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LB01, Lamon bay. LB01, Bifurcation track. vertical black bar: core X: XBT V: vertical net tows O: oblique net tows Red triangle: TRBM Vertical red bar: line moorings. S-max NPsubtropical. “Port Irene bay”. thermocline. “Port Irene bay”. S-min NPIW. Pressure db [meters]. - PowerPoint PPT Presentation
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LB01, Lamon bay LB01, Bifurcation track
vertical black bar: coreX: XBTV: vertical net towsO: oblique net towsRed triangle: TRBMVertical red bar: line moorings
vertical black bar: coreX: XBTV: vertical net towsO: oblique net towsRed triangle: TRBMVertical red bar: line moorings
Pres
sure
db
[met
ers]thermocline
S-maxNPsubtropical
S-minNPIW
Lower thermoclineO2-min
100-200 m frequent O2-min
Polillo depression O2-min
Polillo depressionPolillo depression
All CTD
Stratification: LB01, LB02, LB02 (NE)
“Port Irene bay”
“Port Irene bay”
“Port Irene bay”
LB1
LB2
LB1 LB2
All CTD stations: 1-78
Polillo channel
NPIW
NEC S-max
Kuroshio S-min
LB02 thermohaline pattern (red and cyan) in Lamon Bay reflects dominance of North Equatorial Current (NEC) water; whereas LB01 (black) reflects Kuroshio recirculation gyre regime. The cyan LB02 stations, with Kuroshio T/S, are in the northeastern part of the station array. The LB02 green stations are within the embayment of Port Irene.The LB02 nascent Kuroshio is composed of NEC T/S
LB02 thermohaline pattern (red and cyan) in Lamon Bay reflects dominance of North Equatorial Current (NEC) water; whereas LB01 (black) reflects Kuroshio recirculation gyre regime. The cyan LB02 stations, with Kuroshio T/S, are in the northeastern part of the station array. The LB02 green stations are within the embayment of Port Irene.The LB02 nascent Kuroshio is composed of NEC T/S
NEC S-min
Kuroshio S-max
LB1LB2
CTD 1-78
Kuroshio
Polillo channel
NPIW
NEC, S-max
Black: LB0-1Red: LB02Cyan: LB02Green: LB02
Kuroshio
NECPolillo and ‘Port Irene Bay’
NEC
Kuroshio
All CTD stations: 1-78
Kuroshio
LB02: dominate NEC signature, except in NE part of stations array
Focus on Lamon Bay south of 17.5°N:LB01 BlackLB02 Red
Message: the time period (april/may
2012) of LB02 displays greater presence tropical North Equatorial Current water than the LB01 period (May/June, 2011), why?
Message: the time period (april/may
2012) of LB02 displays greater presence tropical North Equatorial Current water than the LB01 period (May/June, 2011), why?
LB01LB02
LB01
LB02
18.35°N
17.12°N
looking south
looking north
western boundary
western boundary
NEC S-max
North Pacific S-minKuroshio
NEC S-max
looking north
wes
tern
bou
ndar
y
looking north
wes
tern
bou
ndar
y
looking south
western boundary
NEC S-max
North Pacific S-minKuroshio
looking west
NEC S-max
Nor
th P
acifi
c S-
max
& S
-min
Kuro
shio
16.50°N
124.25°E
Southern boundary
looking north
wes
tern
bou
ndar
y
looking westSo
uthe
rn b
ound
ary
Lamon Bay cruise 2, 23-55 m current vectors, as of 8 May 2012
Lamon Bay cruise 2, 23-55 m current vectors, as of 8 May 2012
SSS color coded
Strong NEC source
cyclonic dipole
anticyclonic dipole
Kuroshio feeder current
Polillo current
anticyclone dipole
Lam
on bi
furc
ation
Polillo current
Lamon Bay cruise 1, 23-55 m current vectors, Lamon Bay cruise 1, 23-55 m current vectors,
Lam
on bi
furc
ation
cyclonic dipole
Kuroshio recirculation gyre
Weak NEC signal
Solid arrows denote stronger flow, with clear T/S source water signal. LB02 Kuroshio recirculation gyre retreats northward to be replaced by NEC waters; LB01 shows southward penetration of the Kuroshio recirculation gyre, with
reduced NEC water [vectors not to same scale]
Solid arrows denote stronger flow, with clear T/S source water signal. LB02 Kuroshio recirculation gyre retreats northward to be replaced by NEC waters; LB01 shows southward penetration of the Kuroshio recirculation gyre, with
reduced NEC water [vectors not to same scale]
SSS color coded
Kuroshio recirculation gyre
Nascent Kuroshio
Nascent Kuroshio
LB02 Transports [~±15%?], upper 300 mLB02 Transports [~±15%?], upper 300 m
-10.2 Sv
+12.4 Sv
-5.5 Sv
+15.3 Sv
2.6 Sv
2.2 Sv
+10 Sv, LB01
+11 Sv, LB01
Bifurcation
10° - 11° N North Equatorial Current
NEC bifurcation, April 2012,During R/V Revelle transit, Freemantle to Legaspi.
[stronger] Mindanao Current
North Equatorial Current
Bifurcation
~13° - 14° N
NEC bifurcation, late May 2011, during R/V Revelle transit to south to avoid tyhpoon Songda
[weaker] Mindanao Current
April 2012La Niña
April 2012La Niña
May 2011Neutral
May 2011Neutral
bifu
rcatio
n
bifu
rcatio
n
North Equatorial Current
North Equatorial Current
Mindanao
Mindanao
Kuroshio
Kuroshio
South China Sea throughflow
Luzon Strait throughflowWeak or ~0Luzon Strait throughflow
Weak South China Sea throughflow
Stronge
r Mak
assa
r ITF
Wea
ker M
akas
sar IT
F
For supporting information see ppt slide ‘Notes page’; see next slide for
relation to Aviso
For supporting information see ppt slide ‘Notes page’; see next slide for
relation to Aviso
Stronger Kuroshio, enriched in Equatorial water
Weaker Kuroshio
Possible Implications of an ENSO [bifurcation] dependent Kuroshio source:
§ During La Niña there is increased injection of NEC tropical Pacific water into the subtropical North Pacific; during El Niño the subtropical North Pacific is more 'isolated' from the NEC.
§ The NEC enhanced Kuroshio transport during La Niña, leads to greater northward heat flux into the North Pacific; reduces western pacific warm pool volume.
§ The NEC injection into the subtropical regime, on climatic average (the integrated La Niña/El Niño phases), balances the loss of North Pacific water through the Bering Straits (~1 Sv) and through Luzon Strait (~3 Sv) into the South China Sea (that most likely advects into the Indian Ocean as part of the Indonesia Throughflow). During El Niño the Kuroshio recirculation gyre reaches into Lamon Bay, to can feed the westward ‘leakage’ into the South China Sea, (Luzon Strait westward transport is increased during El Niño, HYCOM, Hurbert et al 2011). In this way the Kuroshio recirculation gyre exports the accumulated NEC injected during the previous La Niña phases.
§ More... effect on ecosystems, linkage with PDO, impact on ITF, WPWP ...
ITF comment: During El Niño the SCS throughflow via Sibutu Passage blocks Mindanao surface layer leakage to Makassar Strait, which lowers the Makassar net transport, counteracting thegreater Mindanao transport associated with the northern bifurcation position.
t = 4°C @ 200 m;18°C isotherm z = @ 70 m
Kuroshio
Shallower isotherms
Deeper isotherms