Neto, A. G., Palter, J., Bower, A., Furey, H., & Xu. X. (2020). Labrador Sea Water transport across the Charlie-Gibbs Fracture Zone. J. Geophys. Res. Oceans , Accepted .
Abstract: Labrador Sea Water (LSW) is a major component of the deep limb of the Atlantic Meridional Overturning Circulation, yet LSW transport pathways and their variability lack a complete description. A portion of the LSW exported from the subpolar gyre is advected eastward along the North Atlantic Current and must contend with the Mid‐Atlantic Ridge before reaching the eastern basins of the North Atlantic. Here, we analyze observations from a mooring array and satellite altimetry, together with outputs from a hindcast ocean model simulation, to estimate the mean transport of LSW across the Charlie Gibbs Fracture Zone (CGFZ), a primary gateway for the eastward transport of the water mass. The LSW transport estimated from the 25‐year altimetry record is 5.3 ± 2.9 Sv, where the error represents the combination of observational variability and the uncertainty in the projection of the surface velocities to the LSW layer. Current velocities modulate the interannual to higher frequency variability of the LSW transport at the CGFZ, while the LSW thickness becomes important on longer time scales. The modeled mean LSW transport for 1993‐2012 is higher than the estimate from altimetry, at 8.2 ± 4.1 Sv. The modeled LSW thickness decreases substantially at the CGFZ between 1996 and 2009, consistent with an observed decline in LSW volume in the Labrador Sea after 1994. We suggest that satellite altimetry and continuous hydrographic measurements in the central Labrador Sea, supplemented by profiles from Argo floats, could be sufficient to quantify the LSW transport at the CGFZ.
Nunez, R. H. (1996). A study of the ocean circulation off the coast of Chile . Ph.D. thesis, Florida State University, Tallahassee, FL.
Nunez, R. H. (1996). A Study of the Ocean Circulation Off the Coast of Chile . COAPS Technical Report, 96(4). Tallahassee, FL: Center for Ocean-Atmospheric Prediction Studies, Florida State University.
Nyadjro, E. S., Rydbeck, A. V., Jensen, T. G., Richman, J. G., & Shriver, J. F. (2020). On the Generation and Salinity Impacts of Intraseasonal Westward Jets in the Equatorial Indian Ocean. J. Geophys. Res. Oceans , 125 (6), e2020JC016066.
Abstract: While westerly winds dominate the equatorial Indian Ocean and generate the well‐known eastward flowing Wyrtki Jets during boreal spring and fall, there is evidence of a strong westward surface jet during winter that is swifter than eastward currents during that season. A weaker westward jet is found in summer. In this study, we report the occurrence, characteristics, and intraseasonal variability of this westward jet and its impact on mixed layer salinity in the equatorial Indian Ocean using the HYbrid Coordinate Ocean Model (HYCOM) reanalysis with the Navy Coupled Ocean Data Assimilation (NCODA). The westward jet typically occurs in the upper 50 m, above an eastward flowing equatorial undercurrent, with peak westward volume transport of approximately −8 Sv. The westward jet builds up gradually, decays rapidly, and is primarily forced by local intraseasonal wind stress anomalies generated by atmospheric intraseasonal convection. Westward acceleration of the jet occurs when the dominant intraseasonal westward wind anomaly is not balanced by the zonal pressure gradient (ZPG) force. The intraseasonal westward jet generates strong horizontal advection and is the leading cause of mixed layer freshening in the western equatorial Indian Ocean. Without it, a saltier mixed layer would persist and weaken any barrier layers. Existing barrier layers are strengthened following the passage of freshwater‐laden westward jets. Deceleration of the westward jet occurs when the eastward ZPG becomes increasingly important and the westward intraseasonal wind anomalies weaken. A rapid reversal of atmospheric intraseasonal convection‐driven surface winds eventually terminates the westward jet.
O'Brien, J., Richards, T. S., & Davis, A. C. (1996). The effect of El Nino on U.S. landfalling hurricanes. Bulletin of the American Meteorological Society , 77 (4), 773–774.
O'Brien, J. J., & Bourassa, M. A. (2000). Scatterometry at COAPS. In Proceedings of the Ocean Vector Wind Science Team Meeting, Arcadia, CA, USA .
O'Brien, J. J., Bourassa, M. A., & Smith, S. R. (2005). Climate variability in ocean surface turbulent fluxes . Annual Report: The State of the Ocean and the Ocean Observing System for Climate. Silver Spring, MD, 20910. USA: NOAA Office of Climate Observation.
O'Brien, J. J., Bourassa, M. A., & Smith, S. R. (2005). U.S. research vessel surface meteorology data assembly center . Annual Report: The State of the Ocean and the Ocean Observing System for Climate. Silver Spring, MD, 20910. USA: NOAA Office of Climate Observation.
O'Brien, J. J., Zierden, D. F., & Griffin, M. (2002). Long-term Forecasting of Wildfire season severity in Florida . Technical Report 02-2. Tallahassee, FL: Center for Ocean-Atmospheric Prediction Studies, Florida State University.
O'Brien, J. J., Richards, T. S., & Davis, A. C. (1996). The effect of El Nino on US landfalling hurricanes. Bulletin of the American Meteorological Society , 77 (4), 773–774.
