Rossby波是地球流体中的一种低频大尺度波动, 在全球海洋动力过程的调整中发挥着关键作用。利用1993~2011年多卫星高度计融合的月均海平面高度异常数据, 基于二维Radon变换方法提取了热带印度洋南北纬5°~20°区域的Rossby波纬向传播速度。结合斜压Rossby波的理论模型, 利用1993~2008年多年平均的简单海洋再分析数据集的温盐资料, 计算了自由线性的一阶斜压Rossby波的理论波速值。通过对比理论波速与高度计的观测波速, 发现在印度洋5°~20°S间理论值与观测值比较接近, 在5°~20°N间两者差别较大, 其误差可能来源于两个方面: 1) 该区域较多陆地阻隔引起了Rossby波的绕射和反射; 2) 多边界激发的多个Rossby波发生相互作用。利用卫星高度计观测提取的Rossby波波速计算了热带印度洋南北纬5°~20°范围内的Rossby波的变形半径, 给出了Rossby变形半径与纬度的解析表达式。该式能够很好地描述热带印度洋不同纬度的Rossby变形半径, 为今后热带印度洋Rossby波速的应用提供了理论和观测依据。
We estimated the Rossby wave phase speed in the tropical Indian Ocean (5°~20°S, and 5°~20°N) based on two- dimensional Radon Transform method, using monthly average sea level anomaly data (1993~2001) from multi-altimeters. We also calculated the first baroclinic gravity-wave phase speed, in combination with Rossby wave theoretical model, and the density by using climatologically averaged temperature and salinity profiles from the Simple Ocean Data Assimilation (SODA) reanalysis data (1993~2008). We found that Rossby wave phase speeds from model simulation and altimeter observations are in good agreement in 5°~20°S, but are quite different in 5°~20°N. The difference is possibly caused by 1) Rossby waves are diffracted and reflected by salient topographic features, and 2) interaction of Rossby waves generated by different boundaries. We computed the Rossby wave deformation radius utilizing the estimated phase speed, and further presented an analytic quadratic formula between latitude and deformation radius.
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