Multiple westward propagating signals in South Pacific sea level anomalies

Abstract

[1] The characteristics of multiple westward propagating signals in the satellite observed South Pacific sea level anomalies (SLA) between 10°S and 50°S are analyzed using the two-dimensional Radon transform (2D-RT). We test the hypothesis that these signals are most likely to be the signature of the first few baroclinic Rossby wave modes. This involves a comparison of the estimated phase speeds of the 2D-RT peaks against the first four baroclinic mode Rossby wave speeds predicted from the extended theory. The 2D-RT analysis typically identified up to three propagating signals in the SLA and very occasionally, a fourth. The first Radon transform (RT) peak phase speeds corresponded very well with first baroclinic mode Rossby wave phase speed estimates from linear theory between 15°S and 25°S and the extended theory phase speed estimates poleward of 25°S. RT peak 2 speeds were less coherent but fell within the range of extended theory estimates of the first four baroclinic Rossby wave modes, consistent with large-scale Rossby wave dynamics. The relationship between peaks 3 and 4 and the extended theory higher-order baroclinic mode speed estimates varied markedly across the basin. Regional variability in the spectral characteristics of the peaks suggests that different dynamical regimes dominate north and south of 30°S in the South Pacific basin. The presence of secondary peaks in the middle to high latitudes suggests that higher-order modes may play a role in these regions.

Propagating Modes of Variability and Their Impact on the Western Boundary Current in the South Atlantic

“…Phase speeds of all the modes north of 26°S have comparable magnitudes with that of the baroclinic mode 1 Rossby waves. This result is consistent with Maharaj et al (), who analyzed SSH anomalies in the South Pacific Ocean. South of 26°S, in the eddy corridor (Garzoli & Matano, ), phase speeds of the modes are larger than the theoretical values.…”

Climatology and seasonality of upper ocean salinity: a three-dimensional view from argo floats

“…7) with a leading timing along the equator. The tongue-shaped bending of thermohaline phases in the tropical oceans is highly consistent with the property of the first baroclinic mode of β-refracted annual Rossby waves, as Rossby waves of this kind are very common in this region (Chelton and Schlax 1996;Maharaj et al 2009). The phase speed as a function of latitude is calculated to examine if the salient phase migration is compatible to the theoretical Rossby wave model.…”

MultiTaper Method Singular Value Decomposition (MTM SVD): variabilidad espacio frecuencia de las fluctuaciones del nivel del mar en el Pacífico suroriental

“…Una de las principales características observadas en el patrón espacial de la frecuencia anual, reconstruido mediante el MTM-SVD, fue la generación costera y posterior propagación hacia el oeste de las anomalías en el nivel del mar, con una configuración similar al primer modo baroclino de una onda de Rossby. Previos estudios basados en registros satelitales, han mostrado como los primeros modos de las ondas de Rossby son las responsables de la mayor parte de la variabilidad del nivel del mar en el Pacífico suroriental (Cipollini et al, 1997;Killworth et al, 1997;Maharaj et al, 2009) y generan el arco de alta variabilidad en el nivel del mar que se observada en el presente estudio al norte de los 30°S (Wakata & Kitaya, 2002). Al sur de los 30°S, las diferencias en la velocidad de fase de las anomalías del nivel del mar respecto de la propagación teórica del primer modo baroclino de una onda de Rossby, han sido atribuidas a la presencia de modos baroclinos de orden mayor (Chelton & Schlax, 1996;Maharaj et al, 2009), a la presencia de remolinos de mesoescala (Leth & Shaffer, 2001;Hormazabal et al, 2004;Correa et al, 2007) y a una Figura 9.…”