions.  相似文献   

A new method for determining weathering rates in weathering pits     

Wei Wang  Rihui Huang  Jing Feng 《地球表面变化过程与地形》2020,45(5):1262-1272

Determining the rates of rock weathering is difficult because, firstly, the weathering rate of rocks is usually so slow that it is difficult to measure; secondly, it is also difficult to determine the start time and duration of weathering. The Shanxi River Valley in Fujian, China dried up after a reservoir was built upstream in 1959, and became a stone quarry site. Quarrying ceased in 1977, so a large amount of quarry wastes with artificially excavated surfaces were left in the valley. The concave-upward curved rocky surface, broken by manual excavation, easily contains rainwater in its central part, which was easily weathered into a more concave surface. Plaster mould casting was performed in situ on such a concave surface of an excavated stone rock in the valley and scanned with a high-precision 3D scanner to obtain 3D data of the concave-upward rock surface and its more concave middle part, which was considered as an initial weathering pit. The 3D model provided an in-depth understanding of the initial formation process of weathering pits, indicating that: (1) the average weathering rate of a weathering pit is 10.8 ± 0.49 cm ka⁻¹; (2) weathering pits are generally formed by standing water in depressions on a flat near-horizontal rock surface due to weathering actions involving water; (3) the deepening rate of a weathering pit is about four times greater than that of the surrounding area; (4) the growth of a weathering pit can begin in some small concavities on the flat rock surface without pre-existing depressions and gradually expands; (5) a weathering pit is generally wider than deep or with a flat bottom due to expansion with a lateral weathering rate that is greater than that of the vertical, and the lamination of the host rock is not necessary for the formation of flat-floored weathering pits. © 2020 John Wiley & Sons, Ltd.  相似文献   

疏浚淤泥化学絮凝−真空预压深度脱水效果评价     

王东星  唐弈锴  伍林峰 《岩土力学》2020,41(12):3929-3938

为实现疏浚淤泥高效快速脱水减容，选取化学絮凝和真空预压相结合的脱水技术，利用自制真空预压抽滤装置对5种类型絮凝剂调理淤泥进行系列室内脱水试验，通过上清液高度、泥水分界面高度、沉降速率、底泥含水率等指标，综合评价疏浚淤泥沉降过程与深度脱水效果。结果表明：5种絮凝剂对应最优添加量分别为Ca(OH)2(1 500 mg/L)、PAFSI(200 mg/L)、PAC(200 mg/L)、HCA(50 mg/L)、APAM(500 mg/L)；与原始淤泥自然沉降过程相比（底泥高度17.14 cm、含水率96.8%），真空预压可实现絮凝调理淤泥脱水减容、底泥平均含水率降至53.5%，使底泥体积进一步压缩20.48%～36.99%；真空预压作用下，絮凝调理淤泥在50 min内达到沉降速率峰值，前120 min内淤泥絮凝效果明显、泥水分离程度占据主导；与原始淤泥真空预压对比，絮凝?真空预压大幅提升淤泥沉降速率、有效缩短峰值对应沉降时间，最优絮凝剂（APAM）底泥沉降速率峰值、淤泥总高度沉降速率峰值对应时间点缩短87.5%和83.33%，峰值速率分别增加3.56倍、5.18倍；添加适量絮凝剂能有效改善淤泥脱水性能，增大泥粒尺寸、防堵促排，加速疏浚淤泥沉降与泥水分离效率。化学絮凝?真空抽滤技术有利于实现疏浚淤泥减量化，显著缩短工期、加快施工进度、减少堆积占地，具有显著的工程应用价值。  相似文献   

Development of All-Weather and Real-Time Bottom-Mounted Monitor of Bed Load Quantity     

窦希萍  左其华  应强  黄海龙 《中国海洋工程》2014,(6):807-814

Quantity of bed load is an important physical parameter in sediment transport research. Aiming at the difficulties in the bed load measurement, this paper develops a bottom-mounted monitor to measure the bed load transport rate by adopting the sedimentation pit method and resolving such key problems as weighing and desilting, which can achieve long-time, all-weather and real-time telemeasurement of the bed load transport rate of plain rivers, estuaries and coasts. Both laboratory and field tests show that this monitor is reasonable in design, stable in properties and convenient in measurement, and it can be used to monitor the bed load transport rate in practical projects.  相似文献   

Multi-dimensional expansion of urban space through the lens of land use: The case study of Nanjing City,China     

Qiao  Weifeng  Gao  Junbo  Guo  Yuanzhi  Ji  Qingqing  Wu  Ju  Cao  Min 《地理学报(英文版)》2019,29(5):749-761

Journal of Geographical Sciences - The study of multi-dimensional expansion of urban space (MEUS) addresses the laws of urban spatial expansion from all directions and angles. Using Nanjing as an...  相似文献   

Tolerance,oxygen consumption and ammonia excretion of Ophiopholis sarsii vadicola in different temperatures and salinities     

Fang  Jinghui  Zhang  Jihong  Jiang  Zengjie  Zhao  Xuewei  Jiang  Xu  Du  Meirong  Gao  Yaping  Fang  Jianguang 《中国海洋大学学报(英文版)》2015,14(3):549-556

There are more than 2000 species of brittle stars in the world. For most of them, many scientific questions including basic characteristics of eco-physiology are still unknown. In the present study, Ophiopholis sarsii vadicola acclimated at 15℃, salinity 31, were assessed for temperature and salinity tolerance. Its oxygen consumption and ammonia excretion were studied at different temperatures(5, 10, 15, 20, 25℃) and salinities(25, 30, 35). O. sarsii vadicola could tolerate 0–24℃ and no brittle star was dead in the salinity range of 19–48 in the experimental situation. Two-way ANOVA showed that the oxygen consumption and ammonia excretion normalized with both dry mass and wet mass, Q10, which is used to describe the temperature sensitivity of respiration, and moisture content were significantly affected by temperature and salinity, and the combined effects of the two factors were significant. Stepwise multiple regression analysis revealed that logarithmic oxygen consumption and ammonia excretion showed a significant positive relationship with logarithmic temperature and salinity. The logarithmic moisture content of the brittle stars showed an inverse relationship with logarithmic salinity, but a positive relationship with logarithmic temperature. This suggests that the tolerance of temperature and salinity of brittle stars is closely related to their living environment, and that the effects of temperature on oxygen consumption are more significant at higher salinity, and that the ammonia excretion is less affected by salinity at lower temperatures.  相似文献