三门峡市2005-08-17暴雨天气过程分析

利用"9210"实时资料,欧洲ECMWF和T213格点资料、物理量分析场,分析了2005-08-17三门峡市暴雨过程中500 hPa、700 hPa、地面天气形势及流场、水汽通量、总温度平流、散度,结果表明:副高东退,随着短波槽的东移加深,850 hPa和700 hPa槽前形成了≥6 m/s的偏南气流,打开了水汽通道,为暴雨形成提供了充足的水汽来源;中高层低槽后部冷空气的斜压作用以及地面西路冷锋的触发抬升,加之散度场上低层强烈辐合、中层上升、高层辐散的耦合机制,为暴雨形成提供了充足的动力条件。     

2003年8月28日至29日铜川区域性暴雨成因分析

对2003-08—28—29铜川市暴雨过程分析发现，暴雨发生在南亚高压由东部型转为西部型的调整过程中，200hPa急流为暴雨区高层辐散提供了动力条件，500hPa陕西处于副高边缘，新疆有冷涡不断分裂冷空气扩散南下，这种形势的稳定，为暴雨区提供了充足的能量和动力作用；700hPa关中及其以南的SW急流和850hPa华北到陕西东部的东风气流，为暴雨过程提供了充足的水汽，铜川处于切变辐合区；物理量场中，铜川处于一个水汽的辐合中心，垂直速度的上升中心，散度场上表现为低层辐合，高层辐散，水汽条件和动力条件配置非常有利。中尺度分离分析表明，暴雨发生过程中，雨区低空700hPa和850hPa有明显的中尺度辐合区存在。     

濮阳市一次大暴雨过程成因分析

应用常规天气图资料、郑州站探空层结资料、FY-2E红外云图和濮阳站降水实况等资料,对2016年7月14—15日发生在濮阳市的区域性暴雨、大暴雨天气过程进行综合分析。结果表明:(1)此次大暴雨过程是由500hPa和700hPa的低涡及其分裂东移的低槽、700hPa和850hPa的切变线、地面辐合线及南下的冷空气共同影响造成的。(2)500hPa槽前西南气流与584dagpm线外围的西南气流叠加加强了西南暖湿气流的输送,为降水提供了水汽来源;地面辐合线的存在加强了动力抬升作用。(3)涡度场和散度场同时表现出的低层辐合、高层辐散的配置,为暴雨的产生提供了有利的动力条件。(4)FY-2E红外云图上,对流云团的持续影响,使降水较长时间维持,造成濮阳市出现区域性的暴雨、大暴雨天气。     

一次中低纬系统结合的暴雨过程分析

利用常规气象观测资料,对2004年9月14日山东暴雨过程的环流形势、物理量特征进行了分析。结果表明,本次暴雨过程是由中低纬系统相互作用造成的,暴雨分布状况主要取决于台风的路径。暴雨发生在高空急流右后方和低空急流左前方的重叠区;台风减弱后的低压环流是形成低空急流的基础,西风槽及高空急流的东移逼近是低空急流维持与加强的关键因素;200hPa散度大于10×10-5 s-1与700hPa散度小于-10×10-5 s-1相重叠的区域与强降水区相吻合;700hPa正涡度梯度和500hPa正涡度平流增强对暴雨具有一定的指示性;台风为暴雨提供了能量和水汽,而西风槽对能量的积聚和水汽的辐合起重要作用。暴雨集中在地面气旋中心经过阶段,山脉的迎风坡和山峰附近有利于暴雨的增幅。     

南阳市2002—03—04暴雪过程分析

利用实时高空资料、物理量场及本站要素，分析了南阳市2002年3月4日暴雪过程，结果表明：700和500hPa西南急流，为暴雪产生提供了充足的水汽条件；700hPa的暖式切变线及高层辐散、低层辐合，为暴雪产生提供了充足的动力条件；地面自东路南下的冷空气，抬升西南暖湿气流，产生强降水。     

河南省2011年8月1—2日暴雨过程水汽条件与垂直螺旋度分析

利用常规资料和NCEP再分析资料,对2011年8月1—2日河南省区域性暴雨过程的环流形势、水汽条件和垂直螺旋度进行了分析,结果发现：这次暴雨是一次较为典型的西南涡东北移影响河南所造成的暴雨过程,500hPa高原槽东移,副热带高压减退之后又增强,中低层西南涡沿切变线东北移出,河南处于涡前的西南低空急流出口区前方及前方左侧,具备了区域性暴雨产生的动力与水汽条件。在本次暴雨过程中,700hPa水汽通量变化对强降水落区有很好的指示作用：豫西南的暴雨区位于水汽通量大值中心附近和前端水汽通量等值线密集带内,豫中东部的暴雨区位于水汽通量大值中心北部水汽通量等值线密集带内、大值中心运动方向的左侧。水汽通量散度场上,850hPa水汽通量散度的变化与暴雨的开始时段和强度有很好的对应：水汽通量散度转为辐合、辐合层增厚为强降水开始的标志,辐合量突然增大标志着降水强度增大。700hPa垂直螺旋度的迅速增强与强降水发生时段有较好的对应,强降水产生在垂直螺旋度大值轴的东南侧。     

2011年7月末商洛区域性暴雨成因分析

利用MICAPS常规气象资料对2011-07-30—31日商洛市暴雨过程分析,发现:暴雨发生在副高调整过程中,500hPa陕西处于副高边缘,高空冷涡不断分裂冷空气扩散南下,这种形势的稳定,为暴雨区提供了充足的能量和动力条件;700hPa关中及其以南的西南急流为暴雨过程提供了充足的水汽,商洛处于切变辐合区;物理量场中,商洛处于水汽辐合中心、垂直速度的上升中心,散度场上表现为低层辐合,高层辐散,水汽条件和动力条件配置非常有利,θse密集区增大有利于商洛市强降水产生;中尺度云团合并加强是本次大暴雨的直接缔造者。     

山西省北中部“09．07．08”区域性暴雨天气过程分析

本文利用常规天气图、物理量场等资料,从大尺度环流形势及影响系统、动力、热力条件等方面,对2009年7月8日山西省北中部区域性暴雨进行了诊断分析。结果表明：500hPa西风槽前部西南暖湿气流与东北冷涡后部下滑的冷空气相互作用,700hPa低涡切变线是造成本次大暴雨的主要影响系统;深厚的湿层和强烈的水汽辐合为暴雨的产生提供了充足的水汽条件;低涡东移和切变线的生成,地面低压向山西发展,为暴雨的形成提供了动力条件;低层850hPa的高能舌轴前的能量锋区为暴雨的形成提供了热力条件。     

引发重庆中西部暴雨的西南低涡特征分析

利用1980-2008年探空资料和地面自动站资料,对重庆中西部西南低涡暴雨个例进行统计和合成分析。结果表明,重庆中西部西南低涡暴雨是在高空急流、高空槽、西太平洋副热带高压和西南低涡相互作用下产生的。对西南低涡的结构研究表明,高层以散度辐散为主,700 hPa附近为气旋性旋转,800 hPa及以下以辐合为主,且700 hPa正涡度中心南侧由于低层辐合、高层辐散抽吸的共同作用造成的上升运动更显著,这一区域恰恰对应暴雨落区。分析v分量发现,暴雨落区主要位于南北风最大值中心连线附近,或其连线北侧等值线密集区,对重庆暴雨预报具有指示意义。分析低空急流和水汽条件表明,重庆地区充沛的水汽输送为暴雨的产生提供了有利条件,孟加拉湾是主要水汽源地。     

陕西历史最早暴雨成因初步分析

利用天气学原理和T213提供的物理量场分析了2004-02-20发生在陕西历史上最早的暴雨过程，发现此次暴雨是在新疆分裂冷空气、高原槽、低涡切变和地面倒槽的共同影响形成的，环流形势为“东高西低”和“北槽南涡”．西南低空急流、低涡切变是此次暴雨的直接影响系统，动力结构为高层强辐散和低层强辐合．能量场具有典型的“Ω”中尺度结构，700hPa层SW低空暖湿急流是主要水汽和能量输送系统，暴雨区水汽辐合强烈，暴雨发生在水汽通量的最大梯度处，与夏季暴雨水汽特征相似。     

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.