B. Qiu et Rx. Huang, VENTILATION OF THE NORTH-ATLANTIC AND NORTH-PACIFIC - SUBDUCTION VERSUS OBDUCTION, Journal of physical oceanography, 25(10), 1995, pp. 2374-2390
Ventilation in the North Atlantic and North Pacific is examined by ana
lyzing the Levitus climatological data and the Hellerman and Rosenstei
n wind stress data. Ventilation between the permanent pycnocline and t
he overlying seasonal pycnocline and mixed layer consists of two physi
cal processes: subduction and obduction. Subduction takes place mainly
in the subtropical basin where surface water is irreversibly transfer
red into the permanent pycnocline below. Obduction takes place in the
subpolar basin where water from the permanent pycnocline is irreversib
ly transferred into the mixed layer above. Ventilation in the North At
lantic and North Pacific can be classified into four physically differ
ent regions: the subductive region, the obductive legion, the ambiduct
ive region where both subduction and obduction take place, and the ins
ulated region where neither subduction nor obduction occurs. Although
the total subduction rates in these two oceans are comparable, the tot
al obduction rates are considerably different. In the North Atlantic,
obduction is strong (23.5 Sv), consistent with the notion of the fast
thermohaline circulation and the relatively shea renewal time of the s
ubpolar water masses in the Atlantic basin Obduction is weak in the No
rth Pacific (7.8 Sv); this is consistent with the sluggish thermohalin
e circulation and the slower renewal process of the subpolar water mas
ses there. Accordingly, the water mass renewal time based on the subdu
ction/obduction rate is calculated and compared with previous estimati
ons.