共查询到20条相似文献，搜索用时 640 毫秒
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对１９８７年４月２５￣２７日寒潮天气过程ＥＣＭＷＦ５００ｈＰａ高度场、８５０ｈＰａ温度场进行了预报检验，得出了些新的预报经验。 相似文献
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θse场在近海台风路径预报中的应用 总被引：1，自引：0，他引：1
通过对９４１４和９４１５号两个近海台风的θｓｅ场分布特征的分析，发现５００ｈＰａθｓｅ场高值区及８５０ｈＰａθｓｅ场高低值轴向对台风的强弱和路径有指示性，可作为日常台风强弱变化和路径预报的重要依据之一。 相似文献
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动态相似方法在长江上游逐日降水预报中的应用 总被引：1，自引：0，他引：1
在考虑环流的动态演变特征在降水预报中重要性的基础上,设计了一种环流演变动态相似预报方法,在１０００ｈＰａ气压场、８５０ｈＰａ温度场、５００ｈＰａ高度场分别提取３个物理意义清晰、又具有立体性和多元性的相似因子,采用本文设计的二级相似标准,以ＥＣＭＷＦ数值预报产品作为预报资料与历史资料库进行滚动映射,寻找最优相似个例,制作长江上游降水面雨量的逐日滚动预报,效果较好。 相似文献
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对９７１１号台风登陆后的路径进行了分析,检验了日本数值预报产品中２４、３６小时预报图对台风路径的预报效果,并从高空环流形势、５００ｈＰａθｓｅ场及地面３小时变压等方面对台风路径的可预报性进行了探讨。结论认为此类台风的路径可在数值预报结果的基础上进行有效的订正预报,并给出了预报着眼点。 相似文献
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夏季东亚大气遥相关型变化行征及其与长江中下游旱涝的关系 总被引：2，自引：1，他引：1
用５００ｈＰａ高度场资料及中国１６０个站的月平均降水资料,采用ＥＯＦ,合成分析和奇异谱分析等方法,分析了长江中下游旱涝年夏季降水与同期东亚大气环流的关系,结果表明长江中下游旱涝与５００ｈＰａ高度场东亚－太平洋遥相关型（ＥＡＰ）关系密切,ＥＡＰ指数能较好地反映夏季５００ｈＡａ高度场的配置及长江中下游降水。文中重点讨论了ＥＡＰ指数的振荡周期及高低指数年西太平洋副高的变化特征。ＥＡＰ指数３￣６年,准两年 相似文献
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在河南省季降水量场（标准化）客观分析￣［２］的基础上，应用优化非线性方法和预报对象与因子时空尺度相匹配原则，对夏季ＥＯＦｓ的前６个特征场建立了与５００ｈＰａ高度之间的优化非线性预报方程，经过集成可以对全省夏季标准化降水量进行长期预报。结果表明，该模型对异常旱涝有较强的预报能力，是一种有效的旱涝长期预测统计方法。 相似文献
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A review of ENSO prediction studies 总被引：10，自引：0，他引：10
M. Latif T. P. Barnett M. A. Cane M. Flügel N. E. Graham H. von Storch J. -S. Xu S. E. Zebiak 《Climate Dynamics》1994,9(4-5):167-179
A hierarchy of ENSO (El Niño/Southern Oscillation) prediction schemes has been developed which includes statistical schemes and physical models. The statistical models are, in general, based on advanced statistical techniques and can be classified into models which use either low-frequency variations in the atmosphere (sea level pressure or surface wind) or upper ocean heat content as predictors. The physical models consist of coupled ocean-atmosphere models of varying degrees of complexity, ranging from simplified coupled models of the shallow water-type to coupled general circulation models. All models, statistical and physical, perform considerably better than the persistence forecast on predicting typical indices of ENSO on lead times of 6 to 12 months. The most successful prediction schemes, the fully physical coupled ocean-atmosphere models, show significant prediction abilities at lead times exceeding one year period. We therefore conclude that ENSO is predictable at least one year in advance. However, all of this applies to gross indices of ENSO such as the Southern Oscillation Index. Despite the demonstrated predictability, little is known about the predictability of specific features known to be associated with ENSO (e.g. Indian Monsoon rainfall, Southern African drought, or even off-equatorial sea surface temperature). Nor has the relative importance for prediction of different regional anomalies or different physical processes yet been established. A seasonal dependence in predictability is well established, but the processes responsible for it are not fully understood. 相似文献
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南海热带气旋大风的遗传－神经网络集合预报 总被引：1，自引：0，他引：1
利用1980-2012年的南海热带气旋实况资料和NCEP/NCAR再分析资料,将热带气旋定位中心周边6×6格点上的地面风速作为预报对象,以气候持续预报因子和前期风速预报因子作为模型输入,采用遗传—神经网络集合预报方法,进行热带气旋定位中心周边36个格点上的风速预报模型的预报建模研究.分别对2008-2012年7-9月共368个独立预报样本进行遗传-神经网络集合方法的分月预报结果表明,南海热带气旋中心周边风速24h的预报平均绝对误差为2.35m.s-1.另外,本文还进一步将该预报方法与国内外普遍采用的逐步回归预报模型进行对比分析,在相同的预报量和预报因子的条件下的对比分析表明,新预报模型对≥10m.s-1的强风预报结果较逐步回归方法的优势明显,预报性能较好,可为沿海热带气旋大风预报提供新的参考. 相似文献
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在城市空气污染预报模型中, 精心挑选的因子具有较好的预报性能, 但是因子的优良性能并非始终不变, 而有时个别因子的不良表现往往可能导致预报的失败。根据集对分析 (SPA) 把不确定性和确定性作为一个动态的同异反系统处理的思想, 动态地分析和处理每次预报中因子作用的变化, 即每次预报前, 先对因子进行态势判别和同异反分析, 然后使可能干扰预报的弱势因子的作用受到有效抑制, 使有助于预报的强势因子的作用得到充分发挥, 从而实现了因子作用大小在各次预报中的动态变化, 取得了较为满意的效果。在预报模型中增加不确定性处理有助于提高预报准确率。 相似文献
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以1960-2007年共48年6月份西行进入南海海域的热带气旋样本为基础, 将热带气旋中心附近最大风速作为台风强度, 以气候持续预报因子作为模型输入, 采用模糊神经网络方法, 进行了热带气旋强度预报模型的预报建模研究。结果表明, 对175个独立预报样本模糊神经网络方法的南海热带气旋强度24 h的预报平均绝对误差为3 m·s-1。另外, 根据相同的热带气旋样本及预报因子, 还进一步将该预报方法与国内外普遍采用的气候持续法热带气旋强度预报方法进行对比分析, 结果表明, 气候持续预报方法的预报误差明显偏大, 独立样本强度预报平均绝对误差为4.54 m·s-1。 相似文献
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夏季南海台风移动路径的一种客观预报方法 总被引：1，自引：0，他引：1
以1960—2003年共44a夏季的7月、8月、9月西行进入南海海域的台风样本为基础,综合考虑南海台风移动路径的气候持续因子和数值预报产品物理量因子,运用条件数方法选取因子并建立回归方程,进行台风路径预报模型的预报建模研究。通过对比分析发现,基于条件数方法的南海台风移动路径模型具有较好的预报效果,7月、8月、9月3个月24h台风路径预报的平均距离误差为153．9km,预报能力明显高于目前国内外的其他一些台风路径客观预报方法。该方法的预报精度相对于逐步回归方法有了很大的提高,相对于气候持续法也为正的预报技巧水平。 相似文献
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Convolutional neural networks(CNNs) have been widely studied and found to obtain favorable results in statistical downscaling to derive high-resolution climate variables from large-scale coarse general circulation models(GCMs).However, there is a lack of research exploring the predictor selection for CNN modeling. This paper presents an effective and efficient greedy elimination algorithm to address this problem. The algorithm has three main steps: predictor importance attribution, predictor rem... 相似文献
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New Models for Long Range Forecasts of Summer Monsoon Rainfall over North West and Peninsular India 总被引：1，自引：0，他引：1
M. Rajeevan Pulak Guhathakurta V. Thapliyal 《Meteorology and Atmospheric Physics》2000,73(3-4):211-225
Summary New models based on (a) Multivariate Principal Component Regression (PCR) (b) Neural Network (NN) and (c) Linear Discriminant
Analysis (LDA) techniques were developed for long-range forecasts of summer monsoon (June–September) rainfall over two homogeneous
regions of India, viz., North West India and Peninsular India. The PCR and NN models were developed with two different data
sets. One set consisted 42 years (1958–1999) of data with 8 predictors and the other, 49 years (1951–1999) of data with 6
predictors. The predictors were subjected to the Principal Component Analysis (PCA) before model development. Two different
neural networks were designed with 2 and 3 hidden neurons. To avoid the nonlinear instability, 20 ensemble runs were made
while training the network and the ensemble mean results are discussed. The LDA model was developed with 42 years of data
(1958–1999) for classifying three rainfall intervals with equal prior probability of 0.33. Both the PCR and NN models showed
useful forecast skill for NW India and Peninsular India. Models with 8 predictors performed better than the models with only
6 predictors. The NN model with 3 hidden neurons performed better than model with 2 hidden neurons. For NW India, the NN model
performed better than the PCR model. The RMSE of the NN model and PCR model with 8 predictors for NW India (Peninsular India)
during the independent period 1984–99 was 12.5% (12.2%) and 12.6% (11.5%), respectively. Corresponding figures for the models
with 6 predictors are 15.0% (13.0%) and 13.9% (11.4%) respectively. During the independent period, model errors were large
in 1991, 1994, 1997 and 1999. However all the models showed deteriorating predictive skill after 1988, both for NW India and
Peninsular India. The LDA model correctly classified 62% of grouped cases for NW India and Peninsular India. The LDA model
showed better skill in classifying deficient rainfall (< − 8%) over NW India and excess rainfall (> 3%) over Peninsular India.
Received October 2, 1999 Revised December 28, 1999 相似文献
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钟元 《热带气象学报(英文版)》1997,3(2):208-214
As shown in a statistical analysis of the relationship between environmental fields at varied timeand tropical cyclone motion, the forecasting ability of the initisl environmental field predictors for tropical cyclone motion decreases with the increase of valid time period of forecast;it is higher with these predictors at a fUture time than at an initial time. The work also indicates that for the tropical cyclone motion over a given period of valid forecast, better predictors appear at times mostly differing from thevalid periods; for periods at 48-120 h the environmental predictors at 48-72 h are more capable of forecasting. With statistical interpretation of NWP products, a predictive model for tropical cyclone motionis superior in performance over a statistical forecasting model that employes predictors of the initial field in the basic framework. The concluding remarks can be used as reference in the construction of an objective prediction model for tropical cyclone motion. 相似文献
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This paper presents the basis for the design of streamflow prediction systems for the hydroelectric dams of Rincón del Bonete (Uruguay) and Salto Grande (Uruguay–Argentina). The prediction is made, independently, for each reservoir and each month of the year with two methodologies: data-driven statistical models and hybrid downscaling that includes atmospheric predictors. We determine a set of potential predictors and then fit linear models coupled with variable selection techniques, under the hypothesis of perfectly known predictors. The predictive skill of the schemes outperforms the climatological forecast throughout the year in both reservoirs (except August in Rincón del Bonete). This remains the case even when the forecast lead does not allow for the use of preceding flows as predictors. While in Rincón del Bonete it is not possible to distinguish a period of high predictability, in Salto Grande, there is a robust signal in March–May and October–December. 相似文献
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带有周期分量的多元逐步回归在橡胶寒害趋势分析中的应用 总被引：1，自引：0，他引：1
本文采用带有周期分量的多元逐步回归方法建立了海口、白沙等五个站的极端最低气温预报模式,用其来分析橡胶寒害趋势。此方法既考虑了预报因子对预报量的影响,又考虑了预报量本身的周期变化及预报因子的相关阶段性。模式的拟合及预报效果都比较好。 相似文献