2018年长江上游严重洪涝的气象水文特征

利用NCEP/NCAR再分析资料及常规气象水文实况观测资料,分析了2018年6—7月长江上游严重洪涝期间的气象水文特征,结果表明：2018年长江上游洪涝期间发生了三次强降水过程,降水落区在长江上游北部地区高度重叠,引发了严重的洪涝灾害。大尺度的环流形势分析表明,中高纬低槽、副热带高压、鄂霍茨克海阻塞高压、乌拉尔山阻塞高压均较历史同期异常偏强,副热带高压的南北摆幅较大,当副热带高压每次北跳后,都会与槽后冷空气在长江上游遭遇,形成一次强降水过程。大尺度环流的“鞍”型场配置有利于孟加拉湾及南海的水汽输送到长江上游地区,并在该地区与中纬度西风带水汽辐合形成强降水。历史对比结果表明：2018年长江上游的降水具有面上强度大、北部支流降水极端性强、降水时间集中的特点。2018年长江上游北部的沱江、涪江、嘉陵江等流域在水位和超警戒时间上均高于2012年。2018年长江上游总的降水量及洪峰流量虽未超过2012年,但在长江上游北部的沱江、涪江、嘉陵江引发的洪涝灾害可超过2012年。     

Characteristics of Drag Coefficient in Different Coastal Regions of the South China Sea Under Tropical Cyclones–An Observational Study

To investigate the values of 10-m drag coefficient (CD) in different coastal areas under the influence of tropical cyclones, the present study used the observational data from four towers in different coastal areas of the South China Sea (SCS) during six tropical cyclone (TC) passages, and employed the eddy covariance method and the flux profile method. The analysis of footprint showed that the fluxes at Zhizai Island (ZZI), Sanjiao Island (SJI) and Donghai Island (DHI) were influenced basically by the ocean, and the flux at Shangyang Town (SYT) was influenced mainly by the land. The results showed that the dependence relationships of CD on 10-m wind speed (U10) in four different coastal areas under the influence of TCs were different. CD at ZZI and SJI initially increased and then decreased as U10 increased, similar to the pattern over the ocean. CD at ZZI and SJI represented the values over shallow water with seawater depths of ~7 m and ~2 m, respectively. Moreover, the critical wind speed at which CD peaked gradually decreased as the seawater depth became shallower in the coastal areas. CD at DHI and SYT decreased monotonously as U10 increased, similar to the pattern over the land. CD at DHI represented the value over the transition zone from shallow water to coastal land, and CD at SYT represented the value over the coastal land. Meanwhile, the eddy covariance method and the flux profile method were compared at ZZI and SYT during TC passages. It was found that their CD values obtained by the two methods were close. Finally, the parameterizations of observed u* and CD as a function of U10 over four different coastal areas were given under the influence of high winds. These parameterizations of observed C may be used in high-resolution numerical models for landfalling TC forecast.     

海洋和冰冻圈变化有关的极端事件、突变及其影响与风险

《气候变化中的海洋和冰冻圈特别报告》（SROCC）于2019年9月在IPCC第一工作组和第二工作组第二次联合大会上得到审议通过,并得到了IPCC第51届全会接受和批准。文中主要对该报告中海洋和冰冻圈变化有关的极端事件、突变及其影响与风险的有关评估内容进行了综合分析。SROCC评估得到的最新结果显示：气候变化背景下冰冻圈变化引起的山体滑坡、雪崩和冰川洪水事件频发。海洋有关的海洋热浪频发,极端El Niño事件加强,大西洋经向翻转环流减弱。同时,沿海地区极端海平面上升,极端海浪增高,极端热带气旋影响增加。这些变化,比如海洋热浪等,是可以归因于人为增暖的。预估结果表明,海洋和冰冻圈变化引起的极端事件未来会进一步加剧。而这些变化已经影响了高山、极地以及沿海地区人群的生产和生活,以及海洋和冰冻圈的生态系统服务功能。应对这一系列变化,需要更加精准的预测和预警,包括对极端事件和突变的季节预测和年际、年代际预测,以便做好充足的准备来降低极端事件风险。同时,加强应对极端事件的科普教育和提供因地制宜的灾害重建措施等也是风险管理的重要环节。     

“艾云尼”台风龙卷天气过程分析

利用常规观测、地面自动气象站、多普勒天气雷达、现场灾调及互联网视频等资料,对2018年6月8日发生在广东省佛山市南海区大沥镇的1804号“艾云尼”台风龙卷天气过程进行分析。结果表明:龙卷发生在台风“艾云尼”登陆后前进方向的右后侧,强度为EF1级。高层辐散抽吸、中低空强劲的东南风急流叠加和地面中尺度辐合线的抬升触发作用是其有利的环流背景。对流参数表现为弱的对流有效位能和对流抑制能量、强低层风垂直切变、低抬升凝结高度和大的风暴相对螺旋度。产生龙卷的风暴为低质心微超级单体风暴,龙卷出现在钩状回波的弱回波区内。速度图上中气旋提前龙卷约30 min,临近龙卷发生时中气旋旋转速度增至最强,尺度缩小,底高降至最低,对龙卷预警有一定指示作用。     

1961—2020年辽宁省暖冬现象气候特征分析

利用1961—2020年辽宁省56个气象站冬季逐日气温数据,根据国家标准《暖冬等级》,以1990—2020年为气候值作为参考,综合采用气候倾向率、IDW、滑动t检验突变分析以及小波分析等方法,分析辽宁省近60 a冬季平均气温的时空变化趋势,单站暖冬及区域暖冬事件的气候变化特征。结果表明：近60 a来辽宁省冬季平均气温以0.3℃/10 a的速率升高,辽宁中部和东部地区变暖趋势最为显著;20世纪90年代前的30 a属于偏冷时段,但增温效应强于后30 a,冬季平均气温在1987年前后出现了明显的由冷转暖的突变,1971年出现了相对较弱的冷暖转变;1988年后逐年单站暖冬事件的发生整体比1961—1987年出现单站暖冬事件明显增多。发生频次较高的地区分布在辽宁中部和东南部地区,为16—20次;近60 a来共有16次区域暖冬事件,21世纪后的20 a内共出现9次区域暖冬事件,占总数的60%;区域暖冬事件以准22 a和2—3 a为振荡周期。     

渤中坳陷油气成藏规律

渤海坳陷下第三系砂岩普遍含有两类油气包裹体，即原生油气包裹体和次生油气包裹体，它们分别记录了本区两次油气运移、聚集成藏过程。次生油气包裹体个体大、分布广、含量明显高于原生油气包裹体，其主要充填分布在次生溶蚀孔隙和裂隙中。均一温度测量、包裹体成分和生物标志化合物分析结果综合表明，次生油气包裹体记录的第二次油气运移是区内最主要的一次油气聚集成藏过程，其油气来源于下第三系湖相泥质烃源岩。本区次生溶蚀孔隙是在早第三纪晚期构造抬升过程中，由大气淡水淋滤作用形成的。结合地质演化特征分析认为，渤中坳陷目前油气勘探的重点应是浅部下第三系地层，而不是深部其他地层。早第三纪晚期构造运动、沉积     

上海光机所小喷泉铷钟的设计和进展

对上海光机所正在研制的小喷泉铷钟及目前正在进行的工作作了介绍.该小喷泉铷钟吸收了原子喷泉的许多新技术,采用紧凑的结构设计,加入空心光束以提高探测原子数.预期该喷泉的准确度为10-14,短、长稳分别为10-13和10-15,信噪比为103.实验室完成了冷原子物理的准备工作,已经俘获冷原子团.     

小波方法在CCD图像处理中的应用

针对天王星卫星位置观测图像中存在的一些问题,提出了一种新的图像处理方法,即二维墨西哥帽小波变换方法.图像处理结果表明,这种方法能够有效地去除背景梯度和噪声,将接近主星的卫星从主星的光晕中分离出来.     

数值算法在DOS图形分析中的应用

在非函数图形数据处理的算法中，目前还没有一个算法可以较好解决求解离散数据点所形成的曲线的积分问题。在扩充最小二乘性质的基础上提出了相关算法，并进行可行性和误差分析。该算法已较好运用于纳米材料的DOS图形分析。     

The correlations between hardness ratios and fitting parameters in GRB spectrum

In this paper, besides general definition of hardness ratio of gamma-ray bursts (GRBs), HR ₃₂, we also presented new definitions of hardness ratios, HR _hl and HR _ll, then presented the results of correlation studies, examining the association between the hardness ratios and the spectral fitting parameters (E ₀ or E _peak, α, β) by using the GRB data observed by BATSE. The HR _hl is defined as the fluence of channel 4 divided by the sum of the fluences of channels 1 to 3,and the HR _ll is defined as the fluence of channel 3 divided by the sum of the fluences of channel 1 and 2. We found that E ₀ and E _peak are correlated with hardness ratios, and β is only correlated with log (HR _hl). The α is not correlated with any hardness ratios in the total sample of GRBs, while it correlated with log (HR _ll) and log (HR ₃₂) in the two subsets seperated at log (HR _ll) = 0.34 ×α +0.66, respectively. These results show that a harder spectra tends to be steeper and has a higher E _peak or E ₀; HR _hl describes the spectral behaviors in high energy, while both of HR _ll and HR ₃₂ reflect the spectral characteristics in low energy; the spectral behaviors in low energy are different for the two subsets. We also presented a brief qualitative analysis discussion to the correlations and suggested that the correlations are caused by both of intrinsic and cosmological effects, but intrinsic effects are dominant. This revised version was published online in July 2006 with corrections to the Cover Date.