The Impact of Moist Physics on the Sensitive Area Identification for Heavy Rainfall Associated Weather Systems     

Huizhen YU  Zhiyong MENG 《大气科学进展》2022,39(5):684-696

The impact of moist physics on the sensitive areas identified by conditional nonlinear optimal perturbation(CNOP)is examined based on four typical heavy rainfall cases in northern China through performing numerical experiments with and without moist physics.Results show that the CNOP with moist physics identifies sensitive areas corresponding to both the lower-(850?700 hPa)and upper-level(300?100 hPa)weather systems,while the CNOP without moist physics fails to capture the sensitive areas at lower levels.The reasons for the CNOP peaking at different levels can be explained in both algorithm and physics aspects.Firstly,the gradient of the cost function with respect to initial perturbations peaks at the upper level without moist physics which results in the upper-level peak of the CNOP,while it peaks at both the upper and lower levels with moist physics which results in both the upper-and lower-level peaks of the CNOP.Secondly,the upper-level sensitive area is associated with high baroclinicity,and these dynamic features can be captured by both CNOPs with and without moist physics.The lower-level sensitive area is associated with moist processes,and this thermodynamic feature can be captured only by the CNOP with moist physics.This result demonstrates the important contribution of the initial error of lower-level systems that are related to water vapor transportation to the forecast error of heavy rainfall associated weather systems,which could be an important reference for heavy rainfall observation targeting.  相似文献   

苏北梁王城遗址黄泛层初步研究     

黄铿  朱诚  马春梅  林留根 《地层学杂志》2009,33(4)

基于黄河下游流域考古遗址中第一次发现的黄泛地层,对苏北梁王城遗址T3902探方南壁剖面上部自然淤积层采样,结合考古断代,并参照历史资料,通过分析重砂矿物和粒度两方面的实验结果,揭示出考古遗址中黄泛地层的沉积物特征。旨在为今后环境考古中对黄泛地层的判别和对比提供可靠的科学依据,特别是为在黄河下游洪泛区考古遗址中疑似黄泛层的确认提供依据。  相似文献   

Analytical solution to 1D coupled water infiltration and deformation in unsaturated soils   总被引：1，自引：0，他引：1  

L. Z. Wu  L. M. Zhang 《国际地质力学数值与分析法杂志》2009,33(6):773-790

An analytical solution to 1D coupled water infiltration and deformation is derived using a Fourier integral transform. Exponential functional forms are used to represent the hydraulic conductivity–pore‐water pressure relationship and the soil‐water characteristic curve. Fredlund's incremental‐linear constitutive model for unsaturated soils is adopted. The analytical solution considers arbitrary initial pore‐water pressure distributions and flux and pressure boundary conditions. The corresponding analytical solutions to coupled steady‐state problems are also obtained. The analytical solutions demonstrate that the coupling of seepage and deformation plays an important role in water infiltration in unsaturated soils. In the early stages of infiltration, the difference between uncoupled and coupled conditions becomes marked over time, and in late stages, the difference caused by the coupling effects diminishes toward the steady state. The difference between the uncoupled and coupled conditions increases with decreasing desaturation coefficient (α). Pore‐water pressure or deformation changes caused by the coupling effects are mainly controlled by the degree of soil volume change due to a change in soil suction (H). The smaller the absolute value of H, the greater the effect of coupling on the infiltration and deformation. The ratio of rainfall intensity to saturated permeability (q/k_s) also has a strong influence on the coupled seepage and deformation. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

苏北灌河口潮间带表层沉积物重金属空间分布特征及其环境效应   总被引：7，自引：0，他引：7  

黄家祥  殷勇  徐军  朱小兵 《海洋地质与第四纪地质》2007,27(5):23-32

灌河是苏北地区最大、航运条件最好的入海河流。重金属元素分析显示,灌河口表层沉积物中Hg、As和Cu的含量高于背景值;Pb和Zn的含量接近背景值;Cd的含量低于背景值。其中Hg元素出现了中等程度的生态危害性,而Cr、As、Cu、Pb、Zn和Cd等元素的生态危害系数均极低,整个灌河口潮滩地区并没有出现较为严重的重金属生态危害。  相似文献   

Influence of thawed soil depth on rainfall erosion of frozen bare meadow soil in the Qinghai–Tibet Plateau     

Xiaofeng Gao  Xiaonan Shi  Tingwu Lei 《地球表面变化过程与地形》2021,46(10):1953-1963

The Qinghai–Tibet Plateau has a vast area of approximately 70×10⁴ km² of alpine meadow under the impacts of soil freezing and thawing, thereby inducing intensive water erosion. Quantifying the rainfall erosion process of partially thawed soil provides the basis for model simulation of soil erosion on cold-region hillslopes. In this study, we conducted a laboratory experiment on rainfall-induced erosion of partially thawed soil slope under four slope gradients (5, 10, 15, and 20°), three rainfall intensities (30, 60, and 90 mm h⁻¹), and three thawed soil depths (1, 2, and 10 cm). The results indicated that shallow thawed soil depth aggravated soil erosion of partially thawed soil slopes under low hydrodynamic conditions (rainfall intensity of 30 mm h⁻¹ and slope gradient ≤ 15°), whereas it inhibited erosion under high hydrodynamic conditions (rainfall intensity ≥ 60 mm h⁻¹ or slope gradient > 15°). Soil erosion was controlled by the thawed soil depth and runoff hydrodynamic conditions. When the sediment supply was sufficient, the shallow thawed soil depth had a higher erosion potential and a larger sediment concentration. On the contrary, when the sediment supply was insufficient, the shallow thawed soil depth resulted in lower sediment erosion and a smaller sediment concentration. The hydrodynamic runoff conditions determined whether the sediment supply was sufficient. We propose a model to predict sediment delivery under different slope gradients, rainfall intensities, and thawed soil depths. The model, with a Nash–Sutcliffe efficiency of 0.95, accurately predicted the sediment delivery under different conditions, which was helpful for quantification of the complex feedback of sediment delivery to the factors influencing rainfall erosion of partially thawed soil. This study provides valuable insights into the rainfall erosion mechanism of partially thawed soil slopes in the Qinghai–Tibet Plateau and provides a basis for further studies on soil erosion under different hydrodynamic conditions.  相似文献   

Comparison of the return period for landslide-triggering rainfall events in Japan based on standardization of the rainfall period     

Haruka Tsunetaka 《地球表面变化过程与地形》2021,46(14):2984-2998

The intensity of rainfall events with potential to cause landslides has varying temporal characteristics. In this study, the time at which the 72-h accumulated rainfall reached its maximum was used to standardize the period of rainfall measurement. The proposed standardization of the rainfall period was used in conjunction with the return level of rainfall intensity, obtained from intensity–duration–frequency curves, to investigate rainfall intensity anomalies associated with 10 hazardous rainfall events that triggered numerous landslides at the regional scale in Japan. These landslides included shallow landslides in volcanic and non-volcanic areas, as well as deep-seated landslides. The rainfall events that triggered the shallow landslides were divided into two types: downpours that repeatedly reached close to the 100-year return level within approximately 3–4 h, and accumulated rainfall that reached close to 200–400 mm over longer time intervals but within 72 h. Lithological differences seemed unrelated to the differences between the two types of shallow-landslide-triggering rainfall; however, precipitation >1000 mm was necessary to trigger deep-seated landslides. Although the characteristics of the hyetographs differed markedly among the landslide-triggering rainfall events, all the landslides could have been triggered when the mean rainfall intensity reached the 100-year rainfall level during the standardized period. Thus, the landslide trigger can be evaluated indirectly based on the increase in the return level of the mean rainfall intensity, which could provide a means for estimating the time of landslide occurrence.  相似文献   

地下流体数据跟踪事件质量分析     

陶志刚  刘春国  樊俊屹 《地震地磁观测与研究》2021,42(4):146-154

以地下流体数据跟踪分析产出事件为研究对象,总结数据跟踪分析工作现状,从观测系统故障、自然环境、场地环境、人为干扰、地球物理、不明原因事件6个方面,分析2019年地下流体数据跟踪分析存在的问题,并对典型事件进行总结,为地震台站跟踪分析事件记录提供参考。  相似文献   

洪水预报模型输入与输出的误差分布及相关性分析     

张琳  王国利 《水文》2022,42(1):23-28

降雨预报信息作为洪水预报模型的输入,该信息的准确性直接影响洪水预报模型输出的准确性.为探究模型输入(降雨预报)误差与输出(洪水预报)误差之间的关系,以英那河流域为例,分析了不同雨量等级下,预报模型的输入误差与输出误差的分布规律,并定性分析了两种误差的相关关系.结果表明,降雨量等级若为无雨及小雨时,两种误差不相关;若为中...  相似文献   

金属矿床的同位素直接定年方法   总被引：20，自引：1，他引：19  

赵葵东  蒋少涌 《地学前缘》2004,11(2):425-434

矿床的直接定年就是直接对成矿流体或矿石矿物进行同位素定年 ,这样确定的年龄就直接代表了成矿年龄。目前主要有石英和闪锌矿中流体包裹体的Rb Sr同位素定年、黄铁矿和石英中包裹体的Ar Ar同位素定年、金属硫化物的Rb Sr同位素定年、金属硫化物和氧化物的Sm Nd同位素定年、金属硫化物的Re Os同位素定年 ,以及单个矿石矿物的Pb逐步淋滤法定年  相似文献   

东营凹陷北部陡坡带稠油成藏机理与油气运聚特征   总被引：6，自引：1，他引：5  

李素梅  庞雄奇  邱桂强  高永进  孙锡年 《地球科学》2004,29(4):451-456,466

东营凹陷北部陡坡带的王庄—宁海地区发现了大量稠油 ,但原油的成因及其成藏机理仍不甚了解 .在以往原油成因与油源调查基础上 ,利用非烃含氮化合物及包裹体均一化温度对该区进行油气运移方向与相对距离、成藏时间与期次的分析 .结果表明 ,东营凹陷北部带原油具有由南而北的运移分馏效应 ,反映北部陡坡带原油来自南部的利津洼陷 ;王庄—宁海地区原油总体具有由东而西的运移分馏效应 ,其东、西两侧各有一主要油气注气点 .王庄—宁海原油烃类与非烃组成与分布特征揭示该区油气具有混合聚集特征 .包裹体测试反映王庄—宁海地区油藏主要为晚期成藏 ,距今小于 5Ma ;而靠近生油中心地带包裹体具有早期成藏的记录 (± 36Ma) .  相似文献