Eda 20100903 Tide Gauge & AVISO. background. John et al. (2001) Tide gauge ∆SSHA Observed Kuroshio transport fv=g( d ƞ / dx ). Goal: Kuroshio variation east off Taiwan and its dynamics. Mean SSH from Rio et al.2009 Black dots are the locations of the tide gauge stations.
John et al. (2001)
Tide gauge ∆SSHA
Observed Kuroshio transport
Kuroshio variation east off Taiwan and its dynamics
Black dots are the locations of the tide gauge stations.
Blue contours are the isobaths.
Time period of data
High tide and low tide (about every 6 hour)
All data had done 40hr low pass first
Then, save into daily format
1.Ganfeng and Keelung (same side)
Fill in the gap of Keelung.
2.Keelung and Ishigaki
Fill in the gap of Ishigaki
Ganfeng & Keelung
Keelung & Ishigaki
Black: monthly mean
Red: 360days running mean
Colored bar are Nino3.4 or WP
Contour is tide gauge SSHA
SSHA does not correlate with Nino3.4.
The correlation is better in WP (yellow box)
What contribute to the variation of the Kuroshio northeast off Taiwan?
In order to answer this, the next part is the regression (correlation) between Tide Gauge SSHA and AVISO SSH, Ug, Vg.
X:tide gauge, Y:AVISO
Plotted here is b
Correlation Coef. Is very similar to regression b. The following plot will only use “b”.
Tide gauge SSHA correlates well with a zonal band region east of Taiwan.
The eddy activity contributes to the variation of Kuroshio transport northeast off Taiwan.
Tide Gauge SSHA has good correlation with Kuroshio upstream and the Mindanao Current
Eddy zone (anti-cyclonic eddy)
Two branches of Kuroshio; East China Sea; Ryukyu Island
p.s. the regressions are very similar to dSSH/dx, dSSH/dy (fig. not shown).
Defined eddy zone
Tide Gauge SSH (black) &
mean eddy zone SSHA (red)
Eddy activity has important influence to the variation of Kuroshio transport east off Taiwan
Regression : AVISO ∆SSH (East Luzon) & AVISO
High regression also shows in eddy zone.
Further south, at east of Luzon, the Kuroshio transport does not have high regression with eddy zone
Interestingly, the Kuroshio transport east off Luzon does not correlate well with futhur north transport.