The vertical structure of the atmospheric boundary layer over the central Arctic Ocean

The tropopause height and the atmospheric boundarylayer （PBL） height as well as the variation of inversion layer above the floating ice surface are presented using GPS （global position system ） radiosonde sounding data and relevant data obtained by Chinas fourth arctic scientific expedition team over the central Arctic Ocean （86°-88°N, 144°-170°W） during the summer of 2010. The tropopause height is from 9.8 to 10.5 km, with a temperature range between -52.2 and -54.10C in the central Arctic Ocean. Two zones of maximum wind （over 12 m/s） are found in the wind profile, namely, low- and upper-level jets, located in the middle troposphere and the tropopause, respectively. The wind direction has a marked variation point in the two jets from the southeast to the southwest. The average PBL height determined by two methods is 341 and 453 m respectively. These two methods can both be used when the inversion layer is very low, but the results vary significantly when the inversion layer is very high. A significant logarithmic relationship exists between the PBL height and the inversion intensity, with a correlation coefficient of 0.66, indicating that the more intense the temperature inversion is, the lower the boundary layer will be. The observation results obviously differ from those of the third arctic expedition zone （800-85° N）. The PBL height and the inversion layer thickness are much lower than those at 870-88° N, but the inversion temperature is more intense, meaning a strong ice- atmosphere interaction in the sea near the North Pole. The PBL structure is related to the weather system and the sea ice concentration, which affects the observation station.     

Theoretical models of the height of the atmospheric boundary layer and turbulent entrainment at its upper boundary

The planetary boundary layer (PBL), which directly interacts with the underlying surface, differs significantly in its nature from the low-turbulent stably stratified free atmosphere. Fluctuations of the Earth’s surface heat balance immediately affect the PBL and assimilate there owing to the effective mechanism of turbulent heat transfer. In this case the upper boundary of the PBL plays the role of a cover, preventing the direct penetration of thermal effects and contaminants into an overlying atmospheric layer. In view of this, air pollution is especially dangerous when associated with shallow PBL. In addition, local peculiarities of climate change are mainly determined by the PBL height due to the high sensitivity of thin stably stratified PBLs to the thermal effects. Deep convective PBLs are not very sensitive to weak thermal effects, but they significantly affect the formation of convective cloudiness and the climate system as a whole by means of the turbulent entrainment of the thermal energy, humidity, aerosols, and other admixtures through the upper boundary. The PBL height and turbulent entrainment must be calculated when simulating and forecasting air pollution, abnormal frosts and heat, and other hazardous phenomena. In this paper we discuss the state-of-the-art knowledge in the area of PBL height simulation and suggest a new model of turbulent entrainment for convective PBLs.     

Formation of electrically active layers in the atmosphere with temperature inversion

The dynamics of the electric field in the planetary boundary layer (PBL) is thoroughly studied from in situ observations of the aeroelectric field and the height profiles of the wind-velocity components in the conditions of temperature inversion and incipient convection. It is established that the formation of a layer with temperature inversion is accompanied by a positive trend in the intensity of the aeroelectric field and by the generation of short-period aeroelectric pulsations. The transfer of a spatially nonuniform space charge and the formation of electrically active layers in PBL are studied by numerical modeling. The response of the electric field to the motion of the space charges simulating the coherent structures of electrogasdynamical turbulence is investigated for the vicinity of the observation point. The key parameters of the model distributions of the space charge are analyzed. The linear dimensions of the model structures range from 20 to 500 m, and the density of the transported charge varies from 0.1 to 1 nC/m³. The layer containing the model structures is located at a height of 60–300 m. It is shown that the spatial distribution and the transfer of the space charge form the dynamical component of the aeroelectric field in the surface layer. The short-period aeroelectric pulsations are induced by the transfer of the spatially heterogeneous space charge in PBL, while the positive trend is due to the accumulation of the space charge below the inversion layer. When the inversion was recorded by a sodar, the intensity of the field at the onset of the convection increased at a rate of 100 V/(m h) on average.     

Spatial spectra and characteristic horizontal scales of temperature and velocity fluctuations in the convective boundary layer of the atmosphere

Using a high-resolution LES numerical model, we calculated the turbulent thermal convection for high ratios of horizontal and vertical sizes of the computational domain (26: 26: 1). The natural analog of the simulated process is a planetary boundary layer (PBL) of the atmosphere growing with height in the background of stably stratified overlying air layers over a horizontally homogeneous heated surface under a weak average wind. We obtained the spectral distributions of variances of fluctuations in potential temperature and velocity components in ranges corresponding to scales from a few tens of meters to a few tens of kilometers. We found energetically significant segments of the spectrum of large-scale fluctuations in the potential temperature for which the power dependences S ～ k ^?1/3 and S ～ k ^?4/3 are satisfied with good accuracy. We calculated the characteristic spatial scales of horizontal fluctuations in velocity and temperature. We obtained a dependence of these scales on the height of the growing convective PBL. We discuss the characteristic features of large-scale distributions in terms of the self-similarity of the growing boundary layer behavior.     

中国近海及临近海域海浪的季节特征及其时间变化

利用1992年12月-2005年3月TOPEX卫星高度计资料,对中国近海波浪季节特征及其时间变化进行了分析。分析结果表明,冬季平均波高最大,台湾海峡、南海北部、中南半岛东南海域以及吕宋海峡外侧是冬季的大浪区;夏季平均波高最小;春、秋两季为过渡期。对冬季大浪所在区域波浪时间变化的研究表明,年变化是其主要时间变化特征,而季节内变化是该海区的另一重要特征,并且以5 a为周期的年际变化与ENSO事件有着很好的对应关系。     

渤海大气二氧化硫浓度分布及陆源输送研究

利用2005年OMI/Aura反演的大气边界层二氧化硫(SO2)垂直柱密度数据,分析了渤海大气SO2浓度分布时空变化特征,并利用FNL气象资料,运用HYSPLIT模型对渤海大气环流后向轨迹进行分析.研究表明:渤海海域大气SO2浓度随季节变化明显,在秋冬季SO2浓度比较高,在冬季高达6.187×1016 cm -2;在春...     

台湾海峡西岸大风的统计分析

本文通过气候特征分析,得出台湾海峡西岸大风的出现主要集中在10月至翌年3月,研究了盛季大风的分布、变化规律及造成大风的环流特征,并通过回归分析,得出在中纬度纬向环流指数偏小,低纬度副高偏弱时大风天数偏多等结论。     

Space and time variations in the fine structure of the upper atmosphere according to acoustic sounding data

The results of studying variations in the fine layered structure of the upper atmosphere (heights of 20–140 km) according to data obtained from acoustic sounding within the range of infrasonic waves are given. The sources of infrasounds were surface explosions equivalent to 10 kg to 70 t of TNT. These explosions were set off in different seasons in different regions of Russia. Experimental data obtained in 1981–2011 have been analyzed. It has been found that the fine structure in the form of vertically distributed layered formations occurs in the upper atmosphere in all seasons. Moreover, the vertical distribution of both air-temperature and wind-velocity inhomogeneities in the upper atmosphere may be invariable over a time interval of no less than several hours. It has also been found that, throughout the entire atmospheric thickness from the stratopause to the lower thermosphere heights (up to 140 km), the instantaneous height distribution of layered air-temperature and wind-velocity inhomogeneities may remain almost unchanged during a time interval of no less than 20 min.     

On the use of discrete seasonal and directional models for the estimation of extreme wave conditions

Extreme value theory is commonly used in offshore engineering to estimate extreme significant wave height. To justify the use of extreme value models it is of critical importance either to verify that the assumptions made by the models are satisfied by the data or to examine the effect violating model assumptions. An important assumption made in the derivation of extreme value models is that the data come from a stationary distribution. The distribution of significant wave height varies with both the direction of origin of a storm and the season it occurs in, violating the assumption of a stationary distribution. Extreme value models can be applied to analyse the data in discrete seasons or directional sectors over which the distribution can be considered approximately stationary. Previous studies have suggested that models which ignore seasonality or directionality are less accurate and will underestimate extremes. This study shows that in fact the opposite is true. Using realistic case studies, it is shown that estimates of extremes from non-seasonal models have a lower bias and variance than estimates from discrete seasonal models and that estimates from discrete seasonal models tend to be biased high. The results are also applicable to discrete directional models.     

基于声学方法的南黄海浮游动物垂直迁移季节变化研究

为研究南黄海浮游动物垂直迁移的季节变化, 分析了2006 年至2007 年4 个季节布放潜标中声学测流仪的观测数据。结果是: 声学测流仪测量的后向散射强度呈现显著的日变化特征, 这是由浮游动物垂直迁移造成的; 在4 个季节中都出现这一凌晨向下、黄昏向上的垂直迁移, 但是垂直迁移发生的时间有季节变化。利用南黄海辐射通量的直接观测数据, 讨论了垂直迁移发生时间与光照的关系,结果表明垂直迁移的季节变化主要受光照的影响。这对于研究浮游动物垂直迁移机制有一定意义。     

潮滩上波高的时空变化及其影响因素——以长江三角洲海岸为例

于2009—2010年的不同季节在崇明东滩北部、中部、南部以及杭州湾北岸东段的芦潮港岸段,利用目前先进的SBE 26plus浪潮仪进行了多个潮周期的波浪观测。研究表明,观测期间潮周期平均风速为1.9～11.0m/s、最大风速为2.8～12.1m/s,各测点潮周期平均水深为0.28～2.12m,高潮位最大水深为0.37～3.19m,潮周期有效波高为0.03～0.45m,最大波高为0.08～1.59m。波高的时空变化受风速、风向、水深和岸滩坡度的综合影响。通常情况下,向岸风期间的波浪较大;风速、水深、岸滩坡度越大,潮滩上的波高也越大。空间上,岸滩坡度最小的崇明东滩中部(坡度0.6‰)测点波高和水深之间的相关性最好,岸滩坡度最大的芦潮港潮滩(坡度8.7‰)测点两者间的相关性最差。时间上,波高和水深之间的相关性与风速、风向的变化有关。因此,只有在潮滩坡度较小(例如<1‰),风速、风向较为稳定时,波高和水深之间的显著正相关关系才存在。要了解某个潮滩的波浪特征,有必要利用先进的仪器进行系统的原位观测,而非简单地借助其它潮滩的波浪研究结果。研究推断,在向岸强台风和大潮高潮位阶段,崇明东滩中潮线附近的最大波高可达1.5～2.0m,芦潮港堤外潮滩的最大波高可达2m以上。     

黄海海浪季节变化的数值模拟研究

利用第三代海浪数值模式SWAN,研究了黄海海浪有效波高的季节变化特征及相关的物理过程。结果表明,在黄海的大部分区域,混合浪有效波高的最大值出现在冬季,而最小值则基本出现在夏季。北黄海北部和山东半岛南岸的近海海域呈现稍微不同的季节变化,有效波高的最大值出现在春季。全年4个季节中混合浪有效波高的空间分布基本一致:均在济州岛西南最大,沿黄海中部区域向北和由中部区域向近岸区域逐渐减小。黄海海浪为风浪占主,涌浪有效波高远小于风浪有效波高。在黄海的大部分区域,白冠耗散和四波非线性相互作用对黄海海浪的季节变化均至关重要;对于外海区域,四波非线性相互作用更为重要,而对于近海区域,白冠耗散则影响更大。本研究旨在研究黄海海浪的季节变化特征及其物理过程,为进一步探讨该海域海浪在其他时间尺度上的变异特征和动力学过程提供研究基础。     

大西洋波高成分研究

利用Topex／Poseidon卫星高度计1992年10月到1998年12月连续75个月，230个重复周期的有效波高资料对南北大西洋的波高成分进行了分析，结果显示频数密度峰值对应的波高成分因子在夏季为1．4左右。冬季为1．2左右，其他季节为1．3左右。7，8，9月份大西洋含涌浪的波高成分占频数密度累积率的比例约为90％左右，其中涌浪成分占优约为65％左右；其余各月占85％左右，其中涌浪成分占优约为60％左右，表明大西洋海域常年有涌浪场存在。     

A classification of hydrological climatic seasons in the China seas

By using a method of boundary temperature index of seasons, a classification of hydrological climatic seasons in the China seas is made on the basis statistics of the sea surface air and water temperatures over the years. The results indicate that the assignment of hydrological seasons in the China seas differs with various sea areas. It may be divided into three climatic belts. In the temperate zone area, four seasons are clearly distinct with very long winter. While in the subtropical zone area, there is no winter throughout the year. The autumn is linked together with the spring, and the summer is unusually long. As for the tropical zone area, it is summer all the year round without any other seasons. In addition , the regular pattern of transformation of the four seasons and the regional characteristics of the length of each season are analyzed in greater detail. The results are in agreement with the continental seasonal classification and it is also shown that the results are reasonable and reliabl     

基于最大熵模型模拟西印度洋剑鱼栖息地的时空分布

剑鱼（Xiphias gladius）是一种高度洄游性鱼类,其迁徙和栖息地利用受海洋环境影响明显,理解其空间分布格局形成的机制对于资源的养护和管理具有重要意义。本研究利用2017?2019年中国印度洋延绳钓渔业观察员数据中剑鱼的渔获物信息作为物种出现数据,结合西印度洋海域的海表温度、海面高度、叶绿素a浓度、混合层深度、海表盐度等环境数据,采用最大熵模型对剑鱼的栖息地适宜性分布进行了模拟。结果表明:（1）模型对印度洋西部剑鱼栖息地适宜性分布的模拟精度非常高,各个季节受试者工作特征曲线的曲线下面积都大于0.9,可用于模拟剑鱼潜在的栖息地适宜性分布;（2）研究区域内剑鱼适宜栖息地分布变化与实际作业位置变动基本一致,干季和湿季剑鱼栖息地高适宜性的区域分布都较为集中,但湿季分布范围要大于干季;（3）海表温度、海表盐度和混合层深度是影响西印度洋剑鱼栖息地适宜性分布的重要环境因子,在干季和湿季的最适范围分别为25.8～31.6℃、34.4～35.9、0.1～24.9 m和25.6～30.5℃、34.8～36.4、13.1～54.1 m。研究结果可为西印度洋海域剑鱼种群的可持续利用和科学管理提供必要参考信息。     

台湾岛周边海域近16a来海平面变化研究

利用1992年10月至2008年6月的卫星高度计融合资料对台湾岛周边海域（20°～28°N,117°～124°E）多年海平面变化进行分析.研究结果表明：（1）采用改进的月平均水位周期信号的谱分析方法计算多年来台湾岛周边海域海平面年均上升速率为0.34±0.02 cm/a,与该海域内的潮位站结果较为一致.（2）台湾岛周边海域海平面高度变化以1 a周期变化为主,其次为0.5 a、准2 a周期变化.（3）通过计算海平面异常的标准差得出多年来台湾海峡西南部海域海平面波动最为激烈.（4）分析了台湾岛周边海域海平面4个季节的变化情况,指出台湾岛周边海域海平面季节变化的主要驱动力是风场.     

Role of Meso-Scale Eddies on Circulation in the South Eastern Arabian Sea in 2009

Spatial current data were collected from South eastern Arabian Sea during July 2009 (summer monsoon) and December 2009 (winter monsoon) using the vessel mounted Acoustic Doppler Current Profiler (ADCP). During July 2009, observed ADCP currents were flowing southward along 75°E longitude with a complex pattern near the coast. During winter (December 2009), an anti-clockwise rotation of currents was observed in the study region, with its eastern arm along the southwest coast of India. The circulation pattern observed during the two seasons from ADCP measured data does not seem to follow any pattern described in climatology. To investigate this aspect, the geostrophic currents were computed utilizing the multi-mission altimeter sea surface height anomaly data for the corresponding months. The analysis of geostrophic currents indicates the presence of multiple eddies embedded in the Laccadive Low (LL) /Laccadive High (LH). Our present study shows that the meso-scale eddies embedded in the LL and LH play a significant role in deviating the observed circulation from climatology in this region. In addition, generating mechanisms of these eddies are addressed to substantiate our findings. The formation of these eddies is attributed to the local wind force during July 2009 and the enhanced baroclinic instability during December 2009.     

南海海面风应力特征分析

用南海的船舶气象资料分析了南海海面风应力的四季特征。指出冬季风应力最大,且指向西南;夏季次之;春、秋两季较弱,最小在春季。本文还进一步分析了南海风应力与大涌频率、浪高的相关关系,并建立了相应的相关方程。     

1991-2011年东海黑潮PN断面流结构与季节变化分析

基于日本海洋信息中心提供的东海黑潮PN断面CTD资料,本文采用动力高度法计算了1991-2011年间90个航次的断面流速,并对流场结构、最大流速、流幅和流量进行了统计分析。结果表明:东海黑潮PN断面流场存在单核、双核、多核3种结构;其中单核结构出现的概率为50%,双核结构为39%,多核结构为11%。东海黑潮的流结构存在显著的季节变化:秋季多核结构所占的比重为4个季节最大,平均流核数最多;冬季主要为单核结构,平均流核数最少;夏季和春季则没有明显的倾向性,单核、双核、多核3种结构出现概率相近,平均流核数介于秋季和冬季之间。其次东海黑潮的流量也存在显著的季节变化:冬季与夏季最强,秋季最小,春季居中。最后东海黑潮的最大流速和流幅也存在季节变化:夏季最大,秋季最小,春季和冬季居中。     

基于南海波浪要素的波浪滑翔机翼板参数优化设计与仿真

针对南海不同波浪要素条件下波浪滑翔机翼板参数设计的问题进行研究。基于欧洲中尺度天气预报中心大气和海洋全球再分析数据集(ERA5), 对南海不同季节以及台风经过时的波高波周期进行统计。并利用FLUENT软件研究南海不同波浪要素条件下翼板最大偏转角度、转轴位置以及翼板间距对波浪滑翔机水下翼板平均推力的影响。仿真结果表明, 波高越大, 翼板最大偏转角度也应相应增大, 才能保证翼板获得更大的推力; 在南海波浪要素条件下, 翼板转轴位置选取在翼板前端1/5处较佳; 适当增加翼板间距能够提高翼板获得的推力。通过对翼板被动摆动进行仿真, 得到了翼板在不同参数设置下产生的推力, 为波浪滑翔机翼板设计提供参考。