共查询到19条相似文献，搜索用时 819 毫秒
1.
杨舵 《沙漠与绿洲气象(新疆气象)》1996,19(6):1-3,14
短期气候变化是指以月、季和年际为时间尺度的气候变率和气候异常。近几年，国外开始注意年际气候变化，即10年尺度的气候变化，并把它也归之为短期气候变化的范畴。短期气候预测的对象是某个气象要素的时间和区域的平均值，或它相对于多年平均值的偏差（即距平）。在作短期气候预测时，首先面临的是可预报性问题。目前，已有大量工作对此问题进行了研究。1大气的可预报上限P．D．”fhompson最先在气象文献中谈到可预报性问题，分析了初始状态的不确定性对大尺度气流可预报性的限制。后来，Lorenz在一次偶然的重复计算中发现初值的微小差… 相似文献
2.
该文系统地介绍了国内外评估月、季尺度短期气候预测结果的方法 ,比较了相关系数(R)、预报技巧分 (S)和准确率 (P)的特点 ,并对当前国内外气候预测业务水平进行了分析 ,着重对大气环流、气温、降水及 ENSO的预测水平进行了评估 ,指出国内外月、季尺度的降水预报的水平目前在 55%～ 60 %左右 ,对 ENSO的发生、结束和强度的预报水平有限 .文中探讨了短期气候预测的可预报性问题 ,提出月、季尺度气候预测的可预报性的理论上限可能为 6～ 1 2月 ,准确率在 80 %～ 85%之间 . 相似文献
3.
对月平均大气环流预报试验、季度预测和中国汛期降水预测进行了总结。结果表明气候预测的对象必须是要素的时间平均场。利用数值模拟进行气候预测是今后的主要发展方向,而季度预测技巧的提高依赖于对物理参数化和物理机制的研究。最后,讨论了季平均气温和季总降水的可预报性问题,即时效性和准确率。 相似文献
4.
短期气候预测的主要对象是气温和降水的月、季平均量和总量，需要做预报是因为它们有年际变率，但是年际变率究竟有多少是可以被预报出来的呢？通常情况下将总的年际变率划分为主要来源于大气下边界条件持续性外源强迫引起的可预报成分和由于大气内部不稳定性产生的日际天气振荡引起的不可预报成分，前者称气候信号，后者称气候噪声，我们用两个成分的方差之比给出潜在可预报性的测度。本文用低频白噪声延伸法估计了吉林省夏季（6～8月）降水量潜在可预报的气候信号方差和天气噪声方差。结果表明，我省各地均存在潜在可预报性信号。以绝对误差小于均方差0．68倍做为预报正确的标准，我省70%的站预报正确率上限达60％以上。 相似文献
5.
回顾了1958－1997年新疆短期气候预测研究取得的主要成果，包括：大气环流变化及其与新疆天气气候的关系；新疆冬、春季水旱以及北疆前冬冷暖长期天气过程的分析；北半球月平均加热场及其在长期天气预报中的应用；海气相互作用、地形影响、低频振荡过程以及在短期气修预测中的应用；新疆短期气候预测方法的应用研究等。 相似文献
6.
本文提出了短期气候预测的基本时间单位应是年，这样可以与天为基本时间单位的天气预报进行对比分析；将天气预报中的某些思路和方法引进短期气候预测中来，如突出灾害性天气的预报思路，多种方法相配套的预报思路，以天气过程为主要预报对象的预报思路和用概率表示预测结果的方法等，要大大开阔知期气候预测的思路和方法。经沈阳地区的预测试验，证明是可行的。 相似文献
7.
大气季节内振荡在华南降水预报中的应用 总被引：1，自引：0，他引：1
大气季节内振荡(ISO)在天气气候演变中扮演着重要角色,是中期和延伸期预报可预报性来源之一,同时大气ISO的年际变化与区域季节降水量的年际变化密切联系,对短期气候预测有指示意义。对热带大气ISO的年际变化研究做了简要回顾;重点介绍了ISO对华南降水的影响及其业务应用情况,主要包括赤道MJO对华南降水的影响、基于准两周振荡的汛期暴雨过程预报、热带ISO与热带外系统多尺度相互作用对强降水的影响、ISO对季节降水的影响、基于ISO建立的降水延伸期定量预测模型;最后对进一步加强ISO应用研究提出了几点思考。 相似文献
8.
长期天气过程的可预报性研究的进展 总被引：2，自引：0，他引：2
在数值天气预报中,大气可预报性问题是一个重要的研究课题。它们有的是从数值预报模式初值场误差探讨,即讨论计算过程中的误差增长使得预报与实况差异太大的时间。这段时间一般为两周,它称为大气可预报的时间。这是短期天气过程可预报性问题。长期天气过程的可预报性,大多是从天气变化稳定性进行探讨。短期天气过程与长期天气过程的关系以及长期天气过程的可预报性问题一直是近十余年来气象学者十分关心的研究课题,本文将着重介绍有关长期天气过程可预报性研究的进展。 相似文献
9.
杨舵 《沙漠与绿洲气象(新疆气象)》1996,19(5):1-6
1引言国外不少国家开展短期气候预测的研究与业务已有几十年历史。目前大多数国家（包括我国）业务预报仍以经验统计方法为主，预报效果不稳定。80年代以来。有关气候变化物理成因及其机制的研究，为短期气候预测尤其是动力模式的发展提供了物理依据，有的已成为短期气候预测很有用的工具。一些发达国家在进行动力模式的研制和气候模拟方面发展很快。为更好开展短期气候预测的研究，有必要了解其发展现状。但限于篇幅，本文只能对短期气候预测的较新进展作比较详细的介绍。2短期气候预测方法2．1经验、统计方法经验方法仍以天气气候的相似相… 相似文献
10.
应用IAP9L-AGCM对2002年中国夏季气候的预测及效果检验 总被引：10，自引：0，他引：10
利用中科院大气所9层大气环流格点模式(IAP9L—AGCM)和IAP—ENSO预测系统对2002年中国夏季气候进行实时集合预测及其检验。结果显示，IAP9L—AGCM较好地预测出了2002年夏季我国大范围旱涝的分布形势，如华南、我国西部多雨，黄河和长江流域之间大范围干旱等；850hPa减弱的夏季风、青藏高原辐散中心以及北太平洋上空的异常气旋性环流中心亦被较好地预报出来；不足的是，模式对降水异常细致分布的预测能力有限。预测结果还表明，该模式对夏季(6—8月)平均降水的预报技巧要高于月平均状况，且月平均预报的准确度从6—8月依次递减。 相似文献
11.
本文用大气环流模式研究了ＥＮＳＯ引起的全球短期气候异常变化的潜在可预报性。大气对ＥｌＮｉｎｏ／ＬａＮｉｎａ事件的响应应分为瞬时响应和迟后响应。最后探讨了这种潜在可预报性形成的可能机理。 相似文献
12.
首先采用方差分析方法，研究了实际大气500 hPa高度场的月尺度可预报性，并进一步分析了不同空间尺度大气运动的可预报性及其对大气整体运动可预报性的影响；对ECMWF和国家气候中心T63谱模式分别模拟和预报的500 hPa高度场，也用同样的方法进行了研究。结果表明，欧洲中心和我国T63模式大气的可预报性均比实际大气可预报性小，特别是在对整体运动可预报性影响最大的0～3波部分，差异较大，说明改进模式对0～3波部分的预报能力，必将提高模式性能。 相似文献
13.
Recent Advances in Predictability Studies in China （1999-2002） 总被引：10，自引：2，他引：8
Since the last International Union of Geodesy and Geophysics (IUGG) General Assembly (1999), the predictability studies in China have made further progress during the period of 1999-2002. Firstly, three predictability sub-problems in numerical weather and climate prediction are classified, which are concerned with the maximum predictability time, the maximum prediction error, and the maximum allowable initial error, and then they are reduced into three nonlinear optimization problems. Secondly, the concepts of the nonlinear singular vector (NSV) and conditional nonlinear optimal perturbation (CNOP) are proposed,which have been utilized to study the predictability of numerical weather and climate prediction. The results suggest that the nonlinear characteristics of the motions of atmosphere and oceans can be revealedby NSV and CNOP. Thirdly, attention has also been paid to the relations between the predictability and spatial-temporal scale, and between the model predictability and the machine precision, of which the investigations disclose the importance of the spatial-temporal scale and machine precision in the study of predictability. Also the cell-to-cell mapping is adopted to analyze globally the predictability of climate,which could provide a new subject to the research workers. Furthermore, the predictability of the summer rainfall in China is investigated by using the method of correlation coefficients. The results demonstrate that the predictability of summer rainfall is different in different areas of China. Analysis of variance, which is one of the statistical methods applicable to the study of predictability, is also used to study the potential predictability of monthly mean temperature in China, of which the conclusion is that the monthly mean temperature over China is potentially predictable at a statistical significance level of 0.10. In addition,in the analysis of the predictability of the T106 objective analysis/forecasting field, the variance and the correlation coefficient are calculated to explore the distribution characteristics of the mean-square errors.Finally, the predictability of short-term climate prediction is investigated by using statistical methods or numerical simulation methods. It is demonstrated that the predictability of short-term climate in China depends not only on the region of China being investigated, but also on the time scale and the atmospheric internal dynamical process. 相似文献
14.
In this paper, the two-layer IAP model with sea surface temperature anomalies in the equatorial central-eastern Pacific is used to investigate potential predictability of global short-term anomalous climate change caused by El Nino via the “switching” experiments. The experimental results show that short-term anomalous climate change in the tropics is mainly caused by instantaneous response of tropical atmosphere to SSTA in the tropics. The effective period of this kind of anomalous climate is shorter and about monthly scale. In the high latitudes, the anomalous cli-mate is mainly caused by the lag response of atmosphere to SSTA in the tropics. The strongest influence appears in the month after a half year when the SSTA in the tropics disappears. Therefore, potential predictability of short-term anomalous climate change may be reached to one year; anomalous climate change in the middle-latitudes is not only affected by instantaneous response to SSTA in the tropics, but also by lag response to that. Therefore, short-term climate change prediction with monthly time scale can be not only done by using SSTA in the tropics, but also predic-tion of short-term climate after a half year can be done and its effective predictable period may be reached to one year. 相似文献
15.
10~30 d延伸期的可预报性既依赖于初始条件,也与缓变的下垫面有关,寻找延伸期时段内可预报性较高的低频特征,识别延伸期的可预报性来源及影响的物理机制是提高延伸期预报水平的关键。近年延伸期可预报性来源、热带大气季节内振荡监测预测和影响等领域的研究取得较大进展,提出和应用了动力统计相结合以及大气低频信号释用等新的延伸期预报方法。对延伸期可预报性来源及其与初值和外强迫异常的关系分析表明,海气相互作用能提高亚洲和西太平洋区域延伸期时段大气环流和要素的可预报性。热带大气季节内振荡、平流层爆发性增温以及各种次季节尺度的海气、陆气耦合作用和大气响应均为延伸期预报提供了重要的可预报性来源。由于数值模式延伸期时段的预报性能与实际业务需求还存在一定距离,基于动力统计相结合和物理统计的延伸期预报方法被广泛应用于业务预报,表现出一定的预报技巧。 相似文献
16.
来自大气内部的季节气候可预测性初探 总被引：3，自引：0，他引：3
这是一个十分初步的工作结果.通常认为,气候的季节-年际可预测性主要来自缓慢变化的大气外强迫的异常(如海表温度、积雪、土壤温度和湿度等).作者从大气月平均风场异常的持续性以及与东亚季风年际异常相关的全球大气环流异常特征两个方面初步探讨东亚夏季气候的可预测性.初步结果说明,大气月平均风场在对流层上层和平流层下层的热带区域及一些关键区域可持续性可以超过一个季节,并且与东亚季风有显著相关,从而使得从大气内部变化来考虑东亚夏季风气候仍然有一定的可预测性. 相似文献
17.
Of great importance for guiding numerical weather and climate predictions, understanding predictability of the atmosphere in the ocean − atmosphere coupled system is the first and critical step to understand predictability of the Earth system. However, previous predictability studies based on prefect model assumption usually depend on a certain model. Here we apply the predictability study with the Nonlinear Local Lyapunov Exponent and Attractor Radius to the products of multiple re-analyses and forecast models in several operational centers to realize general predictability of the atmosphere in the Earth system. We first investigated the predictability characteristics of the atmosphere in NCEP, ECMWF and UKMO coupled systems and some of their uncoupled counterparts and other uncoupled systems. Although the ECMWF Integrated Forecast System shows higher skills in geopotential height over the tropics, there is no certain model providing the most precise forecast for all variables on all levels and the multi-model ensemble not always outperforms a single model. Improved low-frequency signals from the air − sea and stratosphere − troposphere interactions that extend predictability of the atmosphere in coupled system suggests the significance of air − sea coupling and stratosphere simulation in practical forecast development, although uncertainties exist in the model representation for physical processes in air − sea interactions and upper troposphere. These inspire further exploration on predictability of ocean and stratosphere as well as sea − ice and land processes to advance our understanding of interactions of Earth system components, thus enhancing weather − climate prediction skills.
相似文献18.
Martina Weiss Bart van den Hurk Reindert Haarsma Wilco Hazeleger 《Climate Dynamics》2012,39(11):2733-2746
Climate models often use a simplified and static representation of vegetation characteristics to determine fluxes of energy, momentum and water vapour between surface and lower atmosphere. In order to analyse the impact of short term variability in vegetation phenology, we use remotely-sensed leaf area index and albedo products to examine the role of vegetation in the coupled land–atmosphere system. Perfect model experiments are carried out to determine the impact of realistic temporal variability of vegetation on potential predictability of evaporation and temperature, as well as model skill of EC-Earth simulations. The length of the simulation period is hereby limited by the availability of satellite products to 2000–2010. While a realistic representation of vegetation positively influences the simulation of evaporation and its potential predictability, a positive impact on 2?m temperature is of smaller magnitude, regionally confined and more pronounced in climatically extreme years. 相似文献
19.
The North Atlantic is one of the few places on the globe where the atmosphere is linked to the deep ocean through air–sea
interaction. While the internal variability of the atmosphere by itself is only predictable over a period of one to two weeks,
climate variations are potentially predictable for much longer periods of months or even years because of coupling with the
ocean. This work presents details from the first study to quantify the predictability for simulated multidecadal climate variability
over the North Atlantic. The model used for this purpose is the GFDL coupled ocean-atmosphere climate model used extensively
for studies of global warming and natural climate variability. This model contains fluctuations of the North Atlantic and
high-latitude oceanic circulation with variability concentrated in the 40–60 year range. Oceanic predictability is quantified
through analysis of the time-dependent behavior of large-scale empirical orthogonal function (EOF) patterns for the meridional
stream function, dynamic topography, 170 m temperature, surface temperature and surface salinity. The results indicate that
predictability in the North Atlantic depends on three main physical mechanisms. The first involves the oceanic deep convection
in the subpolar region which acts to integrate atmospheric fluctuations, thus providing for a red noise oceanic response as
elaborated by Hasselmann. The second involves the large-scale dynamics of the thermohaline circulation, which can cause the
oceanic variations to have an oscillatory character on the multidecadal time scale. The third involves nonlocal effects on
the North Atlantic arising from periodic anomalous fresh water transport advecting southward from the polar regions in the
East Greenland Current. When the multidecadal oscillatory variations of the thermohaline circulation are active, the first
and second EOF patterns for the North Atlantic dynamic topography have predictability time scales on the order of 10–20 y,
whereas EOF-1 of SST has predictability time scales of 5–7 y. When the thermohaline variability has weak multidecadal power,
the Hasselmann mechanism is dominant and the predictability is reduced by at least a factor of two. When the third mechanism
is in an extreme phase, the North Atlantic dynamic topography patterns realize a 10–20 year predictability time scale. Additional
analysis of SST in the Greenland Sea, in a region associated with the southward propagating fresh water anomalies, indicates
the potential for decadal scale predictability for this high latitude region as well. The model calculations also allow insight
into regional variations of predictability, which might be useful information for the design of a monitoring system for the
North Atlantic. Predictability appears to break down most rapidly in regions of active convection in the high-latitude regions
of the North Atlantic.
Received: 28 October 1996 / Accepted: 21 March 1997 相似文献