一种新的大气稳定度分类方法

提出了一种运用灰色聚类理论对大气稳定度进行分类的新方法,用该方法及上海江湾站1993年1、4、7、10四个月的逐时常规观测资料对当时当地的大气稳定度进行了分类,最后与国标分类法所得结果进行了比较,得到了更优、更合理的类分布,说明该方法是大气稳定度分类中一种简单、实用而且效果更好的新方法。     

东亚季风指数分类初析

回顾了亚洲季风指数定义方法发展历程。将东亚季风强度指数按定义时所使用的要素类型分类为环流类、温湿类、海陆差异类、方程类和综合类，指出了各类指数的特点及适用范围，并为今后开展相关研究提出一些设想。     

湛江市春季连阴雨预报

本文通过对1969－1993年2－4月湛江市台（站）地面气象观测月简表资料的连阴雨情况进行详细的普查和分析，从中找出其气候特点和预报的着眼点，为湛江市春季连阴雨提供预报依据。     

云分类中逐个修改聚类和模糊聚类分类性能的对

利用卫星图像对各种云型进行识别在大气科学领域具有重要意义，为了深入了解云分类过程中逐个修改聚类和模糊聚类对各种云型的识别能力，采用极轨卫星EOS／MODIS图像资料和静止卫星GMS-5图像资料，在样本采集和特征提取的基础上。选择不同的光谱或纹理特征对两种分类器的分类性能进行测试和对比分析。结果发现，不管采用哪种图像资料，提取哪些特征量，逐个修改聚类的平均分类准确率总体上略高于模糊聚类。但就两种分类器对各种云型的识别能力而言，模糊聚类对低云和高云（如层云、薄卷云、密卷云、卷层云、积云）的分类准确率明显好于逐个修改聚类，而逐个修改聚类对积雨云的分类准确率稍高于模糊聚类。从各类别间混判的情形来看，积雨云和高中低混合云、低云之间及卷云子类之间混判的情形较多，模糊聚类与逐个修改聚类相比，混判的类别增多，相对比例减少。     

陇东两类夏季雷暴的活动特征及影响因素分析

利用ECMWF-ERA5再分析资料、常规观测资料分析了甘肃陇东2009—2018年夏季雷暴活动特征及环境条件。结果表明：陇东年均雷暴日数18.8~23.6 d，夏季雷暴占68.5%~74.7%。夏季雷暴主要分为偏北气流型和低槽影响型，其中偏北气流型以分散性干雷暴为主，较大的垂直温差、高空冷平流强度和近地面高温对雷暴发生具有显著影响；低槽影响型多伴有明显降水过程，较高的低空温度、湿度和较强的不稳定能量具有显著影响。低槽影响型和偏北气流型雷暴分别占总数的 30.5%和60%，这两种类型的雷暴更容易出现在陇东北部地区。低槽影响型雷暴呈逐月增加趋势，最大值出现在8月；偏北气流型雷暴呈单峰分布，最大值出现在7月。各站雷暴日数年际变化趋势在6、7月一致性较高；月雷暴日数均有3~5年的变化周期，其中7月与8月同步性较好。雷暴日数的月、年变化与相应类型主导因素相关明显。植被覆盖、气候带以及地形差异也对雷暴空间分布产生了重要影响。     

我国降水量的模糊聚类分区

本文采用模糊聚类中的系统聚类分析法对全国年、季降水量作了分压计算。为了客观地表示区内相关程度,提出了一种计算区内相关系数的方法。并根据实际情况,提出了选择降水分区方案的原则。结果比较令人满意。     

中国葡萄气候区划探讨

根据葡萄的生物学特性及其对气候条件的要求,在全国范围内选取８３个站点,按照９个农业气候指标,利用模糊聚类的数学方法,将全国划分为６个不同的葡萄气候区,并就各区的气候特点和品种选择作出分区评述。     

多光谱云分类技术在锋面云系中的应用

将逐个修改聚类和模糊聚类的多光谱云分类技术应用于2002年6月10日03时锋面气旋云系的识别,并采用同一时次的地面常规观测与其进行了对比分析。结果发现,两种聚类方法对典型锋面气旋云系均有较好的识别能力,分类结果与天气概念模型云层分布情况一致;逐个修改聚类对组间差别较大的情况分类效果较好,而模糊聚类却对性质相近的类别有较好的识别;卫星图像分类结果与地面常规观测比较一致,但在层云、积云、层积云等性质较为相近类别的识别上存在一定差异。     

三明市竹类布局气候区划

分析竹类 (散生竹、丛生竹 )生长的气候条件 ,确定三明市竹类布局的气候区划指标为年极端最低气温 ,根据气象站资料建立其空间分布模式 ,利用地理信息系统和Arcview软件制作分布图 ,按冬季冻害条件进行分区 ,并提出趋利避冻措施。     

加强业务管理提高测报质量

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.     

准两年振荡对大气中微量气体分布的影响

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。     

Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale

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.     

由中国历史气候记录对季风导致唐朝灭亡说的质疑

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.     

流场配置及地形对西南低涡形成的动力作用

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.     

Quantifying the uncertainty of the annular mode time scale and the role of the stratosphere

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.     

On the forecast of the onset and end of the convective season in the Amazon

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     

Analysis of the Characteristics of the Low-level Jets in the Middle Reaches of the Yangtze River during the Mei-yu Season

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...