Abstract

A database of roughly 300 basin-wide CTD stations per year from 1997 to 2003 was used to examine interannual and seasonal variability of nutrients and chlorophyll across the equatorial Pacific. During this period, there were large but not necessarily coherent changes in chlorophyll and nutrients. Comparison of La Nina with moderate El Nino conditions showed surprisingly little difference in phytoplankton biomass and community composition. Multiple linear regression analysis of the physical factors responsible for vertical nutrient fluxes emphasized the importance of zonal winds in the central and western Pacific, and thermocline depth in the east. The role of winds is likely not limited to enhancement of upwelling, but perhaps more importantly to increased vertical mixing of nutrients. These results are yet to explain the seasonal variability in the relationship between surface CO2 and SST, but it is likely due to the influence of tropical instability waves. Recent work has made significant progress in determining equatorial Pacific CO2 concentration from satellite data, and these results will be compared with similar ongoing projects in west coast upwelling regions.

Light refreshments are served in the Interaction Area (4th floor of the Oceanography/Physics Building) at 4:00 p.m.

All seminars begin at 3:00 p.m. and are held in room 200 of the Oceanography/Physics building.