GIS支持下土地生态环境敏感性评价——以金坛市为例

针对传统的生态环境敏感性评价指标体系差异较大,尚未形成统一体系,并且各个指标之间的关系及相互影响的情况并没有得到体现的问题,该文在地理信息系统的支持下,选取土地质量尺度的土地利用类型、土壤质地,及生态尺度的水环境、植被覆盖度、人口密度、坡度作为生态环境敏感性因子,同时建立了以水环境为主要因子的土地生态敏感性指数模型,对金坛市生态环境敏感性进行单因子评价和多因子综合评价。评价结果显示,金坛市生态高敏感区和中敏感区占到全市总面积的78%,低敏感区和不敏感区占到全市总面积的22%。针对不同土地生态敏感性分区因地制宜提出用地策略,为土地利用总体规划和城市生态保护提供参考。     

热带东风中经向扰动与纬向扰动的非线性相互作用

根据非线性的动量方程,利用多时间尺度分析方法,探讨由经向扰动与纬向扰动相互作用在热带东风中所造成的一类正压不稳定。分析表明:在零级近似下,给出了两个扰动传播的频率表达式,在一级近似下,得到了两个零级扰动振幅的解析表达式。鉴于方程中散度项的存在,当不同尺度的三个波相作用而发生共振时,仅总动能守恒,而总位拟能不守恒,这一点与无辐散大气的结论不同。两种扰动动能相互转换的机制则是涡度场与散度场的相互作用。     

基于MODIS的沿海带状植被NDVI/EVI季节变化研究——以江苏沿海互花米草盐沼为例

植被指数的时空变化是目前全球变化研究的热点问题。该文以江苏沿海互花米草盐沼为例,运用MODIS数据探索沿海带状植被NDVI/EVI的季节变化规律。结果表明,互花米草的返青(出苗)、抽穗、种子成熟等主要物候期在VI曲线上均能得到很好体现。本研究可为监测互花米草盐沼扩展趋势、加强管理、趋利避害提供基础数据,同时也为沿海其它带状植被监测提供借鉴。     

世界大洋中绝热运动导致的纬向翻转环流和纬向热输送

Zonal overturning circulation(ZOC) and its associated zonal heat flux(ZHF) are important components of the oceanic circulation and climate system, although these conceptions have not received adequate attentions.Heaving induced by inter-annual and decadal wind stress perturbations can give rise to anomalous ZOC and ZHF.Based on a simple reduced gravity model, the anomalous ZOC and ZHF induced by idealized heaving modes in the world oceans are studied. For example, in a Pacific-like model basin intensified equatorial easterly on decadal time scales can lead to a negative ZOC with a non-negligible magnitude(–0.3×106 m3/s) and a considerable westward ZHF with an amplitude of –11.2 TW. Thus, anomalous ZOC and ZHF may consist of a major part of climate signals on decadal time scales and thus play an important role in the oceanic circulation and climate change.     

地球大气纬向风系、副热带高压和太阳较差自转的形成机制

利用N S(Navier Stokes)方程和一个基本假设推导出星体大气平均纬向风和平均气压公式,根据公式讨论了地球大气纬向风系和平均气压以及副热带高压的成因并进行了数值模拟。结果发现,地球大气纬向风是大气微团密度与基准大气密度存在差异而形成的,大气微团的密度大于（小于）基准密度,则为西风（东风）;密度的差距越大,风速越强。在中高纬度地区大气微团吸收的太阳辐射少而向空间辐射多,导致其密度变大,因此在中高纬度盛行西风;而在低纬度地区,因为吸收的太阳辐射多使大气微团密度变小而盛行东风。夏季（冬季）太阳辐射增强（减弱）使得大气微团密度变小（增大）,进而导致中高纬度地区西风减弱（增强）和低纬度地区的东风加强（减弱）。风速的大小还与纬度的余弦成正比,这就使得最大西风带位于中纬度地区而不是大气微团密度最大的极地附近;也使得最大的东风不是发生在太阳直射点附近而是靠近赤道一侧。根据气压公式和大气密度的经向差异可以得出中高纬度区域气压随纬度的升高而减小的分布特征,而太阳辐射所造成低纬地区密度的减小是该区域气压大于中高纬度的主要原因;在赤道上纬度的正弦为零,使得气压在赤道上存在极小值,导致了赤道槽和副热带高压的形成,且太阳辐射越强、副热带高压越强。因为纬度正弦因子的存在,使得副高脊线总是位于太阳直射点的向极一侧。在假定太阳大气为理想气体的情况下,由N S方程推导出太阳大气自转角速度随纬度的变化公式,由此解释了太阳较差自转的成因在于低纬地区的大气微团密度大于高纬度,并且在赤道上大气微团的密度最大。该公式与观测得到的经验公式在略去高阶小项后一致。由此认为,太阳大气的运动在形成机制上与地球大气没有区别,不同的是在太阳表面没有象地球表面那样受太阳辐射的影响,N S方程是所有星体（包括恒星、行星）大气共同遵守的动力方程。     

南极涛动和北半球大气环流异常的联系

使用ECMWF逐日再分析资料分析研究了北半球冬季南极涛动和北半球大气环流异常之间的联系。资料的分析结果表明, 南极涛动和滞后其25～40天位于北大西洋地区的一个弱的类似于北大西洋涛动 (North Atlantic Oscillation, 简称NAO) 的偶极子模态, 以及伴随这一偶极子模态而出现的北半球中纬度纬向风异常之间存在着统计上的联系。处于正 (负) 位相的南极涛动对应着滞后25～40天后, 北大西洋高纬极区出现位势高度负 (正) 异常, 副热带大西洋出现位势高度正 (负) 异常; 同时, 在北半球中高纬度地区(45°N～65°N) 出现西 (东) 风异常, 中低纬度地区(25°N～40°N)出现东 (西) 风异常。文中也对资料分析结果进行了简单的动力学分析, 表明与南极涛动相联系的涡动动量异常是驱动北半球纬向平均纬向风异常的主要原因。     

Chemical Zone of Nephrite in Alamas,Xinjiang, China

The Hetian deposit, located south of the Tarim Basin in Xinjiang, China, is one of the world's largest dolomite-related nephrite deposits. In the Alamas orebody of the deposit, nephrite occurs as veins or lenses along faults or fissures of the adjacent dolomitic marble. Chemical analyses using electronic microscope probe analysis and X-ray fluorescence spectroscope were carried out on nephrite and dolomitic marble samples collected from a cross section in Alamas to investigate zonal structure of the orebody. The nephrite in Alamas is predominately composed of tremolite with minor calcite, titanite and phlogopite, and that dolomitic marble is relatively pure with a FeO content less than 0.20 wt. %. Contents of color-inducing elements, such as Fe, Mn, and Cr, increase gradually as color changes from white through white-green and then to green, resulting in the formation of color-distinctive zones. Tremolite grain size increases as color changes from white through white-green to green. The trend may be consistent with temperature changes from dolomitic marble to granodiorite, which, in turn, suggests that both change in color from white to green and variations of grain size with increasing temperature resulting in formation of the nephrite zonal structure. Both nephrite zonal structure and minor minerals, such as calcite, titanite and phlogopite found in the contact, indicate that this dolomite-related nephrite orebody is of a metasomatic origin under assumed pressure of 100–200 MPa and temperature <550°C.     

QBO Features of Tropical Pacific wind Stress Field with the Relation to El Nino

Analysis has been implemented of 1970-1992 tropical Pacific wind stress anomaly and sea surface temperature anomaly (SSTA) datasets, indicating that quasi-biennial oscillation (QBO) of the tropical Pacific WS and SSTA is featured both by a standing and a progressive form, the former emerging in the most intense centers of action and the latter travelling east- or west-ward out of the SSTA sources. Results show that the SSTA is in the warm (cold) phase as zonal component of euqatorial wind stress anomaly gets weakened (reinforced) and the QBO of wind stress anomaly is well related to the El Nino cycle.     

金矿床中环带状黄铁矿及其生长演化过程的研究

利用电子探针对黔南卡林型金矿床中环带状黄铁矿进行研究，把它划分成三种类型，并分别测定内外带中Ａｓ、Ｓｂ、Ａｕ、Ｈｇ和Ｔｌ等微量元素的含量，绘制了以步间距１μｍ，横穿环带的这五种元素的Ｘ射线强度变化曲线图，图中清楚显示出环带起因于微量元素含量的变化，这五种元素在微观尺度上呈正相关的振荡式变化，具有同源性。讨论黄铁矿经由胶体粒子的聚集、固结与结晶的生长演化过程，提供了低温热液可能是一种富含成矿质的多相     

Large-scale interannual variation of the summer monsoon over India and its empirical prediction

Large-scale interannual variability of the northern summer southwest monsoon over India is studied by examining its variation in the dry area during the period 1871–1984. On the mean summer monsoon rainfall (June to September total) chart the 800 mm isohyet divides the country into two nearly equal halves, named as dry area (monsoon rainfall less than 800 mm) and wet area (monsoon rainfall greater than 800 mm). The dry area/wet area shows large variations from one year to another, and is considered as an index for assessing the large-scale performance of the Indian summer monsoon. Statistical and fluctuation characteristics of the summer monsoon dry area (SMDA) are reported. To identify possible causes of variation in the Indian summer monsoon, the correlation between the summer monsoon dry area and eleven regional/global circulation parameters is examined. The northern hemisphere surface air temperature, zonal/hemispheric/global surface air and upper air temperatures, Southern Oscillation, Quasi-biennial oscillation of the equatorial lower stratosphere, April 500-mb ridge along 75°E over India, the Indian surface air temperature and the Bombay sea level pressure showed significant correlation. A new predictor parameter that is preceding year mean monsoon rainfall of a few selected stations over India has been suggested in the present study. The stations have been selected by applying the objective technique ‘selecting a subset of few gauges whose mean monsoon rainfall of the preceding year has shown the highest correlation coefficient (CC) with the SMDA’. Bankura (Gangetic West Bengal), Cuddalore (Tamil Nadu) and Anupgarh (West Rajasthan) entered the selection showing a CC of 0.724. Using a dependent sample of 1951–1980 a predictive model (multiple CC = 0.745) has also been developed for the SMDA with preceding year mean monsoon rainfall of the three selected stations and the sea level pressure tendency at Darwin from Jan–Feb to Mar–May as independent parameters.