热带辐合带对防城港市天气影响分析

通过分析汛期影响防城港市的热带辐合带,总结归纳出预报热带辐合带天气的一些模式指标,热带辐合带进入影响区后,出现东海气旋型、副高南压型和大陆高压出海型,次日则无雨(Ⅰ型);出现南海低压型和中纬低槽型,则次日有雨(Ⅱ型);套用暴雨的四个模型,预报次日有没有暴雨(Ⅱ型).     

西太平洋及南海地区一次热带辐合带环流和结构的初步分析

本文对1974年8月上半月西太平洋及南海地区一次强热带辐合带的环流特征作了分析,给出这次热带辐合带的平均结构和天气分布。发现在热带辐合带上空,200毫巴对应有一个弱的孤立反气旋;除了热带辐合带及它北部副高之间有一个垂直经圈环流外,和它南部赤道缓冲带之间还有一个经圈环流,其下沉运动位于赤道缓冲带北侧;在热带辐合带涡旋的南部存在低层强西南气流,主要云区和降水区发生在这支气流的西北侧。本文并对主要云区和降水区为什么集中于热带辐合带南侧和热带辐合带上热带扰动的发展问题作了一些物理解释。     

南海季风槽与江门沿海地区的强降水

利用2005～2009年5月下旬～6月底Micaps每天08时850百帕天气图、江门地区自动站降水资料和NCEP4次/d的1°×1°FNL全球再分析资料,从天气学的角度分析研究了南海中北部南海季风槽的生成、结构和演变特征及其与江门沿海地区强降水的关系。结果表明,在南海中北部建立并影响江门地区的南海季风槽其环流特征和物理结构与有关文献的研究结果是一致的。3种环流形势下会生成南海季风槽,即热带气旋消亡期、西南季风与副高西南侧偏东风辐合及热带辐合带在西南季风的加强冲击下出现曲折时。南海季风槽在南海中北部建立、珠江口西侧为瓶颈出口,江门沿海地区将出现中尺度的强降水,局地出现特大暴雨降水过程。     

辽宁中部地区持续性污染的天气分型

利用NCEP全球再分析资料和地面大气成分观测资料,根据大尺度天气背景,将2010—2012年出现在辽宁中部地区的全部持续性大气污染过程划分为5种类型:蒙古高压型、变性高压型、蒙古气旋型、弱低压型和江淮气旋型。进一步的边界层物理机制研究表明:江淮气旋型与蒙古高压型污染的区域水平气流辐合、垂直的气流输送、大气层结稳定度都比较相近,只是前者的逆温强度更大。相比以上两种类型,其他三种类型的水平辐合程度相当,但下沉气流、大气层结稳定度和逆温现象要明显偏弱甚至未出现。     

夏季南海低空越赤道气流变化与亚澳季风区降水异常的联系

基于1979—2014年ERA-Interim逐月风场和水汽通量资料及GPCP逐月降水率资料,采用相关分析及合成分析等方法研究了夏季南海低空越赤道气流的变化特征及其与亚澳季风区降水异常的联系。结果表明:1)夏季南海低空越赤道气流强度的年际变化特征明显,具有3~4 a的周期。2)夏季南海低空越赤道气流强度变化与热带东印度洋和海洋性大陆区域降水异常具有显著的负相关关系、与热带西太平洋降水异常存在明显的正相关关系、与我国中部地区降水异常存在较好的负相关关系。3)当夏季南海低空越赤道气流强度偏强时,850 hPa上自阿拉伯海向东一直延伸到热带西太平洋为西风异常,这种环流形势有利于热带西太平洋出现水汽辐合,使得该区域降水出现明显偏多,同时热带东印度洋低层为东风异常,受其影响,热带东印度洋和海洋性大陆区域出现水汽辐散,使得该区域降水偏少;此外,在我国东南沿海为一个气旋式风场异常,不利于来自热带海洋的水汽输送到达我国中部地区,使得该地区降水偏少;反之亦然。4)当夏季南海低空越赤道气流偏强时,东亚地区局地Hadley环流表现为异常偏弱,低空偏南越赤道气流异常在20°N附近与来自北半球的冷空气交汇上升,赤道附近及30~40°N地区出现异常下沉运动,使得热带海洋性大陆区域和我国中部地区降水减少;反之亦然。     

阿拉伯海—南海海温距平纬向差异对长江中下游降水的影响

本文从分析阿拉伯海至南海海温距平场为东暖西冷和东冷西暖两种不同纬向分布型时热带大气环流不同的特征中讨论了该区海温异常对长江中下游梅雨影响的物理过程。指出不同类型的海温距平纬向分布,可能导致印度季风和东亚季风位置和强度不同的变异,并通过这两支季风的相互作用和调整,影响西太平洋热带辐合带、副热带高压和我国降水的分布。     

西太平洋副高与ENSO的关系及其对福建雨季降水分布的影响

用低阶大气环流谱模式就前期冬春季南海-热带东印度洋(10 oN～15 oS, 90～120 o E) 海温异常对南海夏季风的影响进行了数值试验。结果表明, 当南海-热带东印度洋海温异常偏暖时,其南北两侧大气低层出现异常气旋性环流,高层出现异常反气旋性环流,其东西两侧, 在南海-热带西太平洋大气低层出现强大的异常辐合,高层出现强大的异常辐散;在热带西印度洋大气低层为明显的辐散,高层为明显的辐合,得到了与Gill理论相一致的结论。此时大气低层赤道两侧异常气旋性环流阻挡了赤道索马里越赤道SW气流进入南海, 加强了赤道西风, 并明显减弱了澳大利亚越赤道SW气流,菲律宾以东的异常反气旋性环流加强了西太平洋副热带高压, 使其位置偏南偏西, 同时大气高层印度洋上空的异常东风加强了南亚高压, 从而导致南海夏季风强度减弱, 爆发可能推迟。在南海-热带东印度洋海温异常偏冷时,大气低层赤道两侧异常反气旋性环流减弱了赤道索马里越赤道SW气流, 加强了澳大利亚越赤道SW气流,菲律宾东北部的异常气旋性环流不利于其东侧的副热带高压发展, 同时大气高层印度洋上空的异常西风减弱南亚高压强度,有利于南海夏季风加强, 爆发可能提前。     

夏季南半球越赤道气流与东南亚地区产生多台风的关系

本文运用1978年夏季850百帕天气图资料,分析南半球越赤道气流的通道、强度以及与北半球热带辐合带中产生多台风的关系。分析表明,东南亚地区存在三个明显的越赤道气流通道。其中105°E处气流出现有季节性变化,125°E,145°E处为准定常通道。三个通道略呈等距分布。当越赤道气流强度达到一定数值后,北半球热带辐合带中容易产生多台风,这给多台风发生的时、空预报提供了一定的客观依据。     

初夏季风低槽活动与华南降水

通过对1971—1980年4—6月十年资料的普查分析,我们将华南季风低槽分为大陆(华南)和海域(南海)两类。前者发生在初夏前期,它与冬、夏季风有密切关系,是华南前汛期强降水的主要系统;后者与热带辐合带及孟加拉湾季风槽东伸至南海部分相联系,此类槽出现频数不多,但对南海及华南的影响也是非常重要的。      

南海地区准单、双周震荡对“碧利斯”降水维持影响分析

利用NCEP资料对2006年5—9月南海地区季风进行带通滤波,分析各频谱传播特征,研究热带气旋"碧利斯"登陆期间季风涌爆发原因及季风涌对其登陆后降水的影响。结果表明,"碧利斯"登陆维持期间在南海季风区高频振荡、准单周和准双周振荡相互作用下使季风涌爆发维持;影响南海地区的经向风的准单周、准双周振荡都有明显的自东向西传趋势,准单周振荡源地在菲律宾海区;南海地区准单周和准双周振荡对热带气旋"碧利斯"卷入气流有明显的加强作用,有利于"碧利斯"环流长时间维持。     

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.     

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     

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.     

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.     

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...