Decadal variability

Decadal variabilityDecadal variability

Qiu and Chen, 2005

KE is characterized by the presence of two quasi-stationary meanders at 144° and 155°E

Up and downstream jets

Decadal variabilityDecadal variability

Qiu and Chen, 2005

Can the observed decadal variability be explained by the forcing of the large-scale wind stress field?

Decadal variabilityDecadal variability

• 1 ½ layer reduced gravity model for the ocean response to surface wind forcing

Data from OFESData from OFES

SSH EOF’s 1 & 2SSH EOF’s 1 & 2

OFES

ROMS

SSH PCs 1 & 2 from OFESSSH PCs 1 & 2 from OFES

Regression maps SSHRegression maps SSH

Regression maps SSTRegression maps SST

Regression maps (lags)Regression maps (lags)

SSH – PC 1

Regression maps (lags)Regression maps (lags)

SST – PC 1

Regression maps (lags)Regression maps (lags)

SSH – PC 2Propagation of SSH anomalies in the SW direction

Regression maps (lags)Regression maps (lags)

SST – PC 2

Zonal SSH EOFsZonal SSH EOFs SSH average zonally between 142°E-180°

EOF 1: 52.98%

EOF 2: 17.96%

Taguchi et al, 2007

Taguchi et al, 2007

The second mode tracks very well with the strength of the KE jet

The first mode represents a north-south shift of the KE jet

Lag correlation betweenNPGO index and Kuroshio zonal PC2

Strength of Kuroshio(Taguchi et al. 2007; Qiu et al., 2005)Isolated as the zonal PC 2 of SSHa field between142-180E

NCEP wind stress curl vs NPGONCEP wind stress curl vs NPGO

NCEP wind stress curl vs PDONCEP wind stress curl vs PDO

KOE SST indexKOE SST indexQiu et al, 2007

GFDL SSHA EOFsGFDL SSHA EOFs

Regression maps (lags)Regression maps (lags) SSH – PC 2

Zonal modes of KOEZonal modes of KOE