OEB Seminar Series: Mark A Altabet
Date and Time
Location
Professor and Chairperson
School for Marine Science & Technology
University of Massachusetts, Dartmouth
The Influence of Mesoscale Features on Oxygen Deficient Zone Biogeochemistry
Abstract: Mesoscale physics are now well known to influence ocean biology and chemistry with respect to both temporal/spatial heterogeneity as well as net oceanic fluxes. Less well known are their influence in oxygen deficient zones of the open ocean (ODZ) which host unique biogeochemical processes of global impact (e.g. fixed N loss; NO3- to N2; N2O flux to atm.). During a cruise to the E. Tropical N. Pacific ODZ (SR2114), satellite imagery was used to target mesoscale features for sampling. A coastal anticyclone, an offshore anticyclone and a high chlorophyll jet of coastal origin were observed. These features are forced by wintertime wind jets blowing through the Tehuantepec and Papagayo mountain gaps. Overall, mesoscale physics impacted ODZ biogeochemistry in at least two distinct ways. The first involved vertical excursions in density layers and the depth of the oxycline of up to 100 m which were associated with spatial variations in productivity, N-loss, and N2O. The second route for mesoscale impact is through subsurface O2 intrusions that originate at coast along specific density surfaces into the geographic interior of the ODZ which are likely to affect O2-sensitive microbial processes.
Host: Professor Peter Girguis