Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean
Observations of the Dispersion Characteristics and Meridional Sea Level Structure of Equatorial Waves in the Pacific Ocean
复制标题
DOI：
10.1175/2007jpo3890.1
复制
发表时间：
2008-08
影响因子：
3.5
通讯作者：
J. Farrar
中科院分区：
文献类型：
--
作者：
J. Farrar
应用于测高数据的光谱技术用于检查赤道太平洋中周期约为 20 至 200 天的波状变化的色散关系和经向海平面结构。海面高度的纬向波数-频率功率谱，在大约 7°S–7°N 范围内平均时，在第一斜压模式赤道开尔文波和罗斯贝波的理论色散曲线附近表现出谱峰。在第一和第二子午模罗斯贝波色散曲线附近有明显的、统计上显着的功率脊。理论开尔文波和第一子午模罗斯贝波色散曲线附近的海平面变化主要（但不完全）关于赤道对称，而理论第二子午模罗斯贝波色散曲线附近的海平面变化主要是反对称的。这些结果在质量上与经典或剪切修正的赤道波理论的预期一致。这些模式的子午结构类似于赤道波理论的子午模式，但子午剖面有一些未预料到的稳健特征。季节内开尔文波段的经向海平面结构与理论上预期的高斯剖面非常相似，但在远至 11.75°S 处也检测到与赤道一致的海平面变化，这可能是这些开尔文波的强迫性质的结果。第一和第二经向模罗斯贝波在北半球都有较大的振幅。热带不稳定波的经向海平面结构与莱曼等人的预测非常相似。使用关于现实赤道纬向流系统的线性化模型。
Spectral techniques applied to altimetry data are used to examine the dispersion relation and meridional sea level structure of wavelike variability with periods of about 20 to 200 days in the equatorial Pacific Ocean. Zonal wavenumber–frequency power spectra of sea surface height, when averaged over about 7°S–7°N, exhibit spectral peaks near the theoretical dispersion curves of first baroclinic-mode equatorial Kelvin and Rossby waves. There are distinct, statistically significant ridges of power near the first and second meridional-mode Rossby wave dispersion curves. Sea level variability near the theoretical Kelvin wave and first meridional-mode Rossby wave dispersion curves is dominantly (but not perfectly) symmetric about the equator, while variability near the theoretical second meridional-mode Rossby wave dispersion curve is dominantly antisymmetric. These results are qualitatively consistent with expectations from classical or shear-modified theories of equatorial waves. The meridional structures of these modes resemble the meridional modes of equatorial wave theory, but there are some robust features of the meridional profiles that were not anticipated. The meridional sea level structure in the intraseasonal Kelvin wave band closely resembles the theoretically expected Gaussian profile, but sea level variability coherent with that at the equator is detected as far away as 11.75°S, possibly as a result of the forced nature of these Kelvin waves. Both first and second meridional-mode Rossby waves have larger amplitude in the Northern Hemisphere. The meridional sea level structure of tropical instability waves closely resembles that predicted by Lyman et al. using a model linearized about a realistic equatorial zonal current system.