Evaluation of the Three-Dimensional Structure of Velocity in the Central Equatorial Atlantic
PIs: Renellys Perez, Rick Lumpkin, Greg Foltz, and Verena Hormann
Collaborator: Fabrice Hernandez, William Johns, and Peter Brandt
The cross-equatorial structure of zonal currents in the central equatorial Atlantic has been described by observations, but much less is known about the meridional and vertical currents. The full three-dimensional structure of these currents plays an important role in the cold tongue surface mixed layer heat balance, and must be better represented in ocean models and coupled climate models. In this project, MERCATOR global ocean analyses are used in conjunction with measurements obtained from Prediction and Research Moored Array in the Tropical Atlantic (PIRATA) moorings, drifters, and satellites, to study the upper-ocean circulation in the central equatorial Atlantic during the past decade. The equatorial circulation is significantly modified by winds and transient phenomena such as westward propagating tropical instability waves (TIWs) and equatorial Rossby waves. From one year to the next the intensity of a TIW season can vary dramatically, and there have been consecutive years of high (2000-2002) and low (2006-2008) TIW intensity. To study how the equatorial circulation differs during these periods, we must first develop a systematic means to characterize the strength of a given TIW season and understand the mechanisms that are responsible for modulating its intensity.
Meridional-temporal structure of the MERCATOR near-surface (15 m) meridional velocity and divergence of meridional velocity along 23W during the 2009 TIW season. Black contours indicate surface temperatures of 25, 26, and 27C. A 8-day low-pass filter has been applied.
Perez, R. C., C. F. Lumpkin, W. E. Johns, G. Foltz, V. Hormann, 2011. Interannual varations of Atlantic tropical instability waves. J. Geophys, Res.