河西走廊中部一次暴雨过程的天气学诊断

2012年7月29日13时至30日03时河西走廊中部遭遇暴雨袭击,利用常规高空和地面资料、区域加密雨量站资料、FY-2静止卫星云图以及6 h一次1°×1°的NCEP再分析资料,对此次暴雨发生前后的天气环流背景及影响系统、物理量特征和卫星云图以及中尺度系统的发生发展进行了天气学综合诊断分析。结果表明:此次暴雨发生在非常有利的大尺度天气背景下,高、低层均为"东高西低"的流场配置,影响的环流系统是巴尔喀什湖冷槽,暴雨发生时高层辐散、低层辐合,形成了强烈的抽吸作用;对流层内出现强烈的上升运动,中低层流场的配置有利于水汽的输送和汇聚;500 hPa垂直螺旋度的分布与天气系统和强降水有很好的对应关系,700 hPa柴达木暖性低涡及地面中尺度系统为不稳定能量的储存和暴雨提供了动力条件,从兰州至河西的强暖湿平流的发展为暴雨提供了热力条件;暴雨发生期间有多个中尺度对流云团在该区域上空活动,表明暴雨过程中存在明显的中小尺度系统。     

2012年初夏滇中首场暴雨过程诊断分析

利用地面加密观测资料、多普勒天气雷达回波强度、卫星云图TBB资料和NCEP 1°×1°分析资料,应用滤波和广义位涡理论, 对2012年6月1—2日云南省中部的首场切变冷锋型暴雨天气过程进行诊断分析。结果表明:中尺度天气系统是该次暴雨产生的直接原因, 强降水均发生在云顶亮温等值线梯度较大一侧,回波强度空间分布不均匀,回波发展高度较低,但回波结构致密,低质心,以液态降水粒子为主,因此降水分布不均匀,但降水效率高;水汽源地为孟加拉湾;低层水汽通量辐合带与冷锋、切变线、中尺度辐合线以及β中尺度低涡位置有较好的对应关系;700 hPa,850 hPa水汽通量强辐合区中心位置叠加时,其所在区域地面降水增强;强降水区域上空中低层广义湿位涡的正异常现象体现了降水区中低层高水汽集中特征;单站上空低层的广义湿位涡正异常增加时,地面降水强度增加,反之减小;800 hPa广义湿位涡正异常区对地面降水分布有一定指示作用,但暴雨中心与广义湿位涡强中心并不完全重合。     

对湖北省2000年5月一次暴雨天气过程的分析

使用2000年5月22－25日500hPa、700hPa、850hPa以及地面天气图资料，描述了当年5月24日发生在湖北境内一次暴雨天气过程的高空和地面天气形势；同时根据武汉暴雨研究MAPS模式提供的有关物理量格点场资料，对此次暴雨天气过程的能量场、散度场、涡度场与水流通量散度场进行了分析。其结果表明，中低层低涡、切变线以及地面中尺度耦合带是形式这次暴雨过程的主要天气系统，且地面中尺度辐合系统与大暴雨落区存在很好的对应关系。     

“7·22”长江中游暴雨中尺度系统的数值模拟与分析

利用中尺度暴雨模式较成功地模拟了2002年7月22～23日发生在长江中游的暴雨中尺度天气系统，结合地面加密和常规观测资料对暴雨中尺度天气系统进行了较为详细的分析。结果表明：(1)大别山西侧的暴雨由中α尺度切变线上中β尺度低涡造成，湘鄂交界地带的暴雨由切变线上气旋性扰动造成。(2)高空槽前的正涡度平流为暴雨中尺度系统形成提供了启动机制：在正涡度平流的作用下，对流层中低层降压产生变压风辐合造成上升运动，低层暖湿气流抬升促使对流不稳定能量爆发形成局地对流产生暴雨。     

一次大暴雨雷达回波特征及数值模拟

利用NCEP再分析资料和天津多普勒雷达等资料,对2008年7月14—15日发生在河北唐山及天津一带的暴雨过程进行了分析,并通过MM5数值模拟阐述了雷达资料分析的正确性。结果表明:此次大暴雨发生在中低纬天气系统相互作用的背景下,700hPa高空槽、850hPa低涡及地面中尺度辐合线是引发此次暴雨主要影响系统;低空急流是暴雨主要的水汽来源;低空辐合高层辐散、锋面抬升是暴雨系统发展的动力机制;对流层中部冷空气活动引起的西南低空急流脉动与暴雨的增幅有密切关系;涡旋状和带状回波是主要降水回波。     

次天气尺度与中尺度正、斜压模演变揭示的武汉暴雨过程

利用滤波原理提取出大气流场中的次天气尺度和中尺度信息，再把大尺度和中尺度水平风场分别分解为正压分量（垂直平均）和斜压分量（扰动）流场。对1998年7月21～22日发生在武汉附近的强暴雨过程进行了次天气尺度与中尺度流场正、斜压分量演变特征的分析。结果表明：次天气尺度与中尺度流场正压分量的演变与此次强暴雨的酝酿、发展和消亡具有内在的联系；次天气尺度与中尺度流场高层200hPa斜压分量很强，低层850hPa正压分量很强；次天气尺度与中尺度流场斜压性占主导地位，随着暴雨的发展，中尺度流场的正压性减弱而斜压性进一步增强，而次天气尺度流场的正压性增强而斜压性减弱。以上结论对于揭示中尺度暴雨过程发生发展的本质有一定的意义。     

一次阻塞型华北对流性暴雨过程的诊断分析和数值模拟

利用常规和地面加密气象观测资料、卫星云图、NCEP再分析资料及中尺度模式MM5,对2006年7月23日一次阻塞型华北暴雨过程进行了诊断分析和数值模拟。结果表明,此次暴雨过程发生在以东西伯利亚阻塞高压为典型特征的大尺度鞍型场的背景下,宽广的低压区及高、低空急流次级环流为中尺度对流系统(MCS)的发生、发展提供了适宜的环境和动力强迫;700hPa和850hPa天气尺度的偏西水汽输送和低涡北侧的偏东水汽输送改善了环北京地区的水汽条件,暴雨发生前850hPa中尺度西南水汽输送对北京暴雨的发生有直接影响;MM5模式再现了导致MCS的形成及演变过程;中-β尺度MCS是这次暴雨的直接触发系统,其水平尺度约为0.5个经距,垂直方向由地面伸展到300hPa左右,具有典型的暖心结构,辐合、辐散中心分别位于900hPa和400hPa;MCS北侧强垂直次级环流为强对流的产生创造了有利条件。同时,MCS南侧相当位温的强梯度高能区及该区域的不稳定能量输送也是暴雨发生的重要条件。     

渭河流域一次致洪暴雨过程的中尺度滤波分析

利用常规高空观测资料和NCEP/NCAR 1°×1°的再分析资料以及25点低通滤波技术,对2003年8月28—29日发生在渭河流域的一次致洪暴雨进行了中尺度分析和探讨,分析出中尺度环流演变特征,总结了渭河流域致洪暴雨的概念模型,认为这次暴雨过程中在以西南气流为主的平均气流场上隐藏着尺度较中尺度平均流场小得多的涡旋,其移动方向和发展程度决定了强降水落区及其强度;高空西风风速脉动与低层南风风速脉动耦合形成了中尺度次级环流圈,其上升支为强降水提供了足够的动力抬升机制;而850 hPa低空急流、700 hPa中尺度低涡、南风脉动以及高空西风风速脉动等条件的合理配置是中尺度次级环流形成的必备因素;地面中尺度辐合线是本次暴雨的触发机制。     

河南省一次副高边缘对流性暴雨的多尺度特征

利用多元观测和探测资料及NCEP 1°×1°再分析资料,诊断2019年8月1日河南省一次分散性对流暴雨过程。结果表明:(1)副热带高压边缘西南暖湿气流与西风槽携带的冷空气在河南上空交汇,高空急流的强大动力作用等,是本次暴雨天气的大尺度环流背景;(2)过程发生前700、850 hPa系统呈前倾结构,郑州站CAPE值达1717.8 J·kg~(-1),850 hPa与500 hPa温差大于27℃、850 hPa比湿大于14 g·kg~(-1);(3)700 hPa低涡和切变线、850 hPa切变线及地面弱冷空气是触发对流的中α尺度系统;出流边界、地面辐合线及中β尺度低压是触发对流的中β尺度系统;(4)当出流边界远离雷暴母体并移速较快时不易触发对流,但若与另一出流边界或中尺度辐合线、中尺度低压等相结合时,则易触发新的对流;(5)后向传播的新生单体在引导气流作用下不断向下游移动,易产生列车效应,利于暴雨发生;(6)基于诊断分析结果归纳出此次对流暴雨的天气概念模型。     

华北“7·19”暴雨中低涡系统演变及多尺度相互作用机制研究

为探究华北暴雨的维持及中尺度系统演变机制,利用NCEP/NCAR的GFS资料、地面自动站观测资料等,借助数值模拟、涡度收支分析和尺度分离等方法,对2016年7月19日前后一次华北暴雨过程进行了观测分析和模拟研究。(1)本次极端降水过程与东移低槽切断形成的深厚低涡密切相关。低涡与副高脊线形成“东高西低”形势且雨区始终处于高层辐散低层辐合的动力配置下,有利于对流维持。涡旋与低空急流的配合使来自西南侧和东侧的水汽在华北辐合,并使雨区处于能量锋区,对流层中低层形成深厚逆温层,为暴雨维持提供水汽和能量保障。(2)低涡系统总体呈增强趋势,中心涡度最高达55×10-5 s-1以上。成熟阶段呈现贯穿对流层的直立正涡度柱,但涡度变化集中在500 hPa以下,中心维持在850 hPa附近。涡度增长主要受正涡度区与辐合中心重合产生的拉伸效应以及干侵入等因素的促进作用。(3)低层辐合中心由三种不同尺度系统叠加而成,其中中尺度系统对中心的强度和位置影响最大,而大中尺度风场间的辐合也使辐合区更大、强度更强。低层涡旋增长与风场辐合加强之间形成正反馈调节,有利于低涡和降水的维持。      

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.     

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。     

Retrieval of outgoing longwave radiation from COMS narrowband infrared imagery

Hourly outgoing longwave radiation(OLR) from the geostationary satellite Communication Oceanography Meteorological Satellite(COMS) has been retrieved since June 2010. The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels. This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm(OLR12.0using the 12.0 μm channel) and three multiple-channel algorithms(OLR10.8+12.0using the 10.8 and 12.0 μm channels; OLR6.7+10.8using the 6.7 and 10.8 μm channels; and OLR All using the 6.7, 10.8, and 12.0 μm channels). The COMS OLRs from these algorithms were validated with direct measurements of OLR from a broadband radiometer of the Clouds and Earth's Radiant Energy System(CERES) over the full COMS field of view [roughly(50°S–50°N, 70°–170°E)] during April 2011.Validation results show that the root-mean-square errors of COMS OLRs are 5–7 W m-2, which indicates good agreement with CERES OLR over the vast domain. OLR6.7+10.8and OLR All have much smaller errors(～ 6 W m-2) than OLR12.0and OLR10.8+12.0(～ 8 W m-2). Moreover, the small errors of OLR6.7+10.8and OLR All are systematic and can be readily reduced through additional mean bias correction and/or radiance calibration. These results indicate a noteworthy role of the6.7 μm water vapor absorption channel in improving the accuracy of the OLRs. The dependence of the accuracy of COMS OLRs on various surface, atmospheric, and observational conditions is also discussed.     

Information for Authors

AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.     

Our Warmest Thanks to AAS Reviewers 2014

正The editorial office of Advances in Atmospheric Sciences(AAS),on behalf of all AAS editors,would like to publicly acknowledge the people listed below who served as reviewers for the journal daring 1 September 2013 to 24 August 2014.We recognize that the time and work of the reviewers is the most important resource in academic publishing.The quality of our journal depends in a crucial way upon the reviewing process and therefore all reviewers'time and efforts taken to sustain the quality of the journal are greatly appreciated.     

Data selection using support vector regression

Geophysical data sets are growing at an ever-increasing rate, requiring computationally efficient data selection(thinning)methods to preserve essential information. Satellites, such as Wind Sat, provide large data sets for assessing the accuracy and computational efficiency of data selection techniques. A new data thinning technique, based on support vector regression(SVR), is developed and tested. To manage large on-line satellite data streams, observations from Wind Sat are formed into subsets by Voronoi tessellation and then each is thinned by SVR(TSVR). Three experiments are performed. The first confirms the viability of TSVR for a relatively small sample, comparing it to several commonly used data thinning methods(random selection, averaging and Barnes filtering), producing a 10% thinning rate(90% data reduction), low mean absolute errors(MAE) and large correlations with the original data. A second experiment, using a larger dataset, shows TSVR retrievals with MAE < 1 m s-1and correlations 0.98. TSVR was an order of magnitude faster than the commonly used thinning methods. A third experiment applies a two-stage pipeline to TSVR, to accommodate online data. The pipeline subsets reconstruct the wind field with the same accuracy as the second experiment, is an order of magnitude faster than the nonpipeline TSVR. Therefore, pipeline TSVR is two orders of magnitude faster than commonly used thinning methods that ingest the entire data set. This study demonstrates that TSVR pipeline thinning is an accurate and computationally efficient alternative to commonly used data selection techniques.     

Temporal vulnerability in hazardscapes: Flood memory-networks and referentiality along the North Carolina Neuse River (USA)

Social models of population vulnerability to disasters increasingly include the notion that vulnerability has a strong temporal component. While this temporality is typically conceptualized as objective (making vulnerability “dynamic,” “multiscalar,” and/or “historical”), it consistently fails to acknowledge that among stakeholders managing hazardscapes temporality is also a social process in which subjective experience of time may play a role in creating situations of population vulnerability. This paper proposes that the temporal situatedness of a population relative to past hazard events and the quality with which stakeholders engage hazard memory-chains combine to significantly influences its vulnerability to natural hazards. It is proposed that this temporal vulnerability is characterized by shared, population level potential for surprise and can be evaluated by exploration of time-series depth and temporal reference points in historical ecological narratives and documents. Based on ethnohistoric research conducted from 2002 to 2006 in flood-prone eastern North Carolina (USA), it is illustrated how temporal vulnerability was relatively higher in the Neuse River watershed located at the City of Kinston than surrounding watersheds. Due to the combination of factors including the damming of the Neuse River in the 1980s, outdated official floodplain maps, relatively unmonitored floodplain development, the stochastic timing of flood events (placing the last major flood more than a generation away), technological optimism, and turnover of floodplain officials and residents, local stakeholders were seriously misinformed about the space-time risks involved both before and after the disaster of Hurricane Floyd (1999) happened. To deal with this inconsistency, the temporal rarity of Hurricane Floyd as a “500-year event” has been motivated and embraced by many in an effort to continue life-as-is. The paper proposes that the concept of temporal vulnerability is further explored and used as key dimension in the vulnerability sciences.     

An assessment of the predictability of the East Asian Subtropical Westerly Jet based on TIGGE data

The predictability of the position, spatial coverage and intensity of the East Asian subtropical westerly jet(EASWJ) in the summers of 2010 to 2012 was examined for ensemble prediction systems(EPSs) from four representative TIGGE centers,including the ECMWF, the NCEP, the CMA, and the JMA. Results showed that each EPS predicted all EASWJ properties well, while the levels of skill of all EPSs declined as the lead time extended. Overall, improvements from the control to the ensemble mean forecasts for predicting the EASWJ were apparent. For the deterministic forecasts of all EPSs, the prediction of the average axis was better than the prediction of the spatial coverage and intensity of the EASWJ. ECMWF performed best, with a lead of approximately 0.5–1 day in predictability over the second-best EPS for all EASWJ properties throughout the forecast range. For probabilistic forecasts, differences in skills among the different EPSs were more evident in the earlier part of the forecast for the EASWJ axis and spatial coverage, while they departed obviously throughout the forecast range for the intensity. ECMWF led JMA by about 0.5–1 day for the EASWJ axis, and by about 1–2 days for the spatial coverage and intensity at almost all lead times. The largest lead of ECMWF over the relatively worse EPSs, such as NCEP and CMA, was approximately 3–4 days for all EASWJ properties. In summary, ECMWF showed the highest level of skill for predicting the EASWJ, followed by JMA.     

汉江流域极端水文事件时空分布特征

利用1960-2012年汉江流域15个气象站点的日降雨资料和3个水文站同时期日径流资料,分析了9个极端降雨指数的空间分布规律,运用广义极值分布（GEV）、Gamma分布两种极值统计模型对各站点的最大1 d降雨、最大3 d降雨极值样本进行拟合,遴选描述降雨极值分布规律最优概率模型,进而推算给定重现期下的降雨设计值,并分析其空间分布规律;选用Gumbel、Clayton和Frank这3种Copula函数建立降雨-洪量极值联合分布模型,优选最合适的Copula函数,由此计算给定重现期下的洪量设计值。结果表明：GEV分布模型能更好地模拟降雨极值序列,不同重现期下的降雨极值在空间上均呈西低东高的特征;3种Copula函数中,Frank Copula函数能更好地拟合降雨-洪量相关关系,由此推求的洪量设计值大于单变量拟合设计值。