Ertel位涡和非线性对称不稳定性问题

本文应用Lagrange质点理论对大气中对称运动方程进行了简化,在此基础上进一步利用分岔和突变理论分析了环境地转风为非线性分布的情况下,Ertel位涡在非线性对称不稳定中的作用,并得到了一些有意义的结果。     

秦皇岛海水浴场环境质量评价

文章分析秦皇岛4个海水浴场6个监测站位2015—2018年采集水质样品中粪大肠菌群和溶解氧的变化趋势,并结合《海水水质标准》和《海滨浴场游泳适宜度分级规定》,对4个浴场的水质进行分析评价。结果表明:粪大肠菌群是海水浴场的主要污染物,粪大肠菌群浓度的变化主要受降雨、游客数量、温度和陆源污染物影响。尤其强降雨后,粪大肠菌群浓度升高较明显。浴场的溶解氧含量变化不大,年均值均满足二类水质标准,其主要受水温和浮游生物等因素影响,高峰值多出现在9月和10月。秦皇岛4个海水浴场的水质优良状况表现为南戴河浴场最好、东山浴场和北戴河浴场次之、西浴场最差。     

非组合精密单点定位算法精密授时的可行性研究

利用基于GPS双频原始观测数据的非组合精密单点定位(PPP)算法进行精密授时,给出了其数学模型与数据预处理策略。实验结果表明,非组合PPP算法可以有效避免传统PPP算法由于观测值组合过程中观测噪声及多路径效应误差被放大而造成的对接收机钟差解算的不利影响,实现亚纳秒级(0.3 ns)的钟差解算精度;同等条件下,非组合PPP算法授时精度优于传统PPP算法,可以用于精密授时解算。     

东北佳木斯-内蒙古地区中二叠世岩相古地理研究

严格按照等时性对比原则,选取岩相古地理图的制图单元.以野外实测剖面为基础,做精细沉积微相研究,在东北地区地层露头剖面识别出海相(浅海亚相、半深海亚相)、三角洲相(三角洲前缘:水下分流河道、河口坝,前三角洲)沉积.在露头点测量基础上,以点带线、以线带面,分析古沉积环境.在野外剖面沉积微相精细划分基础上,结合区域地质资料,...     

Research on the Global Warming Hiatus

A global warming “hiatus” has been observed since the beginning of the 21st century despite the increase in heat-trapping greenhouse gases, challenging the current global warming studies. Focusing on the phenomena and mechanisms of the global warming “hiatus”, the National Key Research Program of China launched a project in July, 2016. The main research themes of this project cover: ①Revealing the spatial and temporal variability of the global warming hiatus, and quantifying the contributions of external forcing and internal (natural) variability, respectively; ②Revealing the role of the atmosphere in the global heat and energy redistribution under global warming hiatus; ③Revealing the role of the ocean in the global heat and energy redistribution under global warming hiatus; ④Investigating the predictability of the global warming hiatus. The key scientific issues to be resolved include: ①Identifying characteristics of the global warming hiatus and discerning the roles of decadal, multi-decadal oscillations; ②Revealing the role of ocean-atmosphere dynamical processes in the global redistribution of heat and energy; ③Understanding the predictability of the global warming hiatus. The research aims to predict the future development of the global warming hiatus, and to point out the possible impacts on China and other important areas, including “The Belt and Road” core area and the Polar Regions.     

贵州威宁麻窝山岩溶盆地剖面中Rb、Sr分布及环境信息

岩溶盆地的演化清晰地记录了流域侵蚀和化学风化等重要过程,Rb/Sr是有效获取地表过程中环境信息的重要手段之一。本文基于14C定年方法,结合研究剖面中K、Ca等元素的组成特征,对贵州威宁麻窝山岩溶盆地中4个沉积剖面的Rb、Sr分布和地球化学行为进行了分析,并讨论了Rb/Sr指示的环境意义和盆地的演化历程。结果表明,剖面中Rb元素含量普遍高于Sr元素且波动幅度较Sr元素大。此外,Rb与K,Sr与Ca之间均有较好的正相关关系,即在流域物质的侵蚀、搬运和盆地沉积物的形成演化过程中,Sr的活动性明显高于Rb。各剖面Rb、Sr垂直分异程度相似,呈大—小—大交替演变,Rb/Sr以大—小—大规律变化,且剖面间具有较好的一致性,与野外特征相吻合,尤其是剖面颜色变化,均体现盆地沉积环境的多旋回特征。Rb/Sr具有重要的环境意义,能够指示研究区古气候变化,Rb/Sr高时(主要受Rb控制),盆地处于干涸或低水位状态,指示降水量较少的干旱气候;Rb/Sr低时(主要受Sr控制),盆地处于富水的高水位环境,指示降水量较多的湿润气候。在距今40ka时间内,岩溶盆地内至少出现312次干—湿环境的旋回演变,其是恢复喀斯特地区古气候的良好载体。     

The Antitumor Components from Marine-derived Bacterium Streptoverticillium luteoverticillatum 11014 Ⅱ

Eight known compounds were isolated from a marine-derived bacterium Streptoverticillium luteoverticillatum 11014 using bioassay-guided fractionations. Their structures were identified by spectral analysis as bis （4-hydroxybenzyl） ether （1）, p-hydroxyphenylethyl alcohol （2）, N-（4-hydroxyphenethyl） acetamide （3）, indole-3 carboxylic acid methyl ester （4）, dibenzo[b,e] [1,4]dioxine （5）, thymine （6）, cytosine deoxyribonucleoside （7） and 2, 3-butanediol （8）. These compounds were evaluated for their cytotoxic activities against K562 cell line with the SRB method for the first time. Compounds 2 and 4 showed cytotoxcities with IC50 values of 101.1 and 165.3 μolL^-1, respectively. All compounds were isolated from S. luteoverticillatum 11014 for the first time.     

Impact of global SST on decadal shift of East Asian summer climate

East Asia experienced a significant interdecadal climate shift around the late 1970s, with more floods in the valley of the Yangtze River of central-eastern China and more severe drought in North China since then. Whether global SST variations have played a role in this shift is unclear. In the present study, this issue is investigated by ensemble experiments of an atmospheric general circulation model (AGCM), the GFDL AM2, since one validation reveals that the model simulates the observed East Asian Summer Monsoon (EASM) well. The results suggest that decadal global SST variations may have played a substantial role in this climate shift. Further examination of the associated atmospheric circulation shows that these results are physically reasonable.     

非静力平衡大气非线性层结对称运动的稳定性和突变

在假定了环境地转风具有水平和垂直的线性切变的情况下,考虑大气层结的线性和非线性切变的作用,建立了一个非线性常微分方程组,然后构造了一个Hamilton函数,通过讨论Hamilton函数的凸凹性,得到了非线性层结对称运动的不稳定判据,同时讨论了非线性层结对称运动产生突变的条件。     

旋转正压大气中的Rossby孤立波和偶极子阻塞

大气中的阻塞动力学一直是大气动力学中所要解决的重要问题之一,随着数学的发展,阻塞动力学的研究也取得了较大的进展。大气中的阻塞可以分为两类:一类是单个非偶极子阻塞(只存在高压或低压),另一类是偶极子阻塞(高压的南侧存在闭合的低压)。关于偶极子阻塞的动力学研究是在80年代以后才进行的。为了解释大气中所出现的偶极子阻塞,Mcwilliams(1980)提出了Equivalent