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.     

对流参数化方案的改进对GRAPES模式台风预报的影响研究

将由NCEP改进之后的SAS(Simplified Arakawa-Shubert Scheme)对流参数化方案（NSAS方案）应用到GRAPES模式中,并对“启德”台风进行模拟,通过和原来SAS方案的预报结果进行比较,发现新方案对台风路径预报有显著改进。通过对NSAS方案中几个新增加的因素进行敏感性试验,发现其中对由于对流引发的扰动气压场如何影响动量输送这个问题的处理使得台风路径预报效果变差,采用动量的水平混合代替风场切变来对扰动气压场进行参数化以后,可有效改进该方案的预报效果。考虑动量的水平混合系数随高度变化可进一步改善预报结果。通过比较多个台风的预报结果发现,这种改进对台风路径预报的改进较稳定      

成因地质模型法在湖南省早震旦世锰矿资源预测中的应用

在充分认识湖南省早震旦世锰矿成矿区域地质背景、矿床特征、控矿因素、成矿规律,矿床成因从而建立该类锰矿成矿模式的基础上,用成因地质模型法将其成矿模式转化为成因地质方法模型及矿床规模、找矿概率和矿床品位预测模型。应用这些模型对预测区进行预测,求出全省该类锰矿的资源总量,划分成矿远景区和预测区,对预测矿床进行技术经济评价和地质解释,论证预测结果的可靠性,提出下步工作意见。这对湖南今后的找锰矿工作具有一定实际意义。     

乌兰局长深入基层检查指导工作

近日，内蒙古气象局乌兰局长在包头市气象局杨耀芳局长、童振宇纪检组长陪同下深入包头市各基层台站检查指导工作。     

文化产业成长对城市空间形态演变的影响——以西安市核心区为例

基于扩展强度指数、等扇分析法、核密度分析及空间句法等方法,运用1998年、2008年、2018年3个时期的文化产业企业地理数据、夜间灯光数据及城市道路网轴线模型分析西安市核心区文化产业空间成长与城市空间形态演变的特征,探究二者空间关系与作用机制.结果表明:①西安市核心区文化产业沿"东北-西南"走向扩展,其空间集聚格局逐...     

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...     

科尔沁沙地夺奈曼旗普通风砂土中的粘土矿物

通过对科尔沁沙地奈曼旗普通风砂土中粘土矿物的研究,结果表明这类土壤中的粘土矿物主要是伊利石,其次为高岭石,绿泥石,伊利石－蒙脱石混层矿物;它们主要来源于母质,其次来自在土过程,降尘输入量极有限。随成土过程不断进行,粘土矿物主要遵循铝硅盐矿物－绿泥石－蒙脱石－蒙脱石顺序演变。由于母质本身贫乏,成土过程较弱以及比重差异使蒙脱石有独特的搬运与沉降行为,共同造成土壤中缺乏蒙脱石。     

SeaWinds散射计海面风场神经网络建模研究

根据Sea Winds散射计只有两个入射角和两种极化方式的特点,利用其L2A数据和F291海上浮标数据,针对传统建模方法的不足和限制,借助神经网络建立了一个两种极化方式下统一的神经网络地球物理模型函数。该模型的主要特点是建模风矢量全部取自海上浮标测量数据,因而所用风矢量更加客观准确。通过与Qscat-1模型的比较和L2B与浮标风速之间的偏差统计分析,证明了该神经网络模型的有效性,并发现Qscat-1模型存在一定的系统性偏差。     

逐时云迹风资料同化对暴雨预报的模拟试验

文中基于不同的云迹风同化方案,用GRAPES模式对2005年7月11—12日长江中下游一次暴雨强降水过程进行了云迹风资料同化试验及数值模拟,通过对比分析不同方案所得的分析场及预报场的差异,研究逐时云迹风资料三维变分同化对分析场及暴雨预报的影响。首先,根据连续性原理及双通道各层次云迹风资料的误差分析,分3个步骤对7月11日00：00—12：00 UTC共12个时次的双通道云迹风资料进行了初步的质量控制;然后,把经过质量控制的云迹风资料放入基于GRAPES 3D VAR三维变分同化方案开发的逐小时循环同化系统中进行同化,将得出的分析场与单一时次未经质量控制的云迹风资料同化得出的分析场进行对比,探讨了逐时云迹风资料同化对数值预报分析场的影响;最后,把同化后的分析场作为初始场,用 GRAPES模式对 2005年7月11—12日长江流域暴雨过程做24 h降水预报试验,分析两个同化方案所模拟得到的预报场的差异。结果表明,经资料的筛选、同经纬度单点通道的选择及资料的稀疏化3个步骤控制后,各层次云迹风资料的误差有明显减小;加入经质量控制的逐时云迹风资料其三维变分同化可以提高分析场中风压场及水汽场的质量;而且在暴雨预报试验中可以相对更准确地预报暴雨落区及雨强。     

长牡蛎(Crassostrea gigas)贝壳与外套膜中黑色素的提取和鉴定

为了提取和鉴定长牡蛎(Crassostrea gigas)贝壳与外套膜中的黑色物质,选取贝壳与外套膜颜色均为黑色的长牡蛎,将贝壳及外套膜进行粉碎、盐酸水解、水浴加热、乙醚抽脂,从3份贝壳中提取出3份黑色固体物质,从3份外套膜中提取出3份黑色固体物质,将提取的黑色固体溶解于0.01m L/L氢氧化钠水溶液中,在150—500 nm的范围内测定紫外吸收光谱,发现其最大吸收峰在210 nm左右,随着波长增加,其吸光值迅速大幅度下降,与公认的黑色素紫外吸收光谱特征一致,从而首次确定长牡蛎贝壳与外套膜中的黑色物质为黑色素。