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71.
钱塘江涌潮简析与预报 总被引:3,自引:0,他引:3
根据1991年观测资料,仑前潮位站出现涌潮184次,涌潮次数多少与江道地形变迁及上游下泄流量大小有关。涌潮高度在1.2-2.2m之间,与涨潮潮差成正比。涌潮潮时预报方法有传播时间法和隔日滞后时间法。涌潮高度的预报,可根据当天涌潮高度预测后一天涌潮高度,也可根据下游站的涌潮高度预报上游站的涌潮高度。 相似文献
72.
利用欧洲中心全球客观分析的7层月平均位势高度距平资料,分别计算了相同格点上12-2月和6-8月各层高度距平之间的同时相关分布。结果表明:全球月平均位势高度距平场的正压、斜压性随地理区域变化很大,并有较明显的季节变化。其中12-2月对流层下部大气环流距平场在海洋上空有较好的相当正压性,在大陆上空正压性较差;对流层上部大气环流异常的正、斜压性分布与下部不同,赤道附近地区是相关系数的高值区,副热带地区主要是低值区;在对流层下部与上部大气环流距平场的相关系数分布图上,海洋上空并不总是高值区,在热带东太平洋区域就出现最强的负相关中心。与6-8月的相关系数分布型比较发现:特别明显的季节变化在非洲大陆和热带印度洋区域,12-2月为强正压区,6-8月为强斜压区。 相似文献
73.
张克非 《武汉大学学报(信息科学版)》1990,(3)
本文在顾及局部地形改正、椭球改正及大气改正的情况下,采用实测数据,应用Meissel方法和Wenzel频谱分析方法,对某盆地边缘的高程异常进行了实际计算。并将计算结果同多普勒高程异常进行了比较,证明结果是良好的。此外还对我国精确高程异常的确定提出了一些建议。 相似文献
74.
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76.
Dirk Goossens 《地球表面变化过程与地形》1985,10(4):353-362
A torn-up road offered the opportunity to sample a dust cloud continuously at different heights during a time interval of 51 hours. In particular the granulometrical characteristics of the dust caught were investigated. It appears that if the air layer in the vicinity of a dust cloud is not too turbulent, the cloud will be clearly granulometrically stratified. The coarse material moves chiefly at the bottom of the cloud, whereas the fine material will occur both at the bottom and at the top. The experiment also shows that the higher the dust in the cloud, the worse it is sorted. Above a critical height, however, the degree of sorting increases again. The variation of the mean dust diameter d50, as a function of the height z, can be expressed in a simple semi-logarithmic equation. The variation of the dust quantity G, as a function of the height z, can also be expressed in a semi-logarithmic form but the correlation is higher when a power equation is used. The ratio of fine silt to coarse silt seems to vary parabolically with height. One can only speak of an optimal transport height in the case of particles > 16 μm. For finer particles, the turbulence of a normal air stream is usually high enough to carry the particles anywhere in the dust cloud, so that one can no longer speak of an optimal transport height. The granulometrical border between aeolian transport in saltation and aeolian transport in suspension lies, according to the results of the experiment, at a diameter of about 63 μm. 相似文献
77.
The heights of the daytime convective boundary layer (CBL), computed by a one-dimensional model for a bare soil surface at a semi-arid station,Anand, during the dry and hot summer month of May 1997, are presented. As input, the model requires surface heat flux, friction velocity and air temperature as functions of time. Temperature data at the one-metre level from a tower and sonic anemometer data at 9.5 m collected during the period 13–17 May 1997 in the Land Surface Processes Experiment (LASPEX-97) are used to compute hourly values of surface heat flux, friction velocity and Obukhov length following the operational method suggested by Holtslag and Van Ulden [J. Climate Appl. Meteorol.
22,517–529 (1983)]. The model has been tested with different values for the potential temperature gradient ( ) above the inversion. The model-estimated CBL heights comparefavourably with observed heights obtained from radiosonde ascents. 相似文献
78.
腰英台油田是东北地区新发现的油田,目前刚开始勘探开发,在勘探开发初期遇到不少问题。其中之一是开采时高含水:就油田的实际油水分布特征进行了分析,分析油水同出的可能原因,认为这是受油藏储层物性及构造幅度和实际油柱高度的影响,由于储层低孔、特低渗。实际构造幅度低,实际油柱高度大多低于油藏产纯油所需的油柱高度,致使油藏大都处于油水过渡带。故开采时多含水,油水同出。根据这一分析,认为进一步的油气勘探重点考虑西部水下冲积扇的有利部位。此处储层物性好,有利于接受更多油源。 相似文献
79.
Barchans of Minqin: Morphometry 总被引:2,自引:0,他引:2
The barchans on the border of Minqin oasis, China, were surveyed. Our data reconfirmed that the height of slipface is proportional to the width of horns and the baseline can be roughly described by parts of an ellipse and a parabola. We attempted to study dune geomorphology using the theory of differential geometry. The geometrical characteristics of the brink can be quantitatively determined by its curvature and torsion. 相似文献
80.
H. Nahavandchi 《Journal of Geodesy》2002,76(6-7):345-352
It is suggested that a spherical harmonic representation of the geoidal heights using global Earth gravity models (EGM) might
be accurate enough for many applications, although we know that some short-wavelength signals are missing in a potential coefficient
model. A `direct' method of geoidal height determination from a global Earth gravity model coefficient alone and an `indirect'
approach of geoidal height determination through height anomaly computed from a global gravity model are investigated. In
both methods, suitable correction terms are applied. The results of computations in two test areas show that the direct and
indirect approaches of geoid height determination yield good agreement with the classical gravimetric geoidal heights which
are determined from Stokes' formula. Surprisingly, the results of the indirect method of geoidal height determination yield
better agreement with the global positioning system (GPS)-levelling derived geoid heights, which are used to demonstrate such
improvements, than the results of gravimetric geoid heights at to the same GPS stations. It has been demonstrated that the
application of correction terms in both methods improves the agreement of geoidal heights at GPS-levelling stations. It is
also found that the correction terms in the direct method of geoidal height determination are mostly similar to the correction
terms used for the indirect determination of geoidal heights from height anomalies.
Received: 26 July 2001 / Accepted: 21 February 2002 相似文献