Long-Term variability of the indian summer monsoon and related parameters

The long-term variability of the Indian summer monsoon rain-fall and related regional and global param-eters are studied. The cubic spline is used as a digital filter to smooth the high frequency signals in the time series of the various parameters. The length of the data series varies from 95 to 115 years during the period 1871-1985. The parameters studied within the monsoon system are: (a) monsoon rainfall of the country as a whole; (b) number of break-monsoon days during July and August; (c) number of storms/ depressions in Bay of Bengal and Arabian Sea during summer monsoon season; and (d) dates of onset of summer monsoon over South Kerala Coast. The parameters studied outside the monsoon system are: (a) the Wright’s Southern Oscillation Index (June-July-August); (b) the January mean Northern Hemi-spheric surface air temperature anomaly; and (c) the East-equatorial Pacific sea surface temperature anomaly.In order to examine the variability under various degrees of the smoothing, the series are filtered with splines of 50% variance reduction frequency of one cycle per 10, 20 and 30 years. It is observed that the smoothed time series of the parameters within the monsoon system comprise a common slowly varying com-ponent in an episodic manner distinctly showing the excess and deficient rainfall epochs. The change of intercorrelations between the time series with increasing degree of smoothing throws some light on the time scales of the dominant interactions. The relation between Southern Oscillation and East equatorial Pacific sea surface temperature and the Indian summer monsoon seems to be dominant on the interannual scale. The low frequency variations are found to have significantly contributed to the instability of the correlations of monsoon rainfall with parameters outside the monsoon system.     

东印度洋水体输运的季节变化及相关盐度变化

利用20年（1992-2012年）的ECCO2模式模拟数据,主要研究了东印度洋（EIO）水体输运的季节变化.在EIO选取3个断面,分别为赤道、80°E和6°N.研究结果表明,跨赤道和80°E的季节输运主体部分大致相补偿.跨赤道的大部分水体输运局限在上层100 m,80°E的水体输运具有复杂结构,与显著的季风流、Wyrtki Jets（WJs）、赤道潜流（EUC）等有关.6°N上层水体净输运较小,但存在较强的边界流和相对较弱的内区流.纬向流的显著变化发生在80°E.在季风盛行季节,由于WJs减弱,赤道附近的水体输运以西向的梯度流为主,上层100 m的其余区域则主要受季风流控制.同样,由于EUC减弱,西向的梯度流与次表层东向的EUC之间也存在转换.在季风转换季节,季风流减弱,WJs与EUC分别在上层100 m和次表层占主导地位.此外,本研究还讨论了与季风流、WJs和EUC相关的盐水和暖水交换,有助于了解研究区域内温度和盐度的水平和垂直结构.     

电热式雨强计

本文介绍一种具有对数响应特性的电热式降雨强度计,该仪器是根据使降落到感应器表面的雨水加热蒸发所需要的电功率,以连续测量0.3—350毫米/小时的降水速率。外场试验表明,此仪器与标准翻斗雨量计的观测结果一致。 1.工作原理这种电热降雨强度计是根据四十年代在飞机积冰现象的研究中使用的液态水含量电测仪器发展而来的,它可以检测落到仪器表面的雨水和云中的水通量。仪器有两个固定电位的金属电极,电极之间是一种多孔、吸     

Data selection using support vector regression

Geophysical data sets are growing at an ever-increasing rate, requiring computationally efficient data selection(thinning)methods to preserve essential information. Satellites, such as Wind Sat, provide large data sets for assessing the accuracy and computational efficiency of data selection techniques. A new data thinning technique, based on support vector regression(SVR), is developed and tested. To manage large on-line satellite data streams, observations from Wind Sat are formed into subsets by Voronoi tessellation and then each is thinned by SVR(TSVR). Three experiments are performed. The first confirms the viability of TSVR for a relatively small sample, comparing it to several commonly used data thinning methods(random selection, averaging and Barnes filtering), producing a 10% thinning rate(90% data reduction), low mean absolute errors(MAE) and large correlations with the original data. A second experiment, using a larger dataset, shows TSVR retrievals with MAE < 1 m s-1and correlations 0.98. TSVR was an order of magnitude faster than the commonly used thinning methods. A third experiment applies a two-stage pipeline to TSVR, to accommodate online data. The pipeline subsets reconstruct the wind field with the same accuracy as the second experiment, is an order of magnitude faster than the nonpipeline TSVR. Therefore, pipeline TSVR is two orders of magnitude faster than commonly used thinning methods that ingest the entire data set. This study demonstrates that TSVR pipeline thinning is an accurate and computationally efficient alternative to commonly used data selection techniques.     

基于全球超导重力仪观测研究海潮和固体潮模型的适定性

利用国际地球动力学合作观测网络中20个台站22个高精度重力潮汐观测系列综合研究了目前使用的海潮和固体潮模型的适定性. 对原始观测数据实施仔细的预处理, 利用国际标准算法计算了潮汐重力参数. 基于负荷理论和不同全球海潮模型获得了8个主波的重力负荷矢量, 用二维平面插值技术获得了14个小波的负荷改正值. 顾及不同潮波振幅特征, 提出了计算台站平均观测残差和剩余残差矢量的“非等权均值法”, 分析了海潮负荷改正的有效性和振幅因子与理论模型间的差异, 同时还讨论了仪器标定问题. 获得了经海潮负荷改正后全球各台站平均潮汐重力参数, 结果说明观测与理论模型间的差异小于0.3%, 最大仪器标定误差不超过0.5%. 另外文章还用地表重力实测数据证实了Mathews理论中相对于周日O₁波而言, K₁波相位滞后略呈正值的结论.     

进入密度不连续层的气泡运动的初步实验模拟

本文介绍一种可清晰地显示孤立气泡内部运动的实验方法。当气泡部分地进入密度不连续层时,除在气泡内生成一个对称主涡环外,还可出现另一个对称的同向次级涡环,其面元比主涡环小一个量级。同向次级涡环的发现揭示了气泡内部运动的细致结构。     

东北太平洋上暴发性发展生成的气旋

1.引言 Sanders和Gyakum(1980年)把24小时内中心气压至少减少24毫巴的温带气旋定义为气象炸弹。他们提到的加深率本来是对北纬60度而言的,为了得到任何纬度θ的     

地形降水机制

从降水量—地形高度对应关系图上可以清楚地看出山脉对水分循环的影响。图1和图2就是例子。在有些地理区城,这种对应关系是已为人们所了解,但在其它区域并非如此,许多年来关于这个问题的科学研究一直进行得很缓慢。本文回顾了目前人们对地形降水的了解。Bonacina(1945),     

飓风中多角形的眼壁和雨带

1.引言飓风中心通常被人们认为是在雷达屏面上出现的圆形或椭圆形的几何中心。为了揭示不同的风暴特征,例如飓风眼大小、椭圆率、回波运动和风暴运动等,许多研究者研究延时电影胶片(time-lapse film)的飓风照片。为了研究风暴路径细节和论证风暴的陀螺形的运动,需要更多的眼中心定位资料。在从地面雷达照片中收集定位资料时,作者观测到飓风眼经常既不是圆形的,也不是椭圆形,而似乎是六角形的、四方形的或三角形的。这些多角形结构虽不太完整,但其直线轮廓却是难以否认的。 2.资料和分析本文所研究的观测资料有:1)平面位置显示器(PPI)显示的16毫米和35毫米延时电影片记录,2)为计算机使用而经过数字转换的雷达反射率的     

热带气旋运动的动力—统计预报业务试验

一、引言近年来,许多热带气旋具有运动异常的性质,从而暴露了纯统计系统所固有的弱点,并促进了动力和统计—动力模式的发展。因此,Miller(1972)等用一种七层模式进行试验,而Neumann和Lawrence(1973)介绍了一种统计—动力模式,即NHC73,它采用美国气象中心的原始方程模式的输出作为统计预报系统的输入。1973年和1974年飓风季节,用NHC73的两种方案在业务预报中作了试验。本文评论了NHC73的发展,介绍了两年中的试验结果,以及提出了将统计、动力概念用于热带气旋预报的发展途径。二、数值预报资料的统计应用 Klein和 Glahn(1974)介绍了两种已成功地将数值预报资料引入统计预报结构的方法。其一是所谓“完全预报”法,另一种称模式输出统计法,简称