基于MODIS遥感影像的直布罗陀海峡内波传播特性研究

Propagation Characteristics of Internal Waves in the Strait of Gibraltar Based on MODIS Remote Sensing Images

选用2014—2016年直布罗陀海峡地区中分辨率成像光谱仪(MODIS)观测图像作为数据源,获得了内波时空分布特征。光学遥感图像观测到内波在Camarinal海底山脊东侧生成,集中分布在地中海西部,呈弧形向东传播;内波的时间分布表现为随季度呈周期性变化,每年的第二、三季度为内波活跃期。为了进一步研究直布罗陀海峡内波的生成与传播特性,使用麻省理工学院通用环流模型(MITgcm),通过海面高程变化、等温线变化分析半日潮与海底山脊的相互作用,在海峡口附近生成弧形向东内波,随着水深增大,频散效应增强,振幅减小。在传播过程中,内波分裂成波包,波峰线之间的宽度和弧形半径增大,波包中内波的数目增多。模拟计算结果与光学遥感观测结果一致。

The moderate-resolution imaging spectroradiometer （MODIS） images from 2014 to 2016 are collected in the Strait of Gibraltar （SOG）. The temporal and spatial characteristics of internal waves are analyzed statistically based on MODIS images. The optical remote sensing images show that internal waves generate at the east of Camarinal sill, and concentrate at the western Mediterranean. The eastward propagation internal waves have arc-like shape. The temporal distribution of internal waves shows that the majority of internal waves are observed in the second and third quarters. The generation and propagation characteristics of internal waves in the SOG are further studied by Massachusetts Institute of Technology general circulation model （MITgcm）. Through the change of surface elevations and isotherms, the interaction between barotropic tide and the sill of the SOG is analyzed. The arc-like eastward internal waves are generated nearby the jaw. The amplitude decreases with the increase of water depth and the strengthening of dispersion effect. The east propagating internal waves disintegrate into a train of rank-ordered internal waves packets in the process of propagation. In addition, the width between the crest lines and the radius of the arc-like crest line increase. The number of inertial wave in the wave packet increases. The simulation results are consistent with the results observed by optical remote sensors.