影响东北的北上温带气旋暴雪的统计特征

利用2000-2016年常规观测、台站降水资料和NCEP的1°×1°再分析资料,对影响东北的北上温带气旋暴雪进行了统计研究。根据500 hPa环流形势分为低涡型、浅槽型和深槽型暴雪,并对这三种类型暴雪的气旋路径、强度变化、降水分布、水汽输送和热动力特征进行了详细分析。结果表明:低涡型和深槽型暴雪气旋路径为东北路,浅槽型暴雪气旋路径偏东,各类暴雪的气旋强度变化和降水分布因路径不同而有所差异;降雪最强时,低涡型和深槽型暴雪700和850 hPa都有低涡,浅槽型暴雪700 hPa为低槽。低涡型和深槽型暴雪中水汽通量散度辐合区与低层低涡气旋性闭合环流引起的辐合密切相关。浅槽型暴雪的水汽辐合源于槽前辐合;低涡型和深槽型暴雪发生在假相当位温暖舌中,浅槽型暴雪发生在较平直的假相当位温场中,深槽型和浅槽型暴雪的锋区要强于低涡型暴雪。降雪最强时,低涡型暴雪有1支高空急流,深槽型暴雪有2支高空急流,浅槽型暴雪高空急流有1支或2支。三类暴雪中心都位于北支高空急流入口区右侧或南支高空急流出口区左侧的位置。综合统计结果提出影响东北的北上温带气旋暴雪概念模型。     

一次入海气旋局地暴雪的结构演变及成因观测分析北大核心CSCD

利用多普勒天气雷达、风廓线雷达、加密自动站、常规探空和地面等多种观测资料,对山东半岛东部地区一次局地暴雪过程的成因及动力结构演变特征进行了分析。结果表明:(1)此次局地暴雪过程分为两个阶段,第1阶段为典型的黄河气旋槽前降雪,降雪强度弱,雷达回波自西南向东北传播;第2阶段降雪为气旋后部的海效应降雪,降雪强度大,1 h降雪量可达到大雪量级,雷达回波自东北向西南移动,较为少见。(2)第1阶段降雪发生在对流层中层有明显低槽、低层有气旋性环流和西南低空急流及地面有气旋的天气系统配置下,水汽来源于中国南海,降雪落区位于高空槽前西南低空气流的右前方和地面气旋的东侧。(3)第2阶段降雪发生在高空槽过后,冷空气自渤海海峡和黄海北部入侵,降雪区域低层的主导风向为东北风,东北风强于西北风,降雪的水汽和热量来源于渤海海峡和黄海,雷达回波自东北向西南移动,降雪落区位于低层的东北风中。(4)海效应降雪各时段对流层低层风场结构不同。降雪初期,山东半岛北部沿海地面存在γ中尺度低压环流,雷达径向速度上表现为低层有β中尺度涡旋,东部沿海有东南风与西北风辐合;强降雪时段,边界层内存在东北风和西北风的切变线,低压环流和切变线是造成强降雪的有利动力条件。该个例揭示了发生在黄河气旋后部、由渤海海峡和黄海影响产生的山东半岛海效应降雪,其风场结构、雷达回波移向、降雪落区与风场的关系及降水相态等和常见的典型渤海海效应降雪有明显差异。     

一次入海气旋局地暴雪的结构演变及成因观测分析

利用多普勒天气雷达、风廓线雷达、加密自动站、常规探空和地面等多种观测资料,对山东半岛东部地区一次局地暴雪过程的成因及动力结构演变特征进行了分析。结果表明:(1)此次局地暴雪过程分为两个阶段,第1阶段为典型的黄河气旋槽前降雪,降雪强度弱,雷达回波自西南向东北传播;第2阶段降雪为气旋后部的海效应降雪,降雪强度大,1 h降雪量可达到大雪量级,雷达回波自东北向西南移动,较为少见。(2)第1阶段降雪发生在对流层中层有明显低槽、低层有气旋性环流和西南低空急流及地面有气旋的天气系统配置下,水汽来源于中国南海,降雪落区位于高空槽前西南低空气流的右前方和地面气旋的东侧。(3)第2阶段降雪发生在高空槽过后,冷空气自渤海海峡和黄海北部入侵,降雪区域低层的主导风向为东北风,东北风强于西北风,降雪的水汽和热量来源于渤海海峡和黄海,雷达回波自东北向西南移动,降雪落区位于低层的东北风中。(4)海效应降雪各时段对流层低层风场结构不同。降雪初期,山东半岛北部沿海地面存在γ中尺度低压环流,雷达径向速度上表现为低层有β中尺度涡旋,东部沿海有东南风与西北风辐合;强降雪时段,边界层内存在东北风和西北风的切变线,低压环流和切变线是造成强降雪的有利动力条件。该个例揭示了发生在黄河气旋后部、由渤海海峡和黄海影响产生的山东半岛海效应降雪,其风场结构、雷达回波移向、降雪落区与风场的关系及降水相态等和常见的典型渤海海效应降雪有明显差异。     

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。     

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。     

乌鲁木齐“2015.12.11”极端暴雪天气的综合分析*

2015年12月11日乌鲁木齐及周边地区的暴雪天气是一次极端暴雪过程,环流形势具有夏季强降雨特征和一定的极端性,南北低值系统结合、高低空"4支气流"汇合为暴雪提供了有利的大尺度环流背景。较好的水汽、动力条件是极端暴雪的重要成因,水汽长时间通过西南和偏西路径输送至暴雪区,并在700 hPa以下辐合和聚集,中低层辐合、高层辐散的空间配置有利于上升运动的发展和维持,低层上升运动增强较5 min降雪强度增强提前5~10 min。地面中β尺度辐合中心和辐合线出现1~2 h后强降雪(降雪强度均1.0 mm/h)出现,雷达回波上零速度区的"S"形结构的出现时间与强降雪时段有一定对应,此次暴雪中GRAPES中尺度数值产品子页报能力好于ECMWF。     

位涡和高空急流在一次强沙尘暴过程中的作用

利用高空、地面资料对2006年4月9—11日大范围强沙尘暴天气分析发现：横槽和高空锋区是沙尘暴的主要影响系统;地面两路冷锋引起西路和西北路沙尘暴。通过中尺度GRAPES—MESO模式数值分析发现：蒙古气旋后部的位涡下传对气旋的发展有着重要作用,是引起西路蒙古气旋区爆发大范围沙尘暴的重要因素;700hPa干位涡斜压项正值区的出现和移动变化可作为预报西北路沙尘暴发生的重要指标。高空急流所形成的次级环流和冷锋前次级环流的耦合是西北路沙尘暴形成的重要垂直动力条件;高空急流下的反环流起到动量下传和加强锋区的作用,是沙尘暴产生的重要动力和热力机制。     

锡林郭勒盟一次暴雪过程分析

2010年11月20日20时到21日08时锡林郭勒盟东北部出现了暴雪天气过程,这次暴雪是在两脊一槽的环流形势中西来斜压槽配合地面蒙古气旋产生的,属强冷空气类。极涡的维持使斜压槽加强,移动缓慢;在印缅槽维持的西南环流场中,700hPa西南槽为华北建立了水汽通道,暖湿的低空西南急流提供了较好的水汽和能量不稳定条件;高低空急流耦合产生了动力抬升作用,大、暴雪就发生在高空急流入口区右侧,低空急流左侧的耦合区。逆温层和高能舌的存在为暴雪的发生储备了潜在能量。     

辽宁一次暴雨过程分析与暴雨落区预报失误原因探讨

从一次高空槽和华北气旋影响的暴雨、局部大暴雨落区预报出发,利用常规地面观测资料、加密自动站资料、高空探测资料和欧洲中心（ECMWF）数值预报产品资料,对2011年7月29-31日辽宁一次暴雨、局部大暴雨过程的天气形势和物理量场进行分析。结果表明：夏季暴雨预报不仅要考虑高层形势、副热带高压强度和位置大尺度环流形势的变化,也要考虑有利的大尺度环流背景下易产生的中小尺度天气系统,此次辽宁暴雨过程中在高空槽和华北气旋的发生发展过程中激发了中尺度气旋,中尺度气旋的强度和移动路径是预报此次暴雨、局部大暴雨落区的关键因素。     

0308号强热带风暴"天鹅"影响过程分析

利用天气图、卫星云图等资料,分析了0308号强热带风暴"天鹅"的高空环流形势及演变、双热带气旋的影响、日本24小时地面预报图和降水预报图以及FY-2云图,探讨了如何预报热带气旋的移动路径、登陆地点和时段,切实提高热带气旋活动的预报准确率.     

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.     

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.     

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.     

Could the Recent Taal Volcano Eruption Trigger an El Ni?o and Lead to Eurasian Warming?

正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment.     

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     

COMPARATIVE ANALYSIS OF VARIOUS DATA OF AIR–SEA TEMPERATURE DIFFERENCE AND ITS VARIATION ACROSS SOUTH CHINA SEA IN THE PAST 35 YEARS

Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.     

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

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.