Formation and erosion of the seasonal thermocline in the Kuroshio Extension Recirculation Gyre
Cronin, Meghan F.
Bond, Nicholas A.
Farrar, J. Thomas
Jayne, Steven R.
MetadataShow full item record
Data from the Kuroshio Extension Observatory (KEO) surface mooring are used to analyze the balance of processes affecting the upper ocean heat content and surface mixed layer temperature variations in the Recirculation Gyre (RG) south of the Kuroshio Extension (KE). Cold and dry air blowing across the KE and its warm RG during winter cause very large heat fluxes out of the ocean that result in the erosion of the seasonal thermocline in the RG. Some of this heat is replenished through horizontal heat advection, which may enable the seasonal thermocline to begin restratifying while the net surface heat flux is still acting to cool the upper ocean. Once the surface heat flux begins warming the ocean, restratification occurs rapidly due to the low thermal inertia of the shallow mixed layer depth. Enhanced diffusive mixing below the mixed layer tends to transfer some of the mixed layer heat downward, eroding and potentially modifying sequestered subtropical mode water and even the deeper waters of the main thermocline during winter. Diffusivity at the base of the mixed layer, estimated from the residual of the mixed layer temperature balance, is roughly 3×10−4 m2/s during the summer and up to two orders of magnitude larger during winter. The enhanced diffusivities appear to be due to large inertial shear generated by wind events associated with winter storms and summer tropical cyclones. The diffusivity's seasonality is likely due to seasonal variations in stratification just below the mixed layer depth, which is large during the summer when the seasonal thermocline is fully developed and low during the winter when the mixed layer extends to the top of the thermocline.
This paper is not subject to U.S. copyright. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 85 (2013): 62-74, doi:10.1016/j.dsr2.2012.07.018.
Showing items related by title, author, creator and subject.
A comparison of in situ bottom pressure array measurements with GRACE estimates in the Kuroshio Extension Park, Jae-Hun; Watts, D. Randolph; Donohue, Kathleen A.; Jayne, Steven R. (American Geophysical Union, 2008-09-10)Ocean bottom pressure estimates from Gravity Recovery and Climate Experiment (GRACE) have been validated by comparisons with an array of in situ bottom pressure measurements. The 600 km by 600 km array comprised 46 bottom ...
Coupled atmosphere–mixed layer ocean response to ocean heat flux convergence along the Kuroshio Current Extension Kwon, Young-Oh; Deser, Clara; Cassou, Christophe (2010-01-28)The winter response of the coupled atmosphere-ocean mixed layer system to anomalous geostrophic ocean heat flux convergence in the Kuroshio Extension is investigated by means of experiments with an atmospheric general ...
Delman, Andrew S.; McClean, Julie L.; Sprintall, Janet; Talley, Lynne D.; Yulaeva, Elena; Jayne, Steven R. (American Meteorological Society, 2015-05)Eddy–mean flow interactions along the Kuroshio Extension (KE) jet are investigated using a vorticity budget of a high-resolution ocean model simulation, averaged over a 13-yr period. The simulation explicitly resolves ...