北雁荡山地形对2020年“黑格比”台风暴雨影响的数值模拟     

童颖睿  郑远东  郑峰 《气象科技》2023,51(5):681-692

2020年第4号台风“黑格比”在浙南登陆后过境北雁荡山期间在山区引发了特大暴雨。基于中尺度数值模式WRFV4.0.2对台风进行高分辨率数值模拟,分析北雁荡山地形对此次台风暴雨的作用,并设置了升降地形敏感性试验。结果表明:数值试验较好地模拟了台风移动及特大暴雨的落区和强度,台风大风区明显不对称分布,台风登陆后第一、四象限过境山区,其东侧强偏南气流向山区输送了充足水汽。台风登陆前山区低空存在一条由台风内核拖曳出的狭长螺旋辐合带,水汽通量辐合与风场辐合相一致。台风眼墙过境时沿着降水中心的迎风坡有强烈上升运动,动力条件极好,水汽输送带由近地面向对流层低层延展,山区有零星对流单体触发加强。台风后部环流影响时在高海拔山区风速减弱、绕流激发了中尺度低涡,强降水中心迎风坡上出现持续性、停滞不动的强正涡度中心,是特大暴雨发生的主要原因。地形敏感性试验中无地形时降水减幅40%~50%,地形高度翻倍降水增幅超过60%。  相似文献   

The construction of high precision geostrophic currents based on new gravity models of GOCE and satellite altimetry data     

Wenyan Sui  Junru Guo  Jun Song  Zhiliang Liu  Meng Wang  Xibin Li  Yanzhao Fu  Yongquan Li  Yu Cai  Linhui Wang  Lingli Li  Xiaofang Guo  Wenting Zuo 《海洋学报(英文版)》2021,40(3):142-152

The new gravity field models of gravity field and steady-state ocean circulation explorer(GOCE), TIM_R6 and DIR_R6, were released by the European Space Agency(ESA) in June 2019. The sixth generation of gravity models have the highest possible signal and lowest error levels compared with other GOCE-only gravity models, and the accuracy is significantly improved. This is an opportunity to build high precision geostrophic currents. The mean dynamic topography and geostrophic currents have been calculated by the 5 th(TIM_R5 and DIR_R5), 6 th(TIM_R6 and DIR_R6) release of GOCE gravity field models and ITSG-Grace2018 of GRACE gravity field model in this study. By comparison with the drifter results, the optimal filtering lengths of them have been obtained(for DIR_R5, DIR_R6, TIM_R5 and TIM_R6 models are 1° and for ITSG-Grace2018 model is 1.1°). The filtered results show that the geostrophic currents obtained by the GOCE gravity field models can better reflect detailed characteristics of ocean currents. The total geostrophic speed based on the TIM_R6 model is similar to the result of the DIR_R6 model with standard deviation(STD) of 0.320 m/s and 0.321 m/s, respectively. The STD of the total velocities are 0.333 m/s and 0.325 m/s for DIR_R5 and TIM_R5. When compared with ITSG-Grace2018 results, the STD(0.344 m/s) of total geostrophic speeds is larger than GOCE results, and the accuracy of geostrophic currents obtained by ITSG-Grace2018 is lower. And the absolute errors are mainly distributed in the areas with faster speeds, such as the Antarctic circumpolar circulation, equatorial region, Kuroshio and Gulf Stream areas. After the remove-restore technique was applied to TIM_R6 MDT, the STD of total geostrophic speeds dropped to 0.162 m/s.  相似文献   

低纬高原地形对强降水过程影响的数值试验研究   总被引：4，自引：0，他引：4  

董海萍  赵思雄  曾庆存 《气候与环境研究》2007,12(3):381-396

在对云南2001年5月31日～6月2日的强降水过程较为真实模拟的基础上,对云南特有的地形对此次强降水过程的影响进行了对比试验.结果表明:红河河谷的喇叭口地形结构对此次云南强降水的落区和降水强度都有着不可忽视的作用,它不但能改变近地层气流的走向,而且对低层水汽通量散度分布也有一定的影响;同时,改变云南南部地形对此次强降水过程的气流走向和水汽分布也都有影响,但相对而言不如红河河谷的作用显著;而降低云南东北部地形,则使云南北部的近地层气流辐合线发生变化,它主要对此次云南北部地区的降水产生影响,但对该地区水汽输送影响不大.  相似文献   

The San Dimas experimental forest: Hydrologic research in semiarid steepland terrain     

Peter M. Wohlgemuth 《水文研究》2021,35(5):e14148

The San Dimas Experimental Forest (SDEF) is located in southern California and is representative of the chaparral shrublands of the Southwest USA. Chaparral – including genera of Ceanothus, Adenostoma, Quercus, Salvia and Arctostaphylos – is a dense, drought-tolerant vegetation assemblage with a closed canopy 3–5 m in height. Chaparral is a fire-prone ecosystem and wildfires have burned the SDEF about every 40 years. The SDEF was established in 1933 to quantify the water cycle in a steep, semiarid landscape. Study catchments range in size from 15 to 1160 ha and measurements of stream runoff are made in a nested weir and flume arrangement to account for the very flashy flows. Apart from native chaparral vegetation, streamflow measurements in these study watersheds have also quantified the hydrologic response of vegetation type-conversion and fire. Innovations in hydrologic monitoring developed on the SDEF include a critical depth flume (the San Dimas flume) and tilted rain gages to better sample precipitation in mountainous terrain. Subsurface runoff and plant water relations have been measured in a large lysimeter complex. Water quality monitoring shows that stream water in the SDEF has very high levels of nitrate, derived from atmospheric deposition of chronic air pollution, that approach the Federal EPA standard of 10.0 mg L⁻¹ for nitrate-N. Spreadsheets of rainfall and streamflow (from 1938 to 2015) – the San Dimas Experimental Forest hydrologic database – may be found at the right-hand side of the web page at https://www.fs.fed.us/psw/ef/san_dimas/index.shtml . Hard copy charts, tables and other records associated with the foregoing data streams are available from the USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, California, 92501 USA or at pete.wohlgemuth@usda.gov .  相似文献   

A new depression‐dominated delineation (D‐cubed) method for improved watershed modelling          下载免费PDF全文

Mohsen Tahmasebi Nasab  Jianli Zhang  Xuefeng Chu 《水文研究》2017,31(19):3364-3378

Prior to hydrologic modelling, topographic features of a surface are derived, and the surface is divided into sub‐basins. Surface delineation can be described as a procedure, which leads to the quantitative rendition of surface topography. Different approaches have been developed for surface delineation, but most of them may not be applicable to depression‐dominated surfaces. The main objective of this study is to introduce a new depression‐dominated delineation (D‐cubed) method and highlight its unique features by applying it to different topographic surfaces. The D‐cubed method accounts for the hierarchical relationships of depressions and channels by introducing the concept of channel‐based unit (CBU) and its connection with the concept of puddle‐based unit (PBU). This new delineation method implements a set of new algorithms to determine flow directions and accumulations for puddle‐related flats. The D‐cubed method creates a unique cascaded channel‐puddle drainage system based on the channel segmentation algorithm. To demonstrate the capabilities of the D‐cubed method, a small laboratory‐scale surface and 2 natural surfaces in North Dakota were delineated. The results indicated that the new method delineated different surfaces with and without the presence of depressional areas. Stepwise changes in depression storage and ponding area were observed for the 3 selected surfaces. These stepwise changes highlighted the dynamic filling, spilling, and merging processes of depressions, which need to be considered in hydrologic modelling for depression‐dominated areas. Comparisons between the D‐cubed method and other methods emphasized the potential consequences of use of artificial channels through the flats created by the depression‐filling process in the traditional approaches. In contrast, in the D‐cubed method, sub‐basins were further divided into a number of smaller CBUs and PBUs, creating a channel‐puddle drainage network. The testing of the D‐cubed method also demonstrated its applicability to a wide range of digital elevation model resolutions. Consideration of CBUs, PBUs, and their connection provides the opportunity to incorporate the D‐cubed method into different hydrologic models and improve their simulation of topography‐controlled runoff processes, especially for depression‐dominated areas.  相似文献   

Plant community patterns in a gypsum area of NE Spain. I. Interactions with topographic factors and soil erosion   总被引：1，自引：0，他引：1  

Joaquín Guerrero-Campo  Francisco Alberto  John Hodgson  Jos Ma. García-Ruiz  Gabriel Montserrat-Martí 《Journal of Arid Environments》1999,41(4):401

The aim of this paper is to explain how topographical factors and soil erosion affect plant community patterns in the gypsum hills of the Middle Ebro Basin (NE Spain).Both the altitudinal location on the hill and, secondarily, the aspect determine a regular distribution pattern of the plant communities, which is closely related to soil and erosion features, as well as to some plant attributes. Tall perennial grasses dominate the valley bottoms, and scrub vegetation the hillsides and hilltops. Water availability, soil depth and particle movement down the slope are the main factors that could explain this segregation.  相似文献   

Ice flow physical processes derived from the ERS-1 high-resolution map of the Antarctica and Greenland ice sheets   总被引：1，自引：0，他引：1  

Frédérique Rémy  Philippe Shaeffer  & Benoît Legrésy 《Geophysical Journal International》1999,139(3):645-656

The ERS-1 satellite, launched in 1991, has provided altimetric observations of the Greenland Ice Sheet and 80 per cent of the Antarctica Ice Sheet north of 82°S. It was placed in a geodetic (168-day repeat) orbit between April 1994 and March 1995, yielding a 1.5  km across-track spacing at latitude 70° with a higher along-track sampling of 350  m. We have analysed the waveform altimetric data from this period to compute maps with a 1/30° grid size. Data processing consists of correcting for environmental factors and editing and retracking the waveforms. A further step consists of reducing the radial orbit error through crossover analysis and correcting the slope error to second order. The high-resolution topography of both ice sheets reveals numerous details. A kilometre-scale surface roughness running at 45° from the flow direction is the dominant topographic characteristic of both continents. Antarctica also exhibits many scars due to local flow anomalies. Several physical processes can be identified: abrupt transitions from deformation to sliding and vice versa, and impressive strike-slip phenomena, inducing en echelon folds.  相似文献   

Introduction to the spectral element method for three-dimensional seismic wave propagation   总被引：28，自引：0，他引：28  

Dimitri Komatitsch  & Jeroen Tromp 《Geophysical Journal International》1999,139(3):806-822

  相似文献   

地貌瞬时单位线研究进展   总被引：14，自引：0，他引：14       下载免费PDF全文

芮孝芳 《水科学进展》1999,10(3):345-350

自从Rodriguez-Iturbe等人开创了地貌瞬时单位线的研究以来,从理论上探讨用流域地形地貌参数定量流域水文响应,已成为近20年来水文学中最富有吸引力的研究课题之一。总结了基于Horton-Strahler河流分级和水系随机模型推导流域地貌瞬时单位线获得的主要研究成果,对地貌气候瞬时单位线作了综述。  相似文献   

GEOSAT卫星遥感资料研究南海海面动力高度场和地转流场   总被引：10，自引：1，他引：9  

毛庆文  施平  齐义泉 《海洋学报》1999,21(1):11-16

利用GEOSAT卫星在1987年和1988年执行ERM任务的雷达高度计资料来分析获取南海海面动力高度偏差的季节分布.根据卫星轨道误差和海域的特点,提出了适用于内海及边缘海域的二维共线轨道校正法,由此方法而得出的南海海面动力高度偏差的季节分布表明,南海表层流场在夏季总的环流形势是反气旋式环流,而冬季是气旋式环流.分析的结果同海上常规调查资料的分析结果相比较表明,在海流季节变化信号较强的海区(如南海中部和北部海区),利用高度计资料能很好地反映该海区的海流季节变化特征.  相似文献