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1.
天气可预报性的时空分布 总被引：10，自引：1，他引：9
为了能从非线件误差增长动力学的角度研究大气的可预报性问题,文章引入了可预报性研究的新方法--非线性局部Lyapunov指数.非线性局部Lyapunov指数及其相关统计量能够被用来定量地确定混沌系统可预报性的大小,真正地实现对可预报性的定量化研究.为了把非线性局部Lyapunov指数方法应用到实际的大气可预报性研究中,给出了一种利用大气的实际观测资料估计非线性局部Lyapunov指数的计算方法.存非线性局部Lyapunov指数方法的基础上,文中利用NCEP/NCAR再分析资料,对大气位势高度场、温度场、纬向风场、经向风场等要素场可预报性的时空分布进行了研究,结果表明:(1)在500 hPa高度层上,对于不同的要素场,其可预报期限的大小以及时空分布规律都不一样;全球大部分地区位势高度场可预报期限最大,温度场和纬向风场次之,而经向风场的可预报期限最小.(2)在500 hPa高度层七,位势高度场和温度场的纬向平均可预报期限基本上表现为一定的南北纬向带状分布,热带地区和南极地区的可预报期限最大,北极地区次之,南北半球中高纬度地区可预报期限相对较小.纬向风场可预报期限在热带地区最高,但是南北极地区可预报期限与邻近的中高纬度地区差别不大.经向风场可预报期限在南北两极地区最高,南北半球的中纬度和赤道附近地区可预报期限最小.(3)在垂直方向上,纬向平均高度场、温度场以及纬向风场可预报期限基本上都是随高度升高而增加,高层的可预报期限明显大于低层;经向风场可预报期限随高度的变化比较复杂,不同的纬度有所不同.(4)可预报性有明显的季节变化,不同要素场可预报期限高低值区的位置和强度随季节鄙有明显变化,对于全球大部分地区来说,冬季可预报性都大于夏季的. 相似文献
2.
基于CMA全球模式（CMA-GFS）2019年10月至2020年12月逐日20:00（北京时）起报的数据,对东北半球高空气象要素预报进行检验评估,检验的要素包括500 hPa位势高度场和风场、 850 hPa温度场和700 hPa相对湿度场。结果表明：（1）从模式预报效果的时间变化来看,预报效果有明显的季节变化,500 hPa位势高度和850 hPa温度的预报场和分析场的相似度在夏季最低,700 hPa相对湿度场的相似度在冬季最低;随着预报时效的增加,各要素的误差幅度在夏季最小。（2）从模式预报效果的空间变化来看,500 hPa位势高度场在东北半球大部分地区预报场与分析场具有较高相似度,且中高纬地区相对低纬地区更相似,预报误差的幅度则在低纬地区相对较小高纬地区相对较大,且预报偏差以大范围负偏差为主。相比而言,模式对东亚地区的位势高度及其梯度具有更高预报技巧。850 hPa温度场预报相似度和误差幅度与500 hPa位势高度场分布相似,预报偏差则主要表现为中高纬地区温度预报整体偏低,中低纬地区偏高。在预报前期（24～48 h）, 20°N以北的中高纬地区温度预报场与分析场相似度较高,均方根... 相似文献
3.
非线性误差增长理论在大气可预报性中的应用 总被引：10，自引：1，他引：9
为了能从非线性误差增长动力学的角度来研究大气的可预报性问题,在非线性动力系统的理论和方法基础上,文中引入了可预报性研究的新方法--非线性局部Lyapunov指数.非线性局部Lyapunov指数及其相关统计量能够用来定量地确定混沌系统可预报性的大小,真正地实现了对可预报性的定量化研究.首先给出了利用大气单个变量的实际观测资料获得其可预报期限估计的计算方法,因而解决了将非线性误差增长理论应用到大气实际的可预报性研究中的问题.然后,以位势高度场为例,详细讨论了逐日时间尺度上全球可预报性的时空分布,得到的主要结论为:(1)在水平方向上,全球位势高度场可预报性表现为一定的南北纬向带状分布,赤道地区和南极地区的可预报期限最长,可以达到两周左右;北极地区次之,可预报期限大约为9-12 d;北半球中高纬度地区可预报期限相对较短,可预报期限大约为6-9 d;而在南半球的中纬度地区最短,可预报期限仅为4-6 d.此外,500 hPa位势高度场可预报性分市随季节有明显变化,季节不同一些可预报期限的高值区和低值区所在的纬度和经度也会不同,总体来说,全球大部分地区的可预报性冬季都大于夏季,尤其在南极地区、热带印度洋以及北太平洋地区.(2)在垂直方向上,位势高度场可预报期限随高度升商而增加,可预报期限从对流层下层的两周以下增加到平流层下层的1个月左右,对流层和平流层天气尺度运动的可预报期限与其时间尺度是十分一致的. 相似文献
4.
海温强迫下的东亚夏季大气环流潜在可预报性特征 总被引：2，自引：2，他引：0
利用大气环流模式NCARCAM3,进行22a（1979—2000年）、每年8个初值的集合试验,并采用方差分析方法,研究了观测海温强迫下东亚夏季大气环流的潜在可预报性。结果表明,夏季东亚地区海平面气压场的潜在可预报性总体偏低,在中国区域呈东南高、西北低的分布特征;850hPa纬向风场、对流层500～200hPa平均温度场和500hPa位势高度场在低纬度地区的潜在可预报性明显高于中高纬度地区。500hPa位势高度场的潜在可预报性较高,东亚大部分地区大于0.5,尤其华南地区大于0.7。夏季东亚500hPa位势高度场的潜在可预报性具有明显的年际变化特征,并与夏季南海海温异常关系密切。与正常年份相比,在夏季南海海温偏暖或者偏冷年,东亚500hPa位势高度场的潜在可预报性较高 相似文献
5.
SMS-WARMS V2.0模式预报效果检验 总被引：7，自引：2，他引：5
对新一代上海区域中尺度模式(SMS—WARMS V2.0)系统预报结果进行了统计检验,检验量包括降水、2 m温度场、10 m风速、500 hPa位势高度场和850 hPa温度场、风场和相对湿度。结果表明:新一代模式的预报性能得到明显改善,模式各量级降水的TS和ETS评分都有提高,说明模式对降水事件发生的捕捉能力进一步增强了。分析2 m温度场的均方根误差及预报准确率发现新版业务模式的2 n、温度场预报优于原业务模式。此外新业务模式的10 m风速预报的均方根误差的逐月和多月平均值都低于原业务模式。高空形势场检验结果显示,新业务模式埘500 hPa位势高度场和850 hPa温度场的预报都优于原业务模式,850 hPa风场预报相关系数高于原业务模式,850 hPa相对湿度提高不明显。个例分析表明,新版业务模式强降水预报产品相对于原业务模式产品埘大气预报更具参考价值。 相似文献
6.
BP-CCA方法用于中国冬季温度和降水的可预报性研究和降尺度季节预测 总被引：8，自引：3，他引：5
使用变形的典型相关分析(BP-CCA)方法,基于交叉检验的结果建立了东亚冬季500 hPa大尺度环流和中国冬季温度、降水的最优BP-CCA降尺度预测模型,并在此基础上进行了中国冬季温度和降水的可预报性研究,表明用东亚冬季500hPa高度场降维后的大尺度环流来解释中国冬季温度,平均距平相关系数(ACC)为0.7左右,最高可达0.9,解释中国冬季降水的平均ACC为0.3左右,最高可达0.7,温度的可预报性远高于降水,且二者的可预报水平存在明显的区域差异。可预报性研究表明东亚冬季500 hPa大尺度环流异常与中国冬季温度、降水异常有密切的联系,BP-CCA方法可以很好地揭示大尺度环流与温度、降水的内在联系,并且物理意义清晰。在东亚大尺度环流系统中,东亚大槽和西太平洋副热带高压是影响中国冬季温度、降水异常的重要系统。进一步利用国家气候中心海气耦合模式(CGCM/NCC)回报和预测的500 hPa环流场和BP-CCA方法对温度和降水进行降尺度预测应用,对温度和降水的预测效果明显高于模式直接输出的结果,而且对温度预测的改善高于对降水的改善。对模式预测的环流进行EOF(经验正交函数)分析,表明BP-CCA方法对降尺度要素预报的可预报性来源于CGCM/NCC对500 hPa高度场主要大尺度特征的模拟能力较好。 相似文献
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8.
应用国家气象中心模式检验方法,对华中区域中尺度业务数值预报模式WRF和中国气象局下发的GRAPES模式2013年1-12月的预报产品（包括降水、2 m温度场、850 hPa温度场、850 hPa风场和500 hPa位势高度场预报）进行统计检验。检验结果表明：所有要素24 h预报均优于48 h;对于晴雨预报,GRAPES模式TS评分高于WRF,但随着降水量级增大,WRF的TS评分基本都高于GRAPES,同时WRF降水预报范围明显偏大;分析2 m温度场的均方根误差及预报准确率发现,WRF的2 m温度场预报优于GRAPES,且暖季预报优于冷季;形势场要素分析表明,WRF对850 hPa温度场和风场预报具有相当大的优势,全年误差变化较稳定,而对500 hPa位势高度场的预报误差存在一定的季节性特征,即夏半年WRF高度场预报优于冬半年,GRAPES模式则相反。总体上,华中区域中尺度业务数值模式产品对天气预报具有一定的参考价值。 相似文献
9.
初值协调性对模式数值积分结果的影响 总被引：2，自引：1，他引：1
利用国家气候中心新一代全球大气环流模式BCC_AGCM2.0.1,考虑了初值协调性对模式数值积分结果的影响,进行了两组数值回报试验(简称S1,S2),对27年(1980～2006年)的夏季基本气候态进行了对比分析,并考察了该模式对夏季气候的回报技巧。使用交叉检验的方法,计算了对模式结果的评估参数值,包括时间和空间距平相关系数,对该模式性能进行了评估和检验。结果表明,BCC_AGCM2.0.1对季节尺度的大气环流场具有良好的模拟性能,模式基本上再现了观测位势高度场、温度场、流场的分布特征以及大尺度降水分布特征。500 hPa位势高度、温度空间距平相关系数对比表明,平均而言,500 hPa位势高度、温度的空间距平相关性,热带区域(30°S～30°N)高于东亚区域(0°～60°N,60°E～150°E)和全球区域。回报与观测的降水距平百分率相关系数分布对比表明,试验S2在我国江淮地区及南方地区的回报技巧要明显优于S1。 相似文献
10.
利用1957年9月—2002年8月ECMWF和NCEP/NCAR月平均再分析资料,分别讨论了冬季和夏季SLP(sea level pressure,海平面气压)、500hPa高度、200hPa纬向风和850hPa经向风年际变率的潜在可预报性特征。结果表明:热带地区的潜在可预报性较高,尤其是赤道中东太平洋地区,而中高纬地区的潜在可预报性则较低。比较两套资料潜在可预报性的异同后发现:南半球的差异均明显大于北半球,特别是南极地区;低层变量的差异均大于中高层变量;东亚大陆在冬、夏季均具有一定的潜在可预报性;冬季各变量均表现出东亚冬季风具有较高的年际变率潜在可预报性,且两套资料的差异较小;500hPa位势高度表现的东亚夏季风潜在可预报性在两套资料中较一致,而低层变量(SLP和850hPa经向风)表现的东亚夏季风年际变率潜在可预报性在两套资料中存在较大差异。 相似文献
11.
Summary This paper presents a trend coefficient as a characteristic index with which to investigate the 1951–1998 secular trend variation
(STV) of northern 500-hPa height on a seasonal basis. Evidence suggests that low (high) latitude 500 hPa geopotential height
displays a remarkably positive (negative) trend; the positive anomaly of the height is maintained over NW Africa, the western
Mediterranean Sea and North Africa, mid-Pacific at lower latitudes, Lake Baikal and area to the east and NW North America;
the height drops significantly over the Aleutians and North Pacific, the area to the south of the Greenland and NE North America
and the sector to the north of the Arabian Sea. Further, analysis of abrupt change shows that the 500-hPa circulations experience
noticeable sudden change twice, once around the early 1960s and again in 1976, during which period the height exhibits great
differences between the Pacific and Atlantic. In the first period it drops (rises) over the mid-Atlantic at lower latitudes
(NW Africa); in the second period the height rises (drops) over the mid-Pacific at lower latitudes and Lake Baikal (the North
Pacific). Statistical tests indicate that in the 1976 case the low-latitude positive abrupt change is even more noticeable
compared to the negative of the North Pacific, thus representing a large-scale jumping event of the northern 500-hPa height.
Received April 9, 1999/Revised October 15, 1999 相似文献
12.
Diagnostic studies have been done of the seasonal and interdecadal variations of the coupling patterns for the air-sea interactions in the northern Pacific region, by using 500-hPa geopotential height field of the Northern Hemisphere and monthly mean SST field of northern Pacific Ocean (1951 ～ 1995) and with the aid of the Singular Value Decomposition (SVD) technique. The results show that: (1) The distribution patterns of SVD, which link with the El Nifo (or La Nina) events, are important in the interaction between the atmosphere and ocean while the atmosphere, coupling with it, varies like the PNA teleconnection does. The coupling of airsea interactions is the highest in the winter (January), specifically linking the El Nino event with the PNA pattern in the geopotential height field. Of the four seasons, summer has the poorest coupling when the 500-hPa geopotential height field corresponding to the La Nina event displays patterns similar to the East Asian-Pacific one (PJ). The spring and autumn are both transitional and the coupling is less tight in the autumn than in the spring. (2) Significant changes have taken place around 1976 in the pattern of air-sea coupling, with the year's winter having intensified PNA pattern of 500-hPa winter geopotential height field, deepened Aleutian low that moves southeast and the summer following it having outstanding PJ pattern of 500-hPa geopotential height field.which is not so before 1976. 相似文献
13.
气候系统模式输出结果是当前开展气候预测业务的重要参考依据之一,如何提高气候系统模式输出结果的可信度是改进气候业务预测能力的关键之一。利用1999—2010年NCEP CFSv2模式每日四次预测未来45天的回算数据,分析了集合样本数对模式预测能力的影响。分析结果表明,模式对月平均500 hPa位势高度的预测技巧在热带地区较高,而中高纬度地区较低;模式对500 hPa位势高度时间异常的预测能力优于空间异常。无论是空间异常还是时间异常,随着模式超前时间的增加,预测技巧均逐渐降低,但是在不同区域和不同月份,模式预测技巧随超前时间的变化存在差异。此外,模式预测技巧存在非常大的年际变率。增加集合样本数,对不同月份和不同起报时间预测技巧的稳定度和预测技巧值均有明显正效果,特别是对亚洲中纬度地区改善度较大。增加集合样本数也可以在一定程度上降低模式预测技巧年际变率。集合样本数增加对于500 hPa位势高度空间异常的改进优于时间异常。 相似文献
14.
Simulation and Analysis about the Effects of Geopotential Height Anomaly in Tropical and Subtropical Region on Droughts or Floods in the Yangtze River Valley and North China 
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下载免费PDF全文 Previous study comes to the conclusion:based on the anomalies of the South Asian high (SAH),100-hPa geopotential height,and 100-hPa circulation over tropical and subtropical regions,we can predict precipita- tion anomaly in the Yangtze River Valley and North China.To test its validity,a series of experiments have been designed and operated,which include controlled experiment,sensitivity experiment (which has added anomalies into 100-hPa geopotential height and wind field),and four-composite experiments.Experiments based on the composed initial field such as EPR-CF,EPR-CD,EPR-HF,and EPR-HD,can reproduce the floods or droughts in the Yangtze River Valley and North China.It suggests that anomalies of the SAH,100- hPa geopotential height,and circulation over tropical and subtropical regions may probably imply summer precipitation anomalies in the two regions.Sensitivity experiment results show that anomalies of the SAH, 100-hPa geopotential height,and southwest flow in the previous period is a signal of droughts or floods for the following summer in the Yangtze River Valley and North China.And it is also one of the factors that have impact on summer precipitation anomaly in the two regions.Positive anomaly of 100-hPa geopotential height and the anomalous intensifying of the SAH and southwest flow will induce floods in the Yangtze River Valley and droughts in North China;while negative anomaly of 100-hPa geopotential height and anomalous weakening of the SAH and southwest flow will induce droughts in the Yangtze River Valley and floods in North China. 相似文献
15.
北太平洋次表层海温异常对中国夏季降水影响的可能途径 总被引：2，自引：0，他引：2
利用Godas月平均次表层海温资料, 分析了冬、春季和夏季北太平洋次表层海温层际相似性特征, 据此对次表层海温进行分层。在此基础上研究了500 hPa位势高度场、北太平洋次表层海温、中国夏季降水三者之间的时滞相关关系, 发现春季北太平洋次表层海温场是联系前、后期大气环流的关键因素。前期冬季大气环流对春季北太平洋次表层海温场影响最显著, 春季北太平洋次表层海温场又持续影响同期及后期夏季大气环流异常。异常的夏季大气环流与同期表层、次表层海温相互作用, 共同造成夏季长江流域与华北、华南降水出现相反异常的分布型式。 相似文献
16.
该文利用 IAP L2 AGCM1 - 1模式进行 1 7年 ( 1 980～ 1 996年 )、每年 9个单个积分的集合后报试验 ,采用方差分析的方法对试验结果进行可预报性研究 .结果表明 :在热带地区 ,海表温度 ( SST)异常引起的可预报性较高 ,50 0 h Pa高度场高值区沿热带呈带状分布 ,在热带外仅有部分相对高值区 ;在中高纬度地区 ,春季的可预报性高于夏季 ;一般来说各场的可预报性海洋高于陆地 .在北太平洋春季 ,50 0 h Pa高度场、海平面气压场和表面气温场有一可预报高值区 .在中国区域 ,降水场、海平面气压场和表面气温场的可预报性从我国南海向西北递减 . 相似文献
17.
The study examined effects of sea surface temperature anomalies (SSTAs) off the east coast of Japan on the blocking high over the Okhotsk Sea in June by diagnostic analysis and numerical simulation. Firstly, based on 500-hPa geopotential height fields, the Okhotsk high index (OKHI) for June from 1951 to 2000 is calculated and analyzed. The result indicates that the OKHI has obvious inter-annual and inter-decadal variations, and there are 9 yr of high OKHI and 8 yr of low OKHI in 50 yr. Secondly, by using the OKHI, the relationship between the Okhotsk high and the 500-hPa geopotential height anomaly is investigated. The results indicate that the "+-+" pattern of geopotential height anomaly crossing Eurasia in the mid-high latitudes and the "+-" pattern of geopotential height anomaly from high to low latitudes over East Asia are in favor of the formation and maintenance of the Okhotsk high. The relationship between the OKHI and the SSTA over the North Pacific is investigated in early summer by using correlation and composite analysis. We found that when the blocking circulation over the Okhotsk Sea occurs, there is an obvious negative SSTA off the east coast of Japan in early summer. We simulated the effects of the negative SSTA of east coast of Japan on the atmospheric circulation anomaly over East Asia through the control and sensitivity experiments using NCAR CAM3 model in order to confirm our analysis results. The simulation shows that the negative SSTA off the east coast of Japan results in the significant positive 40 gpm 500-hPa geopotential height anomaly over the Okhotsk Sea and the negative anomalies off the east coast of Japan which might contribute to the formation and development of the Okhotsk high in June. 相似文献
18.
This study investigates the potential use of a regional climate model in forecasting seasonal tropical cyclone (TC) activity. A modified version of Regional Climate Model Version 3 (RegCM3) is used to examine the ability of the model to simulate TC genesis and landfalling TC tracks for the active TC season in the western North Pacific. In the model, a TC is identified as a vortex satisfying several conditions, including local maximum relative vorticity at 850?hPa with a value?≥450?×?10?6?s?1, and the temperature at 300?hPa being 1°C higher than the average temperature within 15° latitude radius from the TC center. Tracks are traced by following these found vortices. Six-month ensemble (8 members each) simulations are performed for each year from 1982 to 2001 so that the climatology of the model can be compared to the Joint Typhoon Warning Center (JTWC) observed best-track dataset. The 20-year ensemble experiments show that the RegCM3 can be used to simulate vortices with a wind structure and temperature profile similar to those of real TCs. The model also reproduces tracks very similar to those observed with features like genesis in the tropics, recurvature at higher latitudes and landfall/decay. The similarity of the 500-hPa geopotential height patterns between RegCM3 and the European Centre for Medium-Range Weather Forecasts 40 Year Re-analysis (ERA-40) shows that the model can simulate the subtropical high to a large extent. The simulated climatological monthly spatial distributions as well as the interannual variability of TC occurrence are also similar to the JTWC data. These results imply the possibility of producing seasonal forecasts of tropical cyclones using real-time global climate model predictions as boundary conditions for the RegCM3. 相似文献
19.
Winter mean temperature variability in Turkey associated with the North Atlantic Oscillation 总被引：2，自引：0，他引：2
Changes and variability in seasonal average mean and monthly mean winter (DJF) air temperature series at 70 stations of Turkey and the circulation types at 500-hPa geopotential height level were investigated to explain atmospheric controls of temperature variations during the extreme (weak and strong) phases and normal (negative and positive) phases of the North Atlantic Oscillation (i.e., Ponta Delgada–Reykjavik and the Gibraltar–Reykjavik) indices. During the positive phases of the North Atlantic Oscillation indices (NAOIs), northeasterly circulation increased, and thus spatially coherent and significant cold signals dominate over the majority of Turkey. This pattern is closely linked to anomalously low 500-hPa heights over the region of the Icelandic Low, and anomalously high geopotential heights over the regions of the Azores High, the western Mediterranean basin and the Europe, in general including the Balkans and northwest Turkey. Contrarily, during the negative phases of the NAOIs, prevailing westerly winds that originate from the subtropical northeast Atlantic increase, and thus spatially coherent and significant warm signals over the Anatolian peninsula appear. This pattern is closely linked to the increased cyclonic activity and associated increased westerly and southwesterly circulation causing warm maritime air advection over the Mediterranean basin toward Turkey. 相似文献
20.
本文用北印度洋的索马里海区、阿拉伯海、孟加拉湾和南海海区月平均(1951—1972)海温和500hPa高度场(1951—1973)资料分析了各种海区海温的变化特征以及与500hPa高度场的相关。结果表明,在各个海区海温的季节变化、持续性、周期性都存在明显的差异,相互之间有明显的相关性,和500hPa高度场也有较明显的相关关系,尤其是西太平洋和北印度洋的中低纬地区。 相似文献