登陆台风变性发展与消亡的对比分析   总被引：2，自引：2，他引：2       下载免费PDF全文

韩桂荣  唐晓文  魏建苏 《气象科学》2007,27(1):35-41

本文对0421(海马)和0311(环高)台风登陆后不同的演变过程进行了对比分析。分析表明,虽然两次台风登陆的时间和路径都很相似,但是由于环境场的形势的不同,特别是北方冷空气情况的不同,一个变性发展成为温带气旋,给江苏地区带来了大面积的降水,另一个直接减弱消失,仅在登陆点附近产生了一些降水。通过讨论锋生函数各项的性质和计算其主要项的分布特征,对变性过程进行了研究,发现台风变性初期其锋生函数中变形项起主要作用。锋生结果造成强烈的辐合上升运动,引起台风暴雨的增幅。  相似文献   

Seasonal Transition Features of Large-Scale Moisture Transport in the Asian-Australian Monsoon Region   总被引：18，自引：0，他引：18  

何金海  孙丞虎  刘芸芸  李维京 《大气科学进展》2007,24(1):1-14

Using NCEP/NCAR reanalysis data for the period of 1957-2001, the climatological seasonal transition features of large-scale vertically integrated moisture transport （VIMT） in the Asian-Australian monsoon region are investigated in this paper. The basic features of the seasonal transition of VIMT from winter to summer are the establishment of the summertime ＂great moisture river＂ pattern （named the GMR pattern） and its eastward expansion, associated with a series of climatological events which occurred in some ＂key periods＂, which include the occurrence of the notable southerly VIMT over the Indochina Peninsula in mid March, the activity of the low VIMT vortex around Sri Lanka in late April, and the onset of the South China Sea summer monsoon in mid May, among others. However, during the transition from summer to winter, the characteristics are mainly exhibited by the establishment of the easterly VIMT belt located in the tropical area, accompanied by some events occurring in ＂key periods＂. Further analyses disclose a great difference between the Indian and East Asian monsoon regions when viewed from the meridional migration of the westerly VIMT during the seasonal change process, according to which the Asian monsoon region can be easily divided into two parts along the western side of the Indochina Peninsula and it may also denote different formation mechanisms between the two regions.  相似文献   

集合敏感性分析在北半球中纬度高影响天气中的应用     

郑明华  杜钧  Brian A.Colle 《气象科学进展》2020,10(2):42-57

总结回顾了集合敏感性分析(ESA)在诊断中纬度高影响天气预报不确定性中的应用。作为一个简单高效且不需要大量计算资源的方法,集合敏感性分析主要被应用在中纬度气旋、台风或飓风的温带转换,以及在强对流过程中诊断预报误差和不确定性的来源。集合敏感性方法极有灵活性,可以根据实际需要改变不同的预报变量和初始场。在对2010年美国东岸圣诞节暴风雪的分析中,集合敏感性分析通过三种形式来诊断了预报不确定性的初值敏感性,即基于EOF分析的敏感性、预报差别的敏感性,以及基于短期预报误差的向前积分敏感性回归。三种方法证实气旋路径的不确定性主要和位于美国南部大平原的短波槽初始误差相关。此外,气旋强度的不确定性还和产生于北太平洋向下游延伸的罗斯贝波列相关。集合敏感性分析方法对于分析中纬度气旋的不确定性、诊断初值敏感性、分析误差发展机制都非常有效。集合敏感性分析也被应用于分析台风/飓风的温带气旋转换过程的不确定性。在对2019年美国首个主要登陆台风Dorian的分析中发现,加拿大CMC的集合预报主要不确定性来自于强度的不确定性,而这个不确定性与初始时刻的大尺度环流型有关,较连贯的信号可以追溯至东北太平洋的前倾槽。而NCEP和ECMWF的不确定性主要在于气旋位置的东北—西南向移动,而敏感性主要和飓风系统本身(即其北部低压区和中纬度槽)的锁相有关。分析结果进一步验证了集合敏感性分析对诊断模式之间的不一致性,以及模式成员之间不一致性的不确定性来源和发展过程的可靠性。集合敏感性分析方法综合了集合预报、资料同化和敏感性分析,因此对于资料同化技术改进、诊断模式误差(或者缺陷)、附加(目标)观测最优策略,以及评估观测对预报的影响等都有重要意义。同时可以更有效地利用集合预报信息,帮助预报员提高情景意识,最终减少高影响天气预报中的决策失误。  相似文献   

Transition process from nucleation to high-speed rupture propagation: scaling from stick-slip experiments tonatural earthquakes     

Bunichiro Shibazaki  & Mitsuhiro Matsu'ura 《Geophysical Journal International》1998,132(1):14-30

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Fidelity and time resolution of the magnetostratigraphic record in Siwalik sediments: high-resolution study of a complete polarity transition and evidence for cryptochrons in a Miocene fluviatile section     

Wolfgang Rösler  & Erwin Appel 《Geophysical Journal International》1998,135(3):861-875

The Surai Khola section in southwest Nepal, a 5000 m continuously exposed record of fluvial sedimentation since Middle Miocene, was revisited for high-resolution magnetostratigraphy in sequences with expected cryptochrons and reversals of the geomagnetic field. Polarity intervals with durations of a few tens of thousands of years are recorded as zones of stable palaeomagnetic directions. Polarity transitions are recorded as zones with complex demagnetization behaviour of specimens in the sedimentary column. Almost antiparallel palaeoremanence directions, residing in different haematite phases in the same specimens, could generally not be separated properly by thermal demagnetization. Differing demagnetization paths for neighbouring specimens during a reversal suggest that measured transitional directions are not true geomagnetic field directions, but rather are generated by the superposition of variable amounts of at least two almost antiparallel components of magnetization. Accompanying studies of recent river sand deposits demonstrate that these sediments acquire a true depositional remanent magnetization (DRM) with considerable inclination errors and scattered directions for individual specimens.  相似文献   

Thickness estimates of the upper-mantle transition zone from bootstrapped velocity spectrum stacks of receiver functions   总被引：1，自引：0，他引：1  

HaroldGurrola  J.Bernard Minster 《Geophysical Journal International》1998,133(1):31-43

We modify the receiver-functions stacking technique known as velocity spectrum stacking (VSS) so as to estimate combinations of velocity model ( V_P and V_S ) and depth that stack the Ps conversion from upper-mantle discontinuities most coherently. We find that by estimating the differences in the depths to the 660 and 410 km discontinuities using velocities that maximize the stacked amplitudes of P410s and P660s phases we can estimate the thickness of the transition zone more accurately than the depths to either of these discontinuities. We present two examples indicating that the transition zone beneath Obninsk, Russia, is 252±6 km thick and that beneath Pasadena, California, is only 220±6 km thick.  相似文献   

Study on fine structure of crust-mantle transition zone in Yanqing-Hailai basin based on CDP and DSS data     

成瑾  李清河 《地震学报(英文版)》1998,11(1):81-88

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东天山大型韧性剪切带基本特征与金矿预测   总被引：28，自引：3，他引：25  

杨兴科  姬金生 《大地构造与成矿学》1998,22(3):209-218

东天山大型韧性剪切带即秋格明塔什-黄山韧性剪切带,规模宏大,东西长逾600km,宽5～20km。变形标志明显,分四期变形。应变测量、岩组分析、剪切位移量计算、同位素测年等定量分析表明：①以平面单剪应变为主,稍晚向伸长应变转化;②存在逆冲剪切和脆-韧性变形转换;③剪切位移量在75km以上;④变形时代在300～250Ma之间,高峰期在285～265Ma,属海西中晚期。它是康-黄断裂带的重要组成体,控制着康古尔塔格金矿带的空间展布。据现有大中型金矿研究建立了区域脆-韧性变形转换带结构模式和金矿预测模式,可有效指导找矿勘探。  相似文献   

Mantle heat flow and geotherms for major tectonic units in central Europe     

Jacek Majorowicz 《Pure and Applied Geophysics》1978,117(1-2):109-123

The results of seismic measurements along the deep seismic sounding profile VII and terrestrial heat flow measurements used for construction of heat generation models for the crust in the Paleozoic Platform region, the Sudetic Mountains (Variscan Internides) and the European Precambrian Platform show considerable differences in mantle heat flow and temperatures. At the base of the crust variations from 440–510°C in the models of Precambrian Platform to 700–820°C for the Paleozoic Platform and the Variscan Internides (Sudets) are found. These differences are associated with considerable mantle heat flow variations.The calculated models show mantle heat flow of about 8.4–12.6 mW m^–2 for the Precambrian Platform and 31 mW m^–2 to 40.2 mW m^–2 for Paleozoic orogenic areas. The heat flow contribution originating from crustal radioactivity is almost the same for the different tectonic units (from 33.5 mW m^–2 to 37.6 mW m^–2). Considerable physical differences in the lower crust and upper mantle between the Precambrian Platform and the adjacent areas, produced by lateral temperature variations, could be expected. On the basis of carbon ratio data it can be concluded that the Carboniferous paleogeothermal gradient was much lower in the Precambrian Platform area than in the Paleozoic Platform region.  相似文献   

Measurements of Reaction Coefficients of NO2 and HONO on Aerosol Particles     

Roy M. Harrison  Gareth M. Collins 《Journal of Atmospheric Chemistry》1998,30(3):397-406

The reaction coefficients of nitrogen dioxide and nitrous acid with monodisperse sodium chloride and ammonium sulphate aerosols have been measured in a flow reactor at atmospheric pressure. These experiments were performed at relative humidities above and below the deliquescence points of both aerosols (r.h. 50 and 85%) at 279 K. The results for NO₂ afford a reaction coefficient in the range (2.8–10) × 10^-4 and for HONO, (2.8–4.6) × 10^-3. For both species, there appears to be an enhancement of the reaction coefficient on sodium chloride aerosol at 50% r.h. The results are compared with reaction coefficients determined by other experimental methods. A good agreement is found for both gases between this method and the coated denuder method previously developed in our research laboratories (Msibi et al., 1993) and with the majority of other published data for NO₂. In the case of HONO, our estimate of reaction coefficient is smaller than, or at the lower limits of the ranges reported by other published studies.  相似文献