2004年7月10日北京暴雨的中尺度分析

利用常规探测、地面加密观测、NCEP1°×1°的6小时资料和雷达资料对2004年7月10日北京罕见的局地暴雨进行了天气动力学和中尺度分析。结果表明这次暴雨是在比较有利的天气背景条件下产生的,造成强降水的3个雨团在时空尺度上具有中β尺度系统的特征,不断移入的对流回波是降水的直接制造者,中尺度辐合线和小低压为降水发生提供了有利的触发条件。     

恩施“6·24”暴雨中尺度系统特征分析

利用常规观测资料、自动区域站雨量、卫星TBB资料、雷达资料,对恩施州2016年6月24—25日发生的一次大范围暴雨过程进行分析。结果表明:本次强降水,具有典型的两槽一脊"单阻型"梅雨环流特征,在有利的大尺度环流背景下,在高空槽、低层低涡切变、西南急流、地面中尺度辐合线等中尺度天气系统的共同影响、相互作用下,形成了此次大范围强降水。此次暴雨空间上分布不均,局地性强,表现为明显的中尺度对流性特征,雷达回波图上降水性质表现为混合型降水,暴雨的直接影响系统是中β尺度对流系统,且中β尺度对流系统在多个中尺度对流云团合并后加强,时间尺度约为5 h。此次暴雨过程是在上干冷下暖湿强的大气层结不稳定条件下,梅雨锋、边界层辐合线和地形槽的触发作用将前期积累的能量释放产生的强对流天气,同时,副高外围西南气流将南海和西太平洋的水汽向恩施输送,为暴雨的发生提供了有利的条件。     

重庆地区一次暴雨天气过程分析

利用常规探测、地面加密观测、NCEP 1°×1°的6小时资料和卫星、雷达等资料对2008年7月22日重庆地区暴雨进行了天气动力学和中尺度分析.结果表明:这次暴雨是在比较有利的天气背景条件下产生的,造成强降水的雨团在时空尺度上具有中尺度系统的特征,不断移入的对流回波是降水的直接制造者,西南涡及切变线为降水发生提供了有利的触发条件,低空南风急流的激发了对流运动的产生,同时低空南风急流的维持为降水过程提供了有利的水汽来源.     

长江中游一次暴雨中尺度天气系统的观测分析

利用多种加密观测资料，详细分析了长江中游一次暴雨中尺度天气系统的观测特征。结果发现：(1)暴雨由各种尺度的天气系统相互作用造成，直接造成这场暴雨的是中α尺度切变线上活动的多个并不深厚的中β尺度对流系统，该对流系统在发生发展过程中一直伴有明显的中尺度雨团活动。(2)这次中β尺度对流系统活动可能的物理图像为：在切变线东北方和西南方各有一支气流在切变线上辐合抬升并汇入对流系统中，在暖平流的作用下，气流在倾斜的θse锋前上升(或沿锋区爬升)并随高度发生顺转，到7km高度以上开始以西南气流发散，在离对流区400～500km处下沉，并在θse锋区附近构成中尺度垂直环流圈，对流云团发生在该垂直环流的上升支一侧。     

甘肃东南部两次极端致灾暴雨对比分析

为了研究甘肃东南部相同气候背景条件下极端暴雨天气的成因,提高极端暴雨强度和落区预报的准确率,利用NCEP再分析、自动气象站降水、常规观测资料及卫星云图资料,对2013年8月7日和2017年8月7日发生在甘肃东南部两次极端暴雨进行对比分析。结果表明:两次极端暴雨天气过程都伴随着短时强降水等强对流性天气,具有降水量大、雨强强、灾害重的特点,其中冷空气的强度对暴雨落区、空间分布以及影响系统移动以及对流强度产生重要影响。在强冷空气和高空低槽、低层切变线影响下,暴雨区偏南,强降水区域小,持续时间短,不稳定条件更好,对流强度更强;在弱冷空气和高原槽、低层低涡、低空急流作用下,暴雨区偏北,强降水范围大,持续时间长,大气湿层厚度大,低层水汽辐合强度、涡度以及垂直速度更强,降水效率更高,但对流强度相对较弱。卫星云图上,在强冷空气的影响下对流发展旺盛,形成强中尺度对流云团,对流云团呈带状;在弱冷空气作用下对流云团尺度小,发展范围小,有暖云降水特征,降水效率高。     

2009年7月6日山东暴雨的中尺度分析

利用卫星、自动站、加密雨量站等资料,对2009年7月5—6日山东暴雨过程进行天气动力学分析,重点是分析其中尺度特征。结果表明：本次降水过程是在有利的天气尺度环流背景下产生的,副热带高压西侧源源不断的水汽输送至暴雨区;高层强辐散与中低层强辐合以及强上升运动为中尺度对流系统的发生发展提供了有利的动力条件;强降水主要发生在对流云团发展到强盛时期,可用云顶亮温变化来监视云团发展;水汽通量的强辐合是降水的中尺度对流系统发生发展的重要条件之一。     

长江流域雨带形势下的一次低涡暴雨天气过程分析

对发生在嘉陵江到渠江流域的一次西南低涡暴雨天气过程的结构分析表明：本次过程属于长江流域季风雨带形势下中－α尺度雨带中的－β尺度雨团；与其对应的中小尺度初始扰动同次天气尺度低涡、切变线和急流核的形成有关；并利用中尺度扰动的对称不稳定理论诊断扰动波包的发展，指出了热成风偏差和对流不稳定局地变率在暴雨形成中的作用。     

2003年7月淮河流域暴雨中-β尺度特征的观测分析

利用常规和多种高分辨率的非常规观测资料，分析了2003年7月3～4日淮河流域大暴雨过程中安徽省北部暴雨雨团的活动及与之相联系的中尺度对流系统的发展演变特征。结果表明：在有利的大尺度环流背景下，梅雨锋中-α尺度云系中的中-β尺度对流系统的发生发展是导致暴雨的直接原因。暴雨强度和出现地点与中-β尺度扰动密切相关，整个暴雨过程有3次生命史不完全相同的雨团活动期，对应着三次雨强峰值；不同雨团活动期内，中-β尺度对流系统的组织发展形式有所不同，第一次和第三次雨团活动是由几个相对分散的块状中-β尺度对流复合体相继影响所致，而第二次雨团活动则与长约100km的近地层中-β尺度辐合线的迅速发展相联系；中-β尺度对流云团的生命史与雨团的生命史并不一定相同。本次暴雨过程中，起主要作用的是嵌在絮状回波里的一个个对流复合体和个别强对流单体；回波强度和强回波发展高度与地面降水强度呈正相关。     

“2004．6”湘西北低空急流暴雨的中尺度分析

利用常规观测、T213、雷达和MM5中尺度模式输出资料对2004年6月23—24日湘西北地区的暴雨和大暴雨进行了天气动力学和中尺度分析。结果表明：这场暴雨是在有利的天气背景条件下产生的，造成强降水的雨团在时空尺度上具有中尺度系统的特征，中尺度辐合线和低空急流为降水发生提供了有利的触发条件。     

2008年8月10日北京地区暴雨过程的诊断分析和数值研究

利用地面和探空加密资料、FY-2C黑体辐射亮温(TBB)以及NCEP资料,对2008年北京奥运会期间(8月10日)发生的一场区域性暴雨过程进行了初步分析,并利用WRF模式(V3.0),针对此次暴雨过程的性质设计了一系列数值试验,探讨了此次暴雨过程数值模拟和预报中模式物理过程的敏感性。结果发现:(1)引发暴雨的中尺度对流系统经历了3个阶段,即低槽云系中零乱弱对流云活动(北京西部山区)、低槽云系中镶嵌的波状对流云团活动(北京中西部地区)以及尺度较大的中β尺度对流云团发生发展阶段(北京中东部地区)。地面中尺度雨团与中尺度对流系统的活动特征一致,即经历了北京西部山区的零乱雨团和中西部地区波状雨团以及中东部地区中β尺度雨团活动阶段。(2)暴雨中尺度对流系统发展前处于高水汽环境、抬升凝结高度低、一定的对流不稳定能量和有利的地面抬升条件,暴雨中尺度对流系统发展过程中有明显的对流不稳定能量积聚与释放和水汽增减过程。(3)暴雨过程中低空急流特征并不明显,暴雨可能主要由对流层低层扰动、近地面冷空气活动、天气尺度强迫以及地形等共同作用引发中尺度对流系统造成。(4)数值试验结果表明,云微物理过程不足以改变强降雨带的模拟,此次暴雨过程...     

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.     

Information for Authors

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

Connections between the Eurasian teleconnection and concurrent variation of upper-level jets over East Asia

The variation of the East Asian jet stream(EAJS) associated with the Eurasian(EU) teleconnection pattern is investigated using 60-yr NCEP–NCAR daily reanalysis data over the period 1951–2010. The EAJS consists of three components: the polar front jet(PFJ); the plateau subtropical jet(PSJ); and the ocean subtropical jet(OSJ). Of these three jets over East Asia,the EU pattern exhibits a significant influence on the PFJ and OSJ. There is a simultaneous negative correlation between the EU pattern and the PFJ. A significant positive correlation is found between the EU pattern and the OSJ when the EU pattern leads the OSJ by about 5 days. There is no obvious correlation between the EU pattern and the PSJ. The positive EU phase is accompanied by a weakened and poleward-shifted PFJ, which coincides with an intensified OSJ. A possible mechanism for the variation of the EAJS during different EU phases is explored via analyzing the effects of 10-day high-and low-frequency eddy forcing. The zonal wind tendency due to high-frequency eddy forcing contributes to the simultaneous negative correlation between the EU pattern and the PFJ, as well as the northward/southward shift of the PFJ. High- and low-frequency eddy forcing are both responsible for the positive correlation between the EU pattern and the OSJ, but only high-frequency eddy forcing contributes to the lagged variation of the OSJ relative to the EU pattern. The negative correlation between the EU pattern and winter temperature and precipitation anomalies in China is maintained only when the PFJ and OSJ are out of phase with each other. Thus, the EAJS plays an important role in transmitting the EU signal to winter temperature and precipitation anomalies in China.     

THE INFLUENCES OF SSTA OVER KUROSHIO AND ITS EXTENSION ON RAINFALL IN NORTHEAST CHINA UNDER THE BACKGROUND OF TWO DIFFERENT EL NIO CASES

By using the gauged rainfall in 160 stations within mainland China and the NCEP/NCAR reanalysis data, the impacts of anomalous SST in Kuroshio and its extension on precipitation in Northeast China were investigated. The results show that a difference in the meridional circulation such as the East Asia/Pacific teleconnection pattern(EAP)may be responsible for the difference in rainfall between 1998 and 2010. In comparison with 1998, the anomalous meridional circulation pattern in 2010 shifted northeastward, and then the western subtropical high, the mid-latitudinal trough and the northeastern Asia blocking high also shifted northeastward, causing intensified convergence of the cold and warm air masses at the southern region and thus more rainfall in the southwestern region and less in the northwestern region. In 1998, the anomalous cyclone, one component of the meridional pattern, located at the Songhuajiang-Nengjiang River basin, resulted in more rainfall in the majority of the area. The results of observation and the model show that the difference in SSTA in Kuroshio and its extension under the background of different El Ni觡o events is the key point:(1) The anomalous warmth moved westward from the mid-Pacific to the east of the Philippine Sea during the central event, which led the heat resources shifting to the northeast in 2010; subsequently, a shift occurred to the north of the anomalous ascent and decent, followed by a warm SSTA in the region of Kuroshio's extension in 2010 and Kuroshio in 1998.(2) The warm SSTA in the Kuroshio extension causing the Rossby wave activity flux strengthened in 2010, and then the westerly jet shifted northward and extended eastward. A warm SSTA in Kuroshio and cold SSTA in its extension in 1998 caused the westerly jet to shift southward and weaken. As a result,the anomalous anticyclone and cyclone shifted northward in 2010, and the blocking high also shifted northward.     

<p>PARTITION OF SEASON BASED ON MULTIELEMENTS AND THE DECADAL CHANGE OF SEASON DURATION IN CHINA</p>

<p>Using the multielements similarity measurement method and 1950–C2017 NCEP/NCAR gridded daily reanalysis datasets, we analyzed season duration in China during 1950–C2016, and we defined the element with maximum absolute sensitivity as the key impact element at each point using the sensitivity analysis method. The decadal change of season duration and its key impact element before and after 1980 were studied. The results indicated obvious meridional and zonal differences in the distribution of season duration for the 67-year average, and that the key impact element has the same distribution characteristics as season duration. In addition, complementary relationships were found between the durations of spring and summer, autumn and winter, and the cold and warm seasons. Of those, the complementary relationship between the durations of spring and summer was strongest and the regions of complementarity were numerous. The complementary regions of autumn and winter durations were found mainly in western China. In the cold and warm seasons, the complementary regions were widespread and the complementary relationship was generally weak. Comparison of the periods before and after 1980 revealed an east–Cwest difference in the interdecadal variation of season duration. Interdecadal variation in spring and summer was found concentrated in northern and western regions, while that in autumn and winter was concentrated in the western region. Areas of significant interdecadal variation of the key elements were found concentrated in northern and western regions, corresponding well with the areas of significant interdecadal variation of season duration.</p>     

Land-use and sustainability under intersecting global change and domestic policy scenarios: Trajectories for Australia to 2050

Understanding potential future influence of environmental, economic, and social drivers on land-use and sustainability is critical for guiding strategic decisions that can help nations adapt to change, anticipate opportunities, and cope with surprises. Using the Land-Use Trade-Offs (LUTO) model, we undertook a comprehensive, detailed, integrated, and quantitative scenario analysis of land-use and sustainability for Australia’s agricultural land from 2013–2050, under interacting global change and domestic policies, and considering key uncertainties. We assessed land use competition between multiple land-uses and assessed the sustainability of economic returns and ecosystem services at high spatial (1.1 km grid cells) and temporal (annual) resolution. We found substantial potential for land-use transition from agriculture to carbon plantings, environmental plantings, and biofuels cropping under certain scenarios, with impacts on the sustainability of economic returns and ecosystem services including food/fibre production, emissions abatement, water resource use, biodiversity services, and energy production. However, the type, magnitude, timing, and location of land-use responses and their impacts were highly dependent on scenario parameter assumptions including global outlook and emissions abatement effort, domestic land-use policy settings, land-use change adoption behaviour, productivity growth, and capacity constraints. With strong global abatement incentives complemented by biodiversity-focussed domestic land-use policy, land-use responses can substantially increase and diversify economic returns to land and produce a much wider range of ecosystem services such as emissions abatement, biodiversity, and energy, without major impacts on agricultural production. However, better governance is needed for managing potentially significant water resource impacts. The results have wide-ranging implications for land-use and sustainability policy and governance at global and domestic scales and can inform strategic thinking and decision-making about land-use and sustainability in Australia. A comprehensive and freely available 26 GB data pack (http://doi.org/10.4225/08/5604A2E8A00CC) provides a unique resource for further research. As similarly nuanced transformational change is also possible elsewhere, our template for comprehensive, integrated, quantitative, and high resolution scenario analysis can support other nations in strategic thinking and decision-making to prepare for an uncertain future.     

碳交易政策的经济影响:以广东省为例

通过构建广东省两区域动态模型,对广东省碳交易及其他政策措施进行定量评估,分析实施可调控总量的碳交易政策机制对广东省及参与交易部门的经济影响。研究结果表明,按照减排情景到2015年广东完成19.5%的碳强度下降目标,相比基准情景,GDP将减少0.7%;按照强减排情景到2015年将完成20.5%的碳强度下降目标,相比基准情景GDP将减少0.9%;如果在强减排情景的基础上实施碳交易政策,GDP相对基准情景减少0.8%,到2015年实施碳交易政策可减少GDP损失约90亿元,说明广东建立碳排放权交易机制能够发挥支持经济发展和节能减碳双赢的作用。     

气候变化对中国东部季风区水资源脆弱性的影响评价

将耦合暴露度、灾害风险、敏感性与抗压性的脆弱性评估模型应用于中国东部季风区水资源脆弱性评价,从水资源供需平衡角度分析了气候变化对东部季风区水资源脆弱性的影响。结果表明,2000年气候条件下,我国东部季风区接近90%的区域水资源处于中度脆弱及以上状态。其中水资源中度和高度脆弱区域约占全区的75%,极端脆弱区域接近15%。中国北方海河、黄河、淮河和辽河流域的水资源脆弱性最高。未来气候变化影响将加剧水资源脆弱性的风险,不同RCP排放情景下2030年代我国东部季风区水资源中度脆弱及以上区域面积有明显的扩大,极端脆弱区域将达到20%~25%。由于未来需水的进一步增加,中国北方水资源脆弱性的格局并未发生根本变化,而南方东南诸河等区域将面临可能发生的水危机。