FluBiDi – a model to estimate flood based on runoff: validation using extreme and natural basin conditions     

Faustino De Luna-Cruz  O.A. Fuentes-Mariles  J. Gracia-Sánchez 《水文科学杂志》2019,64(3):297-317

FluBiDi is a two-dimensional model created to simulate real events that can take days and months, as well as short events (minutes or hours) and inclusive laboratory tests. To verify the robustness of FluBiDi, it was tested using a previous study with both designed and real digital elevation models. The results highlight good agreement between the models (i.e. Mike Flood, SOBEK, ISIS 2D, and others) tested and FluBiDi (around 90% for a specific instant and 95% for the complete time simulation). In the simulated hydrographs, the discharge peak value, time to peak, and water level results were accurate, reproducing them with an error of less than 5%. The velocity differences observed in a couple of tests in FluBiDi were associated with very short periods of time (seconds). However, FluBiDi is highly accurate for simulating floods under real topographical conditions with differences of around 2 cm when water depth is around 150 cm. The average water depth and velocities are precise, and the model describes with high accuracy the pattern and extent of floods. FluBiDi has the capability to be adjusted to different types of events and only requires limited input data.  相似文献   

海气动量通量研究综述   总被引：1，自引：0，他引：1  

冯兴如  李水清  尹宝树 《海洋科学》2018,42(10):103-109

海气界面动量通量也称为风应力,是海流和表面海浪的主要驱动力,是海洋从大气获得动量的重要途径。因此,合理可靠的海洋表面风应力的参数化对于海洋、大气和波浪以及气候模式的准确预报都具有非常重要的科学意义和实用价值。对风应力拖曳系数的参数化是风应力参数化的主要内容。近来的观测发现,风应力拖曳系数随着风速的增加出现了先增后减的趋势,同时还与海面的波浪状态以及海流有关。基于观测或理论分析,目前已经得到了一系列的风应力拖曳系数计算方法或公式,有的考虑了海浪的作用,有的没有,但这些方案大都是适合中低风速,在高风速下的适用性还有待检验。本文回顾了目前在海气动量通量观测和参数化方面的研究进展,并建议应增加高风速下风速、海流以及海浪等的同步观测,以进一步完善风应力参数化方案。  相似文献   

一次攀西地区飑线天气过程形成机制分析     

李永军  陈科艺 《气象科技》2019,47(6):997-1005

利用地面气象常规观测资料、区域自动站观测资料、雷达及卫星资料和NCEP 1°×1°的逐6h再分析资料,对2018年5月13日攀西地区南部的飑线天气过程的形成机制进行分析。结果表明:飑线发生在高空槽前,高空槽逐渐东移推动冷性气流沿背风坡东移,然后与前方低层暖空气汇合抬升形成对流;露点锋触发了飑线天气过程的形成;产生飑线天气区域的大气具有上干下湿、不稳定能量高、垂直风切变强、高层风速大和形成之前存在逆温层的特点;高空急流和动量下传对飑线的发生和加强具有促进作用;地形对飑线的形成和天气现象的分布有影响。  相似文献   

京津冀地区一次强沙尘天气过程的成因及特征   总被引：1，自引：0，他引：1       下载免费PDF全文

彭舒龄  周树道  卫克晶  沈奥 《大气科学学报》2019,42(6):926-935

利用常规污染物监测资料、卫星资料和再分析资料等,对京津冀地区在2017年春季遭遇的一次强沙尘天气过程进行分析。结果表明,此次过程是由地面冷锋过境,高空槽后冷空气持续补充引起,沙源地主要位于巴丹吉林、腾格里沙漠,随后以西北路径输送至京津冀地区。前期沙源地感热通量迅速增大,与中低层冷平流叠加,导致不稳定层结增强,助于起沙;高空强风速带加强并向下延伸,中低层次级环流发展,不但使沙尘传输并下降至地面,而且使高层高动量和高位涡冷空气下传,促进低空急流形成、低层系统发展,使大风及沙尘天气维持;沙尘过境时,地面至4 km高度存在沙尘型气溶胶,PM_(2.5)和PM_(10)浓度变化趋势较一致并达到重度污染水平,且气溶胶光学厚度(Aerosol Optical Depth,AOD)与空气质量指数(Air Quality Index,AQI)具有较好的时空匹配关系,重污染时段AOD值大于1,污染减弱时AOD值降至0.6以下。  相似文献   

一次强飑线过程极端大风的中尺度分析          下载免费PDF全文

沈杭锋  方桃妮  蓝俊倩  翟国庆  苏涛 《气象学报》2019,77(5):806-822

利用常规气象观测资料、区域自动气象站加密观测资料和GFS 0.25°×0.25°逐6 h的分析场数据以及多普勒雷达、风廓线等资料,通过背景形势场分析、物理量诊断分析和中尺度分析,对2018年3月4日发生在华东地区的强飑线天气过程进行了诊断分析。结果表明,这次过程具有发生时间(季节)早、移速快、范围广、致灾强等特点,是一次比较少见的早春(冬末)十分强烈的飑线天气过程,是在高空急流辐散区、低空西南急流轴前端、低涡南侧的暖区中发展起来的。飑线过程的地面要素变化十分剧烈,地面有强冷池,与飑线前暖空气之间构成了强的水平温度梯度,致使飑线强度更强;飑线经过时气压涌升所形成的雷暴高压、强气压梯度以及飑线的快速移动均有利于地面极端大风的出现。飑线发展过程中观测到弓形回波、超级单体等强天气系统。中高层动量下传和光滑湖面、喇叭口、狭管效应等特殊地形对于大风的增强效应比较显著,这些因素也加剧了地面极端大风的形成。   相似文献   

Barothropic relaxing media under pressure perturbations: Nonlinear dynamics     

《Dynamics of Atmospheres and Oceans》2015

In this paper, we delve into the dynamics of a barothropic relaxing medium under pressure perturbations originating from blast wave explosions in the milieu. Analyzing the problem within the viewpoint of the Lyakhov formalism of geodynamic systems, we derive a complex-valued nonlinear evolution equation which models the wave propagation of the pressure perturbations within the barothropic medium. As a result, we find that the previous system can be circularly polarized and hence support traveling rotating pressure excitations which profiles strongly depend upon their angular momenta. In the wake of these results, we address some physical implications of the findings alongside their potential applications.  相似文献   

近岸波生流运动三维数值模拟及验证   总被引：3，自引：0，他引：3       下载免费PDF全文

解鸣晓  张玮 《水科学进展》2011,22(3):391-399

开发建立了近岸波生流运动三维数值计算模式。模式中,引入了三维时均剩余动量、破波表面水滚、波浪水平与垂向紊动作为主要驱动力,同时考虑了波流共同作用的底部剪切力。推导了可综合反映底坡、能量传递率和密度影响的水滚能量传输方程;将Larson-Kraus的二维波浪水平紊动系数表达式拓展至三维。采用大量实测数据和文献资料测试验证了所建模式,表明所建模式可有效模拟波浪增减水、底部离岸流、沿岸流、裂流、堤后环流等不同维度的波生流现象。此外,研究也表明破波水滚效应可解释波生流峰值向岸推移的物理现象,从而在模拟中不能忽略;破波带内沿岸流速垂向较为均匀的现象与波浪附加垂向紊动有关。  相似文献   

Linear and angular momentum conservation in hydraulic jump in diverging channels     

Alessandro Valiani Valerio Caleffi 《Advances in water resources》2011,34(2):227-242

This paper addresses the integral conservation of linear and angular momentum in the steady hydraulic jump in a linearly diverging channel.The flow is considered to be divided into a mainstream that conveys the total liquid discharge, and a roller where no average mass transport occurs. It is assumed that no macroscopic rheological relationship holds, so mass, momentum and angular momentum integral balances are independent relationships. Normal stresses are assumed to be hydrostatic on vertical, cylindrical surfaces. Viscous stresses are assumed to be negligible with respect to turbulent stresses. Assuming that the horizontal velocity distribution in the mainstream is uniform and that the horizontal momentum and angular momentum in the roller are negligible with respect to their mainstream counterparts, an analytical solution is obtained for the free surface profile of the flow. This solution is fundamental for finding the sequent depths and their positions. Consequently, it permits solving for the length of the jump, which is assumed to be equal to the length of the roller. Mainstream and roller thicknesses can also be derived from the present solution. This model may also be theoretically used to derive the average shear stresses exerted by the roller on the mainstream and the power losses per unit weight. This second relationship, which returns the well-known classical expression for total power loss in the jump, demonstrates that the strongly idealized mechanical model proposed here is internally consistent.  相似文献   

水平轴潮流能叶轮尖速比特性分析研究   总被引：1，自引：1，他引：0  

王兵振  廖微  张巍 《海洋工程》2015,33(6):100-105

针对设计尖速比对水平轴潮流能叶轮动力特性的影响问题开展研究工作。基于叶素-动量理论建立叶轮动力特性仿真模型,以叶片数量分别为2、3、4的叶轮为对象,考察设计尖速比对叶轮的功率系数的影响。研究结果表明:设计尖速比越大的叶轮,其最大效率也越高;叶片数量多的叶轮,其功率系数略优于叶片数量少的叶片。结合分析结果,给出了水平轴潮流能叶轮的设计尖速比的选择建议。  相似文献   

Uncertainty in projections of the South Asian summer monsoon under global warming by CMIP6 models: Role of tropospheric meridional thermal contrast          下载免费PDF全文

Yunqi Kong  Yuting Wu  Xiaoming Hu  Yana Li  Song Yang 《大气和海洋科学快报》2022,15(1):100145

本文基于第六次国际耦合模式比较计划共18个模式的工业革命前实验和CO₂浓度突然四倍实验,发现在CO₂四倍强迫下,南亚夏季风环流呈显著减弱趋势,但减弱强度存在较大模式间差异.利用Webster-Yang指数和经向哈得莱环流指数的下降趋势表征SASM减弱强度,发现该下降趋势与欧亚大陆-印度洋之间对流层上层经向温度梯度的变化值(EUTT-IUTT)高度相关.进一步利用气候反馈-响应分析方法进行分析,发现EUTT-IUTT变化的模式间差异主要来自于大气动力过程,其次是云的短波辐射效应的贡献.地表潜热通量和云的长波辐射效应缩小了EUTT-IUTT变化的模式间差异.  相似文献