国外雨滴谱分布函数的数值试验结果

采用文献［１］方法，对国外温带地区（北威尔士）＾［２］、亚热带地区（瓜得罗普岛）＾［３］和热带海洋（ＧＡＴＥ－１９７７）＾［４］雨滴谱分布进行了数值试验，结果表明：伽玛分布（ｎ（Ｄ）＝ａ．Ｄ＾ａｅ＾－λＤ）能很好地拟合这些实测雨滴谱，特别是非单调下降谱用伽玛分布拟合明显优于Ｍ－Ｐ分布拟合，Ｍ－Ｐ分布仅是伽玛分布的一个特例（α＝０）。     

区域性光化学模式与LLA-C机制的模拟性能比较

以 Ｌ Ｌ Ａ－ Ｃ 机制为基准,在［ Ｎ Ｍ Ｈ Ｃ］／［ Ｎ Ｏ＃ － ｘ］ 比率分别为１７９ 、７１４ 、２８６ 条件下测试了区域性光化学模式（ Ｒ Ｏ Ｓ） 的模拟性能。结果表明 Ｒ Ｏ Ｓ 模式在上述三种初值条件下均能从总体趋势上给出与 Ｌ Ｌ Ａ － Ｃ 机制相似的结果, 但只有当非甲烷烃浓度较高（［ Ｎ Ｍ Ｈ Ｃ］／［ Ｎ Ｏｘ］ ＞ １２） 时 Ｒ Ｏ Ｓ 模式模拟值与 Ｌ Ｌ Ａ－ Ｃ 机制预测值比较接近。在这种条件下, Ｒ Ｏ Ｓ 模型对 Ｏ Ｈ 的预测值有待改进。我国大气中相当高的［ Ｎ Ｍ Ｈ Ｃ］／［ Ｎ Ｏｘ］ 比率说明 Ｒ Ｏ Ｓ 模式用于全国范围内的空气质量趋势模拟是可行的。     

低纬热带大气中的Rossby波

从热带大气波动的频率方程出发，详细分析了过去给出的低频Ｒｏｓｓｂｙ波的近似频率公式ω＝－βκ／［（２ｎ＋１）β／ｃ０＋κ＾２］，发现其对热带Ｒｏｓｓｂｙ波的性质有一定程度的歪曲。针对这一问题，经分析得到一个能更精确地表征热带Ｒｏｓｓｂｙ波性质的近似频散公式ω＝－βκ／［（２ｎ＋１）β／ｃ０＋４ｎ（ｎ＋１）／（２ｎ＋１）＾２ｋ＾２］，还简要地比较了热带线性Ｒｏｓｓｂｙ波和孤立Ｒｏｓｓｂｙ波两者的频散     

边界层风场调整的分析

分析任意气压场在中性、非线性正压边界层中风场的调整问题。结果表明:任意初始风场,将向给定的气压调整。具休调整过程是通过绝对涡度振荡及粘性系数的耗散,其调整的时间尺度为[O(t^(-3/2))],比自由大气地转适应时间尺度[O(t^(-1))]快。     

卫星云参数处理方法和1991年云气候特征分析

参考国际卫星去气候计划和目前出现的几种云参数处理方法＾［１］［２］，设计了一种适用于东亚和热带海洋地区的云参数处理方法，并着重进行了总云量的反演。处理资源取自ＧＭＳ－４的Ｓ．ＶＩＳＳＲ资料＾［３］，覆盖范围为５０＾ｏＮ－３０＾ｏＳ，８０＾ｏ－１７５＾ｏＥ。时间为１９９１年的１、４、７、１０四个月。使用上述方法对卫星资料计算得到了日、旬、月的平均云量。通过与其它资源和处理结果的对比分析，对处理方法和     

高NOx条件下非甲烷烃体积分数的变化对O3生成量的影响

利用ＬＬＡ－Ｃ光化学反应机制,在ＮＯＸ保持高值不变时,模拟分布范围很广的８种初始［ＮＭＨＣ］／［ＮＯｘ］（１０９／１０９）（１．０、３．０、７．１、１４．３、２８．６、５７．２、１００．０、２００．０）条件下臭氧体积分数的变化。模拟结果表明,当［ＮＭＨＣ］／［ＮＯｘ］≥１５．０时,臭氧生成量对ＮＭＨＣ的改变不大敏感而主要依赖于ＮＯｘ的大小。但是,当非甲烷烃与氮氧化物的比北较低（＜７．０）时,臭氧生成量紧密地依赖于非甲烷烃体积分数。进一步的验证工作还有待于加强。     

有扭仿射李代数赋值模的某些性质

设ｇ为有限维复单李代数,＾ｇ［σ］为对应的有扭仿射李代数,Ｕ１,…,Ｕｒ为不可约ｇ－模,ｚ１,…,ｚｒ为互不相同的非零复数．利用生成函数的方法证明赋值模Ｕ１（ｚ１）…Ｕｒ（ｚｒ）为＾ｇ［σ］－模范畴Ｅ中不可约模并证明其同构定理．     

对流边界层中的一个双高斯型PDF扩散模式

对流边界层（ＣＢＬ）中的污染扩散是非高斯型的。本文在下列三个假设下建立了双高斯型几率分布函数（ＰＤＦ）模式：１．对流边界层任一确定高度铅直速度Ｗ的几率分布函数ｐｗ由两个高斯分布迭加而成；２．从污染源释放的粒子具有源高的铅直速度几率分布，且其轨迹是线性的；３．粒子在地面的反射为全反射，在混合层高度Ｚｉ为全反射或有部分吸收。然后分析了三个高度上铅直速度Ｗ的一些统计特征量，比较了由ＰＤＦ模式计算的横风向积分浓度和Ｌａｍｂ的数值模拟［１－３］，Ｄｅａｒｄｏｒｆｆ的水槽模拟［４－６］结果，并用美国ＣＯＮＤＯＲＳ计划的外场试验资料［７］对ＰＤＦ模式进行了验证，结果均相当一致。     

一次干冷锋过程的边界层风场结构和尺度分析

本文利用南京北郊164米气象塔实测资料对一次非降水弱冷锋过程的边界层风场结构一三维风速、横锋向水平散度、湍流通量和能量的时空分布，以及多尺度时空分布进行了计算分析。结果表明，在冷暖空气的过渡区（锋区）风场各参量具有明显的梯度，锋区前线的强上升气流与强冷锋相近，但锋区宽度较强冷锋宽得多，其时间尺度为30分钟，水平距离为35公里。锋面过境对风温场的影响时段为24小时，在这期间，出现阵风浪涌和多种中、小尺度（时间尺度为3－4小时、1－20分钟）的湍涡活动。     

用简表求算避雷针高度及保护范围

建筑物防雷设计规范（ＧＢ５００５７－９４）用滚球法确定避雷针（线）在ｈｘ高度的ｘｘ′平面上和在地面上的保护半径,只能按下列计算式确定：ｒｘ＝［ｈ（２ｈｒ－ｈ）］－［ｈｘ（２ｈｒ－ｈｘ）］…（１）ｒ０＝［ｈ（２ｈｒ－ｈ）］（２）………………ｒ１＝［ｈｘ（２ｈｒ－ｈｘ）］（３）……………式中ｒｘ避雷针（线）在ｈｘ高度的ｘｘ′平面上的保护半径;ｈ避雷针（线）的高度;ｈｒ滚球半径,第一类防雷建筑物３０ｍ,第二类防雷建筑物４５ｍ,第三类防雷建筑物６０ｍ;ｈｘ被保护物的高度;ｒ０为接闪器在地面上的保护半径。…     

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     

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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.