一次黄海海雾事件的观测与数值模拟研究--以2004年4月11日为例

利用各种观测资料和RAMS(Regional Atmospheric Modeling System)模式4．4版对2004年4月11日发生在黄海海域的一次海雾事件进行了研究。利用GOES(Geostationary Operational Environmental Satellite)-9和NOAA(National Oceanic and Atmospheric Administration)-14可见光卫星云图对海雾的发生范围、演变过程等进行了描述，并对海雾发生前的大气背景场和气海温差场进行了分析；利用青岛和韩国济州岛2个站的探空资料对海雾发生时低层大气的稳定度进行了分析；利用RAMS模式对本次海雾事件进行了模拟，并计算了大气的水平能见度分布。计算结果与卫星云图所显示的雾区范围分布吻合很好。     

CALIPSO卫星资料的春夏季黄海海雾高度特征分析

利用2007—2018年CALIPSO卫星数据对春夏季黄海海雾的高度特征进行了统计,并借助MTSAT可见光卫星云图、"葵花8号"可见光卫星云图和KMA地面天气图对控制海雾产生的天气形势进行了分析,进一步讨论了各天气型下黄海海雾的高度特征。研究结果表明:(1)黄海海雾的平均雾顶高度是211 m,海雾高度最大值为370 m,大多数黄海海雾雾顶高度介于100～400 m;(2)7月的海雾雾顶高度高于其他月份,为260 m;(3)控制黄海海雾生成发展的主要天气型有入海变性高压型和大陆低压低槽东移型,入海变性高压控制下的弱偏南风区域的雾顶高度相对较高,大陆低压低槽控制下的槽前风速稍大区域的雾顶高度偏高。     

数值模拟和卫星反演大气能见度对比分析

对2004年4月11日、2005年3月9日和2005年3月27日发生在黄渤海海域3个典型海雾个例数值模拟得到的大气能见度与可见光卫星云图的反照率进行对比分析,利用不同时刻大气能见度与反照率的对应关系进行线性数学拟合,得到新的适合白昼的大气能见度反演公式。利用该公式反演了几次显著海雾过程的大气能见度分布,发现海雾预报系统对大气能见度<200 m的海上浓雾的面积预报准确率约90%左右。对发生在2009年3月1日到2010年5月21日期间的46次较强海雾进行了初步统计,从判别海雾有无的角度来看该海雾预报系统对海雾的预报准确率为91.3%。     

一次海雾过程大气波导形成机理的数值研究

依据船舶导航雷达与沿岸气象探空观测数据得知,2005年6月1～3日黄海海域发生了1次大范围波导现象;进一步结合卫星云图与沿岸测站水平能见度观测,发现此次波导伴随1次明显的平流海雾过程。利用WRF模式对此次海雾与波导过程进行了数值模拟,发现:(1)海雾始于黄海中部,绝大部分海雾的雾顶由于弱逆温、湿度梯度较小而不存在波导;(2)雾区随其北部低压的逐渐东移而向东扩展,呈现西部薄、东部厚的结构,雾体顶部由于存在逆温与湿度锐减而形成了波导,混合均匀的雾体则成为波导基础层,薄雾顶部为非贴海表面波导,而厚雾顶部则为悬空波导;(3)雾区受低压西部冷空气的影响向南消退,波导基础层逐渐变薄乃至消失,雾体之上的逆温与湿度锐减层随之下降,非贴海表面波导被强度较弱的贴海波导所替代。分析结果表明:黄海平流海雾与波导有密切的联系,海雾形成及其发展改变了海洋大气边界层的温度与湿度垂直结构,从而导致了波导的发生与演变,大气波导可认为是海雾的"副产品"。     

黄海平流海雾的观测分析

利用大量的地面站点观测、卫星监测和非常规观测资料,统计分析了海雾的时空分布特征、卫星云图特征及影响黄海海雾的气象和水文因子.结果表明,黄海海雾随时间和空间而变化,在空间分布上,雾频随着纬度增高而增加;海雾与海上风速的大小和方向有密切关系;海雾出现与海表温度、气-海温差、露点温度有关;海流是影响海雾形成的水文因素之一;海雾是大气处在稳定层状态下的一种凝结现象,有海雾不一定有逆温,但是逆温层的消散却为海雾的消散提供了有利的依据.     

青岛近海夏季海雾年际变化的低空气象水文条件分析——关于水汽来源的讨论

本文采用1971-2009年月雾日数资料、1970-2007每日4次能见度观测资料、MICAPS系统提供的每日3h/1次的地面观测资料、JRA-25再分析资料,对青岛近海夏季(6～7月)海雾年际变化的低空气象水文条件进行了合成分析,发现长江口以东的东海海域是影响青岛近海海雾多寡的水汽来源关键区域(122°E～130°E,28°N～32°N),黄海局地海表面蒸发增湿所提供的水汽贡献不大.海表面温度(SST)对海雾的形成在黄、东海起着不同的重要作用.多雾年,东海SST偏高,海面蒸发较大,为低空气流提供了热量和水汽,黄海SST偏低,海面蒸发较小,有利于低空气流的降温增湿,从长江口以东海域向黄海输送的低空暖湿平流是海雾形成的主要物质基础.去掉月平均合成中降水、沙尘等因素对能见度的影响,针对2005-2007年6、7月42个雾日的统计分析,进一步证明了长江口以东海域水汽输送对黄海海雾形成有重要影响;对其中5个雾日的水汽源地追踪,表明在天气时间尺度下,水汽路径是从东海在低空南风的引导下向北到达青岛近海.     

一次典型高压型海雾过程中海上大气波导的数值模拟

2009年4月9—12日黄海海域发生了一次受高压系统影响的海雾过程。利用卫星观测与探空数据、WRF模式(Weather Research and Forecasting Model)对此次海雾过程及相伴的大气波导进行了观测分析与数值模拟。海雾与波导发展可分为3个阶段:(1)大气波导先于海雾存在于黄海海面;受高压下沉影响,黄海上空存在逆温层和较强的湿度梯度,表现为较强的贴海表面波导和非贴海表面波导。(2)海雾始于高压西部,并随高压系统逐渐东移减弱,向黄海北部扩展;辐射冷却虽然使雾顶附近逆温增强,但海雾的机械湍流使其顶部湿度梯度减小,雾顶附近对应弱悬空波导或波导消失。(3)高压系统影响使干空气下沉到雾区导致黄海海雾消散;雾顶附近逆温仍存在,同时湿度梯度增大,黄海上空逐渐变为非贴海表面波导。本研究结果表明:高压系统不仅极易为波导的发生提供有利条件,而且有利于海雾的生成,在海雾演变过程中主要是雾顶水汽梯度的变化导致了波导类型及强度的变化。     

2010年2月一次冬季黄海海雾的成因分析

利用青岛浮标观测、自动气象站观测、Micaps站点观测、L波段雷达等观测数据,New Generation SST,OI-SST和NCEP提供的FNL和CFSR再分析数据。并利用中尺度模式WRF对这次冬季海雾进行诊断分析。得到以下结论:(1)观测表明,这次海雾首先在黄海北部生成,是由于冷暖空气在黄海海域交汇,增大相对湿度,形成混合雾。在22日12:00时(UTC)之后,暖平流北上,冷平流消失。海雾逐渐转成平流冷却雾。青岛出现的海雾是从黄海发展过来的,并且为平流冷却雾。(2)在黄海,冷暖空气混合增大相对湿度,生成混合雾。与后期的平流冷却雾相比,混合雾的高度明显偏低。(3)海温异常偏低。在2010年2月渤海大面积结冰,海温偏低可能与融冰有关系。(4)模式结果表明,混合雾与冷水域的关系密切。平流冷却雾与冷水域的位置基本一致。混合雾和平流冷却雾都受海温影响较大。混合雾雾区变化很大,因为冷空气在移动过程中变性,不利于混合雾生成。冷海面对平流冷却雾起着很关键的作用。这次冬季海雾与春夏季黄海海雾的不同点在:这次海雾的发生机制不同于典型的春夏季黄海海雾。春夏季典型的黄海海雾主要是平流冷却雾,而这次冬季海雾在生成上首先是混合雾,后来转为平流冷却雾。     

直接同化卫星辐射数据的黄海海雾数值试验研究

基于中尺度大气模式WRF及其3DVAR.模块,采用循环3DVAR数据同化方案,针对6次明显的黄海海雾过程,实施了一系列直接同化ATOVS卫星辐射数据数值试验.在试验中设计了不同化任何观测数据、仅同化GTS常规数据、仅直接同化辐射数据,同时同化二者,以及同化不同疏密程度辐射数据的对比研究方案.利用地面水平能见度与卫星云图对模拟的海雾雾区进行了评估,并比较了各种同化方案所形成初始场的差异.对试验结果的统计分析表明:同化试验较好地再现了影响海雾的天气系统,模拟雾区与实际观测较为吻合,并且初始温度场和湿度场对比不同化任何观测数据的试验有明显的改善;仅同化辐射数据的结果略优于仅同化常规数据的结果,疏化或者只同化海上辐射数据几乎不影响模拟的雾区,但却可以大幅节约计算资源;同时同化常规数据与辐射数据的结果为单独同化它们所得结果的综合体现,总体效果最好.     

青岛地区海雾分布及大气边界层条件分析

青岛地区海雾多发,观测表明海雾对沿海地区影响范围不尽相同,特别是海雾影响内陆的机理尚缺乏研究。本文利用观测资料及数值模式统计了青岛地区4月-7月海雾分布特征,并对不同影响范围海雾典型个例进行对比分析,结果表明:海雾发生日数自沿海向内陆递减。胶州湾沿岸雾日数比黄海沿岸明显减少,胶州湾东北部的雾日数要少于胶州湾西北部。海雾多发生于高空形势稳定,低层偏南流场的天气条件下。大气边界层内逆温层的的范围大致影响着海雾的分布。只影响沿海的海雾,地面为偏南风,风速在3~8 m/s之间,内陆风力减弱不明显。500 m以下大气边界层内风速切变大。湍流作用使海雾向内陆推进过程中倾斜抬升为低云,地面雾区减弱。能够影响内陆地区的海雾,多出现在地面风力较弱的情况之下,大部分在1~3 m/s之间。500 m以下大气边界层内风速切变小,大气边界层内湍流强度不强,使沿海到内陆的逆温层能够始终维持,沿海海雾在弱南风影响下延伸影响内陆地区。     

Size-fractionated uranium isotopes in surface waters in the Jiulong Estuary in China

Surface water was collected from the Jiulong Estuary for determination of activity concentrations of uranium isotopes in different size fractions, namely, greater than 53, 10 -53, 2 - 10, 0.4 -2 μm, 10 000 u -0.4 μm and less than 10 000 u fractions by microfihration and cross-flow uhrafiltration technologies. Results indicated that most of the dissolved uranium （ 〈 0.4 μm） exis- ted in the low molecular mass fraction （ 〈 10 000 u）, and the colloidal uranium-238 （10 000 u -0.4 μm） only contributed less than 1% of the dissolved uranium-238. The fractions of colloidal uranium in the dissolved phases decreased with the increasing sa- linity. A positive linear relationship between uranium-238 activities and salinities was observed for the dissolved, colloidal and low molecular mass fractions, indicating a conservative behavior of uranium in the Jiulong Estuary. In the particulate phases （ 〉 0.4 μm）, the partitioning of uranium isotopes among different size fractions was controlled by the partitioning of particle concentrations. In the regions with salinities below 20, the partitioning of uranium-238 among different size fractions was as follows： 10 - 53 μm 〉 2 - 10 μm 〉 0.4 - 2 μm greater than above 53 μm. However, the order at the offshore station with salinities above 30 changed as follows ： 0.4 - 2 μm 〉 10 - 53 μm 〉 2 - 10 μm greater than above 53 μm. The fraction of the 0.4 - 2 μm particles increased at the offshore station, suggesting the increased contribution of the authigenic uranium. The activity ratio of uranium-234 to uranium-238 in the dissolved phases, including the low molecular mass fraction and the colloidal fraction, was larger than unity, showing the occurrence of excess uranium-234. In contrast, the activity ratio of uranium-234 to uranium-238 in all size fractions of the particulate phase was close to the equilibrium value （1.0）. The observed different values of the activity ratio of uranium-234 to uranium-238 in the dissolved phase and the partic     

Recent advances in marine technology in Canada

Much of the recent Canadian activity in marine technology has focused on development of capabilities in Arctic waters, and on the update and replacement of naval vessels. This paper describes some of the significant projects and programs now under way, and suggests future research and development requirements.     

一氧化氮在浮游植物中的研究进展

对一氧化氮在浮游植物中的研究进展进行了归纳,总结了一氧化氮对浮游植物生长的影响,探讨了浮游植物中一氧化氮的产生机制,并对今后的研究重点提出展望。     

Challenges in cross-sectoral marine protection in Europe

Marine environment protection in Europe faces a number of challenges. One is the coordination of relevant sectoral policies — such as agricultural and fisheries policies — with regard to marine protection objectives. The question in the following is on how marine protection issues can be more closely integrated in sectoral policies under the conditions prevailing at present. In particular the strength and weaknesses of the Marine Strategy Framework Directive (MSFD) as the key instrument for marine environment protection in Europe are analyzed in this context. In particular, the MSFD does not adequately address all sectors and policies which are relevant to marine environment protection. One possible means of giving the MSFD greater influences on other policies of relevance to marine waters is to integrate the objectives established under the MSFD in the European maritime policy. The aim should be to require the further development of sectoral policies to take unrestricted account of the objectives of the MSFD implementation process. But also other instruments of marine policy such as maritime spatial planning and marine protected areas are crucial to advance the protection of European seas.     

夏季珠江口沉积物中营养盐剖面分布和界面交换通量

通过对夏季珠江口区域沉积物间隙水营养盐剖面分析,调查了营养盐含量分布和特征,探讨了有机物的降解特性、营养盐的底部通量估算和作用.结果表明,珠江口沉积物间隙水中营养盐以高含量铵盐为主要的存在形式,沉积物中有机物的降解反应主要在厌氧状态下进行,底部水体铵盐的增加来源于底部沉积物有机质的降解释放,而且对水体的营养盐循环有较大的贡献.     

Recent progress in submarine geosciences in China

In China submarine geosciences represents a newly established discipline of oceanography, focusing on the oceanic lithosphere, and its interface with the hydrosphere and biosphere. Recently, supported by the National High Technology Research and Development Program and other high-tech development projects, significant progress has been made in the development of advanced technologies and equipment. This en- ables the scientists in China to carry out explorations of the international seabed area in the Pacific Ocean and on the Southwest Indian Ridge. In addition, they have been active in the research activities associated the mid-ocean ridges and western Pacific marginal seas. It is anticipated that this research field will continue to be highly fruitful in the near future.     

湄洲湾夏季的初级生产力

湄洲湾１９９２年夏季的叶绿素ａ，三磷酸腺苷，碳比积累速率，初级生产力的变化范围和均值分别为０．４５－４．７２，１．４９ｍｇ／ｍ＾３；０．１２－１．０７，０．３１μｇ／ｄｍ＾３；０．０６－０．５８，０．３４ｄ＾－１；０．０７－０．３４，０．２１ｍ／（ｍ＾２．ｄ）。叶绿素ａ与三磷酸腺苷之间。初级生产力与碳比积累速率之间均呈正相关关系。叶绿素ａ三磷本能腺苷的比值为４．８，湄洲湾夏季浮游植物的生长受氮不足     

Seasonality in nutrient concentrations in Galveston Bay

In order to investigate factors controlling nutrient cycling in the shallow and turbid coastal ecosystem of Galveston Bay, data from: (1) the Texas Water Commission (TWC) database 1980–1989, and (2) salinity transects in 1989 and 1993 are presented and analyzed. Statistical regression and time-series analysis were carried out on data acquired by TWC between 1980 and 1989, in an attempt to establish seasonally of nutrient and chlorophyll-a (chl.-a.) concentrations in the bay and to determine factors which regulate these concentrations.A strong seasonality was found for phosphorus and chl.-a. in the upper and mid-bay stations. A recurring maximum for phosphate occurred in September and a chl.-a. maximum occurred regularly in March–April. It is hypothesized that benthic regeneration of phosphorus at the end of summer is responsible for the phosphate maximum. The inverse correlation of the partition coefficient (K_d) for phosphate with the concentration of suspended particulate matter (SPM), coupled to a strong enrichment of phosphate in suspended particles at low SPM concentrations, indicates additional control by geochemical and physical processes such as particle sorting and/or particle-colloid interactions. Nitrate is inversely correlated with salinity at the upper and mid-bay stations, indicating the Trinity River is a major source.Nutrient concentrations in the lower bay (East and West Bay stations) are considerably lower and less predictable, as they are not correlated with salinity or temperature. Data from the 1989 and 1993 transects confirm the yearly maximum in phosphate concentration in late summer months, with peak concentrations in the upper Trinity Bay. It is concluded that despite possible phosphate buffering by physical and geochemical mechanisms, relatively large concentration maxima recur regularly every year during the summer, possibly caused by a benthic source of phosphate.