中国南方春季降水年际变化强度的年代际变化及其与海温异常的联系   总被引：4，自引：4，他引：0  

徐超  乔云亭 《气象科学》2018,38(3):281-292

基于1979—2014年中国756个站逐月降水资料,以及ERA-interim再分析资料、哈德莱中心的逐月海表温度资料,通过EOF和相关分析等统计方法,研究了1979—2014年中国南方春季降水年际变化强度的年代际变化,以及与之相关联的环流特征和海温异常信号。结果表明:中国南方春季降水年际变化强度的空间分布在不同的年代有着明显的差异,1979—1994年间,华南(SC)春季降水的年际变化强度较大,这与该段时间内春季西太平洋海表温度异常(SSTA)以及前期冬季南太平洋海温三极子(SPT)年际变化强度较大有关,西太平洋(WP)的冷(暖)SSTA会在局地激发出异常的下沉(上升)运动以及反气旋性(气旋性)环流,并通过一个垂直环流,使得华南地区出现异常的上升(下沉)运动,导致华南地区春季降水增多(减少),前冬的SPT则通过影响春季WP的SSTA从而间接影响华南的春季降水。而1995—2006年间,则是长江中下游地区(YZR)春季降水的年际变化强度更强,这可能是与这一时期年际变化加强的春季南印度洋偶极子(SIOD)有关,春季SIOD为正(负)位相时,副高异常偏强(弱)、偏西(东),有(不)利于太平洋上的水汽向长江中下游地区输送,同时中高纬西伯利亚高压脊偏弱(强),东亚大槽较浅(深),干冷空气偏北(南),使得长江中下游地区降水偏多(少)。  相似文献   

Extracting cross sections and water levels of vegetated ditches from LiDAR point clouds     

《International Journal of Applied Earth Observation and Geoinformation》2016

The hydrologic response of a catchment is sensitive to the morphology of the drainage network. Dimensions of bigger channels are usually well known, however, geometrical data for man-made ditches is often missing as there are many and small. Aerial LiDAR data offers the possibility to extract these small geometrical features. Analysing the three-dimensional point clouds directly will maintain the highest degree of information. A longitudinal and cross-sectional buffer were used to extract the cross-sectional profile points from the LiDAR point cloud. The profile was represented by spline functions fitted through the minimum envelop of the extracted points. The cross-sectional ditch profiles were classified for the presence of water and vegetation based on the normalized difference water index and the spatial characteristics of the points along the profile. The normalized difference water index was created using the RGB and intensity data coupled to the LiDAR points. The mean vertical deviation of 0.14 m found between the extracted and reference cross sections could mainly be attributed to the occurrence of water and partly to vegetation on the banks. In contrast to the cross-sectional area, the extracted width was not influenced by the environment (coefficient of determination R² = 0.87). Water and vegetation influenced the extracted ditch characteristics, but the proposed method is still robust and therefore facilitates input data acquisition and improves accuracy of spatially explicit hydrological models.  相似文献   

热带气旋强度变化研究进展   总被引：78，自引：10，他引：68  

端义宏  余晖  伍荣生 《气象学报》2005,63(5):636-645

自20世纪90年代后期以来,热带气旋强度变化研究越来越受到人们的重视,随着研究的不断深入,热带气旋强度变化研究取得了可喜的进展,文中总结近年来热带气旋强度变化的主要研究成果,主要包括(1)热带气旋的发生、发展和最大可能强度的研究;(2)行星涡度梯度、环境均匀流、环境流场垂直切变以及热带气旋外流与环境流的相互作用对热带气旋强度的影响及物理机制;(3)热带气旋结构与强度的变化关系,着重总结环境流场导致的非对称结构变化而引起的热带气旋强度变化以及对涡旋倾斜发展理论验证,分析了涡旋Rossby波的最新研究;(4)海洋热状况变化以及海洋飞沫对热带气旋强度的影响研究成果。分析指出,今后进一步开展用现代化卫星探测资料研究热带气旋强度变化外,还应加强热带气旋外流与环境流场的相互作用,海-气交界面的参数化问题,热带气旋结构变化与TC强度变化关系以及这种关系的物理本质的研究,通过深入研究,认识热带气旋强度变化的物理机制,提高热带气旋强度变化的预报能力。  相似文献   

广西岩溶石漠化变化规律及强弱程度遥感分析   总被引：7，自引：1，他引：7  

杨传明 《国土资源遥感》2003,14(2):34-36,63

利用美国Landsat-5TM7、TM5、TM3波段假彩色合成图像,对广西岩溶石漠化分布特征和形成条件进行遥感综合分析.结合石漠化发育严重的平果和大化县,用不同时相的TM图像进行对比,查明岩溶石漠化的萎缩原因.在总结石漠化变化规律的基础上,对石漠化强弱程度的划分进行了探讨.  相似文献   

国家预警工程综合地震波形分析系统设计与实现     

张莹莹  苗春兰  陈经纶  任克新  刘艳琼  苏柱金  沈玉松  欧阳龙斌  刘军  张立文  王兴梅  任枭  代光辉  安艳茹 《中国地震》2024,40(1):40-53

随着国家地震烈度速报和预警工程的建设,中国测震站网的监测能力获得大幅提升,对于地震编目业务的要求也随之提升,传统的编目产品已无法满足新形势下的业务需求,用于支撑全国地震编目业务的系统亟需升级换代。本文介绍了国家预警工程软件系统之一的综合地震波形分析系统,通过对系统概况、功能实现、关键技术和业务应用等详细介绍,阐述该系统如何用于支撑国家预警工程建成后的全国新编目业务。大数据和人工智能技术飞速发展的时代将为该系统及其产出的编目产品提供更加广阔的发展和应用空间。  相似文献   

大震应急产品产出与服务平台建设     

韩光洁  徐泰然  戴丹青  刘敬光  邓文泽  席楠 《中国地震》2024,40(1):208-222

地震时空强参数已不能满足日益增长的最大限度减轻地震灾害的需求。作为国家级地震监测中心,中国地震台网中心联合各研究所和试点省局,建设了大震应急产品产出与服务平台。中强震发生后,该平台准实时产出除地震三要素之外的多类地震参数和图件,为及时准确评估受灾区域和灾损程度、揭示地震成因和致灾机理提供了丰富的基础资料,第一时间服务于救援决策和震情会商,显著提升了国家级地震监测中心的应急处置和践行减轻地震灾害的能力。  相似文献   

Preliminary Research on the Characteristics of the M_S8.0 Wenchuan Earthquake Hazard     

Li Zhiqiang  Yuan Yifan  Li Xiaoli  Zhang Qin  Dai Boyang  Ye Youqing  Ge Peifeng  Zeng Jie 《中国地震研究》2009,23(3):278-298

The M_S8.0 Wenchuan earthquake on May 12, 2008 caused heavy casualties and economic loss. According to the field investigations, the characteristics can be described as follows: The meizoseismal region with an intensity of XI shows an obviously zonal distribution and suffered serious destruction from the earthquake, and the destruction perpendicular to the earthquake surface rupture decreased sharply. At the same time, the intensity X and IX regions perpendicular to the rupture are narrow and therefore their coverage area is small. The intensity on both sides of the rupture attenuates rapidly, but intensity VII and the VI regions are wide, the latter covering about 240,000 km~2. In intensity VI region, the damage area perpendicular to the rupture in the southern part is much larger than that of the northern part. Also, much new understanding about destruction types and destructive modes for all kinds of buildings, landforms and terrain is achieved in this paper.  相似文献   

An investigation on Balakot, Muzaffarabad (Pakistan) earthquake, 8 Oct. 2005, Mw 7.6; geological aspects and intensity distribution   总被引：1，自引：0，他引：1  

Mehdi Zaré  Sepideh Karimi-Paridari  MonaLisa 《Journal of Seismology》2009,13(3):327-337

In this paper, the investigations on seismotectonic and intensity evaluations of epicentral and meizoseismal regions in Muzaffarabad earthquake—8 Oct. 2005, Mw 7.6—are summarized using The European Macroseismic Scale (EMS-98). The observations are compiled based on the field investigations and isoseismal map. The results show that the isoseismals are elongated parallel to the reactivated Muzaffarabad fault, and the attenuation is high in the direction normal to the fault compared with the direction parallel to it. The geotechnical investigations in Muzaffarabad Valley have helped the authors to assign intensity values in the localities where some huge landslides are observed. Finally, the empirical laws, previously developed for intensity attenuation in Iran in EMS-98 scale, are compared with the intensity observations here. The results are roughly consistent with the general form of attenuation laws. However, it is found that the intensity attenuations are different in the directions normal and parallel to the fault.  相似文献   

Validation of a kinematic and parametric approach to calculating intensity scenarios     

Livio Sirovich  Franco Pettenati 《Soil Dynamics and Earthquake Engineering》2009

We employ our semi-empirical kinematic model for shear body waves (KF) [Sirovich L. A simple algorithm for tracing out synthetic isoseismals. Bull Seism Soc Am 1996;86(4):1019–27; Sirovich L. Synthetic isoseismals of three earthquakes in California-Nevada. Soil Dyn Earthquake Eng 1997;16:353–62] to back-predict and then validate the regional intensity scenario of a destructive earthquake (Loma Prieta, California, M_s 7.1, October 17, 1989). Only the pre-1988 geological and seismotectonic knowledge was used to set the 11 source parameters of KF (in this sense, our procedure was deterministic). Then, the ranges of the pre-1988 uncertainties were explored by grid search and the parametric combination produced 59,049 sources. The quality of our prediction was measured using the field intensities of 1989 by the US Geological Survey (in the MMI scale). The squared scenario residuals are: 73 for the mean KF scenario and 123 for the best available empirical attenuation of MMI intensity. We stress that, before using KF in the forward mode, its automatic inverse application has already been validated by refinding a series of earthquake sources [Gentile F, Pettenati F, Sirovich L. Validation of the automatic nonlinear source inversion of the US geological survey intensities of the Whittier Narrows, 1987 Earthquake. Bull Seism Soc Am 2004;94(5):1737–47; Pettenati F, Sirovich L. Intensity-based source inversion of three destructive California earthquakes. Bull Seism Soc Am 2007;97(5):1587–606; Sirovich L, Pettenati F. Source inversion of intensity patterns of earthquakes: a destructive shock in 1936 in northeast Italy. J Geophys Res 2004;109:B10309, doi:10.1029/2003JB002919:1–16]. If our technique had been available at the time, the 1989 pattern of damage south of San Francisco would have been conservatively foreseen even from 1983 on.  相似文献   

Intensity Retrieved from Public Monitoring Video——Cases from the May 12,2008,Wenchuan Earthquake     

Yang Xiaolin  Wu Zhongliang  Xia Min 《中国地震研究》2008,22(3):229-236

Macroseismic investigation is presented with a new potential means of investigation in the ＂digital age＂. In this paper we studied several cases in the May 12, 2008, Wenchuan Ms8.0 earthquake with a view to exploring the feasibility of retrieving intensity, or even strong ground motion parameters, from public monitoring video which was originally deployed for security purposes. We used public monitoring video records from 44 sites across the meizoseismal region and its surroundings to estimate the intensity. By using the video from a bank in Dujiangyan, Sichuan Province and making the simple assumption that ground vibration is in the form of a propagating harmonic wave, we estimated that the local ground motion acceleration was 0.14g.  相似文献