LAUSR

We investigated the intraseasonal variability of equatorial Pacific subsurface temperature and its relationship with El Niño-Southern Oscillation (ENSO) using Self-Organizing Maps (SOM) analysis. Variation in intraseasonal subsurface temperature is mainly found along the thermocline. The SOM patterns concentrate in basin-wide seesaw or sandwich structures along an east-west axis. Both the seesaw and sandwich SOM patterns oscillate with periods of 55 to 90 days, with the sequence of them showing features of equatorial intraseasonal Kelvin wave, and have marked interannual variations in their occurrence frequencies. Further examination shows that the interannual variability of the SOM patterns is closely related to ENSO; and maxima in composite interannual variability of the SOM patterns are located in the central Pacific during CP El Niño and in the eastern Pacific during EP El Niño. These results imply that some of the ENSO forcing is manifested through changes in the occurrence frequency of intraseasonal patterns, in which the change of the intraseasonal Kelvin wave plays an important role.