大尺度加热与东西风带中不稳定扰动的激发

文中通过一些简化假定,得到了包括非绝热加热的一参数模式。导得加热存在下的正压不稳定的必要条件是β-d~2u/dy~2 q~2u S~2H/K=0,研究了大尺度加热对东西风带不稳定扰动及定常波型扰动的作用。结果指出,加热场对东西风带正压不稳定扰动的影响与加热和流场的相对配置有关。此外,大尺度加热可以在西风带激发出定常波型扰动,而在东风带只能产生衰减型扰动。激发西风带定常波型扰动的非绝热加热场的水平半径尺度,应大于L_c=(u/β)~(1/2)。最后还考虑了摩擦的作用。     

四川盆地西部一次大暴雨过程的中尺度特征分析

利用常规观测资料、地面加密观测资料、逐时云顶亮温TBB资料和1°×1°NCEP/NCAR再分析资料,对2010年7月24-25日四川盆地暴雨天气过程中尺度对流系统发生、发展的物理量特征和动力机制进行了分析.结果表明:(1)此次四川盆地西部区域性暴雨天气过程是由中-β尺度云团合并、加强所生成的中-α尺度对流系统造成的.(2)散度、涡度、垂直速度和相当位温的分布与对流系统的发生、发展较一致,特别是在中-α尺度对流系统强烈发展阶段有很好的对应关系,为中-a尺度对流系统的发生、发展提供了有利的动力和热力条件.(3)大气非平衡强迫对发生在四川盆地西部的区域性暴雨有较好的指示意义,是激发暴雨天气的动力机制.(4)暴雨发生期间降水造成的非绝热加热有利于强降水天气的维持.     

大尺度凝结加热与中尺度位温扰动对冷锋锋生的作用

文中导得简化的包括大尺度凝结潜热的半地转锋生模式，利用该模式讨论了大尺度凝结加热和中尺度位温扰动对冷锋锋生的影响，给出了锋生过程中各物理量的演变图。计算结果表明，大尺度凝结加热对冷锋锋生具有加强作用，增大锋生率，增大上升运动速度，缩小上升运动区的范围，使之更具有中尺度系统特征，使非地转越锋环流增强并发生倾斜，凝结加热和中尺度位温扰动的结合是锋前暖区多重雨带形成的可能机制之一。     

非绝热加热对热带气旋非对称结构影响的数值试验

利用含非绝热加热强迫的正压涡度方程。将非绝热加热作适当的参数化处理。对初始对称 热带气旋作了一系列数值试验,结果表明：不仅β项、平流项在热带气旋非对称结构的形成中有重要作用,而且非绝热加热对热带气旋的非对称结构亦有重要影响,从而验证了非绝热加热是热带气旋非对称结构形成的一种可能机制的结论。     

非绝热二维滞弹性流体的动力稳定性

采用滞弹性近似下的二维滞流体动力学方程组，讨论了中尺度对称扰动的动力稳定性，得到其绝热情况下对称不稳定的判据条件。研究结果表明，相对于浅对流的情况而言，深对流情况下对称不稳定的条件更为苛刻一些。在考虑非绝热加热时，扰动增长率随其波长的变化会产生间断现象，中低层加热明显对中－β尺度扰动具有激发增长的作用，并且促使扰动向暖区传播，而中高层加热则具有一定的差异性。     

华南前汛期一次大暴雨过程的扰动位涡反演与数值研究

利用NCEP 1°×1° 6h再分析资料、位涡反演和数值试验方法,分离与不同物理过程有关的扰动位涡进行反演诊断．在此基础上移除模式初始场中包含的与不同物理过程有关的扰动位涡反演的平衡场进行敏感性试验．对2006年5月21—22日一次热带扰动系统北上在广东珠江三角洲地区引发的大暴雨天气过程进行了探讨。结果发现：对流层中低层与潜热释放有关的正扰动位涡是影响热带扰动形成、维持及发展的主要因子之一;与潜热释放无关的扰动位涡对副热带高压的形成和维持有重要作用,影响热带扰动系统的移动路径;边界层内的扰动位涡有利于南海热带洋面北上气旋性扰动的发生、发展与维持;中高层扰动位涡对气旋性扰动系统的直接影响很小;下边界扰动位温不利于气旋性扰动系统的形成、维持与发展。数值敏感性试验表明,初始场中包含的与不同物理过程有关的扰动位涡在暴雨数值模拟中有重要作用,它们不同程度地影响热带扰动的强度、活动路径的模拟．并影响暴雨强度和落区;与非绝热物理过程有关的扰动位涡很大程度上影响暴雨强度,而与非绝热物理过程无关的扰动位涡很大程度上决定暴雨落区。     

非对称的非绝热加热对热带气旋移动影响的数值研究

采用中尺度数值模式（MM4）,以9414号台风为个例,应用卫星资料,引入非对称的非绝热加热,讨论其对9414号台风移动的影响。计算结果表明,引入与实况吻合的非对称非绝热加热分布后,该台风的路径预报和降水预报有明显改进,若同时考虑台风范围初始水汽场的非对称分布,这种改进作用尤为明显。从业务应用考虑,还构造了几种典型的螺旋状结构的非绝热加热计算方案引入模式的热力过程中,结果表明:不同螺旋状结构的加热分布对台风的移动有不同的影响,当选择与实况云系分布相近的螺旋状结构时,也可提高台风路径预报正确率,可应用于业务模式。     

一次梅雨锋暴雨过程中多尺度能量相互作用的研究I.理论分析

本文是讨论梅雨锋暴雨过程中多尺度能量相互作用问题的开始部分。为了分析梅雨锋暴雨过程中的多尺度能量相互作用,从z坐标系中的运动方程和热力学方程出发,把基本物理量分成大尺度背景场（>2000 km）、α中尺度（200~2000 km）和β中小尺度系统（< 200 km）分量,利用滞弹性近似,推导了大尺度背景场、α中尺度和β中小尺度系统三个尺度的动能方程和位能方程。能量方程中包含了各尺度动能之间的转换、位能之间的转换以及动能和位能之间的转换。动能方程主要包括各尺度动能之间转换项、动能输送项、水平气压梯度力做功项、垂直方向扰动气压梯度力做功项、浮力做功项、地转偏向力分量做功项以及摩擦力做功项。位能方程主要包括各尺度位能之间转换项、位能输送项、浮力做功项以及非绝热加热做功项。其中浮力做功项为位能和动能之间的能量转换项,是暴雨发生发展过程中比较关键的能量转换项。关于将能量方程用于梅雨锋暴雨过程中并且诊断能量相互作用影响暴雨发展和消亡过程的物理机制等问题,将在以后的研究中给出。     

近四百年北半球气温变化的分析:EMD方法的应用

利用一个二维非弹性非静力的数值模式，讨论了初始扰动的尺度对于对称不稳定发展的影响。结果表明：虽然对称不稳定是β-中尺度的不稳定，但其不一定必须由β-中尺度的扰动来激发；由不同水平尺度的扰动所激发的倾斜环流有不同的特点；对称不稳定倾斜环流可能存在最小临界尺度；对称不稳定的发展存在最优扰动水平尺度，而扰动的垂直尺度对于对称不稳定的发展影响不大。     

基于位涡反演的台风初值敏感性试验

基于分片位涡反演方法,对2013年7号台风Soulik开展初始涡旋、背景环流对台风发展影响的个例研究。针对不同天气系统进行分片位涡反演,基于反演结果设计敏感性试验,确定影响台风发展的敏感初始物理量扰动,分析讨论与特定物理过程联系的扰动分量以及扰动大小对台风发展的影响。敏感性试验的结果表明,初始弱涡旋扰动中与潜热加热联系的风场扰动分量是决定台风发生发展的关键要素扰动,这一扰动分量的大小对台风路径有直接影响,同时能够直接影响台风云墙的建立,它的重要性表明第二类条件性不稳定(CISK)机制在此次台风过程中扮演了重要角色。     

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。