more normal (colder, richer) conditions in late summer, not to a recurring seasonal
difference. The mean measured productivity for that equatorial strip was 1002 mg C
m−2 day−1 (Table 11.5), approximately twice the central gyre average.
Fig. 11.33 Map of the equatorial Pacific with isopleths of annual mean surface nitrate
concentration (μM). Track line shows stations of the US JGOFS equatorial process
study.
(^) (After Murray et al. 1995.)
Fig. 11.34 Trans-equatorial transects at 140°W of (a) chlorophyll a, (b) primary
production integrated to the 0.1% light level, and (c) assimilation number from two
cruises in different seasons. Productivity is elevated just along the equator by nutrients
supplied by upwelling supporting higher productive biomass.
(^) (After Barber et al. 1996.)