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SEASONAL AND INTERANNUAL CONCENTRATIONS OF METHANE AND NITROUS OXIDE IN THE SURFACE WATERS OF THE OLIGOTROPHIC NORTH PACIFIC SUBTROPICAL GYRE FROM 2008-2016

Long-term climate change due to the increasing atmospheric loading of radiatively important trace gases requires accurate measurements of their inventories at the Earth’s surface. Situated within the oligotrophic North Pacific Subtropical Gyre, the warm, stable, isolated location of Station ALOHA minimizes the influence of episodic variability and provides the opportunity to determine long-term interannual trends in key ecosystem parameters more readily than highly variable marine environments. As such, Station ALOHA has been invaluable for recording changes in carbon dioxide and related parameters. In this study, we report on the seasonal and interannual variability associated with two other important greenhouse gases, methane and nitrous oxide, which have been sampled at near-monthly intervals at Station ALOHA during 2008-2016. Ever since their initial measurements in the open ocean over three decades ago, nitrous oxide and methane concentrations are typically reported to be present in excess of atmospheric equilibrium in the surface waters. We reveal long-term changes in this longstanding pattern for methane at Station ALOHA and relate the temporal changes to variability in the water-column biogeochemistry. Furthermore, we show the seasonal and interannual dynamics associated with both dissolved methane and nitrous oxide in the upper water-column which are unique to each gas and provide an insight into the physical and biogeochemical mechanisms that govern their net concentrations.

Authors

Wilson, S. T., University of Hawaii, USA, stwilson@hawaii.edu

Ferrón, S., University of Hawaii, USA, sferron@hawaii.edu

Karl, D. M., University of Hawaii, USA, dkarl@hawaii.edu

Details

Poster presentation

Session #:036
Date: 02/27/2017
Time: 15:30 - 16:30
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: 334