Thermodynamics and Microphysical Characteristics of an Extreme Rainfall Event Under the Influence of a Low-level Jet over the South China Coast

In this paper, the data of Automatic Weather Stations (AWSs), ERA5 reanalysis, sounding, wind profile radar, and dual-polarization radar are used to study an extreme rainfall event in the south China Coast on 11 to 12 May 2022 from the aspects of thermodynamics and microphysical characteristics under the influence of low-level jets (LLJs). Results show that: (1) The extreme rainfall event can be divided into two stages: the first stage (S1) from 0000 to 0600 LST on May 12 and the second stage (S2) from 0700 to 1700 LST on the same day. During S1, the rainfall is mainly caused by the upper-level shortwave trough and the boundary layer jet (BLJ), characterized by strong upward motion on the windward side of mountains. In S2, the combined influence of the BLJ and synoptic-system-related low-level jet (SLLJ) increases the vertical wind shear and vertical vorticity, strengthening the rainstorm. In combination with the effect of topography, a warm and humid southwest flow continuously transports water vapor to farther north, resulting in a significant increase in rainfall over the study area (on the terrain’s windward slope). From S1 to S2, the altitude of a divergence center in the upper air decreases obviously. (2) The rainfalls in the two stages are both associated with the mesoscale convergence line (MCL) on the surface, and the wind field from the mesoscale outflow boundary (MOB) in S1 is in the same direction as the environmental winds. Due to a small area of convergence that is left behind the MOB, convection moves eastward quickly and causes a short duration of heavy rainfall. In S2, the convergence along the MOB is enhanced, which strengthens the rainfall and leads to strong outflows, further enhancing the surface convergence near the MOB and forming a positive feedback mechanism. It results in a slow motion of convection and a long duration of heavy rainfall. (3) In terms of microphysics, the center of a strong echo in S1 is higher than in S2. The warm-rain process of the oceanic type characterizes both stages, but the convective intensity in S2 is significantly stronger than that in S1, featuring bigger drop sizes and lower concentrations. It is mainly due to the strengthening of LLJs, which makes small cloud droplets lift to melting levels, enhancing the ice phase process (riming process), producing large amounts of graupel particles and enhancing the melting and collision processes as they fall, resulting in the increase of liquid water content (LWC) and the formation of large raindrops near the surface.     

试论地幔柱对于我国两大金矿集中区的控制意义

胶东和滇黔桂是我国两个典型的金矿集中区,它们在成矿特征和矿床成因上各不相同,但作为金矿集中区,它们可能都受到地幔柱构造的制约或影响,金可能都主要来自于深部或者来自于地幔柱头部,而容矿围岩的差别只是一个金的“捕集器”的不同而已。另外,胶东地幔柱演化较成熟,地壳物质剥蚀更强烈,因而大型金矿出露较多;而滇黔桂地区剥蚀相当弱,深部可能存在更大规模的金矿。     

计算机在图书馆管理中应用系统简介

为了改革传统的图书管理手段,实现图书管理系统的现代化,减轻馆员的劳务,提高服务水平和工作效率,使图书情报信息及时广泛的流通。因此,我们设计研制了《计算机在图书馆管理中的应用系统》(简称TS系统)。     

旋卷构造平面应力场之推导

旋卷构造在地壳构造中,特别是在地壳局部构造中,是最普遍的构造型式.据李四光同志的分析,当外力的合力不通过某岩块的重心(质量中心)时,则此岩块将围绕核心部分(砥柱或旋涡)与周围岩块发生旋扭运动,以致产生旋卷构造.旋卷构造有许多类型,如果我们仅考虑其平面应力场,从其成生的构造应力场的推导过程中,除S型和反S型构造以及歹字型构造体系(它们可能与两种构造运动的联合作用有关)之外,都具有统一     

The Longmen Cloud Physics Field Experiment Base, China Meteorological Administration

Aiming at the needs of mechanism analysis of rainstorms and development of numerical prediction models in south China, the Guangzhou Institute of Tropical and Marine Meteorology of China Meteorological Administration and the Chinese Academy of Meteorological Sciences jointly set up the Longmen Cloud Physics Field Experiment Base,China Meteorological Administration. This paper introduces the instruments and field experiments of this base, provides an overview of the recent advances in retrieval a...     

安徽省芜湖市区域农业生态环境质量的综合研究

区域农业生态环境，是一个地区发展农业乃至整个国民经济的重要基础。科学评价区域农业生态环境，既有利于摸清家底，为区域发展提供依据，更有利于进行区域环境规划和国民经济总体规划。然而，影响农业生态环境的要素众多，层次复杂。同时，农业生态系统又具有模糊性、多输入、多输出的特点，因此，评价区域农业生态环境，没有成熟的理论与方法可供借鉴。本文结合芜湖市的实际情况，运用综合的方法，引入模糊综合评价模型，对本区农     

汶川地震重灾区堰塞湖次生灾害危险性遥感评价

地震堰塞湖的破坏性不亚于地震灾害的直接破坏,开展堰塞湖的危险性评估,对灾后重建具有重要的参考意义.利用高分辨率遥感数据,结合辅助数据,确定了汶川灾区52处主要堰塞湖的名称、空间位置,识别出其鲜明的线状空间分布特征.堰塞湖的危险性评价,分为极度危险(1个)、高度危险(5个)和危险(46个)3个等级.遵循溃坝威胁区确定原则和方法,对堰塞湖溃坝威胁区进行了分析和划分,结果表明,重灾区受堰塞湖溃坝威胁的总面积为963.27km2,涉及18个县市(区)的134个乡镇.最后,对汶川地震重灾区的重建规划和堰塞湖风险规避提出了初步的建议.     

折射方法在南海北部潮汕坳陷中生界地层研究中的应用

潮汕坳陷是中生界地层为主的沉积坳陷,被认为是南海油气勘探的重要勘探领域.潮汕坳陷已有丰富的多道反射地震资料,但是由于多次波干扰严重,获取的反射波速度精度低.潮汕坳陷多道反射地震资料中包含丰富的折射波数据,但是很少人重视多道地震记录中的折射波信息并利用他.在此我们通过编写处理程序拾取了折射层的地震速度.试验测线所在海区的水深在600-800m,测线的最大偏移距为6 250m.测线所测的第三系地震折射波速度为2.0-2.5km·s-1,与潮汕坳陷其他地方的第三系地震波速度基本相等.但是潮汕坳陷西南部中生界的地震折射波速度在3.5-4.2km·s-1,低于潮汕坳陷中东部中生界的地震波速度(4.0-5.0km·s-1),预示潮汕坳陷西南部油气储集物性可能较好.