1321号台风“蝴蝶”强度变化特征和影响因素分析

利用NCEP/NCAR全球再分析格点资料（空间分辨率1°×1°）、台风实况资料及海南省气象台站观测资料,选取1321号台风＂蝴蝶＂为研究个例,从天气学原理高低空形势及动力、热力学物理量等多角度分析了＂蝴蝶＂强度演变特征及影响因素.研究结果表明,副热带高压与高空西风槽是影响此次台风的主要大尺度天气系统,弱冷空气南侵、南海海温偏高及越赤道气流强盛是＂蝴蝶＂迅速加强的重要原因.西风槽引导弱冷空气南侵使得台风外围环流气压梯度增加,斜压不稳定状态加剧;南海海温达到29℃,海温偏高使台风区域大气层结降低,深热对流发展;105°E越赤道气流强盛为台风提供了充沛水汽和能量.三者共同作用促使台风强度突然增强.另外,低层涡度、高层散度、湿位涡及水汽通量等物理量能够较好地表征＂蝴蝶＂强度变化特征.低层辐合流入、高层辐散流出为台风的加强提供了动力条件;湿位涡下负上正表明大气热力层结不稳定;水汽通量增加表明水汽条件充足.良好的动力条件、热力条件与水汽条件共同作用,使得＂蝴蝶＂在短时间内迅速加强为强台风.     

寒区工程动荷载模型试验系统设计

寒区工程动荷载模型试验系统主要由模型试验槽、制冷及控温装置、动力加载装置、传感器和数据采集系统四部分组成．系统具有如下特点：能根据实际工程对长3m、宽2．5rn和高1m的模型试验土体进行低温动荷载试验;采用3组冷冻板给土体降温,降温速度快,能提供的最低温度为-20℃,而且能提供多组均匀、稳定的温度边界,冷冻板的温度波动...     

Evidence for freeze–thaw events and their implications for rock weathering in northern Canada

Discussions regarding weathering in cold environments generally centre on mechanical processes and on the freeze–thaw mechanism in particular. Despite the almost ubiquitous assumption of freeze–thaw weathering, unequivocal proof of interstitial rock water actually freezing and thawing is singularly lacking. Equally, many studies have used the crossing of 0 °C, or values close to that, as the basis for determining the number of ‘freeze–thaw events’. In order to assess the weathering regime at a site in northern Canada, temperatures were collected at the surface, 1 cm and 3 cm depth for sets of paving bricks, with exposures both vertical and at 45°, orientated to the four cardinal directions. Temperature data were collected at 1 min intervals for 1 year. These data provide unequivocal proof for the occurrence of the freezing and thawing of water on and within the rock (freeze–thaw events). The freeze event is evidenced by the exotherm associated with the release of latent heat as the water actually freezes. This is thought to be the ?rst record of such events from a ?eld situation. More signi?cantly, it was found that the temperature at which freezing occurred varied signi?cantly through the year and that on occasion the 1 cm depth froze prior to the rock surface. The change in freeze temperature is thought to be due to the chemical weathering of the material (coupled with on‐going salt inputs via the melting of snowfall), which, it is shown, could occur throughout the winter despite air temperatures down to ?30 °C. This ?nding regarding chemical weathering is also considered to be highly signi?cant. A number of thermal stress events were also recorded, suggesting that rock weathering in cold regions is a synergistic combination of various chemical and mechanical weathering mechanisms. Copyright © 2003 John Wiley & Sons, Ltd.     

鄂霍次克海冷泉沉积物真核生物多样性的初步研究

从鄂霍次克海沉积物样品中提取总基因组DNA,进行核糖体rRNA基因内转录间隔区(ITS)的扩增,构建克隆文库并进行测序,对该环境下真核生物的多样性进行了初步研究。结果发现,该环境下的真核生物具有较高的多样性,主要为3大类,真核藻类、真菌和微型浮游动物。藻类和微型浮游动物的组成与前人在该海域浮游生物生态学的研究相吻合,而真菌群落具有较高的多样性,这为该区域真核生物多样性、所参与的生物地球化学过程及生态学意义的研究奠定了基础。     

NUMERICAL STUDY ON THE ROLE OF VORTICAL AND DIVERGENT COMPONENTS OF WIND STRESS IN ENSO CYCLE

The 1960-1991 monthly mean FSU (Florida State University)wind stress data aredecomposed into a vortical and a divergent component with each of which to force the model oceanin the context of a two-layer tropical Pacific model.Evidence suggests that for the seasonalvariation the ocean forcing does not produce a realistic cold tongue using either of the componentsand the tongue will not be effectively improved in its intensity and pattern even if the componentsare doubled or halved:the utilization of climatic mean wind stress(no decomposition is done of thewind stress)that contains its seasonal variation will lead to a realistic SST distribution on which isimposed,separately,the interannual anomalies of each of the components so as to get the SSTApattern:under the action of the interannual anomaly of the vortical(divergent)component therearises qnite intense SSTA oscillation marked by noticeable ENSO periods(feeble SSTA withhigher oscillation frequency for obscure ENSO periods),thereby illustrating that the roles of thetwo components differ from each other in the genesis of SST variation on a seasonal and aninterannual basis such that a realistic cold tongue pattern follows under the joint effects on themodel ocean of the two components of wind stress while rational E1 Nino/La Nina phenomenaresult under the forcing of an anomalous wind stress vortical component.Moreover,the divergentcomponent is innegligible in generating a mean climatic condition of the ocean sector but of lessimportance compared to the vortical component in ENSO development.     

东北地区水稻障碍型低温冷害变化对区域气候增暖的响应

利用东北地区153个气象站1961—2010年逐日气温资料,采用统计学方法分析了水稻障碍型低温冷害的气候变化特征及其对区域气候变暖的响应情况。结果表明,东北大部地区水稻障碍型低温冷害事件呈减少趋势,但区域性较为明显;障碍型低温冷害对关键发育期气温变化响应较为敏感,二者呈显著的负相关关系,表现为气温每升高1 ℃,东北地区冷害减少35个站次。东北地区关键发育期气温均呈上升趋势,但吉林西部地区障碍型冷害却随之增加,分析了关键发育期气温变率和气候变率,将其解释为局地障碍型冷害增加主要受气候变率增大的影响,逐日气温变率对其影响不大。     

太平洋年代际振荡冷、暖背景下ENSO循环的特征

利用英国气象局哈德莱中心的月平均海温距平资料、美国Scripps海洋研究所联合环境分析中心(JEDAC)的海表和次表层海温观测资料以及NCEP/NCAR再分析资料,研究了太平洋年代际振荡(PDO)不同背景下ENSO循环的特征.结果表明,PDO为ENSO循环提供了一个年代际气候背景,在PDO的暖位相时期,El Nino事件发生的频率较高,强度较强;反之,在PDO的冷位相时期,La Nina事件发生的频率较高,强度较强.而且在不同的太平洋年代际振荡背景下,ENSO循环表现出不同的特征.在PDO冷位相时期,发生El Nino(La Nina)事件时,正(负)的SOTA从西太平洋沿温跃层向东传播,正(负)的SSTA从赤道东太平洋向西扩展到中太平洋,ENSO事件先在赤道东太平洋爆发.在PDO的暖位相时期,发生El Nino(La Nina)事件时,正(负)的SOTA首先出现在赤道中太平洋,然后沿温跃层向东传播,正(负)的SSTA从赤道中太平洋向东扩展到东太平洋,ENSO事件首先在中太平洋爆发.这为ENSO预测提供了新的线索.     

寒区灌丛与积雪关系研究进展

在气候变化的背景下, 寒区灌丛与积雪的相互关系成为寒区水文循环研究的重要环节. 综述近几十年来寒区灌丛-积雪相互关系的国内外研究现状, 并对未来研究提出了展望. 寒区灌丛过去几十年来覆盖面积和生物量等呈现增加趋势, 灌丛的增加可截留积雪, 改变积雪重分布, 影响积雪消融过程; 积雪可增加灌丛区地温, 制约灌丛区融雪时空变化过程, 影响寒区灌丛的生理生态过程. 灌丛与积雪同为寒区自然生态系统和环境的重要组成部分, 二者相互作用使地面太阳辐射和地表水分分配过程复杂化, 从而间接地影响寒区冻土环境变化. 最后, 指出了未来研究需要重点关注的几个问题: 寒区灌丛区积雪分布的精确估计; 灌丛-积雪-冻土连续体的研究; 耦合灌丛-积雪作用的寒区水文模型的构建.     

一次罕见大冰雹天气的新一代天气雷达回波分析

利用常规资料和多普勒雷达资料,分析了2011年6月24日洛阳嵩县冰雹天气过程。结果表明：高空横槽转竖,干冷空气入侵,中低层强的偏东风辐合,暖湿气流辐合上升,为冰雹的发生提供了有利的动力和水汽条件;高空冷平流,低层暖平流,为强对流性天气的发生提供了不稳定层结;适宜于冰雹生成发展的0℃层高度,指示有利于对流发展的各类指数,为冰雹的分析预报提供了较好的依据;早期的雷达回波信号及其所带来的天气,为提前对强对流天气性质正确判断和监测预警提供了较好的参考信息;强度〉55dBz的回波高度高于-20℃层高度,VIL值〉60kg／m^2,回波顶高〉12km,有中气旋出现等,是降雹的可靠信号。     

一次东北冷涡天气过程双偏振雷达降水粒子相态识别

本文利用双偏振天气雷达资料,对2019年6月7-9日辽宁地区一次东北冷涡强对流天气过程进行分析。分析了东北冷涡的演变过程以及双偏振雷达的偏振参量在降水粒子相态识别中的作用,研究了不同判别规则对模糊逻辑算法识别结果的影响。结果表明：双偏振雷达的偏振参量可以对水凝物的种类、空间分布、物理形态进行大致判断,但水凝物相态识别结果仍需细化。模糊逻辑算法在强回波区域的识别结果更准确,采用不同的判别规则得到的水凝物分类结果虽存在一定差异,但在大部分观测区域的分类结果基本一致,符合天气演变规律,能够为气象预报预警提供鉴别参考。具有广泛时间、空间适配性的模糊逻辑算法,仍需大量实测案例数据的验证与仿真。