Pacific (Sub) tropical circulation in ORCA025 and ORCA05 DRAKKAR Meeting 2007 Joke Lübbecke

Introduction SST STCs Zonal Currents NGCU Conclusions Schott et al., 2004

NEC EUC nSEC sSEC NECC oIn ORCA05 some problems in the tropical pacific: no Tsuchiya Jets EUC too deep transport too high better representation with higher resolution? Introduction SST STCs Zonal Currents NGCU Conclusions o Differences between the ORCA025 experiments: KAB001 (CORE forcing, weak 3-dim restoring in high lat.) KAB002 (CORE forcing, strong surface restoring) G70 (ERA-40, strong surface restoring)

Nino3 SST COADS obs. ORCA05 ORCA025 Introduction SST STCs Zonal Currents NGCU Conclusions

Meridional Overturning Stream Function ORCA025: KAB001 G70 20/15 Sv30/2035/3545/40 Eq.10°S10°N20°S20°N30°S30°N Introduction SST STCs Zonal Currents NGCU Conclusions

STC Strength ORCA05 KAB001 G70 Introduction SST STCs Zonal Currents NGCU Conclusions explaination for different trends ???

ORCA05ORCA025 EUC: mean equatorial zonal velocity 0.9 Introduction SST STCs Zonal Currents NGCU Conclusions

ORCA05ORCA025 Mean zonal velocity at 155°W EUC nSEC cSEC NEC NECC EIC EUC nSEC cSEC NECC NEC EIC NSCC SSCC Tsuchiya Jets (NSCC, SSCC) in ORCA025 Introduction SST STCs Zonal Currents NGCU Conclusions

Tsuchiya Jets eastward velocities averaged over 26.0<  <27.0 NSCC EUC SSCC Eq. 5°N 5°S 10°S 10°N 155°W165°E110°W

Mean zonal velocity at 155°W KAB001G70 Introduction SST STCs Zonal Currents NGCU Conclusions 0.80 m/s0.85 m/s

mean EUC Transport Introduction SST STCs Zonal Currents NGCU Conclusions Experiment165°E155°W110°W ORCA05 KAB Sv46 Sv28 Sv ORCA025 KAB Sv38 Sv23 Sv ORCA025 G70 22 Sv27 Sv18 Sv Johnson et al., Sv35 Sv26 Sv in density range 22.5<  <26.0

EUC Transport variability Introduction SST STCs Zonal Currents NGCU Conclusions at 155°W, in density range 22.5<  <26.0 KAB001 G70 annual cycle KAB001 KAB002 G70

Introduction SST STCs Zonal Currents NGCU Conclusions Mean velocity in 150m depth

7°S section ORCA2 ORCA05ORCA Introduction SST STCs Zonal Currents NGCU Conclusions

Transport transport variability mean transport (24.0 <  < 26.7) 5°S to 10°S average: ORCA2: ~ 13 Sv ORCA05: ~ 20 Sv ORCA025: ~20 Sv ORCA2 ORCA05 ORCA025 Introduction SST STCs Zonal Currents NGCU Conclusions

improvements with ORCA025:  Tsuchiya Jets present  EUC extension not that deep  more realistic EUC transport  representation of western boundary current KAB001 compared to G70:  structure of zonal currents and OT similar  all wind driven features weaker in G70  EUC transport variability in phase with offset open question:  different STC trends: ORCA05 > G70 > KAB001

KAB001 KAB002

ORCA05 (KAB042) ORCA025 (KAB001) ORCA025 (KAB002) ORCA025 (G70)