“尤特”强降水过程大气层结分析

1311号强台风“尤特”登陆后给广东带来持续性大范围强降水,对流降水特征显著.分析了“尤特”影响期间大尺度环流背景,重点讨论了此次持续性强降水过程中大气层结问题.发现低空急流向广东输送强的暖平流,是广东大气层结不稳定得以持续维持的根本原因.进一步分析发现,低空急流本身并不是“暖”的,当“尤特”趋向陆地时,陆地上的暖气团在“尤特”环流强迫下向南传播扩散,低空急流穿越这一暖区时温度升高才具备“暖”的特性.这一事实在以前并未被关注到.通过个例反查,在许多登陆后造成连续强降水的台风过程中均发现了这一特征.因此,台风登陆引起环境温度场的演变以及与低空急流的配置需引起重视.     

强西南季风背景下1311号台风“尤特”的暴雨特征分析

通过对比多年5—9月逐日平均和1311号台风"尤特"登陆期间逐日平均的西南风分量,分析了"尤特"登陆期间的西南季风强度变化特征,同时还分析了"尤特"登陆期间的环流特征和强西南季风背景下暴雨区的水汽条件、热力条件和动力条件。结果表明:(1)此次持续性暴雨过程的逐日西南风分量明显大于多年平均值且维持时间长;(2)"尤特"东南部有低空急流长时间存在,使得水汽源源不断地输入到"尤特"环流中,同时该次过程强降水区域的850 h Pa假相当位温长时间维持在350K以上;(3)此次过程中同一个降水中心在台风外围环流影响和西南季风辐合影响下,其强上升速度区高度明显不同。     

惠东高潭三次极端强降水过程成因对比分析

基于ECMWF的ERA-Interim全球大气再分析资料、MICAPS实况数据和广东省气象观测资料,对比分析了广东惠东高潭1979年、2013年和2018年的三次极端强降水过程的成因。结果表明:造成高潭极端强降水的影响系统有台风本体环流、登陆后的台风残余环流、季风低压外围环流等,其中2018年季风低压影响过程降水量最大;不同过程对流层低层强迫暖湿气流辐合抬升方式不同,分别为冷暖气流相互作用、西南季风和偏南季风地交汇、季风涌、边界层急流等;各过程中伴随的低空西南气流和偏南气流的风速大小差异明显,2013年台风残余环流影响时低空西南(偏南)风风速最大。相同点有:影响天气系统移动缓慢,并长时间维持,为极端强降水的发生发展和维持提供有利的动力条件;西南(偏南)季风、边界层急流或西南气流源源不断的水汽输送,为极端强降水的发展和维持提供了充足的水汽条件,同时低空暖湿气流的输送使得暴雨区大气层结不稳定状态长时间维持,利于持续性强降水的发展。研究结论可为今后高潭及其附近地区极端强降水的预报和决策服务提供理论支撑。      

边界层急流在粤东暴雨中心两次极端强降水过程中的作用

基于广东省气象观测资料、汕尾多普勒天气雷达产品和全球再分析资料CSFR,分析了2013年8月和2018年8月发生在粤东暴雨中心的破纪录极端强降水过程,阐明边界层急流的作用。结果表明:(1)两次过程的主要影响系统分别为长时间缓慢移动的1311号台风尤特残余环流和季风低压外围环流,当粤东暴雨中心处于台风环流东南侧和季风低压东侧时,边界层急流在该区域辐合抬升,形成的中尺度能量锋利于强降水的触发;(2)边界层急流为强降水提供了充沛的、源源不断的水汽条件,同时配合特殊地形的摩擦、阻挡等作用,在粤东暴雨中心内形成了明显的水汽通量辐合;(3)持续性强降水发展期间,大气层结长时间处于不稳定状态与对流层低空暖湿平流的不断输送密切相关。两次过程中不同点主要表现为边界层急流强度和风向不同,由此带来的气流辐合方式和强降水范围有明显的差异,季风低压影响过程中边界层急流作用更显著。     

0509号台风麦莎的结构与外围暴雨分布特征

利用地面加密观测资料、FY-2C卫星TBB资料和NCEP再分析资料，对2005年8月6～8日0509号台风麦莎登陆后环流结构及暴雨分布特征进行了综合分析。结果表明：台风麦莎具有明显不对称结构，台风东侧和北侧的积云对流较为旺盛；台风环流地面正涡度中心位于台风东侧，并随着台风北上移向台风东北象限并加强。地面强辐合区随着倒槽发展向偏北方向伸展；850hPa台风环流场表现为东侧和北侧的环流强盛，偏东风低空急流在台风北上过程中从东南风急流转为东北风急流；台风东侧暖，西侧冷，其东北侧有强暖平流输送。200hPa高空急流发展，急流入口区右侧强辐散有利于台风登陆后长时间维持。500hPa强上升运动区与台风外围暴雨区有较好对应关系。     

“凡亚比”登陆引发粤西大范围强降水的对流降水分析

利用热带气旋业务资料、业务地面观测、探空观测以及NCEP/NCAR再分析资料,从对流降水分析角度分析了1011号热带气旋“凡亚比”登陆减弱后造成粤西的一次大范围大暴雨局部特大暴雨过程.研究发现,强降水爆发前,粤西上空大气处于强不稳定状态,经中南半岛北部和北部湾输向粤西的一支低空急流爆发性增强,进一步加剧粤西大气不稳定度.在此背景下,低空急流核前缘以及急流与“凡亚比”西侧的西北部在粤西的汇合提供了强对流系统的触发条件.同时讨论了不同大气层结条件下低层动力辐合可能造成的降水性质及降水强度差异,提出一种新的台风登陆减弱后的暴雨业务预报思路.     

引起“碧利斯”强降水的MCS数值模拟研究

利用多种观测资料和数值模拟,对0604号强热带风暴碧利斯登陆后在湖南、广东等地引发强降水的中尺度对流系统活动特征进行了分析.结果表明,在"碧利斯"登陆后西行减弱过程中,由于西南季风的持续维持,"碧利斯"减弱后的低压环流中仍保持有强降水所需的充足水汽供应,造成局地强降水的MCS十分活跃.ARPS模式较好地模拟了7月15日发生在湖南南部的中尺度降雨过程,并揭示出"碧利斯"变性过程中,环境风场垂直切变结构强迫的次级环流决定了MCS活动特点,同时利用湿Q矢量诊断了低压次级环流的垂直运动特征.造成这次强降水过程的MCS在台风低压切变线以北的偏北潮湿气流中生成发展,低层偏北急流造成的动力辐合效应、对流不稳定性层结的建立是MCS在湖南南部迅速发展的重要原因.     

台风“鹦鹉”登陆过程中肇庆降水显著偏弱的原因

主要从环流特征、动力条件等方面分析台风“鹦鹉”登陆过程中肇庆市降水显著偏弱的原因：华南沿海特定的环流背景使台风“鹦鹉”在登陆广东过程中形成“偏心”台风,台风降水云团偏向低层环流西南侧,使台风低层环流正面袭击肇庆所带来的降水显著偏弱。而形成“偏心”台风的主要环流背景是对流层高层强盛的南亚高压及其南侧强劲的偏东风急流;同时,台风前进方向上的副热带高压使台风登陆后迅速减弱,也是一方面的原因。此外,动力条件方面,台风登陆后,肇庆市低层为弱的上升运动,中高层是下沉运动,也不利于强降水的发生。     

2013年影响湖南的两次相似路径台风暴雨对比分析

应用多种常规观测资料、加密自动气象站资料和NCEP 1°×1°再分析资料,对2013年影响湖南的两次相似路径台风暴雨过程进行了对比分析。研究表明：“尤特”台风暴雨直接由台风环流引起,具有锋前暖区降水的特点;而“天兔”台风暴雨由台风低压倒槽与西风带天气系统相互作用引起的,其降水属于典型的锋面降水。“尤特”由东风带进入西风带,其与副高相对位置的变化是导致其登陆后路径北翘的主要原因。“尤特”低压环流与南海季风相互作用,充沛的水汽输送对台风低压环流的长时间维持以及湘东南暴雨的形成和发展起到了重要的组织和促进作用。而“天兔”登陆后南海季风位置偏南,不利于“天兔”的长时间维持以及向暴雨区的水汽输送。低层暖式切变线附近强辐合与高层强辐散耦合、低层强正涡度与高层负涡度的耦合为“尤特”台风暴雨的发生发展提供了动力条件。由中低层冷空气入侵导致的锋生强迫和高低空急流耦合形成的次级环流,加强了“天兔”低压倒槽内冷暖气流的辐合,是触发倒槽内中尺度对流发展和暴雨产生的重要动力机制。     

"北冕"和"黑格比"台风暴雨对比分析

采用多种物理量综合诊断分析方法,对路径相似的强热带风暴"北冕"和强台风"黑格比"在西进途中进行水汽来源、不稳定层结的维持等方面的研究,探讨台风及其减弱后的低压环流发生大暴雨的成因.结果表明:"北冕"和"黑格比"路径相似,两次台风大暴雨落区比较一致,而它们减弱后台风低压环流仍对桂西南造成强降水,低空急流的存在是台风低压环流维持并造成强降水的主要因素.     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

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.     

Revisiting the Concentration Observations and Source Apportionment of Atmospheric Ammonia

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     

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。     

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

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.     

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.     

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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.