第24届冬奥会海坨山赛区近两年冬季地面风场特征

基于北京市海坨山赛区4个自动气象站2014、2015年冬半年地面风场资料,分析第24届冬奥会海坨山赛区冬季地面风场分布特征。结果表明:(1)各站冬季地面风场具有明显的风向取向以及风速值分布区间特征,其中海拔较高的A1492站风向呈明显的西西南至西北4个方位取向,10.0 m·s~(-1)以上风速的发生频率约为49.1%,月平均风速均10.0 m·s~(-1);(2)各站月平均风速最大值均出现在1月,A1489、A1490和A1491站风速最小值均出现在11月,A1492站最小值出现在3月;(3)各站日逐小时平均风速呈典型的日变化特征,08:00—16:00风速逐渐增大、16:00—18:00缓慢减小。     

关于是否漏记大风现象的判据的讨论

本文选用了本省六个台站的日最大风速≥10.0m·s~(-1)及日瞬时极大风速≥17.0m·s~(-1)的资料进行了统计,分析了日最大风速与日瞬时极大风速的相关关系,提出了当日最大风速≥14.0m·s~(-1)时,即有可能产生瞬时风≥17.0m·s~(-1)的大风现象。     

ENVISAT星载合成孔径雷达反演风场在江苏近海风场研究中的应用初探

为了弥补海上风的常规直接观测资料较少的不足,探索将合成孔径雷达(Advanced Synthetic Aperture Radar,ASAR)观测资料用于风场研究,以江苏近海为研究对象,利用沿海地面观测数据和2008年11幅ASAR影像反演获得的风速和风向进行对比,并将卫星反演风场同化至数值模式,分析对海上风场模拟效果的改进。结果表明:ASAR影像反演的海面风场和地面实测吻合度较高,可以作为没有直接风观测的海上区域的补充。风速反演值略大于观测值,均方根误差为1.8 m·s~(-1),83.6%的站点偏差在±2 m·s~(-1)之内;风向反演值比观测值偏北,均方根误差为39.3°,41.8%的站点偏差在±22.5°之内。将反演风场同化至WRF模式后,提高了海上风场的模拟效果,风速均方根误差1月降低至0.9 m·s~(-1),7月降低至1.6 m·s~(-1);风向均方根误差1月降低为57.3°,7月降低为50.6°。     

乌鲁木齐市边界层日变化特征

利用乌鲁木齐市晴天CFL-03型风廓线雷达观测资料,分析了边界层日变化特征。得出结论如下:边界层结构季节变化明显。冬、春季300~600m以下风速较小,小于3m/s,且愈近地面风速愈小;以上风速大、风向恒定,基本为东南大风。夏季和秋季风速比冬季和春季小,流场特征较复杂,水平风速和风向变化较活跃,存在明显的风切变。折射率结构常数春、秋和冬季比夏季分别小1个、3个和1~3个量级;夏季最大,集中在10~(-16)~10~(-13) m~(-2/3)之间。春、夏和秋季晴天湍流动能耗散率量级分别在10~(-6)~10~(-2) m~2·s~(-3)、10~(-4)~10~(-3) m~2·s~(-3)、10~(-6)~10~(-3) m~2·s~(-3)之间;白天比夜间约大1个量级。晴天折射率结构常数和湍流动能耗散率日变化特征与风场日变化特征有较好地对应关系,即湍流发展旺盛的区域与风速较大的区域相一致。风廓线雷达资料反演的湍流动能耗散率对春季和夏季边界层结构日变化演变特征的监测较好。夏季夜间稳定边界层约400~500m,残余层可达到约1800m,对流边界层可发展到约2500m,混合层约2200m,夹卷层约300~400m。     

浙北沿岸海域海面风场反演方法的研究

高质量的海面实况风场是海洋气象监测和预报的基础,卫星反演的大陆沿岸海域海面风场的准确率不高。文章基于反映近地面风速廓线变化的指数律公式,利用浙江北部沿岸海岛或滩涂上布设的中尺度自动站来反演附近海面风场,并使用客观分析方法将反演的离散风场值转换到中尺度网格上,从而获得完整的高分辨率海面风场。指数律中参数α值对于反演风场的准确率至关重要,它主要受到下垫面状况以及大气层结状态的影响,而后者的影响较前者更大。文章使用多个风塔站的风廓线率值进行了反演风场的误差试验,结果表明:目前单一风速廓线还无法取得最优的反演效果,有必要分季节使用多站风速廓线。使用混合风速廓线得到的总体样本的平均偏差为0.04 m·s~(-1),平均绝对误差为1.51 m·s~(-1),均方根误差为2.01 m·s~(-1)。对海面反演风场的优化可以将总体样本的平均绝对误差和均方根误差分别降低到1.28和1.68 m·s~(-1)。     

武汉青山长江公路大桥设计的风参数研究

利用黄陂气象站、武汉青山长江公路大桥桥位处新建的测风塔和湖北省农展中心自动气象站风资料,采用极值I型分布法对武汉青山长江公路大桥设计的风参数进行研究,结果表明:(1)桥位区10 m高度年最大、极大风速为分别为17.0 m·s~(-1)、20.9 m·s~(-1),年均大风日数为5.8 d,年最多风向为NNE;(2)气象站100 a重现期10 m高度10 min平均年最大风速(基本风速)为25.6 m·s~(-1),桥位处100 a重现期10 m高度10 min平均年最大风速(设计风速)为29.0 m·s~(-1);(3)风速较大时水平动量的垂直湍流通量较风速小时大、湍流参数较风速小时小、湍流谱密度值较风速小时增大1～2个量级;极大风速发生时1 h内的风攻角为0°～3°。     

关中盆地近地面风场和大气输送特征分析

利用2017年151个地面气象站的逐时观测数据和相关高空资料分析关中盆地近地面风场与输送特征。首先分析盆地内代表性站点的风速和风向观测事实,然后用CALMET风场诊断模式和轨迹计算模式获取当地逐小时风场和每日逐小时传输轨迹,分析风场类型。结果表明:关中盆地内日平均风速约1～3 m s?1,夏季风速高、秋冬季低;盆地中央的主导风向以沿地形走向的东北风和西南风为主,盆地四周测站的主导风向表现出顺着地形向盆地中央汇流的趋势。各站主导风向的季节变化不大。盆地内风场分为系统控制型、弱天气背景型和局地环流型3类,全年出现日数比例分别占8%、17.3%和74.7%。以山谷风日夜循环为特征的局地环流型风场最多。以西安城区为源点的大气输送轨迹显示,系统控制型风场以偏东北方向的输送为主,弱天气背景型和局地环流型风场的轨迹输送都大致以偏东北和偏西（以及偏西南）沿盆地走向以及偏东南朝向秦岭山地这三个方向为主。局地环流型的轨迹影响范围小,集中于盆地中央和南侧山地之间,表明这是一种不利于污染扩散的风场类型。     

影响云南空气质量的风场特征分析

利用美国NCEP/NCAR风场再分析资料和云南高空、地面、高山风塔实测风资料,对云南地区的大气风场特征进行了分析。结果表明,云南对流层中低层大气风场常年盛行偏西气流,风向稳定,尤以西南风最多,冬-春-夏-秋四季风场变化特征明显。腾冲、思茅高空盛行风向以西风为主。云南除滇东北、滇东南和局地地形影响外,大部分地区近地面全年以盛行西南风为主。山区全年盛行风向以西南风为主。云南近地面年平均风速1.9m/s,北部大于南部,东部大于西部,冬春季风大,夏秋季风小,风速日变化特征显著。昆明地区大气边界层存在逆温现象,冬季突出,夏季微弱,秋冬春季频率高,夏季频率低。云南空气污染具有干湿季分布特点,1-5月为主要污染时段,冬春季节存在西南和东北两条污染传输通道。     

青藏高原中部聂荣亚寒带半干旱草地近地层湍流特征研究

湍流运动是大气最基本的运动特征,是地气间能量物质交换的主要方式。利用2014年7月18日至8月31日青藏高原中部聂荣观测站的近地层湍流观测资料,分析了该地区近地层湍流统计特征以及近地层通量的日变化特征。结果表明:在不稳定和稳定层结下,风速分量归一化标准差σ_u/u_*,σ_v/u_*,σ_w/u_*与稳定度参数z/L满足相似理论的"1/3"定律,近中性条件下趋于常数,并表现为σ_u/u_*≈σ_v/u_*σ_w/u_*;在不稳定层结下,温度、水汽密度和CO_2浓度归一化标准差σT/|T*|、σq/|q_*|和σ_C/|C_*|与|z/L|满足"-1/3"定律,在近中性层结下趋于常数,且明显大于青藏高原其他地区。湍流在风速0 m·s~(-1)U3 m·s~(-1)的环境中发展最为旺盛,垂直风分量的湍流强度较水平风分量更为集中,三个方向的湍流强度基本表现为I_u≈I_vI_w。夏季潜热通量大于感热通量,CO_2通量的日变化以吸收为主,最强达到0.46 mg·m~(-2)·s~(-1)。     

新疆哈密复杂地形风场的数值模拟及特征分析

为了实现复杂地形下高分辨率风场的数值模拟及特征分析,采用中尺度气象模式WRF(Weather Research and Forecasting M odel)结合牛顿松弛逼近Nudging资料同化技术,实现哈密地区水平分辨率1 km的近地层风场数值模拟计算。基于模拟区域测风塔实测数据的对比检验发现,同化观测资料后风速风向的模拟结果均与实测更加接近,70 m高度风速模拟结果的绝对误差降低0. 25 m·s~(-1),同化后的模拟结果可以较好的修正风速较小时模拟值偏高和风速较大时模拟值偏小的问题,同时风廓线的模拟结果也与实测更加吻合。通过分析哈密复杂地形下水平分辨率1 km逐10 min风场输出结果发现:(1)哈密地区地形比较复杂,风速平面分布差异很大,4月份风速较大区域主要分布在山北地区和西部山南垭口附近,而7月份风速较大区域则位于西部的山坳南部和北部地区;(2)复杂地形下风速较小时风速为负切变,且平均风速越小负切变值越大,地形越复杂负切变值越大;风速较大即使是复杂地形下同样为正切变,但是正切变值比平坦地区的值要小,平坦地形下风速越大正切变值越大;(3)哈密地区复杂地形下,风速12～25 m·s~(-1)的风速占比在时间和空间上分布差异较大,风速较大的4月份,大部分地区占比达到20%以上,尤其是山北和西部垭口附近,占比甚至达到了50%以上,风速为12～25 m·s~(-1)的情况下80 m高度平均风速比60 m高0. 60～0. 80 m·s~(-1),比月平均风速的垂直变化值要大;(4)风速较大时,风向10 min变化不明显,风速较小时,风向变化值较大,且地形较平坦地区风向变化值较大,地形复杂地区变化值较小;(5)风向的垂直变化与风速大小关系比较明显,风速越小,其垂直变化越大,风向垂直变化的区域分布与地形复杂程度相关,地形越复杂风向的垂直变化值越大。     

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.