台风异常运动及其外区热力不稳定非对称结构的影响效应

本文数值模拟研究揭示了台风外区热力不稳定非对称结构对其异常路径的影响问题，提出了台风运动非对称结构的影响，不仅表现在台风涡旋动力结构特征上，而且反映在台风外区三维非对称热力结构特点方面，即包括温、湿不稳定层结分布特征及其强弱程度因素。台风外区不同热力非对称分布特征将导致台风移动轨迹的显著差异，且构成各类“旋转”、“打转”、“转向”等复杂异常路径。     

TRMM-retrieved Cloud Structure and Evolution of MCSs over the Northern South China Sea and Impacts of CAPE and Vertical Wind Shear

Cloud structure and evolution of Mesoscale Convective Systems(MCSs) retrieved from the Tropical Rainfall Measuring Mission Microwave Imager(TRMM TMI) and Precipitation Radar(PR) were investigated and compared with some pioneer studies based on soundings and models over the northern South China Sea(SCS).The impacts of Convective Available Potential Energy(CAPE) and environmental vertical wind shear on MCSs were also explored.The main features of MCSs over the SCS were captured well by both TRMM PR and TMI.However,the PR-retrieved surface rainfall in May was less than that in June,and the reverse for TMI.TRMM-retrieved rainfall amounts were generally consistent with those estimated from sounding and models.However,rainfall amounts from sounding-based and PR-based estimates were relatively higher than those retrieved from TRMM-TMI data.The Weather Research and Forecasting(WRF) modeling simulation underestimated the maximum rain rate by 22% compared to that derived from TRMM-PR,and underestimated mean rainfall by 10.4% compared to the TRMM-TMI estimate,and by 12.5% compared to the sounding-based estimate.The warm microphysical processes modeled from both the WRF and the Goddard Cumulus Ensemble(GCE) models were quite close to those based on TMI,but the ice water contents in the models were relatively less compared to that derived from TMI.The CAPE and wind shear induced by the monsoon circulation were found to play critical roles in maintaining and developing the intense convective clouds over SCS.The latent heating rate increased more than twofold during the monsoon period and provided favorable conditions for the upward transportation of energy from the ocean,giving rise to the possibility of inducing large-scale interactions.     

吉南老岭地区控矿构造特征分析

吉南老岭地区矿产资源丰富,大中型矿床众多,是吉林省的主要成矿区带。本文主要研究大地构造背景和地壳的演化规律及本地区韧性断裂、脆性断裂、韧脆性断裂及变质变形作用等构造类型的特征,进而阐明这些构造对矿产的控制作用。     

甘肃中川地区雷暴地闪特征的初步分析

本文分析了1987年6月28日甘肃中川地区一次雷暴过程中地面4个测站的电场资料,并定量估算了4个地闪的8个回击所中和的电荷量及其高度。负地闪回击所中和的电荷离地高度为4km左右(对应的环境温度为-11.2℃),而正地闪回击所中和的电荷离地高度为2km左右(环境温度+4.9℃)。负地闪大多发生在云闪后的电场恢复阶段,且在开始时往往具有持续几百毫秒的云内放电过程。其激发过程可能是首先在云底部正电荷区产生向上传输的持续正流光,导致云中部负电荷向下移动,并引发向下传输的负先导,最终导致地闪回击的发生。     

The Role of β-effect and a Uniform Current on Tropical Cyclone Intensity

A limited-area primitive equation model is used to study the role of the β-effect and a uniform current on tropical cyclone (TC) intensity.It is found that TC intensity is reduced in a non-quiescent environment compared with the case of no uniform current.On an f-plane,the rate of intensification of a tropical cyclone is larger than that of the uniform flow.A TC on a β-plane intensifies slower than one on an f-plane.The main physical characteristic that distinguishes the experiments is the asymmetric thermodynamic (including convective) and dynamic structures present when either a uniform flow or β-effect is introduced.But a fairly symmetric TC structure is simulated on an f-plane.The magnitude of the warm core and the associated subsidence are found to be responsible for such simulated intensity changes.On an f-plane,the convection tends to be symmetric,which results in strong upper-level convergence near the center and hence strong forced subsidence and a very warm core.On the other hand,horizontal advection of temperature cancels part of the adiabatic heating and results in less warming of the core,and hence the TC is not as intense.This advective process is due to the tilt of the vortex as a result of the β-effect.A similar situation occurs in the presence of a uniform flow.Thus,the asymmetric horizontal advection of temperature plays an important role in the temperature distribution.Dynamically,the asymmetric angular momentum (AM) flux is very small on an f-plane throughout the troposphere.However,the total AM exports at the upper levels for a TC either on aβ-plane or with a uniform flow environment are larger because of an increase of the asymmetric as well as symmetric AM export on the plane at radii ＞450 km,and hence there is a lesser intensification.     

Ekman动量近似下中间边界层模式中的风场结构

发展了一个准三维的、中等复杂的边界层动力学模式，该模式包含了EKman动量近似下的惯性加速度和Blackadar的非线性湍流粘性系数，它进一步改进了Tan和Wu(1993）提出的边界层理论模型。该模型在数值计算复杂性上与经典Ekman模式相类似，但由于包含了Ekman动量近似下的惯性项，使得该模式比传统Ekman模式更近于实际过程。中详细地比较了该模式与其他简化边界层模式在动力学上的差异，结果表明：在经典的Ekman模式中，由于忽略了流动的惯性项作用，导致在气旋性切变气流（反气旋性切变气流）中风速和边界层顶部的垂直速度的高估（低估），而在半地转边界层模式中，由于高估了流动惯性项的作用，结果与经典Ekman模式相反。同样，该模式可以应用于斜压边界层，对于Ekman动量下的斜压边界层风场同时具有经典斜压边界层和Ekman动量近似边界层的特征。     

低压倒槽影响下积层混合云形成过程模拟研究

利用多普勒雷达资料和中尺度天气预报模式wRF（Weather Research and Forecasting）模拟结果,对2009年5月9—10日发生在太原及其周边地区的一次积层混合云降水形成过程进行分析。结果表明,在积层混合云的形成初期,局地对流云得到发展,随着其强度不断增强,与周围云发生并合过程（包括局地单体对流的并合、积云团的并合和积层混合云内强中心的并合）,形成范围较大的积层混合云云系。局地单体对流和积云团的并合可带来云体的爆发性增长,霰含量、雨水含量大幅增加。积层混合云内强中心的并合对降水强度影响不大,但有利于降水面积扩大。低压倒槽和弱冷锋是此次积层混合云形成和维持的主要影响因素。低压倒槽有利于低层大范围不稳定能量的积累,风向切变有利于近距离云团的发展和并合,山地动力和热力作用有利于局地对流单体、积层混合云内强中心的形成和加强。     

日光诱导叶绿素荧光辐射传输模型研究进展

日光诱导叶绿素荧光(SIF)是指示植被光合作用过程的无损探针,在不同时空尺度上对植被进行SIF的观测可以反映植被的实际光合作用及生理状态。然而在观测、分析和利用SIF的过程中,仍存在很多不确定因素。SIF的发生具有较为复杂的机理,从机理出发理解SIF与植被结构的相互作用,并分析影响SIF激发的主要因素将有助于更好地理解SIF与光合作用以及生物量的内在联系。因此,植被SIF辐射传输模型在解释和利用SIF遥感信号方面具有重要的作用。植被SIF信号相对较弱,且受环境、植被和生理等多种因子的影响,需要定量化描述,这为SIF辐射传输模型的构建带来挑战。近年来,大量学者已经发展一系列SIF辐射传输模型,为SIF遥感的发展提供了坚实的理论基础。本文回顾了叶片、冠层和生态系统尺度的SIF模型,从建模机理出发,对比模型优劣势,并对未来SIF模型的发展前景进行了展望。     

长春地区对流云起电过程的数值模拟

在三维强风暴动力和电耦合数值模式的基础上,考虑了粒子直径及降落末速差对转移电荷的影响,把非感应起电参数化方案作了进一步改进,对长春地区两次不同强度、不同环境风切变的对流云内电荷累积和电场发展过程进行了模拟分析。结果表明,对流云上升气流达到极大值时,较强和较弱两块云分别具有三极性和反偶极性电荷分布结构。垂直上升气流是表明电场发展强弱的重要参量。对发展强烈的对流云,较强的上升气流使霰和冰晶在云体的中上部维持较长的时间．存在感应和非感应起电的跃增。