厦门海域大气气溶胶特征

1988年12月至1990年3月,利用中美海气实验厦门观测站,采集了厦门海域107个气溶胶样品,利用离子色谱法和原子吸收分光法测定其中的Na+、Cl-、SO₄2-、NO₃-、NH₄+、Al、Fe、V、Pb、Cu、Cd.本文分析了厦门海域大气气溶胶中物质的浓度分布特征及季节变化规律.结果表明,厦门海域大气气溶胶物质主要来源为海水、土壤尘、煤烟尘和燃油灰,陆源物质具有明显的季节变化,湿季浓度明显低于干季,雨水对大气中颗粒物的清除起着重要作用.     

中国近海海水透明度分布特征与季节变化

统计了2006—2007年中国近海环境调查的透明度数据,绘制了中国近海4个季节的透明度分布图,分析了透明度的分布特征及季节变化。结果表明,水深和入海径流对中国近海透明度分布影响最大。总体上,除长江口等重要河口区外,透明度等值线分布趋势基本与等深线一致,即近岸浅水区透明度最小,外海深水区透明度最大。由渤海至南海,透明度有不断增大的趋势。统计表明,冬季透明度最小,夏季透明度最大。从透明度分布特征上看,长江口及其以东海域随季节的变化最为显著。而从透明度值变化上看,渤海海域随季节的变化最为显著。与历史数据对比,渤海、长江口以东海域及海南岛以西海域透明度值的观测结果明显减小。     

盐城近岸海域水质分布特征及富营养化研究

文章于2018年春、夏、秋季对盐城近岸海域海水营养盐和化学需氧量等环境因子进行调查采样,并分析其时空分布特征;应用有机污染指数法和富营养化指数法2种评价方法,对该海域的海水富营养化水平进行评价。结果显示,研究海域环境因子季节变化显著,有机污染指数和富营养化指数的时空分布特征基本一致,指数由高到低的季节依次为春季、秋季、夏季,空间上呈各河入海口向远岸海域逐渐降低的趋势;聚类分析将江苏近岸海域分为废黄河三角洲区域和辐射沙洲区域2个大类;盐城入海河流输入对污染物的分布有强烈影响,同时水动力情况影响环境因子分布;陆源污染和淡水输入是引起海水环境因子变化的关键因素。     

琼东和粤西海表温度锋的季节与年际变化特征分析

以2006—2013年卫星遥感海表温度资料(GHRSST SST)为基础,通过数字图像处理的边缘检测方法提取温度锋面的核心位置,分析了琼东、粤西海域海表温度锋位置及强度的季节变化和年际变化特征,并进一步结合海面高度异常资料和海面风场资料探讨了温度锋变化的可能机制。分析结果表明,琼东、粤西海域温度锋的空间分布及锋面强度存在显著的季节变化,沿岸风应力是影响该海域锋面变化的主要动力因素。夏季温度锋面主要分布于琼东沿岸的东部及南部海域近岸50m到100m等深线之间,而冬季则主要分布在琼东的东部海域和粤西沿岸20m到100m等深线之间,春秋两季为其过渡季节;锋面强度的季节变化表现为冬季最强,春季、夏季次之,秋季最弱,其冬季锋面强度平均值可达到3℃?100km–1,夏季为1.7℃?100km–1;同时,锋面核心位置及强度的分析结果表明,琼东和粤西海域温度锋也存在较强的年际变化。     

南海深水海盆环流和温跃层深度的季节变化

受南海季风和复杂地形的影响,南海环流场具有复杂的空间结构和明显的季节变化,同时此海域又是中尺度涡多发海域,这些特征必然对南海温跃层深度的水平分布及季节变化有显著影响。首先,基于GDEM(General-ized Digital Environmental Model)的温、盐资料和利用P矢量方法计算并分析了南海的表层环流和多涡结构的空间分布特征和季节变化规律。在此基础上,分析了南海温跃层深度的空间分布特征和季节变化规律。结果表明,南海环流和多涡结构对南海温跃层具有显著的影响。     

南海深水海盆环流和温跃层深度的季节变

受南海季风和复杂地形的影响,南海环流场具有复杂的空间结构和明显的季节变化,同时此海域又是中尺度涡多发海域,这些特征必然对南海温跃层深度的水平分布及季节变化有显著影响.首先,基于GDEM (Generalized Digital Environmental Model)的温、盐资料和利用P矢量方法计算并分析了南海的表层环流和多涡结构的空间分布特征和季节变化规律.在此基础上,分析了南海温跃层深度的空间分布特征和季节变化规律.结果表明,南海环流和多涡结构对南海温跃层具有显著的影响.     

基于潜标观测的黑潮-亲潮混合区近惯性能量季节变化特征研究

近惯性内波广泛存在于全球海洋,是维持深层海洋跨等密度面湍流混合及海洋层结的重要能量来源。基于黑潮-亲潮混合区的多年深海潜标数据,分析了:(1)该海域近惯性内波及其能量的季节变化特征与影响因素,(2)上层和深层近惯性运动的频率、波数谱及垂向分布等特征。结果表明,该海域存在丰富的近惯性动能,无论海洋上层还是深层均呈现显著的冬季强、夏季弱的季节变化特征,冬季(12～2月)上层的近惯性能量可占全年能量的41%,深层近惯性信号同样显著,同潮汐信号相当。平板模型分析表明,该区域近惯性动能的季节循环特征主要受风场的季节变化所主导,同时受到黑潮延伸体流轴的摆动调制。     

长江口表层沉积物有机碳分布及其影响因素

根据长江口及其邻近海域2007年2、5、8、11月4个航次野外调查资料,系统地探讨了长江口表层沉积物总有机碳(TOC)的时空分布特征及其主要影响因素.结果表明,长江口及其邻近海域表层沉积物类型以细砂和粉砂为主,细颗粒泥沙主要分布在调查水域南部,北部海域以砂组分为主,沉积物组成和分布具显著的季节变化特征;长江口及其邻近海...     

台湾海峡西部海域浮游端足类的分布

本文根据1984年5月—1985年2月台湾海峡西部海域调查所获的样品及资料,分析报道了本海域浮游端足类的种类组成、总量的季节变化与平面分布、主要种的季节变化、昼夜垂直移动节律,并探讨其分布与环境因子的关系。     

东、黄海海表面温度季节内变化特征的EOF分析

基于1998—2004年的TRMM/TMI卫星遥感海面温度(SST)数据,在初步分析东、黄海SST的季节分布特征的基础上,采用EOF方法分析了SST的季节内变化特征,进而对SST季节内变化的可能机制进行了探讨。EOF分析获得的前4个模态的累积方差贡献率为57.07%,其结果基本反映了东、黄海SST变化的主要物理过程。其中,EOF的第一模态的方差贡献率占30.17%,其空间模态揭示了以东海北部为中心的、整个海域SST变化趋于一致的特征,这一模态的显著变化周期为6.3周;第二模态的方差贡献率占14.36%,其空间模态呈现东南海域与西北海域SST的反相变化趋势,显著变化周期为8.7周和10.6周;第三模态的方差贡献率占7.02%,其空间SST变率最大的区域位于黄海海域,显著变化周期为6.8,8.7,10.2周等;第四模态的方差贡献率占5.52%,其空间SST变率最大的区域位于东、黄海近海,显著变化周期为6.8周。东、黄海SST季节内变化与此海区大气中的季节内振荡是紧密相关的。     

Climatic parameters of wind-field variability in the Black Sea region: Numerical reanalysis of regional atmospheric circulation

A reanalysis of atmospheric circulation in the Black Sea region is performed with a high spatial resolution of 25 × 25 km for the period from 1958 to 2001. Climatic wind speed fields are estimated, as are their spatial structure and seasonal variability. Mesoscale regions of cyclonic and anticyclonic speed vorticity, which are connected with edge effects and orography, are distinguished. To single out the monsoon mechanism in the annual votricity cycle, numerical experiments on the sensitivity that the regional atmospheric circulation has to the sea-surface temperature perturbations have been carried out. Large-scale regional peculiarities of the surface wind field are considered for different seasons. The vorticity of the surface wind speed and strength is assessed. Large annual average values of the vorticity are obtained which are comparable with the range of seasonal variability; they evidence the defining role that wind plays in the generation and seasonal variability, as well as the average cyclonic water circulation in the Black Sea.     

Estimates of carbon monoxide emissions from wildfires in northern Eurasia for airquality assessment and climate modeling

The emissions from fires in the boreal zone of northern Eurasia significantly contribute to the global emissions of greenhouse gases, their precursors, and aerosols. These emissions are an important component of the global carbon balance, and they significantly affect both seasonal and long-term variations in the chemical composition and radiation properties of the atmosphere on both regional and global scales. The atmospheric emissions of carbon monoxide (CO) from biomass burning have systematically been estimated for the entire territory of northern Eurasia over the period of 2000–2008 on the basis of satellite (MODIS MCD45A1) data on burned vegetation and the Seiler-Crutzen emission model with consideration for both regional and seasonal features. On the whole, for Russia, the annual emissions of CO from biomass burning ranged from 10.6 to 88.2 Mt/y over the indicated period. Depending on fire activity, the atmospheric emissions of CO from natural fires and agricultural work may yield from 25 to 200% of the total technogenic emissions according to the EDGAR-2000 model. In this case, the dominant contribution is made by boreal forest fires (8–57 Mt/y), whose portion amounts to 63–76% of the total emissions from biomass burning. This relatively short observational series does not allow one to reliably estimate long-term variations; however, on the whole, a stable increase in burned areas has been observed in forest, steppe, and agricultural regions over the last decade. Our analysis suggests significant spatial and seasonal variations in the large-scale fields of fire emissions, which are determined by the physical, geographic, and climatic features of individual regions. The calculated fields of emissions can be used in transport-chemical models, studies of the regional transport and quality of air, and climate models.     

Numerical modeling of the influence of land–sea temperature contrasts on the atmospheric circulation in the Black-Sea region

The formation of the fields of surface winds over the Black Sea occurs under the action of numerous physical factors. One of the most important factors is the monsoon mechanism connected with the seasonal variations of buoyancy contrasts over the sea and surrounding land. To separate the effects caused by this mechanism, we performed and described the numerical experiments aimed at the evaluation of the sensitivity of the regional model of atmospheric circulation to the variations of land–sea temperature contrasts. It is shown that the influence of these effects is restricted to the lower part of the atmosphere. The presented estimates of the climatic fields of disturbances enable us to describe the monsoon mechanism specifying the seasonal variability of the field of vorticity of the wind velocities and, as a consequence, the seasonal variability of the large-scale circulation of waters in the Black Sea.     

三沙市海域海平面变化

使用1993-2011年的台站和卫星高度计资料详细分析了三沙市海域近19 a的海平面变化特征及规律。结果表明:三沙市周边海域海平面存在明显的季节变化,且区域特征明显。海平面变化除了明显的年和半年周期,2~3 a、4~7 a和准9 a的周期也较显著。海平面长期变化呈现明显的波动上升趋势,且空间分布上区域特征显著,西沙群岛南部海域海平面上升趋势最强,西沙群岛北部与中沙群岛西部次之,南沙群岛东部海平面上升速率较快,南沙群岛西部上升趋势最弱。受大气环流等异常气候事件的影响,1998年和2010年海平面的年际变化波动较大,年变化振幅显著偏高。未来三沙市海平面将继续上升,预计2030年、2050年、2070年和2100年海平面将比常年分别升高约11 cm、20 cm、30 cm和45 cm。     

An analysis of regional climate model performance over the tropical Americas. Part II: simulating subseasonal variability of precipitation associated with ENSO forcing

The El Niño/Southern Oscillation (ENSO) constitutes a major source of potential predictability in the tropics. The majority of past seasonal prediction studies have concentrated on precipitation anomalies at the seasonal mean timescale. However, fields such as agriculture and water resource management require higher time frequency forecasts of precipitation variability. Regional climate models (RCMs), with their increased resolution, may offer one means of improving general circulation model forecasts of higher time frequency precipitation variability.
Part I of this study evaluated the ability of the Rossby Centre regional atmospheric model (RCA), forced by analysed boundary conditions, to simulate seasonal mean precipitation anomalies over the tropical Americas associated with ENSO variability. In this paper the same integrations are analysed, with the focus now on precipitation anomalies at subseasonal (pentad) timescales.
RCA simulates the climatological annual cycle of pentad-mean precipitation intensity quite accurately. The timing of the rainy season (onset, demise and length) is well simulated, with biases generally of less than 2 weeks. Changes in the timing and duration of the rainy season, associated with ENSO forcing, are also well captured. Finally, pentad-mean rainfall intensity distributions are simulated quite accurately, as are shifts in these distributions associated with ENSO forcing.     

Coupled seasonal variability in the South China Sea

The present study documents the relationship between seasonal variations in sea surface temperature (SST) and precipitation in the South China Sea (SCS) region. There are strong interactions between the atmosphere and ocean in the seasonal variations of SST and precipitation. During the transition to warm and cold seasons, the SST tendency is primarily contributed by net heat flux dominated by shortwave radiation and latent heat flux with a complementary contribution from ocean advection and upwelling. The contribution of wind-driven oceanic processes depends on the region and is more important in the northern SCS than in the southern SCS. During warm and cold seasons, local SST forcing contributes to regional precipitation by modulating the atmospheric stability and lower-level moisture convergence. The SST difference between the SCS and the western North Pacific influences the convection over the SCS through its modulation of the circulation pattern.     

Some features of seasonal variations in the methane content in the atmosphere over northern Eurasia

The climatic trends and basic features of seasonal variations in and anomalies of the concentration of methane in the atmospheric surface layer are considered on the basis of the current notion of the processes that form the global field of methane in the Earth’s atmosphere. Measurement data on the surface concentration of methane, which were obtained in Moscow and at a number of observation stations in Europe and Siberia in the fall-winter period of the first decade of the 21st century, have been analyzed. It is shown that, in the anomalously warm winter months of 2006/2007, the concentration of methane in the atmosphere over Moscow was higher than in the previous and following years. The excess concentration of methane amounted to 10% in March 2007, which is higher than the mean range of seasonal variations in the monthly mean concentration of surface methane. A comparison between the data obtained in Moscow and the data obtained at three stations of the NOAA global monitoring network and at three Russian Hydrometeorological Research Center stations shows the high spatial variability of the methane concentration in the atmosphere over northern Eurasia. The complex and multifactor processes that determine the content of methane in the atmospheric surface layer result in noticeable spatial and interannual deviations from the mean seasonal cycle of its concentration, which can manifest themselves on both regional and global scales. It is possible that the resumed increase in the content of methane in the Earth’s atmosphere recorded in 2007 (after its relative stabilization in the early 2000s) at the global monitoring network was also caused, to some extent, by the anomalously warm winter of 2006–2007 in northern Europe and western Siberia.     

中国近海声速剖面的模态特征

利用WOA05数据集提供的气候态声速场数据,通过模糊C-均值聚类分析,得到了中国近海声速剖面模态特征的区域性分布和季节性变化。结果表明,中国近海的声速剖面结构可分为深海型(D型)、浅海型(S型)和过渡型(T型)三个基本类型。深海型剖面为"季节性跃层/正梯度+主跃层+深海声道+深海正梯度"结构,南海和菲律宾海因所属水系不同呈现出明显差异;浅海型剖面季节性变化强烈,冬季为正梯度或均匀型结构,其它季节为"混合层+季节性跃层+下均匀层"结构,负梯度强度与季节性跃层的变化有关,在夏季达到最强;过渡型剖面形态与邻近的深海型上层结构类似,但因受地形制约产生与深海型不同的声传播特征。海面太阳辐射、海洋环流、混合层以及水团配置的季节性变化导致的温盐场空间分布差异是造成不同海区、不同季节声场速剖面结构差异的根本原因。     

Evaluation of a dynamically downscaled atmospheric reanalyse in the prospect of forcing long term simulations of the ocean circulation in the Gulf of Lions

The paper evaluates atmospheric reanalysis as possible forcing of model simulations of the ocean circulation inter-annual variability in the Gulf of Lions in the Western Mediterranean Sea between 1990 and 2000. The sensitivity of the coastal atmospheric patterns to the model resolution is investigated using the REMO regional climate model (18 km, 1 h), and the recent global atmospheric reanalysis ERA40 (125 km, 6 h). At scales from a few years to a few days, both atmospheric data sets exhibit a very similar weather, and agreement between REMO and ERA40 is especially good on the seasonal cycle and at the daily variability scale. At smaller scales, REMO reproduces more realistic spatio-temporal patterns in the ocean forcing: specific wind systems, particular atmospheric behaviour on the shelf, diurnal cycle, sea-breeze. Ocean twin experiments (1990–1993) clearly underline REMO skills to drive dominant oceanic processes in this microtidal area. Finer wind patterns induce a more realistic circulation and hydrology of the shelf water: unique shelf circulation, upwelling, temperature and salinity exchanges at the shelf break. The hourly sampling of REMO introduces a diurnal forcing which enhances the behaviour of the ocean mixed layer. In addition, the more numerous wind extremes modify the exchanges at the shelf break: favouring the export of dense shelf water, enhancing the mesoscale variability and the interactions of the along slope current with the bathymetry.     

Statistics of mesoscale cyclonic Eddies over the Black Sea

On the basis of the results obtained by using the PRECIS regional climate model with high space resolution (25 km), we study the mesoscale specific features of the atmospheric circulation in the Black-Sea region for a period of 30 yr. To separate and trace the subsynoptic eddies, we use a method based on the Okubo–Weiss criterion. Several types of cyclonic eddies are selected and described: winter Caucasian coastal eddies, summer Caucasian separated eddies, cyclonic eddies of the open sea, and seldom quasitropical cyclones. For various types of eddies, we present the statistics of their lifetime and intensity and the histograms of diurnal and seasonal cycles.