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1.
2017年7月28日四川省东北部出现了一次罕见的湿下击暴流大风天气过程。本文利用地面自动站、雷达、卫星等观测资料以及FNL数据、视频资料,对下击暴流风暴的成因和结构特征进行研究分析。研究表明:此过程发生前,对流层中低层的环境温度及其直减率均达到同期历史极端值,有利于雷暴大风类型中尺度对流风暴的形成;此次下击暴流,主要由阵风锋与地面中尺度辐合线相交后触发,阵风锋水平涡度不断输入对流系统内,产生正的相对风暴螺旋度,利于对流风暴持续发展到较高高度,为下击暴流的产生提供条件;下击暴流发生前的对流风暴,在视频截图和反射率因子剖面图上均表现为悬垂倾斜结构,倾斜方向与对流层中层平均风向较一致;对流风暴中层的气旋性涡旋结构特征可作为下击暴流的预警指标之一。  相似文献   

2.
一次宏下击暴流的雷达回波特征分析   总被引：1，自引：0，他引：1  
石磊 《气象研究与应用》2009,30(3):16-19,I0006
利用常规探测资料、区域自动气象站资料和烟台新一代天气雷达资料，对2007年7月28日发生在烟台招远、龙口的一次下击暴流引起的灾害性大风天气进行分析。结果得出：此次下击暴流是在副热带高压边缘“上干下湿”不稳定层结中，由于高空冷空气侵入，不稳定能量得到释放，从而发展起来的多单体团风暴和弓型回波复合体所产生的，其主要特征是强反射率因子核从中高层开始发展，迅速下降到达地面，形成辐散大风，风暴前沿有阵风锋出现。  相似文献   

3.
利用高、低空常规气象观测资料、卫星云图和多普勒雷达资料,分析了2006年6月12日发生在太原机场的一次强对流风暴过程,结果表明：高空气旋性冷槽的迅速东移和地面冷锋过境是本次强对流风暴发生的天气尺度系统背景,机场发生的地面大风是由下击暴流引起的,近地面强辐散引起阵风锋发生在弓形回波中低辐合层对应的下方;雷暴单体回波剖面随时间的演变发现确有反射率因子核心重心下降并接地的现象,并据此证实有两次下击暴流过程.第一次出现在16时前后距本场西北90 km处,第二次出现在18时04分,第二轮下击暴流直接造成本场的地面大风.下击暴流发生的过程始终伴随着中低层长时间的辐合和反射率因子核心的重心下降接地过程.  相似文献   

4.
基于多普勒雷达、闪电定位、地面观测资料和现场勘察情况,对2016年5月2日皖西南发生的一次连续下击暴流天气的成因进行分析。结果表明:引起2次微下击暴流的风暴为同一风暴单体,且为超级单体,旺盛阶段的雷达回波表现为钩状分布和倾斜结构;下击暴流产生的初始原因是液态或固态降水粒子下降的拖曳作用,中后期则主要源于热力不稳定、对流层中层的动量下传和补偿性气流作用,伴随的水成物与环境之间的负浮力增大是下击暴流发生的重要原因;对流层中层盛行风向造成的动量下传决定了2次微下击暴流的地面风走向;超级单体风暴具有反射率因子核最高和下降速度最快的特点,反射率因子核高度超过6 km,1个体扫间隔下降3 km左右或以上;当6 min降水达4 mm以上时,是发生下击暴流的征兆之一。  相似文献   

5.
2019年3月21日广西桂林市临桂区发生一次极端大风天气过程(以下简称"3·21"临桂大风),当日21:13临桂观测站记录最大阵风风速为60.3 m·s-1(17级)。通过风灾现场调查判断这是强度为EF2级的微下击暴流过程。应用常规观测资料以及加密自动气象站、探空、多普勒雷达等资料,分析了"3·21"临桂大风的环流背景与影响系统及其形成原因。结果表明:低层暖湿气流活跃,中层显著干层,强的低层垂直风切变是大风发生的有利条件,地面中尺度辐合线、冷锋南压为其提供了触发机制。"3·21"临桂大风由2个超级单体风暴合并加强造成,在下击暴流发生前,风暴单体最强反射率因子核心高度(HGT)超过6 km,有中等强度中气旋伴随,中层径向辐合明显,辐合值达36 m·s-1;当反射率因子减弱、风暴顶高下降、HGT下降时,下击暴流发生;当HGT剧降,一个体扫间隔下降3.5 km,17级极端大风发生,低层0.5°仰角在强中气旋的出流区观测到强的径向辐散,其值达27 m·s-1;中气旋表现出最强切变加强,底高迅速下降到1 km以下等特征。本次下击暴流发生与极端强降水和冰雹的拖曳作用有密切关系,冰雹与雨水粒子的拖曳和融化蒸发作用使下击暴流加强。当分钟降水量大于3 mm时,风速超过12级;当分钟降水量大于6 mm时,则出现17级极大风速。  相似文献   

6.
下击暴流指对流单体强下沉气流引发的地面或地面附近的爆发性辐散出流,单个下击暴流会导致千米尺度地面强阵风,而下击暴流簇可导致较大范围间断性地面灾害性强阵风,其形成机制亦不限于强下沉气流辐散。文章回顾了下击暴流的界定,然后分为孤立风暴产生的下击暴流和中尺度对流系统内嵌的下击暴流两种情况进行讨论,内容包括对流大风和下击暴流产生的物理机理、风暴结构特征以及基于多普勒天气雷达的预警技术。在上述回顾基础上,对下击暴流形成机理及监测预警难点进行了讨论,提出了与下击暴流相关的亟需研究的问题。  相似文献   

7.
利用常规气象资料、跑道自动观测资料(AWOS)、自动观测站资料和多普勒天气雷达资料等,对武汉天河机场的一次下击暴流天气过程进行了分析。结果表明:1)本次下击暴流发生在副热带高压减弱,西风槽向东移动,地面辐合线相配合的天气背景下;2)下击暴流影响机场期间,具有气压陡升、温度骤降、风向变化和风速突增等气象要素的演变特征;3)阵风锋与雷暴之间距离的变化一定程度上可以预示未来雷暴的强弱;4)本次下击暴流与阵风锋有紧密的联系,阵风锋北移过程中激发出β中尺度对流单体,β中尺度对流单体产生了下击暴流,并且雷达速度图上沿雷达径向的正负大值速度对是下击暴流发生的典型特征之一。  相似文献   

8.
利用山东威海CINRDA/SA多普勒雷达探测资料,结合常规天气图资料、地面自动气象观测站资料等,对2018年9月8日发生在威海文登机场附近的一次下击暴流天气特征进行分析。结果表明：1)此次下击暴流天气发生在高低空一致的西北气流背景下,午后太阳辐射使得低空大气加热显著,形成了强烈的不稳定层结。2)大气层结特征呈喇叭状温湿分布,850 hPa以下接近干绝热的温度直减率,为下击暴流的发生提供了有利环境条件。3)地面辐合线为风暴单体的产生提供了动力抬升条件。4)从多普勒雷达产品上看,风暴初始回波发生在午后海风锋触发的晴空窄带回波上,通过单体间的合并加强,发展成为多单体风暴;下击暴流出现前,对流风暴回波强度及高度明显发展,成熟阶段的对流风暴伴有回波悬垂结构和三体散射特征,伴随着强反射率因子核心的持续下降,下击暴流迅速到达地面,径向速度图上存在明显的中层辐合、旋转、低层辐散的现象;5 km以上60 dBZ强反射率因子核心的下降,结合径向速度中层辐合、低层辐散特征可提前3～9 min预警下击暴流的发生。  相似文献   

9.
对2017年8月1日在广州白云机场产生的42.1 m/s强阵风成因进行分析,发现此次强阵风是微下击暴流的下沉气流到达地面造成的。利用广州白云机场的地面自动观测资料和C波段多普勒天气雷达资料分析微下击暴流经过机场时地面各气象要素的演变特征以及产生强风切变的对流单体的移动和强度演变情况。分析表明:微下击暴流到达地面后造成了强烈的风速和风向的低空风切变,气压骤升,温度迅速降低,利用高时空分辨率的地面自动观测数据可以发布低空风切变的告警;在微下击暴流产生强地面风前,对流风暴单体的雷达回波反射率强度突然降低、回波顶高减弱,径向速度图上出现了中气旋以及在近地层有强烈的反气旋辐散,可利用多普勒天气雷达发布低空风切变的预警。  相似文献   

10.
夏羽  肖湛臻  唐巧珍 《气象科技》2019,47(4):663-672
利用湖北省区域站资料、Micaps常规观测资料和雷达资料,对2017年盛夏季节一次副高控制下的下击暴流事件进行分析,结果表明:①本次过程是一次典型的由脉冲风暴产生的大风天气,过程中出现明显的阵风锋;②受地形及局地热力条件共同作用,强回波向西南方向移动;③阵风锋形成初期与回波主体距离很近,强回波持续时间长,造成局地的强降水,强下沉气流和强降水导致了大范围的大风天气,此时大风主要分布在强回波移动方向的前沿附近;④后期阵风锋快速移动,远离回波主体,回波迅速减弱,强下沉气流向外流出导致地面出现大风,地面出现两条阵风锋,且两条阵风锋相遇,此时大风主要出现在两条阵风锋交汇处和雷暴冷出流最强处,对临近预报有一定的参考意义。  相似文献   

11.
The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.  相似文献   

12.
正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on  相似文献   

13.
The moving-window correlation analysis was applied to investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the synchronous autumn precipitation in Huaxi region, based on the daily precipitation, sea surface temperature (SST) and atmospheric circulation data from 1960 to 2012. The correlation curves of IOD and the early modulation of Huaxi region’s autumn precipitation indicated a mutational site appeared in the 1970s. During 1960 to 1979, when the IOD was in positive phase in autumn, the circulations changed from a “W” shape to an ”M” shape at 500 hPa in Asia middle-high latitude region. Cold flux got into the Sichuan province with Northwest flow, the positive anomaly of the water vapor flux transported from Western Pacific to Huaxi region strengthened, caused precipitation increase in east Huaxi region. During 1980 to 1999, when the IOD in autumn was positive phase, the atmospheric circulation presented a “W” shape at 500 hPa, the positive anomaly of the water vapor flux transported from Bay of Bengal to Huaxi region strengthened, caused precipitation ascend in west Huaxi region. In summary, the Indian Ocean changed from cold phase to warm phase since the 1970s, caused the instability of the inter-annual relationship between the IOD and the autumn rainfall in Huaxi region.  相似文献   

14.
正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography.  相似文献   

15.
The variation of the East Asian jet stream(EAJS) associated with the Eurasian(EU) teleconnection pattern is investigated using 60-yr NCEP–NCAR daily reanalysis data over the period 1951–2010. The EAJS consists of three components: the polar front jet(PFJ); the plateau subtropical jet(PSJ); and the ocean subtropical jet(OSJ). Of these three jets over East Asia,the EU pattern exhibits a significant influence on the PFJ and OSJ. There is a simultaneous negative correlation between the EU pattern and the PFJ. A significant positive correlation is found between the EU pattern and the OSJ when the EU pattern leads the OSJ by about 5 days. There is no obvious correlation between the EU pattern and the PSJ. The positive EU phase is accompanied by a weakened and poleward-shifted PFJ, which coincides with an intensified OSJ. A possible mechanism for the variation of the EAJS during different EU phases is explored via analyzing the effects of 10-day high-and low-frequency eddy forcing. The zonal wind tendency due to high-frequency eddy forcing contributes to the simultaneous negative correlation between the EU pattern and the PFJ, as well as the northward/southward shift of the PFJ. High- and low-frequency eddy forcing are both responsible for the positive correlation between the EU pattern and the OSJ, but only high-frequency eddy forcing contributes to the lagged variation of the OSJ relative to the EU pattern. The negative correlation between the EU pattern and winter temperature and precipitation anomalies in China is maintained only when the PFJ and OSJ are out of phase with each other. Thus, the EAJS plays an important role in transmitting the EU signal to winter temperature and precipitation anomalies in China.  相似文献   

16.
By using the gauged rainfall in 160 stations within mainland China and the NCEP/NCAR reanalysis data, the impacts of anomalous SST in Kuroshio and its extension on precipitation in Northeast China were investigated. The results show that a difference in the meridional circulation such as the East Asia/Pacific teleconnection pattern(EAP)may be responsible for the difference in rainfall between 1998 and 2010. In comparison with 1998, the anomalous meridional circulation pattern in 2010 shifted northeastward, and then the western subtropical high, the mid-latitudinal trough and the northeastern Asia blocking high also shifted northeastward, causing intensified convergence of the cold and warm air masses at the southern region and thus more rainfall in the southwestern region and less in the northwestern region. In 1998, the anomalous cyclone, one component of the meridional pattern, located at the Songhuajiang-Nengjiang River basin, resulted in more rainfall in the majority of the area. The results of observation and the model show that the difference in SSTA in Kuroshio and its extension under the background of different El Ni觡o events is the key point:(1) The anomalous warmth moved westward from the mid-Pacific to the east of the Philippine Sea during the central event, which led the heat resources shifting to the northeast in 2010; subsequently, a shift occurred to the north of the anomalous ascent and decent, followed by a warm SSTA in the region of Kuroshio's extension in 2010 and Kuroshio in 1998.(2) The warm SSTA in the Kuroshio extension causing the Rossby wave activity flux strengthened in 2010, and then the westerly jet shifted northward and extended eastward. A warm SSTA in Kuroshio and cold SSTA in its extension in 1998 caused the westerly jet to shift southward and weaken. As a result,the anomalous anticyclone and cyclone shifted northward in 2010, and the blocking high also shifted northward.  相似文献   

17.
<p>Using the multielements similarity measurement method and 1950–C2017 NCEP/NCAR gridded daily reanalysis datasets, we analyzed season duration in China during 1950–C2016, and we defined the element with maximum absolute sensitivity as the key impact element at each point using the sensitivity analysis method. The decadal change of season duration and its key impact element before and after 1980 were studied. The results indicated obvious meridional and zonal differences in the distribution of season duration for the 67-year average, and that the key impact element has the same distribution characteristics as season duration. In addition, complementary relationships were found between the durations of spring and summer, autumn and winter, and the cold and warm seasons. Of those, the complementary relationship between the durations of spring and summer was strongest and the regions of complementarity were numerous. The complementary regions of autumn and winter durations were found mainly in western China. In the cold and warm seasons, the complementary regions were widespread and the complementary relationship was generally weak. Comparison of the periods before and after 1980 revealed an east–Cwest difference in the interdecadal variation of season duration. Interdecadal variation in spring and summer was found concentrated in northern and western regions, while that in autumn and winter was concentrated in the western region. Areas of significant interdecadal variation of the key elements were found concentrated in northern and western regions, corresponding well with the areas of significant interdecadal variation of season duration.</p>  相似文献   

18.
Understanding potential future influence of environmental, economic, and social drivers on land-use and sustainability is critical for guiding strategic decisions that can help nations adapt to change, anticipate opportunities, and cope with surprises. Using the Land-Use Trade-Offs (LUTO) model, we undertook a comprehensive, detailed, integrated, and quantitative scenario analysis of land-use and sustainability for Australia’s agricultural land from 2013–2050, under interacting global change and domestic policies, and considering key uncertainties. We assessed land use competition between multiple land-uses and assessed the sustainability of economic returns and ecosystem services at high spatial (1.1 km grid cells) and temporal (annual) resolution. We found substantial potential for land-use transition from agriculture to carbon plantings, environmental plantings, and biofuels cropping under certain scenarios, with impacts on the sustainability of economic returns and ecosystem services including food/fibre production, emissions abatement, water resource use, biodiversity services, and energy production. However, the type, magnitude, timing, and location of land-use responses and their impacts were highly dependent on scenario parameter assumptions including global outlook and emissions abatement effort, domestic land-use policy settings, land-use change adoption behaviour, productivity growth, and capacity constraints. With strong global abatement incentives complemented by biodiversity-focussed domestic land-use policy, land-use responses can substantially increase and diversify economic returns to land and produce a much wider range of ecosystem services such as emissions abatement, biodiversity, and energy, without major impacts on agricultural production. However, better governance is needed for managing potentially significant water resource impacts. The results have wide-ranging implications for land-use and sustainability policy and governance at global and domestic scales and can inform strategic thinking and decision-making about land-use and sustainability in Australia. A comprehensive and freely available 26 GB data pack (http://doi.org/10.4225/08/5604A2E8A00CC) provides a unique resource for further research. As similarly nuanced transformational change is also possible elsewhere, our template for comprehensive, integrated, quantitative, and high resolution scenario analysis can support other nations in strategic thinking and decision-making to prepare for an uncertain future.  相似文献   

19.
碳交易政策的经济影响:以广东省为例   总被引：1，自引：0，他引：1  
通过构建广东省两区域动态模型,对广东省碳交易及其他政策措施进行定量评估,分析实施可调控总量的碳交易政策机制对广东省及参与交易部门的经济影响。研究结果表明,按照减排情景到2015年广东完成19.5%的碳强度下降目标,相比基准情景,GDP将减少0.7%;按照强减排情景到2015年将完成20.5%的碳强度下降目标,相比基准情景GDP将减少0.9%;如果在强减排情景的基础上实施碳交易政策,GDP相对基准情景减少0.8%,到2015年实施碳交易政策可减少GDP损失约90亿元,说明广东建立碳排放权交易机制能够发挥支持经济发展和节能减碳双赢的作用。  相似文献   

20.
气候变化对中国东部季风区水资源脆弱性的影响评价   总被引：3，自引：0，他引：3  
将耦合暴露度、灾害风险、敏感性与抗压性的脆弱性评估模型应用于中国东部季风区水资源脆弱性评价,从水资源供需平衡角度分析了气候变化对东部季风区水资源脆弱性的影响。结果表明,2000年气候条件下,我国东部季风区接近90%的区域水资源处于中度脆弱及以上状态。其中水资源中度和高度脆弱区域约占全区的75%,极端脆弱区域接近15%。中国北方海河、黄河、淮河和辽河流域的水资源脆弱性最高。未来气候变化影响将加剧水资源脆弱性的风险,不同RCP排放情景下2030年代我国东部季风区水资源中度脆弱及以上区域面积有明显的扩大,极端脆弱区域将达到20%~25%。由于未来需水的进一步增加,中国北方水资源脆弱性的格局并未发生根本变化,而南方东南诸河等区域将面临可能发生的水危机。  相似文献   

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