贵阳市酸雨过程的天气学研究

１９９４－１９９５年在贵阳市眍５个监测站进行了雨水ＰＨ值观测，取得资料４７６份。从资料分析中得到：雨水ＰＨ值与天气背景有关，其中以静止锋天气影响最为显著，酸雨出现机率达４８．２９％；在其他天气影响下，酸雨出现机率也达３０％以上。     

南京梅雨降水的pH值测定

本文对1982—1984年梅雨期内的雨水pH值进行了测定,三年共采集33天的雨水样品。测定结果表明,梅雨降水的雨水中pH<5.6(出现酸雨),约占降水次数的40％,雨量的65％,梅雨降水中的酸雨,大约80％是在工业区的下风方区域观测到的,形成酸雨的主要原因是局地污染源。     

广州酸雨现状及影响因素分析

通过对广州1992—2008年酸雨资料的统计分析表明,广州酸雨年变化明显,17年的年平均pH值为4.05,酸雨年均pH值最低达3.41,最高达4.53;17年的酸雨年均发生频率为86.9%,最低为71.8%,最高为98.6%;酸雨季节变化明显:春季pH值最低,夏季pH值最高;酸雨月平均pH值变化幅度大:pH值最低出现在2月,最高在12月。通过对广州雨水离子组分和污染物浓度分析表明,影响广州雨水酸度的主要离子为: 、Cl-、Ca2+、 和 ,主要大气污染物为SO2和NOx。广州酸雨形成机制不仅与污染源有关,还与污染物在迁移扩散过程的天气系统和边界层气象特征有关。      

不同城市的雨水酸度分析

本文通过长春市区和郊区、四平、怀德四站1983—1984年酸雨监测资料的统计分析,给出了降水酸度的时空分布规律;给出了pH值与风向、风速、降水类型、逆温层等气象要素的关系;pH值与雨水化学组分的关系;并比较了市区和郊区,大、中、小不同城市雨水酸度的差异。表明酸雨的形成以局地污染源为主。     

2017年南京酸雨特征及连续发生的成因分析

利用南京市1992—2017年逐日酸雨监测数据、2017年大气污染物浓度和探空资料,研究了2017年连续酸雨出现特征及成因。结果表明:2017年南京酸雨发生频率38%,为近5 a来最低;年降水pH值为4.92,大于2014年,小于2015年和2016年;秋季酸雨发生频率最高、酸度最强,春季次之,夏季酸雨污染最轻;全年共出现了4次连续酸雨过程,高空多短波槽活动和低空切变的长时间维持为连续酸雨的产生提供了有利的环境背景,局地污染源、受低层风引导的外来污染物以及“假日效应”的叠加影响共同造成南京强酸雨的出现;此外,由于大气中水汽和能量的季节差异,也造成每次过程在降水强度、降水pH值上有所不同。     

广州市区酸雨初探

本文通过对广州市区雨水酸度的分析,认为广州是酸性基础甚强的城市,酸雨出现的频率为60%左右,并有冬春强,夏秋弱的季节变化趋势。指出逆温和微风等稳定天气条件是产生酸性降水的有利天气条件。对水样的化学分析结果可见,广州酸雨中SO₄=为主要酸根,各类酸根的浓度变化受环境和人为因素的影响较大。阳离子浓度的强弱对市区酸雨起着重要的缓冲作用,在碱性污染源附近尤为明显。水化学分析结果表明局地污染源的作用是明显的,所以广州市区酸雨主要是由于本地大气污染所致。      

昆明准静止锋的发现和研究

昆明准静止锋也称西南准静止锋,早在20世纪40年代已被中国学者所发现。这是在东亚冷空气爆发并向南扩展时,受西南高原地形阻挡形成的一种独特的锋面系统。在北美等地虽然也有类似现象,但昆明准静止锋在形成原因、活动规律和天气影响上都十分不同。在青藏高原大地形、低纬高原和横断山脉的作用下,昆明准静止锋沿地形呈准南北走向,具有东西摆动和跳跃式西进的独特活动规律。若静止锋转变成冷锋西进,往往伴随着西南地区寒潮等转折性天气出现;若静止锋长期稳定维持,不仅在冬季会造成冻雨等灾害性天气,还会在春季带来雷暴、冰雹、大风等强对流天气。从昆明准静止锋的发现开始,全面的回顾和总结相关的研究进程,对该领域研究的未来方向从以下几个方面做出展望:1)昆明准静止锋的定义仍需明确;2)锋区强烈逆温的成因和水汽来源;3)昆明准静止锋的气候结构和环流特征;4)昆明准静止锋的气候变率及其影响因子;5)昆明准静止锋的维持和进退机理;6)昆明准静止锋的可预报性和数值预报能力研究。     

上海梅雨季节云水和雨水的化学组分分析

1986年6—7月梅雨季节在上海进行了云水和地面雨水的pH值测量和化学组分分析，结果表明:上海酸雨属于硫酸型酸雨；雨水酸度与其化学组分有关，pH≥6的云、雨水中含有大量的Ca2+离子浓度，而pH＜5的云、雨水中有大量的SO2-4离子浓度；As雨水的酸化以云下冲刷过程为主；Ns雨水的酸度可能主要决定于云内雨除过程，NS云内云水的酸化过程，不仅受向上输送局地污染物的影响，而且受平流输送外来污染物的影响。     

青岛奥帆赛期间海风锋触发的对流性降水特征

根据自动气象站、多普勒雷达、卫星云图、风廓线、NCEP资料和MODIS卫星遥感反演结果等多种资料,对2008年青岛奥帆赛期间(8月12—14日),在不同环流形势下海风锋触发的对流性降水特征进行分析。结果表明:海风锋与中低空切变线叠加易使局地辐合加强,出现对流天气;当同时有地面静止锋南压时,海风锋则缓慢向内陆推进,在交汇地区产生对流天气;当有大尺度天气系统过境时,前期海风锋触发对流,北推发展与系统性天气相结合,后期若高空槽发展较强则是一次典型的系统过境过程,易出现强对流天气。     

1991～2004年不同环流背景下南宁市降水化学成分变化特征的研究

利用1991～2004年广西南宁市降水化学成分资料，结合NCEP／NCAR再分析资料，分析了不同大气环流背景下南宁市降水化学成分的变化特征。结果表明，南宁市的酸雨属硫酸型，酸雨的形成与大气环流密切相关，影响南宁市酸雨的大气环流主要是高空槽锋面，其次是高压后部和热带气旋，受高空槽锋面特别是东路冷空气影响时，出现酸雨的频率最高，pH值最小，雨水中SO4^2-明显增多，热带气旋降水时，雨水酸度最轻，离子浓度甚至比高空槽锋面影响低2～3倍。     

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.     

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.     

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     

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...