C primary production data collected during the deployment and recovery cruises of STIE in 1979 showed a simple relationship with light and nutrient concentrations in the euophotic zone. A simple empirical relationship, calibrated using these data, was derived so that weekly averaged observations of fractional cloudiness, sea-surface temperature and mixed layer depth could be used to estimate primary production on a weekly basis for the years 1976–1979. 15N-uptake measurements, which estimate new production, were combined with the 14C data to estimate particulate carbon fluxes from the euphotic zone. Results of calculations showed that production may vary by a factor of three and particulate carbon flux by a factor of ten on a week to week basis with peak values corresponding to times when the mixed layer became enriched in nutrients. Mean euphotic zone production and particulate carbon flux estimated for the STIE deployment cruise were 286 and 138 mg C m–2 d–1, respectively; they were 174 and 59 mg C m–2 d–1 for the recovery cruise. Mean production and flux values were 261 and 122 mg C m–2 d–1, respectively for the duration of STIE. Three high production and particle sedimentation events may have occurred during STIE in September and October 1979. 1979 appeared to be a year of lower than average primary production compared with 1976 and 1977.