We have observed a very strong NSEC in the western equatorial Pacific which reached as deep as 150m in December 1996. During this event, simultaneous deepening of the upper limit of the EUC and the isotherm below the mixed layer occurred, but there was no significant increase of westward current between the bottom of the NSEC and the EUC. After this event, there was a series of similar but weaker events in 1997. The penetration depths of many of these NSECs were limited to the bottom of the mixed layer which started shoaling from April 1997 and reached 30m in September. When the WWB, which was stronger than the one in December 1996 but centered south of the equator, occurred in March, the deepening of the isotherm at 147｡?-0｡? was less than the deepening of the isotherm during the NSEC in December 1996 but a very strong northward current occurred at that location. This appeared to be the result of non-symmetrical forcing at the equator.
The temporal variations of the depth of the uper limit of the EUC coincided with the variations of isotherms, and it was correlated with the variations of local wind. These changes occurred quickly. However we note that we need careful examinations before concluding whether these responses to “local wind” were truly local or not because our observations were made relatively close to the western boundary and these wind events had large zonal extent as described before. Other than these variations which appeared to be related to the variations of local wind, there was a long-term shoaling of the EUC toward the end of our 1997 observation.
Acknowledgment
The NSCAT data were obtained through the internet (http://www.eorc.nasda.go.jp/ADEOS; as of May, 1998). The TOGA/TAO data (TAO Project Office, Dr. Michael J. McPhaden, Director, NOAA/Pacific Marine Environmental Laboratory) were also obtained through the internet (http://www.pmel.noaa.gov/toga-tao/realtime.html; as of May, 1998). We would like to express our appreciation toward those people who work hard to make these and other data available through the internet. We thank Dr. Kutsuwada and Mr. Kashino who made useful comments on our manuscript. We thank also Dr. Muneyama, Mr. Yano and Mr. Yoneyama who planned and organized TOCS cruises, Ir. Ilyas, Ir. Syamsudim and Capt. Wiyanto who helped us recovering our latest records, and the captain and the crew of R/V Kaiyo for their hard work.
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