蓄满-超渗兼容模型与神经网络模型的应用对比研究

利用河北省1980-2009年20个气象站的电线积冰观测资料,分析了河北省电线积冰的时空分布特征和不同方位电线积冰的特征。结果表明：河北省电线积冰平原多于山区;年际变化较大,呈减少的趋势;季节变化十分明显,1月份电线积冰日数最多;东西方向和南北方向的电线积冰在最大重量上有一定差别。利用常规观测资料、1°×1°间隔6h的NCEP资料和2010年1月19-20日黄骅气象站逐时风向风速资料,对一次引起线路舞动的电线积冰天气过程进行了分析。结果表明：这次电线积冰是在地面冷空气与500hPa、700hPa低槽共同影响下由雨凇形成的。20日受冷空气影响,黄骅地面气温快速降至0 ℃附近,而850 hPa温度由零上逐渐转为零下,在对流层低层有逆温层,气温的垂直结构有利于形成雨凇;发生舞动的线路走向与风向夹角较大;舞动发生在较大风速出现之后。     

河北省输电线路冰害的气象要素时空分布特征

冰害是电网的主要气象灾害之一,电线积冰与雾凇和雨凇密切相关。利用1980—2009年河北省142个气象观测站的雾凇、雨凇日数和20个气象站的电线积冰、相对湿度、气温、风速及站点海拔高度,以及近年来输电线路冰害事故和附近区域站同期气温、相对湿度、风速等资料,采用逐步回归等统计分析方法,对雾凇、雨凇和电线积冰的时空分布特征、冰害与气象要素的关系进行分析,并构建电线积冰的逐步回归预报模型。结果表明:1980—2009年,河北省雾凇和电线积冰日数均呈现先升后降的阶段性变化特征,1980年代末至1990年代中期为一高峰期,而雨凇日数年变化特征不明显;在空间上,雾凇、雨凇多出现在平原地区,雨凇中心比雾凇中心更偏东。电线积冰与雾凇、雨凇以及站点海拔高度密切相关,相关系数分别为0.988 5、0.760 6、-0.601 8,但仅雾凇日数和站点海拔高度被引入电线积冰日数预报方程。对河北省电线线路冰害事故分析发现,当气温低于3℃时,导线可能出现舞动;导线舞动或冰闪时的相对湿度都在60%以上,舞动时风速大于5 m·s~(-1)。     

华家岭2008年电线积冰的变化特征与气象条件分析

利用华家岭气象站不同高度、不同方向、不同导线直径的电线积冰观测资料,分析了电线积冰在不同高度、不同方向、不同导线的变化特征,以及与气温、水汽压、风速等气象要素的关系。分析表明,电线积冰量随高度增加而增加,随电线直径增大而增大;在相同高度、相同导线上,不同方向的积冰量与风向有关。电线积冰量与水汽压、风速分别呈正相关和反相关。在一定阈值内,电线积冰量和气温存在较好的相关性。     

贵州冬季电线积冰及其天气成因分析

利用气象部门长期电线积冰观测和电力部门线路覆冰调查资料,对贵州冬季电线积冰的分布、类型特征与气象条件进行了综合分析,着重探讨了贵州电线积冰的形成机理和天气成因,主要结论:(1)贵州电线积冰的类型复杂多样,除具有雨凇、雾凇、雪凇(湿雪)三种基本类型外,还有雨雾混合凇、雨雪混合凇(雪凝)两种混合冻结类型;贵州电线积冰以危售最大的雨凇冰为主,混合冻结在贵州省分布十分普遍,这也是造成2008年贵州电网严重冰害的重要原因;(2)持续低温阴雨的凝冻大气是贵州电线积冰总的天气成因,其表现形式主要是冻雨但不局限于冻雨,此外还包括冻毛雨、雨夹雪、湿雪和过冷雾等多种天气现象,持续的凝冻天气过程往往有多种天气现象同时或交替出现,从而导致严重的覆冰灾害;(3)贵州电线积冰总体上属于较高环境温度下的低风速湿物理过程积冰,当地面气温持续降到0℃以下,出现降雨或浓雾是电线积冰开始与增长的关键气象条件,而最高温度上升到0℃以上是判断积冰转入消融的临界气象指标。     

陕西省电线积冰特征

选用陕西省宝鸡、华山、洛川、吴旗、榆林5站1980—2005年电线积冰观测资料, 分析了陕西省雨凇、雾凇及混合凇的分布特征与物理特性。结果表明:陕西省华山电线积冰最多、最大、最重。电线积冰以雨凇最多, 雾凇次之, 混合凇最少, 分别占55.2%, 27.9%和16.9%。各地积冰日多出现在11月至次年3月。雨凇、雾凇、混合凇的平均等效直径为10~25 mm, 极大值为78 mm; 平均质量为86~236 g/m; 华山积冰质量极值最大, 为1290 g/m; 积冰平均密度为0.22~0.34 g/cm 3, 混合凇最大, 雾凇最小。南北向等效直径的平均值、积冰质量、密度均大于东西向。近26年, 年最大积冰质量有增加的趋势。     

湖北电线积冰统计分析及积冰逆温层结研究

利用2009~2013年冬季华中电网电线覆冰在线观测系统对湖北省500 k V高压输电线路积冰状况进行实时观测获取的资料,结合MICAPS常规气象资料、探空数据及NCEP再分析资料,对湖北形成积冰的天气形势、积冰持续时间以及形成积冰的逆温层结进行研究。结果表明:积冰的高空环流形势主要是小槽发展型、横槽型和低槽东移型3类,分别占43.8%、31.2%、25%;电线积冰主要发生在每年的1月、2月、11月、12月,月平均积冰时数分别为65、42、11、9;积冰可分为降水型积冰和云雾型积冰,降水型积冰过程中,900~700 h Pa高度间存在由北至南风向切变,冷暖空气交汇形成愈加深厚的逆温对降水积冰维持与发展起到重要的作用。     

陕西省电线积冰区划

采用华山气象站1980—2007年的电线积冰观测资料和陕西省95个气象观测站资料,分析了电线积冰厚度与常规气象资料的相关性,并据此推算出各地距地面10m高度上历年标准的电线积冰厚度,用极值Ⅰ型推断30和50年一遇的最大积冰厚度。结合陕西省电力设计院设计经验、陕西省电网运行现状及历史电网冰灾事故调查情况,对陕西省电网冰区进行了初步划分。结果表明:最大积冰厚度与年雾凇日数、年雨凇日数有较好相关性;将全省分为6个积冰区,并分别绘制出全省不同区域30和50年一遇的1:500000积冰分布图。该结果已作为陕西省电力建设中电线积冰厚度设计的重要依据。     

两次电线积冰过程气象条件实时观测研究

根据湖北地区2008年2月和2009年1月500 k V高压输电线实时观测资料,结合MICAPS常规气象资料和NCEP再分析资料,研究了湖北张恩高压输电线上电线积冰形成的天气形势和气象条件。结果表明:两次积冰过程中500 h Pa深厚的低压槽和850 h Pa低涡配合切变线靠近湖北促使积冰加重;气温和风速在两次积冰过程的形成阶段起到主要作用。     

两种导线观测的电线积冰资料的对比分析

应用直径26.8和4 mm两种导线平行观测的电线积冰资料,对比分析两种观测资料中电线积冰直径、厚度、重量和标准厚度的差异,并对不同天气现象和气象条件下两种电线积冰观测资料的差异进行了讨论.结果表明:总体上,2011年1-5月全国大部分台站观测的两种导线电线积冰直径、厚度和标准厚度值差异不明显,重量差异较明显,且差值较大的站点主要分布在长江以南地区;分析不同天气现象和气象条件下两种观测资料的差异后发现,两种电线积冰直径和厚度值差异在雾凇和混合凇条件下较显著,而重量值差异在雨凇、风力0～3级和气温-5～0℃的条件下时相对最大.     

金华近56年电线积冰气候特征及灾害防御

利用金华市1953-2008年56年的逐日雨凇、雾凇资料,分析了电线积冰目的年代、年、季节、月变化,电线积冰起止时间、持续期、持续时间、最大直径等气候特征,并对金华电线积冰形成条件、灾害特点进行了分析.结果表明:金华市年平均电线积冰日数为0.8天;集中在冬季,1月最多,2月次之,12月最少;电线积冰可出现在一天的任何时间;最早初日是12月10日,最晚终日是2月19日;电线积冰持续时间最长64小时,最大直径为16mm;雨凇形成条件与雾凇不同,最大直径相近时雨凇灾害更严重,高海拔山区的电力冰灾比丘陵盆地严重.根据电线积冰灾害的特点,提出了加强灾害防御的具体措施.     

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.     

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.     

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     

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.     

Editorial

As we will soon celebrate the 90th anniversary of the founding of the Chinese Meteorological Society （CMS）,Acta Meteorologica Sinica （AMS）,which was originally named as Bulletin of the Chinese Meteorological Society,has gone through 89 years of development and excitement since her first issue in July 1925.According to archived documents （CMS Editorial Committee,1925）,AMS was founded to report the research findings of Chinese meteorologists,record their recommendations for improving meteorological services,and share their common meteorological interests in order to promote the growth of AMS such that more members could be inspired to conduct atmospheric research and meteorological knowledge would be better disseminated to and benefit the general public.By upholding and carrying forward this purpose,AMS has published many highly valuable scientific papers.Some could be treated as classical articles,which have produced important influences on both domestic and international meteorological communities and the related fields.