副高持续偏强对福建气候的影响          下载免费PDF全文

许金镜  唐文伟  林仲平 《气象》1997,23(1):36-37

作者以１９５１－１９９５年副高持征量的气温、降水等气象要素为素材，分析了副高持续性偏强的基本事实和对福建天气气候的影响。  相似文献   

一次暴雨过程多普勒天气雷达风场资料分析   总被引：1，自引：2，他引：1       下载免费PDF全文

俞莲芬  陈大任  张代平 《气象》1997,23(2):25-28

通过对１９９御７月１４日的大－暴雨天气过程所获取的３８２４多普勒天气雷达平均径向风场资料的分析，发现边界层急流与较强的降水相伴。表明多普勒天气雷达对中小尺度天气系统和灾害性天气预报有预警作用。  相似文献   

台风路径及闽南台风天气预报业务系统          下载免费PDF全文

何歆  林伙海 《气象》1997,23(9):17-20

该文应用ＨＵＲＲＡＮ相似台风路径预报方法，引进５００ｈＰａ天气形势，提高了台风咱径预报能力；应用天气学方法、物理量诊断和预报员的丰富实践经验，以及卫星云图上的台风云系特征，研制台风影响下的闽南台风天气（大风、暴雨）预报专家系统，得出定量、客观的预报结论。该系统运行所需的资料易于获取，从采集资料到输出预报结果，１０分钟便可完成，大大缩短了制作台风预报的时间。  相似文献   

数字滤波方法在月尺度数值预报中的应用：II.保留不同低频过程的效果比较          下载免费PDF全文

杨燕  纪立人 《大气科学》1997,21(5):533-534

用数字滤波方法对观测资料序列进行处理，得到初始场用于Ｔ４２Ｌ９全球谱模式的月预报，以去除误差增长较快的高频扰动对低频过程的影响，并且利用多时刻的观测资料提取低频过程的信息。对冬季和夏季两个不同个例进行了实例，并比较了取不同长度的观测序列，截取不同周期的过程作为初值对预报效果的影响。结果说明，经过滤波后对低频分量和平均场的预报都有显著的改进。而且对于较长时效的预报，应保留更低频的过程（比如１０ｄ以上  相似文献   

国外中期数值预报业务模式的性能及发展趋势   总被引：1，自引：0，他引：1       下载免费PDF全文

杨学胜 《气象》1997,23(1):3-10

作者简单介绍了国内预报员较为熟悉的欧洲中期天气预报中心，美国国家气象中心和日本气象厅三个中期预报模式的性能及预报效果，包括近几年颇为流行的半拉格朗日时间积分方案，物理过程参数化方案的完善和改进，中期数值预报业务模式的发展趋势等。  相似文献   

Gravitational (Rayleigh-Taylor) instability of a layer with non-linear viscosity and convective thinning of continental lithosphere   总被引：8，自引：0，他引：8  

Gregory A. Houseman  Peter Molnar 《Geophysical Journal International》1997,128(1):125-150

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Numerical models of mantle convection with secular cooling     

Wanda DeLandro-Clarke  Gary T. Jarvis 《Geophysical Journal International》1997,129(1):183-193

A 2-D time-dependent finite-difference numerical model is used to investigate the thermal character and evolution of a convecting layer which is cooling as it convects. Two basic cooling modes are considered: in the first, both upper and lower boundaries are cooled at the same rate, while maintaining the same temperature difference across the layer; in the second, the lower boundary temperature decreases with time while the upper boundary temperature is fixed at 0°C. The first cooling mode simulates the effects of internal heating while the second simulates planetary cooling as mantle convection extracts heat from, and thereby cools, the Earth's core. The mathematical analogue between the effects of cooling and internal heating is verified for finite-amplitude convection. It is found that after an initial transient period the central core of a steady but vigorous convection cell cools at a constant rate which is governed by the rate of cooling of the boundaries and the viscosity structure of the layer. For upper-mantle models the transient stage lasts for about 30 per cent of the age of the Earth, while for the whole mantle it lasts for longer than the age of the Earth. Consequently, in our models the bulk cooling of the mantle lags behind the cooling of the core-mantle boundary. Models with temperature-dependent viscosity are found to cool in the same manner as models with depth-dependent viscosity; the rate of cooling is controlled primarily by the horizontally averaged variation of viscosity with depth. If the Earth's mantle cools in a similar fashion, secular cooling of the planet may be insensitive to lateral variations of viscosity.  相似文献   

Multivariate nonparametric resampling scheme for generation of daily weather variables     

B. Rajagopalan  U. Lall  D. G. Tarboton  D. S. Bowles 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(1):65-93

A nonparametric resampling technique for generating daily weather variables at a site is presented. The method samples the original data with replacement while smoothing the empirical conditional distribution function. The technique can be thought of as a smoothed conditional Bootstrap and is equivalent to simulation from a kernel density estimate of the multivariate conditional probability density function. This improves on the classical Bootstrap technique by generating values that have not occurred exactly in the original sample and by alleviating the reproduction of fine spurious details in the data. Precipitation is generated from the nonparametric wet/dry spell model as described in Lall et al. [1995]. A vector of other variables (solar radiation, maximum temperature, minimum temperature, average dew point temperature, and average wind speed) is then simulated by conditioning on the vector of these variables on the preceding day and the precipitation amount on the day of interest. An application of the resampling scheme with 30 years of daily weather data at Salt Lake City, Utah, USA, is provided.  相似文献   

三维溶质运移问题的分步广义迎风解法     

姚磊华 《吉林大学学报(地球科学版)》1997,(4)

对对流占优的三维溶质运移问题提出了分步广义迎风解法，首先利用Ｎ．Ｎ．Ｙａ－ｎｅｎｋｏ对水动力弥散方程分步求解的思想，将原来的一个定解问题分解为两个定解问题即对流定解问题和扩散定解问题，对对流定解问题采用广义迎风对偶单元均衡法求解，对扩散定解问题采用一般的Ｇａｌｅｒｋｉｎ有限元法求解，不仅避免了用一般有限元法和有限差分法求解对流占优的地下水水质数学模型时常出现数值弥散和过量问题，而且避免了求节点速度这一步，节省运算步骤，对井点的浓度变化给出了更合适的求解方法。  相似文献   

岩浆活动旋回与地球多层对流系统   总被引：2，自引：2，他引：2  

邓晋福  莫宣学  赵海玲  罗照华  赵国春 《地学前缘》1997,(Z2)

从地球历史的节律角度讨论岩浆活动旋回。岩浆活动旋回可按时间与空间分出相互对应的不同尺度，进而可与深度尺度不同的地球多层对流系统相互对应，从而给予了岩浆活动旋回的动力学意义。岩浆活动的时间周期愈长，空间尺度亦愈大，需要的维持岩浆源存在的热能、挥发分供给的数量与深度亦愈大。  相似文献