Jennifer Ayers
IMAS

Date/Time: Friday, 23^rd March, 15:30 – 16:30
Venue: IMAS Sandy Bay Seminar Room

Abstract:
The North Pacific Transition Zone, spanning the North Pacific basin from Japan to California between ~30-40°N latitude, exhibits strong seasonal variability in many characteristics.  This two-part work first investigates and explains the mechanisms responsible for the pronounced seasonal variability in the latitude of the Transition Zone Chlorophyll Front (TZCF).  We identify horizontal Ekman transport as the primary supplier of nutrients to the region, and quantify its contribution to primary productivity.  Secondly this work investigates and quantifies controls on the seasonal and annual mean air-sea CO₂ flux in the region, which is a strong annual sink.  We find that while biological drawdown and geostrophic advection of carbon out of surface waters play approximately equal roles in lowering pCO₂ and thus supporting the region as an annual sink, the location of this sink is determined by the geostrophic flow alone.  This work highlights the need to consider lateral processes in studies of upper ocean biogeochemistry, supporting a revision of the traditional paradigm that nutrients are supplied to surface waters from below.