PROPAGATION OF 30—60 DAY LOW FREQUENCY OSCILLATIONS AND THEIR INFLUENCE UPON THE SUBTROPICAL WESTERLIES JET STREAM DURING NORTHERN HEMISPHERE WINTER

Based on daily ECMWF gridpoint data of two winters during 1981—1983 including an ENSOyear,propagation of low frequency oscillations(LFO)during Northern Hemisphere winters andtheir influences upon 30—60 day oscillations of the subtropical jet stream are studied with the sta-tistical methods as complex empirical orthogonal function(CEOF)and so on.Results show that inthe winter of a normal year(1981—1982),30—60 day oscillations in the subtropical zone aremainly in the northern and southern flanks of exit region of jet stream.In the ENSO year(1982—1983),they are mainly in the vicinity of entrance and exit regions of jet stream.Intraseasonalchanges of subtropical jet stream manifested themselves as latitudinal fluctuation or longitudinalprogression or regression of about 40 day period.There are marked differences between propagat-ing passages of low frequency modes responsible for changes of subtropical jet stream in the normalyear(1981—1982)and in the ENSO year(1982—1983).Changes of oscillation amplitude showobvious phases.In general,the one in late winter is stronger than that in early winter,strongestone occurs in February.     

A MESO-β SCALE SIMULATION OF THE EFFECTS OF BOREAL FOREST ECOSYSTEM ON THE LOWER ATMOSPHERE

Based on the Intensive Field Campaign(IFC-1)data of Boreal Ecosystem-Atmosphere Study(BOREAS).a three-dimensional meso-β scale model is used to simulate the effect of boreal forests onthe lower atmosphere.A fine horizontal resolution of 2 km×2 km is used in order to distinguish thevegetative heterogeneity in the boreal region.A total of 20×25 grid points cover the entire sub-modeling area in BOREAS' South Study Area(SSA).The ecosystem types and their coverage ineach grid square are extracted from the North American Land Cover Characteristics Data Base(NALCCD)generated by the U.S.Geographical Survey(USGS)and the University of Nebraska-Lincoln(UNL).The topography of the study area is taken from the Digital Elevation Map(DEM)of USGS.The model outputs include the components of the energy balance budget within the canopyand at the ground.the turbulence parameters in the atmospheric boundary layer and the wind.temperature and humidity profiles extending up to a height of 1500 m.In addition to the fine timeand spatial step,the unique feature of the present model is the incorporation of both dynamic andbiological effects of the Boreal forest into the model parameterization scheme.The model resultscompare favorably with BOREAS' IFC-1 data in 1994 when the forest was in the luxuriant growingperiod.     

浅论土工格栅在软土路基处理中的应用

随着公路工程施工工艺和措施的不断拓新 ,运用土工格栅处理软土路基在我国公路工程中正在越来越多地被采用。其良好的力学性能有力地保证了路基、路面的工程质量。1　概述早在 5 0年代的时候 ,西方较先进的一些国家已开始使用土工格栅 ,并逐步在公路工程建设中推广应用 ,取得了良好的效果。土工格栅代替传统的建筑材料能节省大量经费。在公路路基中使用能有效改善土的物理力学性质 ,特别是对特殊路基的处理具有增大土体内摩擦角 ,形成承重板体 ,阻止毛细水上升等功能 ,我处在临河西环线改建工程中针对该段位于城市郊结合处的特殊地理位置 ,其路基状况具有原路基边沟长期遭水浸泡而形成的湿软土壤、城市建设垃圾、生活垃圾及工业废渣等特点 ,我们在查阅大量文献的基础上 ,决定对局部特殊路段使用土工格栅处治软土路基 (包括建筑垃圾和工业废渣垃圾 )。2　现状分析本工程主要对原路基加宽 1 0 m,加铺基层和面层 (结构为 1 5 cm二灰土 2 0 cm水泥稳定石屑 5 .5 cm沥青碎石 )。而需要加宽的部分 ,多为原路基边沟。由于城市出入口排水不畅加之郊区农田灌水积存等原因 ,使边沟水长期浸泡路基 ,造成 5 0 -1 5 0 cm...     

栉孔扇贝大规格苗种培育的初步试验

栉孔扇贝[Chiamys farreri(Jones et Preston)]的人工育苗,在我国已经形成了一套较为完整的工艺流程,并进入了生产阶段。同时,采自然苗也在一些海区(山东长岛县)取得了很大地进展。但是,由于培育的扇贝种苗规格过小(壳高10mm左右),利用率和成活率都较低,养殖器材成本高,养殖周期长等因素的影响,目前扇贝养殖的发展仍甚缓慢。近年来,农牧渔业部多次组织召开有关技术协作攻关会议,提出提高成活率、降低养殖成本、增加经济效益、扩大养殖生产,作为扇贝养殖的发展方向。我们认为,实现上述目标,除了因地制宜、就地取材发展人工筏式养殖和底播养殖外,育成大规格扇贝种苗(壳高     

小西南岔金铜矿带围岩蚀变特征的初步研究

围岩蚀变不仅是良好的找矿标志,同时对矿床的成因及其评价也有着实际和理论意义。笔者近年来在小西南岔地区进行1/5万区调工作中,对该区围岩蚀变做了点面相结合的研究,现将所取得的成果作了初步总结,不妥之处请批评指正。一、地质矿产概况     

在中意卫星时钟同步试验期间国内诸台站主钟之间的比对结果

本文列出了在1984年5月25日到6月7日中国和意大利两国利用Sirio-1卫星进行双向法卫星时钟同步试验期间,国内参加台站的主钟之间进行多种手段比对的统计结果,作了分析比较,并列出了最后采用的UTC(BAO)—UTC(i)逐日相位差表。中意卫星地面站工作钟之间的比对结果和意方台站钟之间的比对结果将另文刊载。根据本文及以上资料将很容易得出任何国内参加台站之间和国外参加台站之间的时钟比对结果.     

THE TRANSITION OF A MULTI-DIMENSIONAL LORENZ SYSTEM

A multi-dimensional Lorenz system, which includes thirty-three amplitude equations describing time evolution of convection, is derived from two-dimensional Boussinesq equations by using the Galerkin method. Its transition is studied by numerical solution. It is found that, with Rayleigh number increasing from zero to one hundred, five different types of motion appear one after another as follows: stationary motion, periodic motion, quasiperiodic motion with two-fundamental frequencies, quasi-periodic motion with three fundamental frequencies, and chaotic motion. By comparing with the Lorenz model and Curry's fourteen-dimensional model, it is shown that as retained modes increase, the critical values of transition become larger and the types of bifurcation change. The results of dynamic behavior happen to be in agreement with the Ⅲa route of the Gollub and Benson experiments.     

大城市气象要素日变程数值模拟

众所周知,在大工业中心,人们的生产活动,导致了大气污染及气象状况的改变。近年来,在小气候研究中,物理——数值模拟方法得到了广泛的应用。采用这一方法可以在一定程度上阐明地球边界层污染的形成过程,深入研究各种气象特征的发展动力。     

南岭及其邻区热液和层控型铅锌矿床中方铅矿的微量元素及物性研究

南岭及其邻区两种不同成因类型铅锌矿床中方铅矿的微量元素标型较为明显,热液型方铅矿富Ag、Sb、Bi、Te、Se;层控型方铅矿含上述元素较低,而Au、Mo、Ge、In稍高。热液型方铅矿的Sb/Pb、Ag/Pb比值比层控型大,Sb/Bi、Se/Te、S/Se比值则比层控型小。此外,热液型方铅矿的比重、硬度、反射率、比层控型大,晶胞常数热电系数比层控型小。     

八十年代英国中学地理教学

八十年代,地理教学在英国学校中占有众所承认的地位,英国学校把地理教学纳入教程的方式因地方教育机构所管理的学校学制不同而异。最普遍的学制是5～11岁的儿童上小学,9—13岁的儿童上中学,这些学校均将地理纳入综合的教学课程中,或做为环境教育的部分内容。