Cryosphere evapotranspiration in the Tibetan Plateau: A review

Land surface actual evapotranspiration is an important process that influences the Earth's energy and water cycles and determines the water and heat transfer in the soil-vegetation-atmosphere system. Meanwhile, the cryosphere's hydrological process is receiving extensive attention, and its water problem needs to be understood from multiple perspectives. As the main part of the Chinese cryosphere, the Tibetan Plateau faces significant climate and environmental change. There are active interaction and pronounced feedback between the environment and ET_a in the cryosphere. This article mainly focuses on the research progress of ET_a in the Tibetan Plateau. It first reviews the ET_a process, characteristics, and impact factors of typical underlying surfaces in the Tibetan Plateau (alpine meadows, alpine steppes, alpine wetlands, alpine forests, lakes). Then it compares the temporal and spatial variations of ET_a at different scales. In addition, considering the current greening of cryosphere vegetation due to climate change, it discusses the relationship between vegetation greening and transpiration to help clarify how vegetation activities are related to the regional water cycle and surface energy budget.     

基于地理国情数据的城市扩张和生态格局分析——以武汉市为例

城市扩张是城镇化的主要特征,研究城市扩张规律对城市空间规划、高质量发展提供决策依据。本文以武汉市为研究区,以2015—2018年地理国情监测成果为主要数据源,通过数据整理与提取、计算城市扩张特征指数、提取城市格局变化、计算生态景观指数等处理,对研究区城市扩张和生态格局变化特征进行分析。研究结果表明：2015—2018年间,武汉市从快速扩张阶段逐渐减缓,紧凑度逐渐下降;中心城市扩张主要以种植土地破坏为代价;远城区快速扩张主要以林草面积减少为代价;在生态指数上,各生态景观类型破碎度均有下降,但水域面积保持良好。     

2018?2019年舟山近海浮游动物群落结构春季年际变化及其与水团的关系

根据2018?2019年春季两个航次在舟山近海进行的浮游生物调查结果,对舟山近海的浮游动物群落结构(类群组成、优势种数量)年际变化进行了研究,利用典范对应分析(Canonical Correspondence Analysis, CCA)研究了两年春季浮游动物类群组成差异、优势种变化的原因,初步探讨了春季浮游动物群落结构动态变化的机制。结果表明:根据表层温度(Sea Surface Temperature,SST)、表层盐度(Sea Surface Salinity,SSS)的聚类分析,将该区域分为3个水团:杭州湾内水团(I区)、舟山本岛上升流水团II区)、舟山近海水团(III区)。不同水团对浮游动物类群组成影响显著,引起2018年和2019年春季3个水团区差异的主要贡献种(贡献率>10%)均为中华哲水蚤,同一水团两年间年际差异的贡献种如下:I区为捷氏歪水蚤(56.91%)和真刺唇角水蚤(12.34%);II区为中华哲水蚤(72.64%)、五角水母(13.35%);III区为中华哲水蚤(41.93%)、夜光虫(22.94%)。CCA分析表明,第1 CCA轴(CCA1)和第2 CCA轴(CCA2)共解释了两年春季浮游动物优势种累计方差的46.14%和物种?环境累计方差的97.82%。CCA1主要反映了空间(近海水团和湾内水团)的差异。CCA2主要反映了2018年和2019年站位的年际差异。盐度是影响春季浮游动物群落结构空间差异的主要因素,而温度、叶绿素a浓度是春季浮游动物群落结构年际差异的主要因素。     

2017年春季季风间期南海中北部浮游植物生长与微型浮游动物摄食

Phytoplankton growth rates and mortality rates were experimentally examined at 21 stations during the 2017 spring intermonsoon(April to early May) in the northern and central South China Sea(SCS) using the dilution technique, with emphasis on a comparison between the northern and central SCS areas which had different environmental factors. There had been higher temperature but lower nutrients and chlorophyll a concentrations in the central SCS than those in the northern SCS. The mean rates of phytoplankton growth(μ_0) and microzooplankton grazing(m) were(0.88±0.33) d~(–1) and(0.55±0.22) d~(–1) in the central SCS, and both higher than those in the northern SCS with the values of μ_0((0.81±0.16) d~(–1)) and m((0.30±0.09) d~(–1)), respectively.Phytoplankton growth and microzooplankton grazing rates were significantly coupled in both areas. The microzooplankton grazing impact(m/μ_0) on phytoplankton was also higher in the central SCS(0.63±0.12) than that in the northern SCS(0.37±0.06). The microzooplankton abundance was significantly correlated with temperature in the surface. Temperature might more effectively promote the microzooplankton grazing rate than phytoplankton growth rate, which might contribute to higher m and m/μ_0 in the central SCS. Compared with temperature, nutrients mainly affected the growth rate of phytoplankton. In the nutrient enrichment treatment,the phytoplankton growth rate(μn) was higher than μ_0 in the central SCS, suggesting phytoplankton growth in the central SCS was nutrient limited. The ratio of μ_0/μn was significantly correlated with nutrients concentrations in the both areas, indicating the limitation of nutrients was related to the concentrations of background nutrients in the study stations.     

Experimental Study and Fatigue Analysis of Vortex-Induced Vibration of Umbilical Cable Considering Internal Friction

In order to investigate the effect of internal friction of umbilical cable on its vortex-induced vibration(VIV)responses, the experimental study on VIV of bond umbilical cable(BUC) and un-bond umbilical cable(UBUC) was carried out in an experimental tank. A current generator in the laboratory simulated the uniform current, and the current velocities were observed in real time by using a Doppler Velocimeter. In addition, different sizes of top tension were applied to the umbilical cable model. The VIV responses of the umbilical cable model were measured by using Fiber Bragg grating(FBG) strain sensors. The displacement responses of umbilical cable model were reconstructed based on the experimental strain data processed by modal superposition method. In this paper, the traveling wave characteristics, the spatial-temporal distribution characteristics of frequency and fatigue damage of the BUC and UBUC under VIV are studied. The experimental results show that there are obvious differences between BUC and UBUC in the response characteristics of VIV. The UBUC appears the traveling wave sooner than BUC, but its standing wave characteristics are more obvious than those of BUC at high velocities. Compared with BUC, the spatial-temporal distribution of UBUC frequencies appears wide-band distribution sooner, but has narrower bandwidth in the "lock-in" state. The level of fatigue damage of BUC was approximately the same as that of UBUC.     

Python脚本在湖南省第三次国土调查数据库自检中的应用

第三次国土调查数据库是第三次国土调查工作的主要成果,是支撑未来自然资源管理各项工作的关键,其质量必须得到充分重视.对数据库进行充分自检并依据自检问题逐一修改,是减少后期工作量、保障第三次国土调查数据库质量的重要手段.本文通过对湖南省第三次国土调查数据库自检内容和方法的分析,梳理了第三次国土调查数据库自检工作存在的不足,...     

基于CFD的单个建筑物风场模拟参数选择

运用流体力学软件FloEFD对沽源单个建筑物周围的风场进行数值模拟。通过不断改变模型中计算参数的设置进行一系列模拟试验,对比模拟试验结果,并与观测资料进行比较,分析不同计算参数对模拟结果的影响,并获得适用于该模型的最佳参数。主要研究的计算参数包括计算域高度,初始网格等级,局部初始网格等级和不同平均风速剖面形式。结果表明:计算域高度从3倍建筑物高度开始,空腔区的长度、漩涡中心位置以及再发展区的边界位置基本保持稳定。随着初始网格等级的增加,空腔区的长度、再发展区的边界位置及计算时间逐渐增大。局部初始网格等级对模拟结果影响不显著。以两种不同平均风速剖面形式进行模拟,迎风漩涡长度不同,背风面影响不大。与观测资料比较显示,最优参数组合为:计算域高度为3倍建筑物高度,初始网格等级为4、局部初始网格等级为4、平均风速剖面形式为指数律。     

基于虚拟化云平台的气象终端集约化管理

气象终端的集约化管理是气象业务系统和气象服务需求发展到一定阶段后的必然趋势和结果。从气象终端管理的现状和需求、虚拟化云平台的技术体现和应用部署中,体现基于虚拟化云平台的气象终端集约化管理的应用特点和实施效果:提供虚拟防护、桌面管理及行为控制等的策略管理和策略服务,提升气象现代化支撑和保障气象用户个性化需求的能力,为气象平台建设、信息共享、应用服务的终端管理提出了全新概念,是集"应用"、"集成"、"运维"、"安全"到"成本控制"的解决方案。     

障碍物对风速风向影响的观测试验

随着城市化进程的加大,测站周围障碍物的存在使风观测资料失去代表性、准确性和比较性。为定量化研究障碍物对风观测的影响,开展了河北沽源构筑物观测试验,通过对比构筑物修建前后各测点的风速风向资料,分析了障碍物对风速风向的影响。分析结果显示:1障碍物对风速的衰减作用与背景风速大小有关,风速越大,衰减作用越强;2背景风速在2~6m/s时,障碍物背风面测点风速衰减随距离增大而减小,在10倍障碍物高度距离处平均约衰减15%;背景风速大于6m/s时,背风面各测点风速衰减先增大后减小,在大约5倍障碍物高度的距离处衰减最大,10倍障碍物高度的距离处平均约衰减20%~30%;3障碍物的存在使主风向的风向频率减小,对风向的影响距离为6倍障碍物高度。