Bjerknes-like Compensation in the Wintertime North Pacific
Observational and model evidence has been mounting that mesoscale eddies play an important role in air–sea interaction in the vicinity of western boundary currents and can affect the jet stream storm track. What is less clear is the interplay between oceanic and atmospheric meridional heat transport in the vicinity of western boundary currents. It is first shown that variability in the North Pacific, particularly in the Kuroshio Extension region, simulated by a high-resolution fully coupled version of the Community Earth System Model matches observations with similar mechanisms and phase relationships involved in the variability. The Pacific decadal oscillation (PDO) is correlated with sea surface height anomalies generated in the central Pacific that propagate west preceding Kuroshio Extension variability with a ~3–4-yr lag. It is then shown that there is a near compensation of O(0.1) PW (PW ≡ 10^(15) W) between wintertime atmospheric and oceanic meridional heat transport on decadal time scales in the North Pacific. This compensation has characteristics of Bjerknes compensation and is tied to the mesoscale eddy activity in the Kuroshio Extension region.
© 2015 American Meteorological Society. Manuscript received 5 August 2014, in final form 18 February 2015. This work was supported by the Advanced Study Program at the National Center for Atmospheric Research (NCAR). We thank Ari Solomon and comments from two anonymous reviewers that greatly improved the manuscript. We also thank Alison Baker and Andy Mai for their assistance in running these experiments. Computational resources for the simulation analyzed here were provided by the NCAR Computational and Information Systems Lab (CISL) under the ''Accelerated Scientific Discovery'' program.
Published - jpo-d-14-0157.1.pdf