"8·19"甘肃区域暴雨的特征分析及数值模拟

分析了“8.19”甘肃区域暴雨发生的天气气候背景,不同层次的环流特征;重点分析了不同物理量场的变化,云系的演变;应用MM5中尺度非静力模式模拟了暴雨过程,并对模拟结果进行了分析。结果表明:“8.19”甘肃区域暴雨除了有利的天气系统配置外,低层强烈的风场辐合是导致暴雨的重要原因。强雨带的移动滞后于云顶温度最低的强对流云带;MM5对降水过程的强度、落区有较好的预报能力,尤其是12~48 h的预报效果相对最好,对强降水天气预报有较好的指示意义。     

0308号强热带风暴天鹅路径和降水分析

详细分析了0308号热带气旋天鹅在南海中部加强为强热带风暴后云系的演变以及对路径和降水产生的影响，结果表明：强对流云团的“吸附”作用是天鹅登陆后路径南折的主要原因；垂直速度场对热带气旋路径短期偏折方向有较好的预报指示意义，热带气旋有向强上升运动区偏折的趋势；中尺度暴雨出现在强对流云团中小涡旋的螺旋云带上或云顶亮温的梯度密集区与地面风向辐合区重叠处。     

影响广西热带气旋暴雨的环境流场和一些物理量特征分析

通过综合利用ECMWF提供的热带风场、气压场、高度场等资料,对24例影响广西的热带气旋环境流场和一些物理量特征进行了较为深入的分析。结果表明:大多数热带气旋的发生、发展都与赤道西风急流向东扩展或热带气旋东侧南风急流向北扩展有关;造成广西大范围台风暴雨的因素不仅取决于台风登陆地点和登陆后的路径以及中心是否直接进入广西内陆有关,而且还与副热带高压脊线的位置和面积指数、强度指数的变化关系密切。登陆台风在影响广西的过程中,其台风东侧的偏南风急流中心涌进广西和正涡度中心进入广西对产生大范围的暴雨起着重要的作用。     

HLAFS显式云降水方案及其对暴雨和云的模拟（Ⅱ）暴雨和云的模拟

在HLAFS业务数值预报模式的动力框架下，利用文章(I)所述的显式云降水方案，对一次暴雨过程和伴随着的云物理过程进行了模拟研究和分析。模拟结果表明，显式方案对降水落区和强降水中心位置的预报较原HLAFS的大尺度饱和凝结方案有明显改进。模式能合理地揭示出暴雨发生、发展过程中的云系演变规律和云物理过程。冰相过程对降水、中尺度热力和动力场有明显影响，特别是冰相过程有利于降水的早期的形成速率。与卫星TBB资料的对比分析表明，引进显式方案后，模式能较合理地模拟出云系的轮廓、位置、范围、强度、生消和移向，模式模拟出的云顶温度与卫星测量出的云顶温度较为一致。     

影响广西热带气旋暴雨的环境流场和一些物理量特征分析

通过综合利用ECMWF提供的热带风场、气压场、高度场等资料，对24例影响广西的热带气旋环境流场和一些物理量特征进行了较为深入的分析。结果表明：大多数热带气旋的发生、发展都与赤道西风急流向东扩展或热带气旋东侧南风急流向北扩展有关；造成广西大范围台风暴雨的因素不仅取决于台风登陆地点和登陆后的路径以及中心是否直接进入广西内陆有关，而且还与副热带高压脊线的位置和面积指数、强度指数的变化关系密切。登陆台风在影响广西的过程中，其台风东侧的偏南风急流中心涌进广西和正涡度中心进入广西对产生大范围的暴雨起着重要的作用。     

FY2卫星云图分析系统在热带气旋北冕过程中的应用

利用FY2卫星云图分析系统的各项分析功能,结合常规观测资料对热带气旋北冕的天气形势、云图演变以及路径变化、风雨情况等进行了分析。结果表明,副热带高压摆动,中纬度西风小槽东移,低层西南气流加强和减弱是"北冕"出现两次北抬和一次南折的直接原因;对流云团的发展和减弱对应低层西南气流的加强和减弱;强降水与云顶亮温的最低值中心及强度密切相关,而云团面积和云顶亮温与强降水也有很好的对应关系,其中发展的云系是强降水发生的信号。FY2卫星云图分析系统较好地分析了"北冕"整个过程的变化特点,对于短时临近预报有较好的辅助作用。     

热带气旋影响广西造成大范围暴雨的天气类型及预报

利用EC数值预报资料,对影响广西热带气旋进行了分析,归纳整理出影响大范围暴雨的天气类型,并寻找其相关的气象要素和预报因子,通过建立各型的预报规则并进行预报应用,效果较为理想,为防台工作有一定的参考价值。     

利用静止卫星云图特征对黑龙江省冰雹天气进行估计

利用静止卫星云图资料分析黑龙江省在冷涡云系或冷锋云系的影响下,对灾害性天气冰雹的预测。主要是利用现代化的手段通过对云顶亮温、云顶亮温梯度特征与冰雹的关系,进行深入分析,得出数值计算关系,从而实现自动化、智能化对冰雹天气的预测。根据该原理编制软件,实现了计算机化,以图像方式显示,划分等级,其特点为操作简便、预报确率高等。     

HLAFS显式云降水方案及其对暴雨和云的模拟(II)暴雨和云的模拟

在HLAFS业务数值预报模式的动力框架下,利用文章(I)所述的显式云降水方案,对一次暴雨过程和伴随着的云物蓝砸淮伪?雨过程和伴随着的云物泪果表明,显式方案对降水落区和强降水中心位置的预报较原HLAFS的大尺度饱和凝结方案有明显改进.模式能合理地揭示出暴雨发生、发展过程中的云系演变规律和云物理过程.冰相过程对降水、中尺度热力和动力场有明显影响,特别是冰相过程有利于降水的早期的形成速率.与卫星TBB资料的对比分析表明,引进显式方案后,模式能较合理地模拟出云系的轮廓、位置、范围、强度、生消和移向,模式模拟出的云顶温度与卫星测量出的云顶温度较为一致.     

热带气旋影响广西造成大范围暴雨的天气类型及预报

利用EC数值预报资料,对影响广西热带气旋进行了分析,归纳整理出影响大范围暴雨的天气类型,并寻找其相关的气象要素和预报因子,通过建立各型的预报规则并进行预报应用,效果较为理想,为防台工作有一定的参考价值。     

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     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.     

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.     

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.     

Information for Authors

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

INFORMATION FOR AUTHORS

正Aims Scope Advances in Atmospheric Sciences(AAS)is an international journal on the dynamics,physics,and chemistry of the atmosphere and ocean with papers across the full range of the atmospheric sciences,co-published bimonthly by Science Press and Springer.The journal includes Articles,Note and Correspondence,and Letters.Contributions from all over the world are welcome.