The secondary nitrite maximum was observed in May 1965 at nine stations south of the boundary between the western extension of the California Current and the Nor th Equatorial Current. A ssociation of high nitrite concentrations with low dissolved-oxygen concentrations and high salinity in the Equatorial Pacific salinity maximum suggests that the northern boundary of the secondary nitrite maximum is related to the northern limit of penetration by Equatorial Pacific water.
Wooster, Warren S.. 1967. "Further observations on the secondary nitrite maximum in the Northern Equatorial Pacific." Journal of Marine Research 25, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1094