高原地区降水性质浅谈

高原地区降水性质与平原地菜有相同之处 ,又有其独特的地方 ,这里就个人经验小叙如下 :首先从降水的特征及所见的现象看 ,阵性降水一般开始和停止都较突然 ,降水强度变化很快 ,骤降骤止 ,天空会出现时而昏黑时而明亮开朗的现象 ,伴有雷暴或闪电 ;而非阵性降水中 ,连续过程中强度变化很小 ;间隙性降水虽时降时止或强度变化时大时小 ,但这种变化的过程很缓慢 ,天空也看不出有什么明显变化。其次从气象要素变化看 ,压、温、湿、风自记记录明显起伏变化的伴有的降水一般为阵性。如有系统过境时 ,温度计迹线陡降 ,湿度计迹线陡升 ,气压计有显著升…     

浅谈阵性降水的观测

阵性降水是指强度变化大 ,骤降骤停 ,有时伴有雷暴 ,降自积雨云、积云、层积云中的降水。对阵性降水的观测 ,不能全以雷暴或者云状来确定 ,有的地面测报员一听到雷声后 ,在同一分钟内便将雨改记为阵雨 ,于是一日之中 ,雨、阵雨、雨、阵雨 ,这样反复转来转去 ,使记录不连续 ,失去了真实性。笔者在此浅谈观测阵性降水的体会 ,以供同行参考。首先在思想上对阵性降水要有明确的认识 ,阵性降水一定降自积雨云或对流旺盛的浓积云 (积云性层积云有时也可降阵雨 ,但量较少 ) ,一般有雷电现象。但在积雨云本身 ,对流不旺盛时 ,就可能没有雷电现象。因…     

雨和阵雨的转换

测报值班中常遇到有时天空一直是雨层云并为连续性降水,但突然闻雷,而当地整个云层与降水性质均无变化,这是暖锋云系(或缓行冷锋云系)上产生的局部不稳定现象.此时虽闻雷,但要根据情况判明Cb云量,正确判断降水性质.当降水阵性较明显,本站气象要素也随之有剧烈变化时,这时的云层就不再是雨层云布满全天,而在相当一部分或天顶部分已为Cb云控制,这时应将雨转记为阵雨.     

虹吸雨量计迹线跳跃异常分析

在地面测报工作中，由于多种原因，虹吸雨量计自记记录迹线有时发生异常，常常表现为阶梯形上升，这在台站记录中是比较普遍的，从查到的原始记录中发现，有的观测员把这种不正常的记录迹线按正常处理，忽略了不合理的因素，造成记录资料的不真实性。自记迹线呈阶梯形上升，有两种原因，一是确有阵性降水而突升，二是由于仪器本身的毛病如摩擦力过大而产生突升。那么如何判断、处理这两种情况呢？根据经验可以从以下三个方面去考虑。一、了解当天的观测记录，尤其是降水云层。一般较稳定云层如SC、AC、AS、NS与云降小雨，迹线上升比较平…     

雨和阵雨的转换

测报值班中常遇到有时天空一直是雨层云并为连续性降水 ,但突然闻雷 ,而当地整个云层与降水性质均无变化 ,这是暖锋云系 (或缓行冷锋云系 )上产生的局部不稳定现象。此时虽闻雷 ,但要根据情况判明Ｃｂ云量 ,正确判断降水性质。当降水阵性较明显 ,本站气象要素也随之有剧烈变化时 ,这时的云层就不再是雨层云布满全天 ,而在相当一部分或天顶部分已为Ｃｂ云控制 ,这时应将雨转记为阵雨。雨和阵雨的转换@王元秀$固始县气象局!河南固始465200     

怎样理解降自蔽光高层云下的霰

20 0 4年 3月 1 7日 1 7时 2 3分至 1 7时 37分 ,我站降形似圆锥形且着地反跳的颗粒状固态降水 ,骤降骤止 ,强度变化也很大。按规定应记阵性霰 ,报“87”才对 ,但在观天判云时发现上空为蔽光高层云。根据降水性质与降水云层的联系判断 ,有两种不同的见解 :一是确实记霰 ,但由于上层为蔽光高层云 ,其降水性质应按非阵性处理 ,按“77”编报 ;二是认为应记阵性霰 ,报“87”才对。霰的出现标志云中对流强 ,大气不稳定 ,降水期间肯定有对流云存在。两种见解各有道理 ,但笔者认为上述第二种记法较适宜。理由是 ,尽管上层有蔽光高层云 ,但所降之物…     

怎样理解降自蔽光高层云下的霰

2004年3月17日17时23分至17时37分,我站降形似圆锥形且着地反跳的颗粒状固态降水,骤降骤止,强度变化也很大.按规定应记阵性霰,报"87"才对,但在观天判云时发现上空为蔽光高层云.根据降水性质与降水云层的联系判断,有两种不同的见解:一是确实记霰,但由于上层为蔽光高层云,其降水性质应按非阵性处理,按"77"编报;二是认为应记阵性霰,报"87"才对.霰的出现标志云中对流强,大气不稳定,降水期间肯定有对流云存在.     

北方强降水的气候特征

本文利用最近30—40年的资料，分析了北方强降水的气候特征。文中指出:北方暴雨日数明显少于南方，但强度大。我国大陆上的不同历时降水极值均出现在北方；降水时间集中在盛夏；最大一日降水量的强度对年降水量多寡有显著影响，且最大一日降水量的年际变差明显；北方的强降水常伴有强烈雷暴活动、历时短、降水覆盖面积小。     

龙嘉机场一次春季雨夹雪复杂天气个例的观测与分析

1引言春季雨夹雪天气既影响能见度,又会造成跑道积冰,严重影响飞行安全,一直以来是民航观测较为关注的问题。2012年3月31日,长春龙嘉机场迎来了首轮对流云阵性雨夹雪天气,降水强度变化很快,骤降骤止,天空时而昏暗时而明亮,能见度短时间内在万米和百米之间转换,24小时内     

1996年4月19～20日我省暴雨过程分析

1过程概况今年4月19日02时开始到20日止，本省经历了～次全省性的暴雨到特大暴雨过程。这次降水过程主要是由移动性槽影响造成的，降水特点是：范围广——全省性，省内有58个站出现暴雨，14个站出现特大暴雨；强度强——6小时降水量超过50mm的台站有10个，台山最大达1llmm；降水时间短——降水过程从开始到结束2天左右。过程降水总量最多的市（县）有肇庆、斗门、阳山、连山、台山、东范分别为213．l、212．4‘203．8、200．i182．2‘181．4mm。最大降水时段集中在19日08～14时。本省的西北和中部偏西北地区降水较明显。2天气形势分析2．120…     

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.     

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     

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.     

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.     

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...     

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.     

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.