Seasonal and interannual variations in the Indian Osean

印度海洋的季节和年际变化

基本信息

批准号：
06452085
负责人：
YAMAGATA Toshio
金额：
$ 4.67万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06452085/
关键词：
Indian Ocean Ocean General Circulation Model Monsoon Seasonal Variations Interannual Variations Indonesian Throughflow Nondispersive Long Possby Waves Coastal Trapped Waves ロスビー長波海洋物理学吉田-Wyrtkiジェットケルビン・ジェット

项目摘要

A holizontally high resolution Indo-Pacific ocean general circulation model, which can resolve the detailed geometry and bottom topography in the Indonesian archipelago as well as the whole Indo-Pacific region, is developed and used to investigate seasonal and interannual variations in the upper layr thermal structure and the circulation in the Indian Ocean and the Indonesian Throughflow. The outcomes of this study are as follows :(1) Simulated seasonal variability of the Indonesian Throughflow, seasonal and interannual variations of the upper layr thermal structure in the Indian Ocean are both consistent with the observed data such as the XBT and CTD data, the sea surface height variations derived from satellites, the surface drifting buoys, and the tide gauge dada. This indicates that the numerical model is an efficient tool to investigate the seasonal and the interannual variability in the Indian Ocean.(2) The seasonal variability of the Lombok throughflow consists of the annual and … More the semiannual harmonics. While the annual siganl is forced by the local monsoonal winds over the Indonesian archipelago, the semiannual signal is associated remotely with the Kelvin waves generated twice a year during the monsoon transition time in the central equatorial Indian Ocean. On the other hand, the coastally trapped waves around Australasia, which are forced by the winds along the southwestern coast of Australia associated with the meridional movement of the southern hemisphere westerlies, play an important role in the seasonal transport variation through the Timor Sea. Furthermore, the simulated annual-mean Throughflow does not show the simple Sverdrup dynamical balance. It turns out that considerable concellation of terms in the momentum equation is involved in producing a near-Sverdrup balance in the model.(3) The seasonal and the interannual variations of the simulated and the observed depth of the 20ﾟC isotherm show a band of large amplitude between 8ﾟS and 20ﾟS across the Indian Ocean, and the signals propagate to the west. The generation of those signals is well explained by a simple model which consists of the local Ekman pumping velocity and the nondispersive, long Rossby waves. The signal radiating from the eastern boundary of the Indian Ocean contributes only about 10% of the annual signal ; however, it affects the interannual variations in the eastern part of the southern tropical Indian Ocean. Less

开发了水平高分辨率印度-太平洋大气环流模型，该模型可以解析印度尼西亚群岛以及整个印度-太平洋地区的详细几何形状和底部地形，并用于研究上层热量的季节和年际变化研究结果如下：(1)模拟了印度洋环流的季节变化、上层的季节变化和年际变化。印度洋热力结构与XBT、CTD等观测数据、卫星海面高度变化、海面漂流浮标、潮汐计数据等均一致，表明该数值模型是有效的。研究印度洋季节性和年际变化的工具。(2) 龙目岛通流的季节变化由年度和半年度谐波组成，而年度信号则受当地影响。印度尼西亚群岛上空的季风，半年信号与赤道印度洋季风过渡期间每年两次产生的开尔文波远程相关，而澳大利亚周围的沿海困波则受到洋流的强迫。沿着澳大利亚西南海岸的风与南半球西风带的经向运动有关，在帝汶海的季节性运输变化中发挥着重要作用。此外，模拟年平均流量没有表现出简单的斯维尔德鲁普动态平衡，结果表明，在模型中产生近斯维尔德鲁普平衡涉及动量方程中的大量项的叠加。(3)模拟的季节和年际变化。 20°C等温线的观测深度显示出横跨印度洋的8°S至20°S之间的大振幅带，信号向西传播。这些信号的产生可以通过一个简单的模型得到很好的解释，该模型由当地的埃克曼泵速和非色散长罗斯贝波组成，但从印度洋东部边界辐射的信号仅占年度信号的 10% 左右。对南热带印度洋东部地区的年际变化影响较小。