Oceanic pycnocline depth retrieval from SAR imagery in the existence of solitary internal waves

Oceanic pycnocline depth is usually inferred from in situ measurements. It is attempted to estimate the depth remotely. As solitary internal waves occur on oceanic pycnocline and propagate along it, it is possible to retrieve the depth indirectly in virtue of the solitary internal waves. A numerical model is presented for retrieving the pycnocline depth from synthetic aperture radar （SAR） images where the solitary internal waves are visible and when ocean waters are fully stratified. This numerical model is constructed by combining the solitary internal wave model and a two-layer ocean model. It is also assumed that the observed groups of solitary internal wave packets on the SAR imagery are generated by local semidiurnal tides. A case study in the East China Sea shows a good agreement with in situ CTD （conductivity-temperature-depth） data.     

Marine Upper Triassic Fossils from Kochiu, Yunnan

INTRODUCTION The material which forms the present study is collected by Messrs.H. M. Meng, K. Chern and T. Ho from the village of Hopachung, near Kochiu,Yunnan province. According to them, the fossils are recorded from seven localities.     

Distinctive MJO Activity during the Boreal Winter of the 2015/16 Super El Nino in Comparison with Other Super El Nino Events

Many previous studies have demonstrated that the boreal winters of super El Nino events are usually accompanied by severely suppressed Madden-Julian oscillation(MJO) activity over the western Pacific due to strong descending motion associated with a weakened Walker Circulation. However, the boreal winter of the 2015/16 super El Nino event is concurrent with enhanced MJO activity over the western Pacific despite its sea surface temperature anomaly(SSTA)magnitude over the Nino 3.4 region being comparable to the SSTA magnitudes of the two former super El Nino events(i.e.,1982/83 and 1997/98). This study suggests that the MJO enhanced over western Pacific during the 2015/16 super El Nino event is mainly related to its distinctive SSTA structure and associated background thermodynamic conditions. In comparison with the previous super El Nino events, the warming SSTA center of the 2015/16 super El Nino is located further westward, and a strong cold SSTA is not detected in the western Pacific. Accordingly, the low-level moisture and air temperature(as well as the moist static energy, MSE) tend to increase in the central-western Pacific. In contrast, the low-level moisture and MSE show negative anomalies over the western Pacific during the previous super El Nino events.As the MJO-related horizontal wind anomalies contribute to the further westward warm SST-induced positive moisture and MSE anomalies over the western tropical Pacific in the boreal winter of 2015/16, stronger moisture convergence and MSE advection are generated over the western Pacific and lead to the enhancement of MJO convection.     

分层密度流体的边界波动在不透水刚性底床的运动行为——Ⅱ分层条件对传动波型的影响

在两层流体中,内波的特性受到许多控制变因的影响,其中包括上下层水深比、造波区位能差(位能大小)、上下层的密度比等。本文以成功大学水工试验所研发的MNDAS套装软件记录,协助数据分析及处理,研究上下层水深比对内波波型的影响,当水深比值差异越大造成的孤立波形与明显,且Kdv及修正mKdV可以合理描述内波振幅与频率之间的关系。     

分层密度流体的边界波动在不透水刚性底床的运动行为——Ⅰ造波条件对波型演化的关系

在一座二维内波实验水槽(12 m×0.7 m×0.5 m)、于总水深H等于40 cm的条件下,以淡、盐水依密度分层布置的两层流体,从事孤立内波生成的研究。内波水槽内的上下层水深比H₁/H₂、造波区位能差(η₀)、上下层的密度比皆为实验主要的控制变因。在各种不同实验条件配合之下,试验及比较以上变因对内波振幅能量及相关传递系数的影响,进而产生几种不同的波动特性:上举型孤立内波、下沉形孤立内波、非周期性的重力内波等,且不同形式的重力内波需要配合固定的造波条件使能达成。     

夏季东亚热带和副热带地区经向和纬向环流型的特征

根据1958年7月8—18日和1957年7月21—30日东亚低纬度的两个悬殊的环流型,分析了在这两个时期内东亚低纬度环流的各种特征。结果得出,在经向和纬向环流期间,无论北半球纬向风带的位置,长波系统的配置,副热带高压活动的情况以及赤道辐合区的分布都有着很大的不同。此外,台风活动的次数也表现有很大悬殊。其所以有如此悬殊,可以从该两时期低纬度流场的特点来说明原因。在中国大陆上,在这两个时期的天气过程也很不同,在经向环流期间,大陆上的主要雨带成东北—西南向的,而在纬向环流期间,雨带便成东西向分布,并集中在江淮流域之间。 另外,我们又研究了在这两个时期内南北半球间环流关系,从手头所掌握的资料分析结果看,两者关系相当密切。在东亚低纬度经向环流期间,南半球(特别在澳洲)也盛行经向环流,并且在澳洲附近从南半球向北半球的质量输送也最强烈;而在东亚低纬度纬向环流期间,南半球也盛行纬向环流,澳洲附近的冷空气活动不显著,越过赤道向北的质量输送也比较弱。     

起伏条件下重力碰并造成的暖性薄云降水

本文中考虑了云中垂直气流的湍流起伏,来計算云滴的碰并增长.发現在这种上升气流有起伏的环境下,同样大小的云滴在云中可以长成不同大小的較大云滴,包括降水胚滴和降水微元(雨滴),从而对暖性薄云如何形成降水給出一个此較合理的解释。