共查询到20条相似文献,搜索用时 383 毫秒
1.
气候系统的非平稳行为和预测理论 总被引:22,自引:5,他引:17
到目前为止,有关非平稳复杂系统及其在气候预测中的应用研究(它有着比混沌系统更为复杂的行为)是一个较少被人理解并有重大科学意义的前瞻性研究课题。在大气运动中,气候正是一个典型的非平稳系统,但是现有的气候预测理论,包括统计预测理论和非线性预测理论,几乎都无一例外地建立在平稳性假定的基础之上,这有悖于气候过程的基本性质,因此它有可能是导致气候预测水平低下的重要的理论原因。另外,近10年来,气候过程具有层次结构已经成为许多科学家的共识,但是如何发展和完善这一理论,使之成为一个完整的体系,人们似乎还没找到合适的途径。事实上,气候系统的多层次结构(它与通常的多尺度结构是两个完全不同的概念)正是产生非平稳行为的原因,而气候系统的非平稳特性正是层次结构的集中表现。在这样的思想指导下,文中系统地讨论了非平稳气候的一些基本问题和相应的预测理论,并为之搭起了一个初步的理论框架。 相似文献
2.
3.
4.
5.
Huijun Wang Yongjiu Dai Song Yang Tim Li Jingjia Luo Bo Sun Mingkeng Duan Jiehua Ma Zhicong Yin Yanyan Huang 《大气和海洋科学快报》2022,15(1):2-11
过去几十年,气候变化和极端气候事件造成的经济损失和灾害显著增加.虽然全球的科学家在理解和预测气候变异方面做出了巨大的努力,但当前在气候预测领域仍然存在几个重大难题.2020年,依托于国家自然科学基金基础科学中心项目的气候系统预测研究中心(CCSP)成立了,该中心旨在应对和处理气候预测领域的三大科学难题:厄尔尼诺-南方涛动(ENSO)预测,延伸期天气预报,年际-年代际气候预测,并为更加准确的气候预测和更加有效的灾害防御提供科学依据.因此,本文介绍了CCSP的主要目标和面对的科学挑战,回顾了CCSP在季风动力过程,陆-气相互作用和模式开发,ENSO变率,季节内振荡,气候预测等方面已取得的重要研究成果.未来CCSP将继续致力于解决上述领域的关键科学问题. 相似文献
6.
申乐琳 《气候变化研究进展》2011,(2)
截至2010年7月,喧嚣半年多的气候门事件暂告一段落。英国东英吉利大学的最终调查报告显示,尽管气候科学家间的保密文化不足取,但相关科学家的严谨和诚实是没有疑问的,调查也没有发现可能影响IPCC结论的证据。 相似文献
7.
北京大学地球物理系统计预报组 《气象》1976,2(2):11-14
气候变化,不但有以万年计算的地质时代冰期与间冰期的变化,也有几千年来历史时期的变化。但是,与我们关系最密切的,还是周期为几十年到百年左右的气候振动。对于几年到十几年时间的气候变化,我们可以称为气候变动。这种气候变动往往是长期气候振动的一个片断,因此从气候振动角度来研究气候变动是非常必要的。我国多数气象台站是在解放后建立的,一般只有二十几年的资料,因此就要求我们从较长时期的气候振动来了解这二十几年的气候特点,这样才能正确运用二十几年的资料,来作长期预报和超长期预报。 相似文献
8.
潮汐和地震对全球气候变化的影响 总被引:1,自引:0,他引:1
2004年12月26日印尼地震海啸后,全球低温冻害和暴雪灾害频繁发生。"潮汐调温说"和"深海巨震降温说"是一种合理的解释。根据"潮汐调温说"和"深海巨震降温说"理论,2005年全球气温将因为印尼地震海啸和强潮汐南北震荡而降低。美国国家航空航天局(NASA)的科学家认为,一个较弱的厄尔尼诺现象和人类排放的温室气体将使2005年成为人类有记载以来最热的一年。事实上,2005年的温度低于1998年。现在,西方科学家也承认了2005—2007年自然气候的变化抵消了全球气候变暖效应这一客观事实。 相似文献
9.
10.
11.
我局从1999~2003年,测报工作连续4年未出现错情,在此期间共有1个250个班,9个百班无错通过上级业务部门验收.在仪器保管、使用、维护上符合要求,对外报送的各种表、簿都能做好出门合格. 相似文献
12.
13.
Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale 总被引:1,自引:0,他引:1
G. Terence Meaden S. Kochev L. Kolendowicz A. Kosa-Kiss Izolda Marcinoniene Michalis Sioutas Heino Tooming John Tyrrell 《Atmospheric Research》2007,83(2-4):446-449
2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita's damage scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita's Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita's Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F′half = T / 2 = (B / 4) − 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F′double = T = (B / 2) − 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit scale has all the criteria needed for world-wide practical effectiveness. 相似文献
14.
准两年振荡对大气中微量气体分布的影响 总被引:11,自引:5,他引:6
NCAR的包含化学、辐射、动力相互作用的两维模式(SOCRATES)移植回国后进行了初步的模拟试验,用以研究某些对环境问题重要的微量气体的化学、辐射、动力传输过程。在不考虑极地平流层云和气溶胶表面非均相化学等情况下,模式积分多年,计算结果稳定,模拟的风场、温度场显示出正常的季节变化,模拟的微量气体分布与卫星实测资料对照,结果也比较一致。为了探讨热带平流层风场的准两年周期振荡(QBO)对平流层微量气体分布的影响,我们做了QBO强迫的数值试验,即在模式中加入QBO强迫,并与不考虑QBO强迫的模拟结果对比。结果表明,QBO与其相关的次级环流所引起动力输送的变化,使平流层微量气体分布发生变化。 相似文献
15.
The impact of high resolution modern vegetation cover on the West African climate is examined using the International Centre for Theoretical Physics Regional Climate Model implementing the NCAR Community Land Model. Two high resolution 25 km long-term simulations driven by the output from a coarser 50-km resolution simulation are performed for the period 1998–2010. One high resolution simulation uses an earlier and coarser-resolution version of plant functional type distribution and leaf area index, while the other uses a more recent, higher-quality, and finer-resolution version of the data. The results indicate that the new land cover distribution substantially alters the distribution of temperature with warming in Central Nigeria, northern Gulf of Guinea and part of the Sahel due to the replacement of C4 grass with corn; and cooling along the coastlines of the Gulf of Guinea and in Central Africa due to the replacement of C4 grass with tropical broadleaf evergreen trees. Changes in latent heat flux appear to be largely responsible for these temperature changes with a net decrease (increase) in regions of warming (cooling). The improved land cover distribution also results in a wetter monsoon season. The presence of corn tends to favor larger precipitation amounts via more intense events, while the presence of tropical broadleaf evergreen trees tends to favor the occurrence of both more intense and more frequent events. The wetter conditions appear to be sustained via (1) an enhanced soil moisture feedback; and (2) elevated moisture transport due to increased low-level convergence in regions south of 10N where the most substantial land cover differences are present. Overall the changes induced by the improved vegetation cover improve, to some extent, the performance of the high resolution regional climate model in simulating the main West African summer monsoon features. 相似文献
16.
由中国历史气候记录对季风导致唐朝灭亡说的质疑 总被引:1,自引:0,他引:1
张德二 《气候变化研究进展》2008,4(2):126-130
2007年1月4日杂志发表了Yancheva等10人的题为"Influence of the intertropical convergence zone on the East-Asian monsoon"(热带辐合带对东亚季风的影响)的论文[1],这是德国波兹坦地学研究中心气候动力与沉积学科的主管豪格(G.H.Haug)率领的科研小组的一项成果,认为是季风的变化引起的长期干旱导致了唐朝的灭亡. 相似文献
17.
流场配置及地形对西南低涡形成的动力作用 总被引:10,自引:8,他引:10
本文采用定常二层模式讨论较小地形及高、低层流场配置对西南低涡形成的动力作用。指出了西南低涡的形成是与盆地、河谷以及其上气流分层有关的一种定常态.在上、下为西风分层时期,低层的浅薄暖湿西风有利于西南低涡的形成.在上、下为东、西风分层时期,上层浅薄东风亦有利于西南低涡的形成.小型的凸起山脉对西南低涡的形成没有作用. 相似文献
18.
19.
Summary ?Some features of the climate system that can be considered predictors of the onset and end of the convective season over
the Amazon were identified using one-month lag correlations and field composites. The fields analyzed were sea surface temperature
(SST), outgoing long-wave radiation (OLR), vertical velocity and upper tropospheric winds.
Warm (cold) anomalies in the SST in the tropical North Atlantic and the Caribbean Sea tend to be associated with delayed (early)
onsets. Likewise, there is a tendency towards a delayed (early) end of the convective season with cold (warm) anomalies in
these ocean regions. In addition, the SST in the cold tongue region of the equatorial Pacific is negatively, though weakly
correlated with the onset date. The signal of this SST is more evident in the case of the end date, which is earlier with
respect to its mean date in most of El Ni?o cases.
The convective activity intensity itself conditions the onset and the end of the convective season, as it is evidenced by
the behavior of the OLR and the vertical velocity fields. The more (less) intense the convective activity over South America
during the preceding month, the earlier the onset and the later the end of the convective season on the Amazon region.
The prediction of the onset and end dates of the convective season in the Amazon region was explored using a simple multiple
regression technique based on the variables that have shown precursor signals with respect to these dates. The correlation
coefficient between the predicted and the observed onset date is 0.81, and in the case of the end date, it is 0.76. The skill
to predict early, delayed and normal categories was high, since in more than two thirds of the cases the category was successfully
predicted, and there were no predictions of categories opposed to those observed.
Received July 23, 2001; revised February 22, 2002; accepted April 26, 2002 相似文献
20.
Chunguang CUI Wen ZHOU Hao YANG Xiaokang WANG Yi DENG Xiaofang WANG Guirong XU Jingyu WANG 《大气科学进展》2023,40(4):711-724
Here, we analyze the characteristics and the formation mechanisms of low-level jets(LLJs) in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5) reanalysis dataset. Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs) concentrated at heights of 900–1200 m.The BLJs occur most frequently at 230... 相似文献