热带大气的CISK-Rossby波和30-50天振荡

利用斜压准地转滤波方法，通过引入一个反映ＣＩＳＫ机制的无量纲凝结潜热参数η（Ｚ），建立了描述热带大气的ＣＩＳＫ－Ｒｏｓｓｂｙ波模式，并求得了该模式的解析解。理论研究表明，考虑ＣＩＳＫ机制的ＣＩＳＫ－Ｒｏｓｓｂｙ波与经典的Ｒｏｓｓｂｙ波有明显差别，它可较好地解释热带大气３０—５０ｄ振荡现象。     

青藏高原上空一次重力波过程的识别与天气影响分析

应用再分析资料、多套卫星反演资料和WRF中尺度数值模拟资料,识别了2005年1月10日青藏高原上空一次重力波过程,以及重力波对青藏高原西部降雪的影响。结果表明,此次重力波位于急流出口区的左方,以西南-东北走向覆盖青藏高原大部分地区。大尺度的冷暖平流相间分布和不断增强的非平衡流为重力波的形成提供了有利背景场。小波交叉谱分析显示垂直涡度与水平散度在对流层中层满足重力波的极化性质,在青藏高原西部的上升支对应有降雪过程发生。WRF可以较好地再现这一过程,并且能够模拟出再分析资料中无法分辨的中尺度重力波。数值模拟表明,青藏高原近地面强烈非绝热加热使得低层大气静力不稳定,在近地面暖区触发对流后引起高层凝结释放潜热,低层融化冷却,有利于激发重力波,并在其上升支产生固态凝结物,随后到来的冷气团提供了有利的水汽输送条件,大范围的弱抬升运动取代了原间隔进入降雪区的强对流上升支,使得固态凝结物得以落至地面,最终在青藏高原西部形成本次降雪过程。      

南海深水区水下溢油三维可视化模拟系统研发与应用

针对南海油气田勘探开发溢油污染防治需求,开发了国内首套深水区水下溢油三维可视化模拟系统,由三维海流预报模型、深水溢油模型、三维可视化仿真系统和数据库组成。海流预报模型基于ROMS模式,通过考虑波致混合影响,并利用最优插值技术同化卫星测高资料和嵌套技术,保障了预报结果的准确性。深水溢油模型由羽流模型和对流扩散模型组成,考虑了卷吸、油气分离、溶解、水合物生成、漂移、扩散等复杂过程。系统能够预测深水区水下油气泄漏后行为和归宿过程,提供油、气、天然气水合物粒子的大小、分布、移动速度和漂移轨迹、扩散面积、水体溢油残存量、水面溢油量等三维可视化动态模拟结果。目前系统已经在油气田勘探开发中得到应用,为南海深水溢油应急提供了重要支撑。     

夏季东亚季风与西太平洋副高对福建旱涝影响的诊断分析

利用NCEP/NCAR发布的850 hPa风场和OLR场以及福建38个站月降水资料, 分析了福建夏季旱涝与东亚夏季风及西太平洋副高的关系。结果表明夏季旱涝与夏季风强弱及副高南北位置密切相关。涝 (旱) 年在东亚季风系统中的热带季风环流出现异常加强 (减弱), 副热带季风环流则出现异常减弱 (加强); 涝年副高平均脊线位置偏北于27°N附近, 旱年则偏南于24°N附近; 由春入夏, 再由夏入秋副高南北位置的季节位移, 涝年先是急速北跳, 而后又急速南撤, 旱年却进退平缓。旱涝年东亚中高纬度环流亦表现出不同特征, 涝 (旱) 年一般没有 (有) 出现阻塞形势, 中纬度纬 (经) 向环流发展, 副热带锋区北抬 (南压), 研究还进一步揭示了夏季副高位置南北偏离影响夏季各月降水及其分布的不同形式。     

Simple features of mantle-wide convection and the interpretation of lower-mantle tomograms

Simple fluid dynamic constraints aid in the interpretation of lower mantle tomograms. The geothermal gradient away from slabs and plumes is subadiabatic between the upper (lithosphere) and lower (D″) boundary layers by ～400 K. Slabs widen proportionally with the square root of the viscosity as they sink through the lower mantle. The time scale for the persistence of slab graveyards at the base of the mantle is comparable to the time for plate motions to reorganize ～120–200 Myr. At most a few starting plume heads currently exist in the lower mantle. Tomographic inversions may include more sophisticated numerical-modeling versions of these constraints.     

Ventilation of the Black Sea pycnocline. Parameterization of convection, numerical simulations and validations against observed chlorofluorocarbon data

Data from field observations and numerical model simulations are used to understand and quantify the pathways by which passive tracers penetrate into the Black Sea intermediate and deep layers. Chlorofluorocarbon (CFC) concentrations measured during the1988 R.V. Knorr cruise show strong decrease with increasing density in the Black Sea and illustrate the very slow rate of ventilation of deep water in this basin. We develop a 3D numerical model based on the Modular Ocean Model (MOM), and calibrate it in a way to produce consistent simulations of observed temperature, salinity and CFCs. One important feature is the implementation of a special parameterization for convection, which is an alternative of the convective adjustment in MOM and handles the penetration of the Bosporus plume into the halocline. The model forcing includes interannually variable wind, heat and water fluxes constructed from Comprehensive Ocean–Atmosphere Data Set and ECMWF atmospheric analysis data and river runoff data. The analysis of observations and simulated data are focused on correlations between thermohaline and tracer fields, dynamic control of ventilation, and the relative contributions of sources at the sea surface and outflow from the Bosporus Strait in the formation of intermediate and deep waters. A simple theory is developed which incorporates the outflow from the strait along with the vertical circulation (vertical turbulent mixing and Ekman upwelling) and reveals their mutual adjustment. The analyses of simulated and observed CFCs demonstrate that most of the CFC penetrating the deep layers has its source at the sea surface within the Black Sea rather than from the Marmara Sea via the Bosporus undercurrent. Under present-day conditions, the surface CFC signals have reached only the upper halocline. Intrusions below 600 m are not simulated. The major pathways of penetration of CFCs are associated with cold-water mass formation sites, Bosporus effluent, as well as with the diapycnal mixing in the area of Rim Current. Future CFC sampling strategies coherent with the unique conditions in the Black Sea are discussed.     

Cascades of dense water around the world ocean

Dense water overflow off continental shelves (cascading) is one of the contributing processes of shelf-deep ocean exchange, and of topical interest to climate studies and nutrient fluxes. Dense water originating from cooling, evaporation, freezing and salinization on a shallow shelf spills over the shelf edge and may develop as near-bottom gravity current or an intermediate-depth intrusion. It is difficult to observe in nature due to its intermittent character.This paper provides an extensive inventory of observed cases of water cascades around the World Ocean, summarises their locations and individual properties, and provides statistics of the identified cases. The search for cascading was carried out using oceanographic databases and a literature review. This study identified 61 confirmed cases world-wide, including 25 cases in the Arctic seas, 12 at mid-latitudes, seven in sub-tropical and tropical regions, and 17 off the Antarctic shelves. Eighteen cascades had not been reported before. We analyze a set of numerical parameters of dense water cascades, allowing us to quantify, compare and contrast the properties of water cascades. The overall average density contrast between the confirmed cascades and ambient water is 0.37 (kg/m³); it can be as much as 2 (kg/m³) on some Arctic shelves. Frequently initiated by strong cooling at the surface, cascades often remain colder through the descent, thus supplying the deep ocean with colder and fresher water. In non-dimensional variables, the data from all climate zones fit well to a unique curve, which represents a relationship between a cascade’s internal structure and the parameters describing its forcing. On average, the down-slope volumetric flux provided by dense water cascades is estimated as 0.05 to 0.08 Sv per 100 km of shelf edge.Regional terms: Arctic, Antarctic, North Atlantic Ocean, Barents Sea, Mediterranean Sea, Skagerrak, Tasman Sea, Sea of Okhotsk     

从气象卫星资料揭示的青藏高原夏季对流云系的日变化

文中利用日本静止气象卫星观测的1981～1994年1天8次的TBB观测值和1978～1994年NOAA卫星观测的1天2次OLR观测值研究了青藏高原地区夏季对流云系季节变化以及对流云的日变化及其东西向移动规律,并对1994年的资料进行了个例分析。结果表明,青藏高原夏季对流云有极为明显的日变化,以00～05SUTC为最弱,15～17UTC最强。在季风雨爆发后的7月中旬到8月上旬在高原中部（30～32°N,90°E）、东部（30°N,97°E）和西部（30°N,85～87°E）有3个TBB低值中心,多年月平均对流中心区云顶高度可达9．6km,而旬对流中心个别地区平均可达13km。对流云区开始发展于东部地区,随后对流云中心逐步向西移动,并于7月中下旬达到最西,此时西部地区从多年平均而言可以有短暂的强对流发展。     

南海夏季风爆发与海温和大气对流的低频变化

根据云顶黑体温度（ＴＢＢ）相位变化并参考西沙站海面温度（ＳＳＴ）状况确定了南海夏季风爆发时间,分析研究了与夏季风爆发时间和强度有关的ＴＢＢ和ＳＳＴ变化过程,结果表明：南海夏季风爆发平均时间是５月第４候,爆发的时间和强度有显著的年际变化,爆发期间的海气状况与大气的低频振荡密切相关。夏季风爆发早年（５月第２候）,大气对流活动较强,西南风较强,海温下降我年（６月第１候）情况则相反;它爆发的强度还与爆发期     

地幔对流的实验研究:非立柱状幔柱和地幔涡旋

地幔对流的物理模拟实验结果表明 ,在地幔介质和温度非均匀分布的复杂条件下 ,热卷流 (地幔柱 )往往由立柱状转变为非立柱状 (含斜柱状、涡旋状等 )。在忽略科里奥利力的情况下 ,板块的下插和滞积下沉、岩石圈根的存在以及地幔介质粘度的非均匀分布等都可能构成不同形状的障碍 -导流体 ,导致地幔的涡旋运动。软流圈中的水平涡旋环带属于对数螺线型 ,环带旋转半径及线速度逐渐减小 ,最终在旋转中心处下沉 ,而旋转角速度大致保持恒定