Ocean spiciness is referred to as density-compensated temperature and salinity variations with warm (cool) and salty (fresh) waters having high (low) spiciness, respectively. The structure and evolution of density-compensated (warm/salty or cool/fresh) spiciness anomalies are investigated in the North Pacific thermocline using Argo observations during the period 2004–20. Two well-organized decadal spiciness events are identified through isopycnal surface analyses. One warm/salty spiciness anomaly of about 0.15°C and 0.05 g kg?1 temperature and salinity perturbations on the 25 kg m?3 isopycnal surface appeared in the eastern subtropical North Pacific at (18°–30°N, 120°–150°W) in 2007, which then migrated southwestward along the mean circulation and arrived in the western tropics at (～15°N, 145°E–175°W) in 2012–13, with the reduced salinity perturbation of about 0.043 g kg?1. Another cool/fresh spiciness anomaly of about ?0.2°C and?0.07 g kg?1 temperature and salinity perturbations originated from the eastern subtropics at (120°–150°W, ～30°N) in 2014 and followed a similar advective pathway during the period from 2014–15 to 2019–20. The subduction pathway can be adequately determined by the mean Montgomery stream function on the isopycnal surface; the propagation direction and speed are in good agreement with the expectation for the role played by advection due to the mean geostrophic current. Moreover, the subducted decadal spiciness anomalies can have negative feedback on sea surface temperature (SST) variability in the western tropical Pacific through the diapycnal processes. The identifications of these density-compensated spiciness anomalies and their propagation pathways provide a clear illustration of the oceanic extratropics-tropics interactions in the North Pacific Ocean.

Guanghui ZHOU;Rong-Hua ZHANG

CAS Key Laboratory of Ocean Circulation and Waves,Institute of Oceanology,and Center for Ocean Mega-Science,Chinese Academy of Sciences,Qingdao 266071,China;University of Chinese Academy of Sciences,Beijing 100029,China;Laboratory for Ocean and Climate Dynamics,Pilot National Laboratory for Marine Science and Technology,Qingdao 266237,China;Center for Excellence in Quaternary Science and Global Change,Chinese Academy of Sciences,Xi'an 710061,China

大气科学进展（英文版）

[1]Guanghui ZHOU;Rong-Hua ZHANG-.Structure and Evolution of Decadal Spiciness Variability in the North Pacific during 2004–20, Revealed from Argo Observations)[J].大气科学进展（英文版）,2022(06):953-966

Spiciness,spiciness,isopycnal,advective

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