二次降雪过程B模式物理量场的对比分析

本文分析了两次降雪过程,从B模式36—48小时短时预告物理量场结合环境场、单点要素场和卫星云图、云分析图作对比分析,从中归纳出一些大雪过程的预报因子和信息:特大降雪过程发生在明显高空槽云系(冷锋云系)与切变线云系合并过程中;西南气流强风速轴形成在降雪过程前,是暴雪过程所需能量、水汽的理想输送带。暴雪区往往位于西南气流强风轴左前侧一带;最大水汽通量中心、θ_(es)大值中心高舌区及最大上升运动中心叠置区附近基本上是未来大降雪的落区所在。     

松花江流域春季暴雪分析

分析了１９９６年３月１６－１７日松花江流域出现的大－暴雪天气，指出大范围的连续性暴雪是在特定的大尺度环流背景下产生的。分析了产生暴雪的条件，成因及云系的发生，演变和发展过程。     

一次特大降雪的分析预报

1980年10月25—27日,受渤海低压北上影响,黑龙江省中部和东部出现了一场罕见的大暴雪,降雪中心在三江平原。48小时过程降水量最大约90毫米(图1),是本区自1909年有气象记录以来出现的最大降雪量。由于雪量特大,造成火车停运,电力电讯中断,建筑物倒塌,农作物被捂等严重雪灾。 在雪前12小时,597农场气象站用云系演变与天     

东北低涡造成黑龙江暴雪天气过程分析

利用NECP再分析资料、卫星云图资料、新一代天气雷达资料及实况观测资料对2010年4月12-13日一次东北低涡产生的黑龙江省暴雪天气过程进行分析,详细讨论了此次暴雪的发生机制及天气特点。此次降雪过程由地面气旋北上引发,高空低涡前部东风暖平流和槽后冷平流相遇形成暖锋锋生,低涡东北部产生暴雪。低空急流对水汽的输送作用和低层较强的辐合上升运动为此次降雪过程提供增强机制。云系的发展、移动与降雪有较好的对应关系,较大降雪出现在逗点云系顶部。     

Analysis of the weather process of blizzard caused by Northeast Cold Vortex in HeUongjiang province

利用NECP再分析资料、卫星云图资料、新一代天气雷达资料及实况观测资料对2010年4月12-13日一次东北低涡产生的黑龙江省暴雪天气过程进行分析,详细讨论了此次暴雪的发生机制及天气特点。此次降雪过程由地面气旋北上引发,高空低涡前部东风暖平流和槽后冷平流相遇形成暖锋锋生,低涡东北部产生暴雪。低空急流对水汽的输送作用和低层较强的辐合上升运动为此次降雪过程提供增强机制。云系的发展、移动与降雪有较好的对应关系,较大降雪出现在逗点云系顶部。     

一次突发性中尺度暴雪天气过程分析

对2004年12月丹东地区一次突发性中尺度暴雪天气过程的成因进行了分析。结果表明:造成此次暴雪天气过程的影响系统除天气尺度的冷锋外,其直接影响系统是中尺度海岸锋,它在有利的天气尺度环境下发展加强并向内陆移动,其上的中尺度环流形成的低云与冷锋云系的叠加是产生暴雪的主要原因。     

新疆北部地区一次特大暴雪天气诊断分析

使用NCAR再分析资料,对新疆北部阿勒泰地区2000.11.20-24特大暴雪天气进行诊断分析,结果表明:500hPa极涡、贝加尔湖后部的东南气流、850hPa暖切变以及地面气旋的共同作用是产生新疆北部阿勒泰地区2000.11.20-24特大暴雪天气过程的环流背景条件。特大暴雪天气发生在较强的能量锋区、高湿区和水汽通量辐合区内。特大暴雪天气发生时,在阿勒泰地区上空形成一个由低层到高层强盛的动力性纬向垂直环流圈,为冷暖气流共同作用提供了持续不断的动力条件。正涡度的输送,使得阿勒泰地区上空的低值系统和锋区得以维持和加强。高空急流加强了特大暴雪天气的上升运动;低空偏南急流将巴尔喀什湖以南的高温高湿的不稳定大气源源不断地输送到阿勒泰地区上空,为特大暴雪天气提供了热力、水汽和不稳定能量的条件。     

雷州半岛一次特大暴雨的特点及成因

2007年8月8-11日雷州半岛西南部出现了一次特大暴雨,日雨量和时雨量均超出当地历史观测资料的极大值.对本次暴雨过程雨量、日雨量和时雨量进行了特征分析,讨论了热带气旋"帕布"和"蝴蝶"的路径、天气形势、卫星云图和雷达回波的演变与特大暴雨的关系.结果表明:此次特大暴雨具有降水强度大、持续时间长、雨量大、地段集中的特点.前期受"帕布"环流和外围云系影响,雷州半岛普降大到暴雨;后期由于"帕布"路径转向,大气环流调整,受"帕布"环流和外围云系、北部湾低涡云团共同作用,强降水中心长时间维持和摆动.天气形势有利于大量的水汽和能量汇合,南北降水云系、回波相汇雷州半岛西南部,致使出现特大暴雨.     

长江中下游一次暴雪冻雨微物理过程模拟研究

根据NECP1°×1°客观再分析资料和常规观测资料,利用中尺度数值模式WRF对2008年1月25—29日长江中下游暴雪冻雨过程进行了数值模拟,结果表明：WRF模式可以很好地模拟出此次强降雪过程高低空环流形势演变特征以及降水带的分布。分析表明,中层西南急流对暖湿空气的输送以及低层冷空气的持续扩散为暴雪和冻雨的发生提供了很好的温度层结条件。云微物理过程特征分析表明,此次暴雪冻雨过程存在多种云系共同降水,中低空600—850 hpa强逆温层尤其是0 ℃层的存在使得雪、冰晶等冰相粒子融化形成过冷却水,是大范围冻雨形成的必要条件,同时也是区分大范围冻雨暴雪形成的重要条件。     

2009年山东一次特殊雨雪天气的云物理特征分析

利用探空、CloudSat卫星、山东自动气象站及NCEP再分析资料,对2009年11月11-12日山东西部大暴雪过程的天气形势、云物理特征及动力场结构特征进行了分析。结果表明:(1)700hPa切变线和西南急流是造成暴雪的直接影响系统,中低层偏南风急流与冷空气交汇形成较强的动力辐合和水汽辐合,有利于天气系统的发展和增强。(2)暴雪区上空水平能量锋区明显,垂直方向上等θse线密集且随高度向北显著倾斜,为暴雪的产生提供了重要的热力条件。(3)强降雪发生前,低层冷空气的南侵触发了暴雪系统的发展;暴雪强盛期,高层气旋性环流促使暴雪区中高层西南暖湿气流输送加强;暴雪后期,冷空气加强并逐渐控制了中低层,切断了暖湿气流的供应,导致降雪逐渐停止。(4)上升气流有助于水汽的输送和云滴、冰晶、雪晶粒子之间的碰并、淞附,冰水含量大值区与上升速度大值区相一致,冰晶数浓度中心对应着上升运动顶部。高层冰晶下落过程中经过凝华、结淞及碰连增长在低层形成数浓度较低的大冰相粒子,为降水发展提供了有利条件。(5)结合CloudSat卫星资料、NCEP再分析资料及探空秒数据,分析了一定动力条件下暴雪云系的物理过程和垂直演变特征。     

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.     

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.     

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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. Contributions from all over the world are welcome.SUBMISSIONAll submitted     

A Brief Introduction to Marine Meteorological Science Experiment Base at Bohe Town,Maoming City,Guangdong Province

<正>With the support of specialized funds for national science institutions,the Guangzhou Institute of Tropical and Marine Meteorology,China Meteorological Administration set up in October 2008 an experiment base for marine meteorology and a number of observation systems for the coastal boundary layer,air-sea flux,marine environmental elements,and basic meteorological elements at Bohe town,Maoming city,Guangdong province,in the northern part of the South China Sea.     

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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.     

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