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Interannual Variability of the Natal Pulse
Author(s) -
Yamagami Yoko,
Tozuka Tomoki,
Qiu Bo
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015525
Subject(s) - barotropic fluid , eddy , anticyclone , advection , oceanography , meander (mathematics) , climatology , baroclinity , forcing (mathematics) , current (fluid) , altimeter , pulse (music) , environmental science , geology , geography , meteorology , turbulence , remote sensing , physics , geometry , mathematics , optics , detector , thermodynamics
Satellite altimetry data and high‐resolution model output are used to investigate the mechanism of interannual variations of the solitary meander in the Agulhas Current, called the Natal Pulse. It is shown that most of the Natal Pulses are triggered by anticyclonic eddies originating from the Southeast Madagascar Current (SEMC) and anticyclonic eddies of the Mozambique Channel are the secondary source. In addition to the barotropic conversion suggested by previous studies, the advection of eddy kinetic energy (EKE) plays a statistically significant role in the growth of the Natal Pulse. The number of anticyclonic eddies arriving at the Natal Bight largely explains the interannual variations in the Natal Pulse. The barotropic conversion from the SEMC, whose interannual variations are likely related to the remote wind forcing, is the main EKE source and corresponds well with the interannual variations of anticyclonic eddies generated off the southern coast of Madagascar. It is also shown that the interannual variations of the Natal Pulse are linked to large‐scale wind variability in the southern Indian Ocean.