降水条件下风廓线雷达数据质量分析及处理

风廓线雷达是当前获取大气三维风场信息的有效途径,但受其本身探测原理的约束,降水时的观测数据(尤其是边界层风廓线雷达的观测数据)将受到较大影响。为提高降水时边界层风廓线雷达数据的可信度,依据五波束探测和三波束探测原理,结合风廓线雷达功率谱再分析,建立了风廓线雷达数据筛选、填补的重处理方法,通过选取不同降水强度下的从化、潮州、阳江三个边界层风廓线雷达站的观测数据,开展了基于该方法的数据质量评估。研究结果指出:降水时虽能提高风廓线雷达的数据获取率,但风场数据质量并不一定较好(尤其是在特大暴雨时数据质量较差);经过数据重处理后,风廓线雷达的有效数据获取率得到提高,且内陆站点提升的幅度超过沿海站点;降水对2 km以下的观测数据影响较小,对于2 km以上的数据,若降水只是对部分高度造成数据缺失,则经过重处理后数据质量仍可以保持较好,但若连续多个高度数据缺失,则经过数据重处理后也不能较好地提高数据质量。     

科尔沁边界层风廓线雷达探测性能评估

利用2016—2017年科尔沁边界层风廓线雷达每6 min的风场资料评估雷达探测性能,对风廓线雷达数据获取率、风廓线雷达与气球探空探测风的相关性等进行了分析.结果表明:风廓线雷达平均数据获取率随高度的增加先增大后减小,3000 m以下平均数据获取率都在60％以上.雷达探测数据存在日出后数据缺测率高、午后缺测率低的变化趋...     

高原地区风廓线雷达资料评估

在简述风廓线雷达原理的基础上,将风廓线雷达探测资料与探空资料进行对比分析,发现风速风向一致性较好,温度一致性较差。对风廓线资料总的数据获取率及不同天气条件下的数据获取率进行了统计,大理风廓线雷达边界层高度的数据获取率大于80%,在对流层低层以及边界层的探测能力要远远大于高层,高空雨季后的探测高度大于雨季前的探测高度。不同天气条件下低空的数据获取率差别不大,高空阴雨天的数据获取率大于晴天的数据获取率,阴雨天的探测高度大于晴天的探测高度。     

宁波风廓线雷达数据获取率和降雨预报应用分析

利用2018—2021年宁波市奉化区和余姚市两部6～8 km对流层风廓线雷达实时观测资料,对两部风廓线雷达的数据传输稳定性、探测性能和降雨辅助预报能力进行了统计与对比分析。结果表明,通常情况下宁波两部对流层风廓线雷达运行稳定,故障率低,数据获取率则会因月份、季节、天气条件和降水等级的变化而有所不同。从月份来看,1月、12月数据获取率最差,6月、7月最好;从季节来看,数据获取率按照夏季、秋季、春季和冬季从高到低排序;按晴天、雨天来分,雨天有降水的数据获取率普遍好于晴天无降水;从降水等级(中雨、大雨、暴雨)来看,12 h内,大雨情况下的数据获取率和有效探测高度最好,中雨情况下的数据获取率最差、有效探测高度最低。风廓线雷达对垂直速度的观测资料对降雨预报具有一定的指导意义。     

风廓线雷达资料的应用:质量评估

利用FNL全球再分析资料(Final Operational Global Analysis)、探空资料对2019年6—9月位于中国华北地区20个站点共5种型号(CFL-06、GLC-24、TWP8-L、CFL-03、CLC-11-D)的边界层风廓线雷达资料进行了质量评估。结果表明:各型号雷达均具有较强的探测能力,但不同雷达在水平风资料数据获取率以及有效探测高度上差异极大。不区分天气状况时,所有型号雷达均为V风质量优于U风质量。TWP8-L雷达U风测风质量相对最佳,CFL-03雷达紧随其后,GLC-24雷达U风测风质量最差,V风质量则差异不大,U风数据使用前需进行偏差订正以及质量控制。风廓线雷达观测对于降水较为敏感,降水使各型号雷达数据获取率在底层减小,中高层增加,增幅最大达到53％,但探测能力加强并不代表测风质量增加,统计结果表明降水是造成U风平均误差以及均方根误差较高的重要原因,其中,GLC-24、CLC-11-D雷达对降水最为敏感,降水状态相较于非降水状态均方根误差增幅均达到了5.5 m/s以上,降水情况下的U风及V风资料需进行进一步质量控制才可使用。     

山地丘陵地区ST风廓线雷达的探测性能评估

利用淮南2015年3月至2016年2月ST风廓线雷达探测资料,从雷达运行模式和不同高度数据获取率的年、季、日变化角度,对该型号雷达在山地丘陵地区的探测能力进行评估。结果表明:山地丘陵地区,ST风廓线雷达能够获取高时空分辨率的探测资料,雷达正常工作时间占比为85.6%。雷达的探测能力在边界层和对流层中层明显高于对流层高层,年平均有效探测高度约14.0 km,占雷达最大探测量程的67%。可能受大气湿度、温度影响,探测能力在5—8月和12月对流层低层变低。受大气湍流影响,探测能力综合表现为夏季较高,春季次之,秋、冬季依次降低的季节差异,以及正午较低、凌晨较高的日变化特征。     

降水过程的风廓线雷达资料特征统计分析

利用宜春TWP3型边界层风廓线雷达2012年观测资料,统计分析了50次降水过程的风廓线雷达资料特征。从水平风向风速、垂直速度、折射率常数Cn2、径向速度、速度谱宽和信噪比SNR这六个参数分析得到:降水过程各指标呈现各自不同且与降水强度息息相关的变化特征,降水前探测高度升高、垂直速度由负转正和1km以下信噪比达到20d B可作为是否产生降雨的预示,,低空西南急流、冷暖平流的垂直方向交替变化以及Cn2达到-16m-2/3可作为中等以上量级降水的参考指标,对于短时强对流性降水,信噪比大于50d B以及出现大于4m·s-1的向下垂直速度可作为重要指示。对于弱降水过程,本文从风廓线特征方面给出预报指示特征,为降水预报准确率的提高提供新的参考。     

两种垂直风廓线的对比及应用Ⅱ:不同降水条件下风廓线特征

利用2013年重庆多普勒天气雷达(SA)和风廓线雷达(TWP8-L)观测的垂直风廓线数据,对晴空、弱降水、一般性降水和强降水四种不同天气条件下垂直风廓线特征及其演变情况进行了分析。结果表明:(1)风廓线雷达的探测高度随降水增加逐渐增加;(2)晴空天气条件下,边界层(1 km以下)风向存在明显的日变化,夜间以偏东气流为主,白天以偏南气流为主,高空(3 km以上)为一致的偏西气流,风速较小;(3)弱降水天气条件下,边界层风向以偏东气流为主,相对较为杂乱,高空与晴空一致,中高层(1~3 km)以偏南气流为主;(4)一般性降水天气条件下,低层与弱降水较一致,而高空出现较一致的西南气流,有利于水汽输送,同时垂直切变具有较好的单一方向性,较有利于对流的发展和维持;(5)强降水天气条件下,风廓线雷达和多普勒雷达观测的垂直风廓线较为一致。降水前期风向随高度的增加逐渐由偏东气流转为偏西气流,有利于对流的触发;降水期间风切变具有很好的单一方向性并在中低层出现低空急流区,有利于对流系统的维持,同时西南气流厚度加深,也有利于水汽的输送;降水结束期风速减小,中低层风向也逐渐转为偏北气流,对流系统逐渐消亡。     

上海TWP3型边界层风廓线雷达探测性能评估

基于2018年7月—2019年6月上海宝山移动式风廓线雷达（mobile wind profiler radar,MWPR）资料,从获取率、水平风误差和上海6类典型天气条件下测风数据的可靠性三方面,对其探测性能进行了评估与分析。结果发现：（1）获取率受湍流强度影响最大,受大气温度、湿度影响次之。获取率具有较明显的日变化和季节变化特征,边界层内夏秋季获取率高于冬春季,且有午后获取率高、深夜和清晨低的特点;自由大气中冬春季获取率高于夏秋季。以获取率80%为其业务准入标准,边界层内MWPR的获取率达标。（2）相比L波段探空测风数据,MWPR整层的水平风速均偏小,低模态时有34.4%的数据位于偏小2.0~6.0 m·s^-1区间内;风向偏差超过±15°以上的水平风向数据占比为48.9%。（3）定性分析结果显示,MWPR探测到的垂直速度的指向性是合理的。雨强较大时,MWPR探测的垂直速度实际上是降水粒子的下降速度与大气湍流速度之和。MWPR的水平风数据在台风天、雪天等大气均一性强的时段内可靠性高。总体上,上海宝山MWPR的探测性能基本能满足日常监测服务之需,但其测风精度与业务准入标准相比尚有一定差距。

     

临安一次梅雨锋暴雨过程的风廓线雷达探测资料分析

利用临安CFL-03型边界层风廓线雷达探测资料对2017年6月23—24日的一次梅雨锋暴雨过程进行了详细分析,结果表明风廓线雷达能够揭示江淮梅雨系统中的中尺度切变线特征,低空切变线是这次暴雨过程的降水主要集中在降水前段和后段的主要原因,高空西风急流使降水得以维持发展。由功率谱数据估算的回波强度反映了此次暴雨过程的发展变化细节,降水集中区的降水云体发展深厚,达到5 km以上。垂直速度和大气折射率结构常数(C_n~2)与降水的变化趋势一致,10 mm的降水量对应的垂直速度接近7 m/s,C_n~2对数值接近-11。由于与降水的良好对应关系,风廓线雷达产品可以应用于强降水灾害天气的监测业务。     

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.     

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.     

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.     

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.