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首页> 外文期刊>Journal of Geophysical Research, C. Oceans: JGR >The dynamics of wind-driven intraseasonal variability in the equatorial Indian Ocean
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The dynamics of wind-driven intraseasonal variability in the equatorial Indian Ocean

机译：赤道印度洋风驱动的季节内变化的动力学

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Variability in the equatorial Indian Ocean on intraseasonal time scales (defined as periods of 30-110 days) is investigated using satellite and in situ observations and a simple analytical linear long-wave equatorial β-plane model. Despite the extreme simplicity of the model, which includes just the two gravest baroclinic mode Kelvin waves and first meridional mode Rossby waves, simulated surface zonal velocity and sea surface height compare very well with observations. Both observations and model are characterized by a red shift in the velocity spectrum relative to the wind forcing spectrum, which is attributable to a combination of factors, including (1) the near resonant excitation of Kelvin waves by eastward propagating winds, (2) constructive interference between wind-forced waves and Rossby waves reflected from the eastern boundary, and (3) the favored excitation of low-frequency waves whose zonal wavelengths are long compared to the zonal fetch of the wind. We decomposed variability in two broad period bands, namely, 30-70 days and 70-110 days, for detailed analysis. At periods of 30 70 days, zonal velocity tends to be stationary in the directly forced region along the equator owing to the competing contributions of Kelvin and Rossby waves. In contrast, at 70-110 day periods, zonal velocity propagates westward despite eastward propagation of zonal wind stress because of the combined influence of eastern boundary generated and wind-forced Rossby waves. Kelvin waves reflected from the western boundary are negligibly small, indicating that basin mode resonances are not prominent as has been previously suggested.
机译：利用卫星和原地观测以及简单的线性长波赤道β平面线性分析模型，研究了赤道​​印度洋在季节内时间尺度（定义为30-110天）上的变化。尽管该模型极其简单，仅包括两个最严重的斜斜模式开尔文波和第一子午模式罗斯比波，但模拟的地表纬向速度和海面高度与观测值相比还是非常好。观测和模型都以速度谱相对于强迫谱的红移为特征，这归因于多种因素的组合，包括（1）向东传播的风对开尔文波的近共振激发，（2）构造性的风力波与从东部边界反射的Rossby波之间的干扰;（3）纬向波长比风向波长的低频波受到激励。为了详细分析，我们在30-70天和70-110天这两个广泛的时间段内分解了变异性。在30 70天期间，由于开尔文波和罗斯比波的竞争作用，沿赤道的直接受力区域地带速度趋于平稳。相反，在70-110天的时间段内，纬向风速向西传播，尽管纬向风应力向东传播，这是由于东部边界生成和强风Rossby波共同作用的结果。从西边界反射的开尔文波很小，可以忽略不计，这表明盆地模式的共振并不像以前所建议的那样突出。

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