麻粒岩的成因

从压力—温度—时间(P-T-t)路径可以推演下部大陆地壳和区域麻粒岩地体形成和演化的构造环境,其受岩石学和地球物理方面条件所制约。区域麻粒岩的P-T条件要求有平均大于35℃km~(-1)的瞬时地热梯度。这意味着热流至少要达到100mWm~(-2)。这样高的热流可能起因于岩浆加热。符合这种条件的构造环境包括会聚板块边缘、大陆裂谷、热点以及深部大岩基的边缘。然而,一定的P-T-t路径并不从属于目前所能认识出的特定构造环境。顺时针     

非洲的黎明

亚洲无可争议是文明的故乡;非洲满可以说是人类本身的发源地。作为曾在亚洲工作过的一个地质考古学家,当比较这两个洲的时候,曾为这种想法找到一个有益的修正。在这种比较中,人们倾向于把古埃及与亚洲归为一类;但是,即使把埃及包括在非洲如象在种族和地理上应该把埃及包括在非洲一样,我开头的意见仍然是适用的。著名的埃及文化,当今被认为是仅次于美索不达比亚文化。亚洲在人类进步方面引了路,但决不能肯定伊甸园或更科学的同类东西不应当位于非洲。     

准噶尔盆地头屯河地区侏罗系沉积环境与构造意义

准噶尔盆地头屯河地区侏罗系陆相层序包含4种沉积:(1)冲积扇平原湿地中的砾石质河流沉积(八遭湾组),其特征提示在湿地中发育了规模不同的大河道(深3—5m,宽1OOm左右)及较小的分流或决口河道(深2m以下,宽6—30m)。(2)沙质低弯度河沉积,晚三工河、早西山窑、头屯河及齐古组沉积期的河流沉积属之。其特点是河道相与河间相间的界线清楚,提示河道在某一段时期固定于平原的特定地带;河道规模受古气候和构造的制约;气候干旱化和构造抬升(如头屯河组沉积时期),侵蚀基面降低,河流动力增加,因而河流规模变大,反之变小;晚头屯河组沉积期的干旱气候存在暂时性河道。(3)三角洲前缘沉积(河口中坝),见于八道湾、三工河及喀拉扎组中。(4)开阔湖相沉积,以三工河组厚的页岩层序为代表。 砂岩成分逆向反映源区剥蚀顺序。下侏罗统富含泥质岩屑,表示天山上古生界浅变质及沉积层系被剥蚀。自下而上,碎屑中稳定矿物增加,粒度变细,反映源区由于剥蚀而后退。中—上侏罗统砂岩成分演化方向不同于下侏罗统,可能与三工河组沉积末期盆地边缘构造回春有关。在Q-F-L三角图中,侏罗系样品大都落在构造区之间,反映陆相盆地充填物的混合来源。下—中侏罗统的煤既有原地生成,亦有重要的他生类型。     

一种评价休耕与播种问题中天气预报经济效益的动态决策模式

本文用决策分析方法评价不完全天气预报的经济价值并研究马尔可夫过程的一组动态决策模式.这种动态模式的数学表达式将未来天气状态的不确定信息与决策过程结合在一起.同时,研究了天气信息价值以及模式在气象学上的应用实例.作为模式的一个具体应用,详细讨论了休耕和播种问题.在这一问题中,假设农场主的目的是在无限时段中使总期望效益增至最大.还估计了当前的季节降水预报以及这种预报质量提高之后对农场主的经济价值.     

INFLUENCES OF TOPOGRAPHY ON BAROCLINIC SOLITARY ROSSBY WAVES IN A MULTILEVEL MODEL

The KdV equation with topography included in an N-level model is derived. It is shown that if the topography ex-ists. the KdV equation may describe the solitary Rossby waves in the case of basic current without vertical shear, and itis no necessary to introduce the MKdV equation. The results of calculations show that the change of horizontal shearpattern of basic flow may cause an important change of the streamline pattern of the solitary waves with the oddmeridional wavenumber m, and has no effect for the even meridional wavenumber m. The vertical shear increases thesteepness of the barotropic solitary modes, and it has a complicated effect on the baroclinic modes. The influences oftopographic slope on the solitary waves are very great. The southern and northern slopes of topography may cause dif-ferent solitary wave patterns, with the effect of northern slope greater. The effect of Froude number on the solitarywaves is generally to steepen the solitary waves, however, the effect also depends on the meridional wavenumber m andthe modes of solitary wave.     

Construction of vertical wind profile from satellite-derived winds for objective analysis of wind field

During summer Monex-79, a variety of observing systems viz. research ships, research aircrafts, constant pres-sure balloons and geostationary satellite etc. were deployed, besides the regular conventional observations The pur-pose of these additional systems was to make the best possible data for the studies on various aspects of monsoon cir-culation. The present study is aimed at the construction of vertical wind profile using cloud motion vectors obtained from GOES (I-O) satellite and to examine whether the constructed wind profiles improves the representation of the monsoon system, flow pattern etc. in the objective analysis. For this purpose, climatological normals of the wind field are considered as the initial guess and the objective analyses of the wind field are made with, first using only data from conventional observations over land areas, subsequently including the constructed winds from cloud motion vectors. These analyses are then compared with the standard analyses of wind field obtained from Quick Look Atlas by T. N. Krishnamurti et al. (1979).It is inferred that satellite estimated mean wind profiles show good agreement with the mean wind profiles of the research ships with RMS errors less than 5 mps below 500 hPa and less than 8 mps above 500 hPa. It is further infer-red that the inclusion of constructed winds shows a positive impact on the objective analysis and improvement is seen to be more marked in the data-sparse region of the Arabian sea. Analyses which include the constructed winds show better agreement with the standard analysis, than the analyses obtained using only conventional winds. Thus, results of our study suggest that the wind profiles constructed using cloud motion vectors are of potential use in objective analysis to depict the major circulation features over the Indian region.     

土壤侵蚀测量

“在土地资源方面,许多国家乃缺乏全面的数据,侵蚀区域扩大业已发生,并且看来还将成为公害”(Hauck,1985)。Walling 强调,在流域研究中,需要有一种简便技术,来测量长期性土壤流失的时空分布;为了标定和测试现有的各种土壤流失模型,也需要土壤侵蚀速度数据。本文回顾了近10年来,自然状况下土壤侵蚀测量技术的进展情况。土壤水蚀和风蚀的量测技术,可以分为小区域收集器法,各种测量方法,和示踪法三类。     

湍流对云滴谱增长的作用(摘译)

一、引言云中总有一定程度的湍流存在,然而究竟多大强度的湍流扰动对降水形成的微物理过程有影响,目前尚不清楚.研究湍流对处在发展初期的积云中碰并过程的作用是特别有趣的,有研究证实,湍流增强,则微滴增长.又有人认为,在海洋上弱的湍流可以引起云滴谱的明显展宽.其结果是,对于起伏的湍流速度场,不同尺度的云滴对应不同的