三体散射长钉（TBSS）在C波段雷达中的应用研究

利用普洱CIND3830-CC天气雷达资料、地面观测资料进行统计分析,研究2004-2013年普洱C波段天气雷达中27次三体散射长钉(TBSS)的统计特征、地面降雹与TBSS的对应关系,并对TBSS在冰雹预警方面的应用进行探讨,结果表明:(1)C波段雷达中,产生TBSS的回波的反射率因子范围为55.0~68.4 dBz,70%的TBSS出现在反射率因子≥60 dBz时。(2)TBSS的维持时间为10~79 min,63%的TBSS维持时间超过20 min。(3)TBSS一般出现在4.0~9.5 km,最低出现在2.6 km,最高出现在11.4 km。(4)TBSS长5.6~22.4 km,宽1.5~14.6 km,TBSS宽度与强回波区径向外侧的60 dBz以上回波的面积成正比,但TBSS的长度与反射率因子核心的强度和宽度无明显对应关系。(5)出现TBSS时,59%的回波出现了降雹,11%的回波出现了强冰雹。(6)出现TBSS且出现降雹的过程中,TBSS预报冰雹的时间提前量为5~100 min,平均为34.5 min。(7)在出现TBSS且出现降雹的过程中,TBSS的宽度与冰雹的大小或降雹密度成正比。此外,分析了出现TBSS但未降雹的原因,找出了TBSS配合垂直液态水含量密度(D_(VIL))和45 dBz伸展高度、TBSS配合回波宽度和45 dBz伸展高度的预报冰雹的方法,在出现TBSS特征的回波中,上述方法的预报准确率分别达89%和94%(临界成功指数为0.89和0.94)。     

强雹暴的雷达三体散射统计与个例分析

利用我国各地11次强对流事件中23个产生S波段雷达三体散射的雹暴的新一代天气雷达数据,总计499个三体散射样本资料,综合并详细地讨论了我国S波段多普勒天气雷达三体散射的统计特征,也讨论了将这一现象应用于强冰雹辅助预警的可能性。同时对目前国内S波段雷达所观测到的最典型的三体散射个例从"三体散射回波"出现到消失的全过程进行了仔细分析,结果表明:(1)在最小反射率因子显示阈值为-5 dBz的情况下,产生S波段雷达三体散射的最小反射率因子在60 dBz左右,86%的三体散射长钉(TBSS)出现在反射率因子强度≥63 dBz时;(2)TBSS长度与强反射率因子核心区面积大小及反射率因子核最大强度呈密切的正相关,也就是说,反射率因子核心强度越大,高反射率因子的区域越大,TBSS的长度就越长;(3)TBSS出现的最大高度为12.5 km,最低高度是1.1 km;61%的TBSS出现在3~6 km高度之间,TBSS在4~5 km高度出现次数最多,然后向上、向下减少;TBSS长度≥10 km的出现次数同样以4~5 km高度最多,然后向上、向下迅速减少;(4)TBSS主要在雹暴位于雷达的西半边时出现;(5)雹暴云在不同性质的下垫面上空均能产生雷达TBSS;(6)TBSS的持续时间几乎都超过30 min,其中持续时间在30~60 min的情况居多,还有部分TBSS持续时间超过90 min;(7)在出现TBSS时,几乎所有雹暴都降了2 cm以上的强冰雹,同时80%左右的产生2 cm以上直径冰雹的强雹暴都产生了三体散射,因此TBSS可以作为强冰雹的一辅助预警指标,以有效降低强冰雹预警的虚警率;(8)在产生三体散射的23个强雹暴中,有一半以上是超级单体和准超级单体风暴,超级单体雹暴中的中气旋有利于大冰雹的形成。     

强冰雹天气的多普勒天气雷达探测与预警技术综述

主要介绍了强冰雹天气的有利环境背景条件和强雹暴的多普勒天气雷达识别和预警技术.主要结论如下:(1)有利于强冰雹的环境条件是-10 ℃和-30 ℃之间的对流有效位能较大;0～6 km之间的垂直风切变较大;0 ℃层距离地面高度适中.(2)强冰雹的主要的雷达回波特征:高悬的强回波;低层的弱回波区(WER)、中高层的回波悬垂和有界弱回波区(BWER);中气旋.(3)能够有效判断强冰雹发生的3个辅助特征指标:VIL密度,风波顶辐散和S波段三体散射长钉(TBSS),具体如下:① 强冰雹发生对应的VIL密度阈值是3.5 g/m3,如果达到4 g/m3,几乎肯定发生强冰雹;②产生强冰雹的正负速度差值的阈值是38 m/s;③ S波段雷达回波中出现TBSS是存在强冰雹的充分非必要条件.     

基于S波段双偏振雷达和X波段相控阵雷达的超级单体观测分析

利用广州S波段双偏振雷达和X波段相控阵雷达资料,对2022年3月26日一次降雹超级单体风暴成熟阶段的雷达观测特征开展分析,结果表明:超级单体呈现出钩状回波、回波悬垂、中气旋、三体散射等经典结构特征。径向速度上观测到中低层辐合、高层辐散以及中气旋和反气旋共存的双涡旋结构,有助于超级单体的维持发展。偏振特征分析发现,超级单体低层出现了反射率因子(ZDR)弧,低层强回波区对应偏小的差分反射率(ZDR)、低的相关系数(CC)和大的差分相移率(KDP),符合融化的冰雹特征。中层观测到ZDR环、CC环和三体散射(TBSS)的偏振特征。高层强回波区对应低的ZDR、较高的CC和低的KDP,对应空中干的大冰雹。垂直方向上观测到ZDR柱和KDP柱,ZDR柱最大发展高度达到8 km。X波段相控阵雷达更快的扫描速度还精细监测到超级单体钩状回波和中气旋的形成演变过程,低层也观测到与S波段双偏振雷达类似的ZDR弧特征和融化中的冰雹特征,但是使用中要留意衰减造成的影响。     

贵州一次暖区飑线大风与大冰雹的雷达结构特征分析

利用常规高空和地面探测、观测资料,地面加密自动站分钟数据资料以及榕江站、贵阳站C波段多普勒天气雷达探测资料,分析了2020年3月23日贵州强对流天气的环流形势,并重点分析了榕江飑线大风及长顺大冰雹雷达回波特征。结果表明:(1)此次飑线大风与大冰雹发生在南支槽前暖区,地面热低压发展推动辐合线移动、低层西南暖湿气流、中层干冷空气、合适的0℃和-20℃高度均为此次飑线大风及大冰雹的产生提供了有利的环境条件。(2)雷达回波大冰雹特征突出:强回波悬垂,有界弱回波区,弓形回波,中心强度强(60 dBz以上)且50 dBz强回波伸展超过-20℃高度达到9 km以上,垂直积分液态水含量最高达到了70 kg/m~2,连续超过两个体扫VIL≥60 kg/m~2,回波顶高连续超过两个体扫在15 km以上。(3)飑线雷达回波大风特征明显:弓形回波形态特征明显且移动较快,移速约40 km/h,低层径向速度大,中层径向辐合大风区下传,速度零线通过观测站后大风加速。(4)短临预警业务中,对飑线大风天气,应重点关注低仰角速度大值区、中层径向辐合和弓形带状回波生成后移动发展对下游地区的影响;对大冰雹天气,应重点关注大于50 dBz强回波垂直扩展的高度、VIL和ET高值区的维持等。     

青海省东部农区冰雹天气分析及预警研究

采用青海省东部农业区14个地面气象站冰雹观测资料,对2003—2017年青海东部农区冰雹天气进行特征分析,利用天气雷达、高空、雷电观测资料对2003—2017年青海东部农区20例典型冰雹天气个例进行分析。得出:(1)冰雹和雹灾集中出现在每年5—9月,7月冰雹天气最多,8月冰雹成灾最多。(2)0℃层高度变化对冰雹融化作用不明显;高空垂直风切变比对流有效位能更有指示意义。(3)冰雹雷达回波顶高普遍10 km,冰雹直径与回波顶高的线性相关强于冰雹直径与强回波中心高度的线性相关;垂直累积液态水含量普遍20 kg·m~(-2)且垂直累积液态水含量增量10 kg·m~(-2)时易发生雹灾;风暴顶部辐散正负速度差值对雹灾预警有指示意义,但与冰雹直径无明显相关性。(4)不同冰雹云产生的闪电频次差别很大,同一雹云相同时间内正闪次数越多,则降雹直径越大。利用以上结论统计得出冰雹预警指标、权重和预警区间,通过对预警指标进行历史回代和预报检验,历史回代拟合率达86.9%,预警准确率为80%。     

一次冰雹天气过程的多源资料观测分析

利用地基微波辐射计、风廓线雷达和雨滴谱仪等观测资料,对2015年4月28日发生在南京的一次冰雹天气进行了分析,探讨新型探测资料在冰雹监测预警中的应用。结果表明:(1)华北冷涡后部冷空气南下,与低层暖湿气流交汇,是产生这次冰雹的天气背景;高空冷平流叠加在低层暖湿气流之上,使得对流层中低层形成不稳定层结;地面辐合中心及辐合线是降雹的触发机制。(2)微波辐射计监测显示,降雹期间冰雹云中上升气流将底层空气的感热和潜热向上输送,导致2 km以上大气有明显升温,由于低层水汽聚集及冰雹在近地层融化造成降雹时近地层相对湿度、水汽密度增大。冰雹发生在云液态水含量快速增长的波峰上,对冰雹的发生具有较好指示意义。(3)对比南京3站风廓线雷达资料表明各站上空环境风场存在一定差异,六合地区降雹前6 km高度高空急流有利于六合上空形成有利的辐散形势,降雹时0~6 km存在较深厚的垂直风切变,配合地面中尺度低压,降雹最为强烈;南京站降雹时,对流层中下层有一槽过境,而高淳地区冰雹由近地面垂直风切变激发。(4)六合站、高淳站雨滴谱仪分析表明不同降水相态对应的滴谱特征有差异,两站雨滴谱型分别呈指数型、多峰型分布。高淳站雨滴谱仪监测到直径达到15 mm的冰雹粒子,六合站冰雹直径最大为5 mm。两站速度谱大致为单峰型,在较强降水时刻,粒子下落峰值速度在3~4 m·~(-1)。(5)影响六合的超级单体存在钩状回波、回波悬垂、三体散射等雷达回波中尺度特征,地面中尺度低压系统、中低层的中气旋及高层的辐散环流配置造成了雹云中维持较强的旋转上升气流,有利于出现大冰雹。     

青海省东部农业区冰雹天气特征分析及预警指标研究

采用青海省东部农业区14个地面气象站冰雹观测资料，对2003-2017年青海东部农业区冰雹天气进行特征分析，利用天气雷达、高空、雷电观测资料对2003-2017年青海东部农业区20例典型冰雹天气个例进行分析研究。得出：(1)冰雹和雹灾集中出现在每年5-9月，冰雹天气7月最多，冰雹成灾8月最多。(2)0 ℃层高度变化对冰雹融化作用不明显；高空垂直风切变比对流有效位能更有指示意义。(3)冰雹雷达回波顶高普遍大于10 km，冰雹直径与回波顶高的线性相关强于冰雹直径与强回波中心高度的线性相关；垂直累积液态水含量普遍大于20 kg?m-2且垂直累积液态水含量增量大于10 kg?m-2时易发生雹灾；风暴顶部辐散正负速度差值对雹灾预警有指示意义，但与冰雹直径无明显相关性。(4)不同冰雹云产生的闪电频次差别很大，同一雹云相同时间内正闪次数越多，则降雹直径越大。利用以上结论统计得出冰雹预警指标、权重和预警区间，通过对预警指标进行历史回代和预报检验，历史回代拟合率达86.9％，预警准确率为80％。     

基于多源探测资料的“4.12”非典型冰雹特征分析

针对2020年4月12日发生在江苏苏州的一次大范围雷暴大风、局部伴有冰雹的强对流天气过程,基于常州S波段双线偏振多普勒天气雷达、湖州和青浦的单偏振雷达以及再分析资料,详细分析了此次过程的天气背景,不稳定机制、抬升条件和雷达回波及双偏振雷达参量演变特征,并结合双雷达风场反演技术分析超级单体的动力结构及云物理机制。结果表明此次过程发生在高空冷涡南掉、横槽南摆,上下层强烈不稳定的环流背景下,地面有辐合线提供了触发条件。苏南地面附近至600 hPa为θ_se随高度减小的对流不稳定层和0~6 km强烈的垂直风向切变分别为此次过程提供强热力和动力不稳定条件。此次降雹天气过程,雷达回波强度超过50 dBZ,有明显的三体散射、气旋式辐合、高层回波悬垂和强风暴顶辐散等特征;但是VIL和ET都很小,呈现非典型冰雹特征。双线偏振雷达各偏振参量(差分反射率Z_DR、差分相移率K_DP和相关系数CC)也都反映出冰雹云的典型特征:在Z_H大、Z_DR小、CC小的区域出现冰雹,Z_DR值通常为-1.0~0.2 dB,CC值普遍小于0.85。上述双偏振参量特征在强对流短时临近预报和冰雹识别方面具有很强的应用潜力。利用双雷达风场反演技术对降雹时段研究,发现1~5 km各层高度的风垂直切变、辐合的存在,有利于超级单体的发展和加强。双雷达能较好地反演雷暴大风的三维风场精细结构,有助于加深对冰雹云结构的认识进而提高冰雹等强对流天气的预报预警能力。      

榆林新一代天气雷达冰雹云识别指标分析

利用2005-2007年5—9月榆林雷达站观测资料和同期的常规高空、地面观测资料及榆林市境内的冰雹灾情资料,对其中的14次冰雹天气过程分析,重点考察冰雹产生过程中冰雹云在新一代天气雷达图上的演变特征。通过对地面降雹资料和相应的雷达产品资料分析,结果表明：榆林新一代天气雷达对责任区内的冰雹预报预警具有较好的指示作用。冰雹云识别指标为：强反射率因子区（回波强度≥50dBz）在-20℃层高度附近及以上,且强回波强度越强,高度越高,愈有利于大冰雹的产生;反射率因子剖面图上出现有界弱回波区（BWER）或弱回波区（WER）,区域的大小影响降雹的持续时间和冰雹的大小;垂直累积液态水含量VIL的大值区（≥40kg／m^2）代表降冰雹的潜势,VIL值越大。降大冰雹的潜势越大。三体散射现象可作为冰雹的预报指标。     

COMPARATIVE ANALYSIS OF VARIOUS DATA OF AIR–SEA TEMPERATURE DIFFERENCE AND ITS VARIATION ACROSS SOUTH CHINA SEA IN THE PAST 35 YEARS

Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.     

Could the Recent Taal Volcano Eruption Trigger an El Ni?o and Lead to Eurasian Warming?

<正>The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth’s climate and environment.     

VARIABILITY OF INTER-ANNUAL RELATIONSHIP BETWEEN INDIAN OCEAN DIPOLE AND HUAXI REGION’S AUTUMN PRECIPITATION

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.     

IMPACT OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION ON THE IMMIGRATION OF NILAPARVATA LUGENS(STL) IN HUNAN AND JIANGXI PROVINCES

Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.     

A COMPARATIVE ANALYSIS OF ATMOSPHERIC AND OCEANIC CONDITIONS BEFORE THE OCCURRENCE OF TWO TYPES OF EL NIO EVENTS

The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o.     

全球贸易隐含碳变化及其影响分析

基于最新的GTAP8 (Global Trade Analysis Project）数据库,使用投入产出法,分析了2004年到2007年全球贸易变化下南北集团贸易隐含碳变化及对全球碳排放的影响。结果显示,随着发展中国家进出口规模扩张,全球贸易隐含碳流向的重心逐渐向发展中国家转移。2004年到2007年,发达国家高端设备制造业和服务业出口以及发展中国家资源、能源密集型行业及中低端制造业出口的趋势加强,该过程的生产转移导致全球碳排放增长4.15亿t,占研究时段全球贸易隐含碳增量的63%。未来发展中国家的出口隐含碳比重还将进一步提高。贸易变化带来的南北集团隐含碳流动变化对全球应对气候变化行动的影响日益突出,发达国家对此负有重要责任。     

Analysis of Atmospheric Boundary Layer Height Characteristics over the Arctic Ocean Using the Aircraft and GPS Soundings

正ERRATUM to: Atmospheric and Oceanic Science Letters, 4(2011), 124-130 On page 126 of the printed edition (Issue 2, Volume 4), Fig. 2 was a wrong figure because the contact author made mistake giving the wrong one. The corrected edition has been updated on our website. The editorial office is sincerely sorry for any     

Index to Vol.31

正AN Junling;see LI Ying et al.;(5),1221—1232AN Junling;see QU Yu et al.;(4),787-800AN Junling;see WANG Feng et al.;(6),1331-1342Ania POLOMSKA-HARLICK;see Jieshun ZHU et al.;(4),743-754Baek-Min KIM;see Seong-Joong KIM et al.;(4),863-878BAI Tao;see LI Gang et al.;(1),66-84BAO Qing;see YANG Jing et al.;(5),1147—1156BEI Naifang;     

Information for Contributors

正Journal of Meteorological Research is an international academic journal in atmospheric sciences edited and published by Acta Meteorologica Sinica Press,sponsored by the Chinese Meteorological Society.It has been acting as a bridge of academic exchange between Chinese and foreign meteorologists and aiming at introduction of the current advancements in atmospheric sciences in China.The journal columns include Articles.Note and Correspondence,and research letters.Contributions from all over the world are welcome.