Interannual changes in the Kuroshio Extension System

The Kuroshio Extension oscillates between an elongated state and a contracted state.
                                                                           Yearly averaged kinetic energy distributions in the Kuroshio Extension
 

In the elongated state (relative to the contracted state)

        Kuroshio Extension jet has larger surface transport
                                                                             Zonally averaged SSH difference across the Kuroshio Extension
        Kuroshio Extension jet has a more northerly position
                                                                             Zonally averaged axis position of the Kuroshio Extension
         the recirculation gyre is stronger
                                                                             Zonally averaged SSH in the recirculation gyre
 
 
 

As the recirculation gyre intensifies, it elongates zonally, increasing the zonal-mean eastward transport of the Kuroshio Extension and shifting its zonal-mean position northward  (1995 to 1998)

When the recirculation gyre weakens, it decreases the eastward transport of the Kuroshio Extension and shifts its zonal-mean position southward  (1992 to 1995)

                                                                                                     SSH fields on 20 Nov 1992, 15 Nov 1995, and 21 Nov 1998
  Kinetic energy calculation
 

During the T/P period, the zonal penetration of the Kuroshio Extension change from long in 1992/93 to short in 1996 and back to long after 1997
     

The high KE band extends beyond 175° E
     
 
 
 
 
 
 
 

The zonal extent of the high KE band is reduced significantly in 1994
 
 
 
 
 
 
 
 
 
 

A further decrease in size of the high KE area is seen in 1995.
 
 
 
 
 
 
 
 
 
 

The zonal penetration of the high KE band was at its minimum in 1996.

In 1996 while the maximum KE level dropped further in the upstream Kuroshio Extension region, the high KE band showed a sizable expansion in the meridional direction.
 
 
 
 

The widening of the high KE band continued in 1997 in the upstream Kuroshio Extension region
 
 
 
 
 
 
 

In 1998 and 1999 the KE field appear to be returning to its pre-1994 condition with the high KE band expanding gradually in the zonal direction

When the recirculation gyre weakens, it decreases the eastward transport of the Kuroshio Extension and shifts its zonal-mean position southward (1992 to 1995)

As the recirculation gyre intensifies, it elongates zonally, increasing the zonal-mean eastward transport of the Kuroshio Extension and shifting its zonal-mean position northward  (1995 to 1998)