Two Lateral Stirring Regimes in the Northeast Pacific. Talbot, L. C., Klymak, J. M., Ross, T., & Han, G. JGR Oceans, 131(3):e2025JC023699, 2026.
doi  abstract   bibtex   
Abstract Lateral stirring is a key process shaping the physical and biogeochemical state of the ocean, yet it remains under-sampled and poorly understood, particularly at submesoscales (1–80 km). Along Line P, a long-term transect in the Northeast Pacific, lateral stirring was characterized using 15 glider lines with an effective horizontal resolution of 3 km, collected between September 2019 and December 2024. Temperature anomalies along an isopycnal reveal distinct offshore and nearshore lateral stirring regimes and significant inter-annual variability, particularly in the offshore regime. Nearshore, tracer gradient spectra follow a power-law of , and thus have a weighting toward more high wavenumber variance than many previous studies, but less than predicted by Surface Quasi-Geostrophy or Interior-Quasi Geostrophy. Offshore, tracer gradient spectra vary with eddy activity: slopes follow in the submesoscale during active periods and , consistent with Kolmogorov scaling, during quieter phases. Large-scale temporal changes in the temperature field are also seen, marked by shifts in water mass circulation and temperature range, though the driving mechanisms remain uncertain. To contextualize these observations, a regional ocean model is analyzed. Simulated temperature variability was consistent with glider observations in the mesoscale but underestimated at the submesoscale and did not have the distinct regime change between the nearshore and offshore waters. These discrepancies suggest that the model parameterizations of lateral stirring should be investigated and possibly improved. , Plain Language Summary The mixing of nutrient-rich coastal water with nutrient-poor open-ocean water in the Northeast Pacific (NEP) is critical to both human and ecological life, yet the processes driving this motion are not understood. Recent advances in technology now allow us to send robotic vehicles, commonly referred to as gliders, to 1,000 m depths and across 1000s of kms measuring ocean properties at the small scales necessary to observe this mixing. We drove a glider along a transect connecting from Vancouver Island out to the middle of the NEP (1,400 kms) 15 times to study how the ocean stirs. Near the coast, stirring patterns remain consistent with time and depth. Offshore, however, the stirring statistics changed depending on the presence of eddies, swirling currents that carry coastal water offshore. Over the study period, we also observed warmer water moving nearshore and colder water appearing offshore, suggesting that changes in regional ocean circulation introduced new water masses along the transect. Finally, we compared our observations with a computer simulation and found that the simulation sometimes underestimated key features, like the strength of circulation and stirring at small scales ($<$80 km), which could be improved by fine tuning the model parameters. , Key Points The number of mesoscale eddies and the width of subtropical-influenced water along Line P varies significantly from year to year There are two contrasting stirring regimes along Line P, neither explained by Surface Quasi-Geostrophy theory Regional model shows consistent mesoscale stirring but less submesoscale stirring and does not show regime differences
@Article{	  talbotetal26a,
  Title		= {Two {{Lateral Stirring Regimes}} in the {{Northeast
		  Pacific}}},
  Author	= {Talbot, Lauryn C. and Klymak, Jody M. and Ross, Tetjana
		  and Han, Guoqi},
  Year		= 2026,
  Journal	= {JGR Oceans},
  Volume	= {131},
  Number	= {3},
  Pages		= {e2025JC023699},
  DOI		= {10.1029/2025JC023699},
  URLDate	= {2026-03-14},
  Abstract	= {Abstract Lateral stirring is a key process shaping the
		  physical and biogeochemical state of the ocean, yet it
		  remains under-sampled and poorly understood, particularly
		  at submesoscales (1--80~km). Along Line P, a long-term
		  transect in the Northeast Pacific, lateral stirring was
		  characterized using 15 glider lines with an effective
		  horizontal resolution of 3~km, collected between September
		  2019 and December 2024. Temperature anomalies along an
		  isopycnal reveal distinct offshore and nearshore lateral
		  stirring regimes and significant inter-annual variability,
		  particularly in the offshore regime. Nearshore, tracer
		  gradient spectra follow a power-law of , and thus have a
		  weighting toward more high wavenumber variance than many
		  previous studies, but less than predicted by Surface
		  Quasi-Geostrophy or Interior-Quasi Geostrophy. Offshore,
		  tracer gradient spectra vary with eddy activity: slopes
		  follow in the submesoscale during active periods and ,
		  consistent with Kolmogorov scaling, during quieter phases.
		  Large-scale temporal changes in the temperature field are
		  also seen, marked by shifts in water mass circulation and
		  temperature range, though the driving mechanisms remain
		  uncertain. To contextualize these observations, a regional
		  ocean model is analyzed. Simulated temperature variability
		  was consistent with glider observations in the mesoscale
		  but underestimated at the submesoscale and did not have the
		  distinct regime change between the nearshore and offshore
		  waters. These discrepancies suggest that the model
		  parameterizations of lateral stirring should be
		  investigated and possibly improved. , Plain Language
		  Summary The mixing of nutrient-rich coastal water with
		  nutrient-poor open-ocean water in the Northeast Pacific
		  (NEP) is critical to both human and ecological life, yet
		  the processes driving this motion are not understood.
		  Recent advances in technology now allow us to send robotic
		  vehicles, commonly referred to as gliders, to 1,000~m
		  depths and across 1000s of kms measuring ocean properties
		  at the small scales necessary to observe this mixing. We
		  drove a glider along a transect connecting from Vancouver
		  Island out to the middle of the NEP (1,400~kms) 15 times to
		  study how the ocean stirs. Near the coast, stirring
		  patterns remain consistent with time and depth. Offshore,
		  however, the stirring statistics changed depending on the
		  presence of eddies, swirling currents that carry coastal
		  water offshore. Over the study period, we also observed
		  warmer water moving nearshore and colder water appearing
		  offshore, suggesting that changes in regional ocean
		  circulation introduced new water masses along the transect.
		  Finally, we compared our observations with a computer
		  simulation and found that the simulation sometimes
		  underestimated key features, like the strength of
		  circulation and stirring at small scales ({$<$}80~km),
		  which could be improved by fine tuning the model
		  parameters. , Key Points The number of mesoscale eddies and
		  the width of subtropical-influenced water along Line P
		  varies significantly from year to year There are two
		  contrasting stirring regimes along Line P, neither
		  explained by Surface Quasi-Geostrophy theory Regional model
		  shows consistent mesoscale stirring but less submesoscale
		  stirring and does not show regime differences},
  langid	= {english},
  Keywords	= {cproofrefereed,jmkrefereed},
  File		= {/Users/jklymak/Zotero/storage/ZVFVGZTJ/Talbot et al. -
		  2026 - Two Lateral Stirring Regimes in the Northeast
		  Pacific.pdf}
}
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