南亚高压季节变化中的正斜压环流转换特征

利用１９５８～１９９７ 年的 Ｎ Ｃ Ｅ Ｐ／ Ｎ Ｃ Ａ Ｒ 再分析资料，采用将大气环流在垂直方向分解为正压和斜压环流两个分量的方法，讨论了南亚高压季节演变中的正斜压环流的转换特征。指出（１）夏季，南亚高压以斜压性为主，其斜压分量约占 ７０ ％ 的比重，冬季以正压性为主，其正压分量约占 ７０ ％ 的比重；（２）由冬季的正压性高压向夏季的斜压性高压的季节演变中，南亚高压是在其斜压分量环流的引导下移动的，即其斜压分量环流的变化超前于其自身的变化；（３）由夏季的斜压性高压向冬季的正压性高压的季节演变则相反，南亚高压是在其正压分量环流的引导下移动的。

黄、东海环流的数值研究IV——斜压环流的诊断计算

基于黄、东海Lagrange环流数值模型 ,对黄、东海Lagrange斜压环流进行了诊断计算。采用流速分解法将La grange流速分解为梯度流、风海流、潮致余流、热盐环流、零阶环流耦合流 5种分量 ,实现三维计算的准二维化。计算结果较成功地模拟了冬夏两季黄、东海Lagrange环流 ,表明密度环流在冬、夏季均是东海环流的重要分量 ,可显著增强了东海黑潮、东海黑潮、台湾暖流和对马暖流 ;在夏季还是黄海环流的主要分量。

黄、东海环流的数值研究V——斜压环流的动力调整

由于温盐变化对Lagrange环流的重要性,采用1种在流体静力一致条件下保证收敛的有效差分格式,在σ坐标下求解斜压梯度力,将此方法引入黄、东海Lagrange环流模式,引入温盐输运方程,对陆架区以内黄、东海的夏季环流实现了斜压环流的动力调整,并与诊断计算的斜压环流进行了对比分析。结果表明:经过动力调整的夏季总环流与诊断计算的夏季总环流总体趋势一致,但经过动力调整的夏季斜压环流在济州岛西南附近形成了封闭的逆时针环流,并且在陆架边缘海槽附近明显地形成了较大的沿黑潮流向环流,而诊断计算的斜压环流不明显。分析2种斜压环流在总环流中所占的比例,结果表明:在黄、东海北部,2种斜压环流占总环流的比例基本一致,但在陆架海槽附近,黑潮流向上经过动力调整的斜压环流所占比例要比诊断计算的斜压环流大得多,说明在该区域对环流有必要进行动力调整。

污染物在河口中的混合与离散(上)

河口的混合与离散特性是河口污染治理及合理开发其环境容量的一个基本问题。本文综合分析了国内外的研究工作,对河口混合的成因与特点,研究途径,混合输移方程,离散的机制,离散系数的概念与计算方法作了概括与总结,在此基础上对今后河口混合的研究工作提出了一些看法。

Impacts of Indonesian Throughflow on seasonal circulation in the equatorial Indian Ocean

Impacts of the Indonesian Throughflow(ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing from NCEP reanalysis data during 2000–2011. It can reproduce vertical profiles of mean density and buoyancy frequency of World Ocean Atlas 2013 data. The model also simulates well annual oscillation in the central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies(SLA) using satellite altimeter data, as well as the semiannual oscillation of surface zonal equatorial currents of Ocean Surface Current Analyses Real Time current data in the equatorial Indian Ocean. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on LICOM output. Wave analysis suggests that ITF blockage mainly influences waves generated from the Indian Ocean but not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillations of SLA and zonal current dif ferences in the equatorial Indian Ocean associated with ITF. Reconstructed ITF-caused SLA using wave decomposition coefficient dif ferences between closed and open ITF-passage experiments suggest both Kelvin and Rossby waves from the first baroclinic mode have comparable contributions to the semiannual oscillations of SLA diff erence. However, reconstructed ITFcaused surface zonal currents at the equator suggest that the first meridional-mode Rossby wave has much greater contribution than the first baroclinic mode Kelvin wave. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has a greater contribution than other baroclinic modes.