Se. Wijffels et al., MULTIPLE DEEP GYRES OF THE WESTERN NORTH PACIFIC - A WOCE SECTION ALONG 149-DEGREES-E, J GEO RES-O, 103(C6), 1998, pp. 12985-13009
The top to bottom large-scale ocean circulation in the northwest Pacif
ic is described using a World Ocean Circulation Experiment (WOCE) onet
ime hydrographic section along 149 degrees E between Papua New Guinea
and Japan. The circulation is quantified using a combination of geostr
ophic and lowered acoustic Doppler current profiler velocity estimates
. At the northern end of the section the flow regime is distinct in th
at the deep flow largely reflects that at the surface: the Kuroshio je
t and its northern and southern recirculations have deep expressions.
South of 25 degrees N, the deep and bottom water flows do not mirror t
he surface flows, and the circulation assumes a highly baroclinic stru
cture. Below the depth of local North Pacific ventilation the how in t
he upper deep waters (800-2500 m) alternates in sign roughly every 10
degrees of latitude revealing a set of deep clockwise gyres with signi
ficant transports of 40 Sv (1 Sv 10(6)m(3)s(-1)) for a tropical gyre (
south of 6 degrees N) and 20 Sv in a subtropical gyre (6 degrees - 24
degrees N). These gyres provide a pathway for South Pacific influences
to reach 22 degrees N (the location of a strong water mass front) thr
ough exchange along the western boundary. Maps of properties on densit
y surfaces suggest that the zonal extent of the upper deep water gyres
found along 149 degrees E is basin wide. Below 2500 m, flow across th
e section is isolated from the Philippine Sea by the Izu-Ogasawara-Mar
iana Ridge and the how regime and property distribution reflect this:
Lower Circumpolar Water flows west in a deep western boundary current
near 10 degrees N and coalesces at the Izu-Ogasawara-Mariana Ridge wit
h a tongue of North Pacific Deep Water also flowing west near 15 degre
es N. About 4 Sv of a mixture of these waters flows east again near 25
degrees N, associated with an abyssal water mass front. North of the
front, the water properties are laterally homogeneous on density surfa
ces in the strongly recirculating gyres associated with the deep Kuros
hio system.