Response of Atmospheric Low-frequency Wave to Oceanic Forcing in the Tropics     

FuZuntao  Zhao Qiang  QiaoFangli  Liu Shikuo 《大气科学进展》2000,17(4):569-575

1. IntroductionInvestigations about atmospheric LFW have been a focus of research since Madden andJulian/s outstanding analysis works (1971, 1972). Many dynamical and thermal mechanisms(Chao et al., 1996; Fu et al., 1998; Hendon et al., 1998; Krishnamurti et al., 1988; Lau andChan, 1988) have been advised to explain LFW. Among them are oceanic effects, such as SSTeffect, thermal forcing and others. Usually atmosphere and ocean are taken as a coupled system, which is used to explain ENS…  相似文献   

1981年7月9-14日四川持续性暴雨分析   总被引：3，自引：0，他引：3  

张小玲  张建忠 《应用气象学报》2006,17(Z1):79-87

1981年7月9—14日岷江、沱江、涪江和嘉陵江流域出现持续性暴雨,并在四川省造成了历史上最严重的洪涝灾害。该文利用逐日降水资料、NCEP/NCAR 2.5°×2.5°逐日再分析资料和日本GMS卫星资料反演的TBB资料进行诊断分析以探讨此次暴雨持续的原因。结果表明:由于对流层低层的暖平流和其他大尺度强迫,高空槽长时间维持在长江上游地区,有利于槽后冷空气下沉南伸,与来自孟加拉湾的暖湿气流在盆地交汇,致使西南涡东移甚慢,于7月11—14日活跃在四川盆地上空。当西南涡沿梅雨锋缓慢东移时,长生命史的中尺度对流系统(MCS)在岷江、沱江、涪江和嘉陵江流域连续多次生消,导致暴雨系统持续维持在这些地区。大尺度的强迫在暴雨区上空产生了大范围持续性的上升运动,而暴雨所需的强上升运动主要由大量局地对流有效位能释放提供。对流层低层持续的水汽辐合和位势不稳定能量的输送则为暴雨的持续提供了充足的水汽和能量。与2004年9月发生在四川盆地东部的严重致洪持续性暴雨比较发现,虽然两次持续性暴雨发生的环流背景不同,但暴雨发生的物理机理一致,暴雨过程中持续性的上升运动均主要由大尺度强迫等引起,而且两次持续性暴雨的发生均与来自孟加拉湾的强水汽输送有关。  相似文献   

大试管回流消解-等离子体发射光谱／质谱法测定植物样品中多元素   总被引：2，自引：1，他引：2  

马生凤温宏利  巩爱华孙德忠 《岩矿测试》2007,26(3):183-187

采用大试管和红外加热的多孔控温消解炉的简单装置消解植物样品，电感耦合等离子体发射光谱／质谱法测定其中的主量和痕量元素，对消解温度、消解时间、消解溶剂、样品取样量等条件进行考察。用植物国家一级标准物质进行前处理及测定，验证方法的可行性，测定值与标准值基本吻合。方法不仅能同时测定B、Ba、Ca、Cd、Cu、K、Mg、Mn、Na、Ni、P、S、Zn、CoSr、Pb、Cr等元素，还适用于Hg、As挥发性元素的消解测定。方法的精密度（RSD，n=10）≤10％。  相似文献   

东亚夏季风强弱年大气环流和热源异常对比分析   总被引：1，自引：0，他引：1       下载免费PDF全文

吕俊梅张庆云陶诗言琚建华 《应用气象学报》2007,18(4):442-451

根据黄刚等定义的东亚夏季风指数, 对强、弱东亚夏季风年大气环流、大气热源和外强迫源SST的差异进行分析, 结果表明:强 (弱) 东亚夏季风年前期冬季到夏季, 太平洋SSTA为La Ni?a (El Ni?o) 型分布, 西太平洋暖池SST暖 (冷), 使得暖池附近对流活动较强 (较弱)。与此同时, 南亚大陆从印度半岛、青藏高原南部、中南半岛至华南大气异常加热 (变冷), 并且海陆热力对比加强 (减弱), 有利于出现强 (弱) 的东亚夏季风。此外, 由于暖池附近对流活动强 (弱), 该地区上升气流较强 (弱), Walker环流增强 (减弱), 当强 (弱) 的东亚夏季风向北推进时, 副热带西风急流北撤位置偏北 (南), 副热带高压位置也偏北 (南), 7月至8月华北 (江淮流域) 位于副热带西风急流南侧, 降水偏多, 江淮流域 (华北) 降水偏少。并给出与东亚夏季风年际变异有关的大气环流和SST异常的物理图像。  相似文献   

夯扩桩沉管控制贯入度计算法     

周武阶 《地质与勘探》1998,34(5):53-55

通过改造格尔谢万诺夫打桩公式,提供了夯扩桩沉管控制贯入度计算表达式,在此 ,介绍了沉积控制贯入度在夯扩桩设计和施工中的用途,并举例验证。  相似文献   

Sea level,climate change and coastal evolution in Morar,northwest Scotland     

Shennan  Ian  Tooley  Michael  Green  Frances  Innes  Jim  Kennington  Kevin  Lloyd  Jeremy  Rutherford  Mairead 《Geologie en Mijnbouw》1998,77(3-4):247-262

Analyses of geomorphologically contrasting sites in Morar, NW Scotland, describe the forcing mechanisms of coastal change. Isolation basins (i.e. basins behind rock sills and now isolated from the sea following isostatic uplift) accumulated continuous marine and freshwater sediments from c.12 to 2 ka BP. Raised dune, marsh and wetland sites register breaching, migration and stability of dunes from c. 9 to 2 ka BP. High-resolution methods designed to address issues of macroscale and microscale sea-level changes and patterns of storminess include 1-mm sampling for pollen, dinocyst and diatom analyses, infra-red photography, X-ray photography and thin-section analysis. The data enhance the record of relative sea-level change for the area. Major phases of landward migration of the coast occurred during the period of low sea-level rise in the mid-Holocene as the rate of rise decreased from c. 3 to < 1 mm/year. Relative sea-level change controls the broad pattern of coastal evolution at each site; local site-specific factors contribute to short-term process change. There is no record of extreme events such as tsunami. Within a system of dynamic metastable equilibrium, the Holocene records show that site-specific factors determine the exact timing of system breakdown, e.g. dune breaching, superimposed on regional sea-level rise. The global average sea-level rise of 3 to 6 mm/yr by AD 2050 predicted by IPCC would only partly be offset in the Morar area by isostatic uplift of about 1 mm/yr. A change from relative sea-level fall to sea-level rise, in areas where the regional rate of uplift no longer offsets global processes, is a critical factor in the management of coastal resources.  相似文献   

钢管高强混凝土叠合柱的抗震性能研究   总被引：11，自引：1，他引：10  

李惠  吴波  林立岩 《地震工程与工程振动》1998,18(1):45-53

通过周期性往复试验,研究了钢管高混凝土叠合柱柱的破坏形态,耗能能力、延性、承载力以及各种组成部分共同工作等内容,并与钢管高强混凝土核心柱进行了对比;随后通过计算,讨论了叠合柱中有关参数对其极限承载力和影响;最后给出了叠合柱正截面极限承载力的简化计算方法。  相似文献   

探讨气候变化的新热点:大气气溶胶的气候效应   总被引：12，自引：0，他引：12  

付培健  王世红  陈长和 《地球科学进展》1998,13(4):387-392

气溶胶的气候效应是近年来研究的热点问题。针对这一问题已开展过许多观测研究和模式研究。但是由于气溶胶问题的复杂性以及对气溶胶的观测历史短,至今尚缺少全球范围的气溶胶系统观测资料,所以目前气溶胶的辐射强迫仍是个很不确定的量。这直接影响对全球气候变化的预测。目前国内外正在加强这方面的研究工作,并且有了一些初步的结果。概述了近期国内外对气溶胶的气候效应的研究状况及结果,介绍了今后国际上将要在这一领域开展的研究工作。  相似文献   

    

Li Xingsheng  Zhou Jianqiang  Li Zhe  Fang Xiumei  He Zhuanshi  Farn Parungo 《大气科学进展》1998,15(1):63-73

Combining the Penn State/NCAR mesoscale (MM4) model, the dust transport model and an atmospheric radiative transfer model, a super duststorm process occurred in the Gansu province on 5 May 1993 has been simulated. Based on the observations of duststorms occurred in the northern China and the field measurements of dust particles' physical and optical properties, model simulating dust plume transport processes and dust particle radiative forcing have been devloped. The models are described and verified with real cases of dustorms.  相似文献   

SOUTHERN BOUNDARY FORCING RELATIVE TO GENESIS, MAINTENANCE AND OSCILLATION OF A SUBTROPICAL HIGH^*     

Lu Weisong  Tao Li 《Acta Meteorologica Sinica》1998,12(1):40-49

A nonlinear critical layer and a Kelvin cat's eye excited thereupon are simulated through four schemes in the context of a nonlinear quasi-geostrophic barotropic vorticity equation model with forced stationary wave acting along the southern boundary to investigate effects of tropical steady forcing on the genesis,maintenance and oscillation of a subtropical high(STH).Evidence suggests that the southern forcing is responsible for the planetary quasi-steady anticyclonic Kelvin cat's eye-form flow field inside the nonlinear critical layer,with the eye shifting,vigor and shape changing quite similar to the behaviors of a summer STH,in striking contrast to the northern stationary forcing.As such,the southern boundary-caused cat's eye is likely to be an even more important mechanism for STH genesis and evolution.In addition,a physical mechanism is introduced for quasi-steady planetary wave moving through the critical layer at subtropical latitudes.  相似文献