共查询到20条相似文献，搜索用时 671 毫秒
1.
2.
诊断分析CMA-MESO(China Meteorological Administration Mesoscale Model,原GRAPES-MESO)3 km系统冬季2 m温度预报效果,为冬奥气象保障服务以及CMA-MESO模式系统开发优化改进提供参考,选取2020年12月至2021年2月2 m温度预报。诊断发现,每日低温预报较好,高温预报较差,00—06时(世界时,下同)升温过程预报效果好于06—21时降温过程。滑动双权重平均法订正显示,2 m温度预报偏差以系统性偏差为主,订正前均方根误差和标准差较大地区改善效果更为明显。依据温度订正前后标准差差异选择华北、华东、西南三个区域的个例和华北地区连续试验进行波谱分析发现,功率谱随着尺度增大逐渐增多,2 m温度预报偏差和2 m温度不同尺度功率谱信息存在一定的对应关系,当不同尺度上的功率谱存在缺失或异常大值时,2 m温度预报与实况存在明显差异。 相似文献
3.
四、ECMWF的业务 1.业务预报中心每天作间隔是12或24小时的10天预报,目前没有其它业务预报工作.每天从12时(格林威治时间,下同)开始分析,17时出来对头一天18时的分析结果,这是第一预测值.18、18.30、20时分别完成00、06、12时的分析(参见图3),从开始分析到截止约8小时.再从这个结果制作10天预报,完成时间是第二天02时. 相似文献
4.
5.
6.
一、前言随着数值预报的不断发展和改进,给要素预报提供了越来越多的信息,但是在同属于一个天气尺度系统下的某地区用纯MOS预报欲分离出某一个点(县)的预报是较为困难的。统计分析表明,湖州站降水与各县站降水的相关系数都超过了0.8。因此,作为分县预报要达到较理想的目的,就必须足够地考虑单站要素所提供的有用信息。因为它们在一定程度上反映了 相似文献
7.
淄博市冬季偏北大风的分县预报 总被引：1，自引：0，他引：1
在分析淄博市冬季偏北大风时－空分布特征的基础上,首先用ＰＰ法建立了大风的初步筛选预报方程,尔后选用不同的预报判据进行冬季偏北大风的分县预报。经试用,对大风分县指导预报有一定意义。 相似文献
8.
9.
一、基本情况我市分县预报的研制试行分两个阶段进行.第一阶段从一九九○年四月份开始进行全市分县预报对比试验.从九○年、九一年二年的对比试验结果来看,九○年市台预报和县局独立预报差距甚微,而九一年市台预报质量则明显高于县局独立预报.第二阶段从一九九二年开始,用市台预报替代县局独立 相似文献
10.
做好县站预报,关键是要有一套行之有效的县站预报工具和方法。我国县站预报从1958年诞生以来,经过广大气象工作者的努力,已经创造了曲线图、时间剖面图、点聚图等各种县站预报工具,为我国县站预报的发展做出了贡献。但要形成一套完善的县站预报工具和方法,还有待于继续开展县站预报工具的研究和改革。 为了适应县站独立制作预报的需要,一种好用的县站预报工具或方法,必须具备:①反映天气过程较明显;②反映天气系统的能力较强,③对本地未来天气(特别是重大灾害性天气)有较好的预示作用 相似文献
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.
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.
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
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