08/06/06

The goal of this project was to measure air-sea gas transfer rates during hurricane force winds.  By measuring air-sea gas exchange rates during extreme conditions we can provide information on the functionality of the gas transfer rate with wind speed. These kind of measurements are also  important to address the role of hurricanes in releasing previously trapped CO2 back to the atmosphere.

Funded by NSF, and  in collaboration with Eric D'Asaro at the Applied Physics Laboratory at the University of Washington, we deployed neutrally buoyant gas-sensing floats from a plane into the path of advancing Hurricane Frances in September 2004.  The floats  parachuted to the ocean surface, lost their packaging, then begin their mission.  As the hurricane passed overhead, the floats measured dissolved gases in the near surface ocean.  Interpretation of the gas measurements provide estimates of the air-sea gas exchange rate.

This project involves development of new fast-response dissolved gas sensors in collaboration with Pro-Oceanus Systems, Inc.  Some pictures of tests in Puget Sound, WA during August 2003 are shown below:

B) Parameterization of Gas Flux at High Wind Speed (NSF-OCE-0550000, 04/01/06-03/31/11)

This goal of this 5-yr project, again  in collaboration with Eric D'Asaro at the Applied Physics Laboratory at the University of Washington, is to improve current parameterizations of air-sea gas transfer for high wind speeds.  This will involve continued field work in hurricanes duirng 2008-2009 seasons. We will also participate in the UK SOLAS Deep Ocean Gas Exchange Experiment (DOGEE), involving two experiments in the North Atlantic (winter 2006 and Spring 2007). During these cruises, we will validate our new water-side O2 covariance  measurement techniques based on fast-response O2 measurements on the floats.  This program funds Matt Horn (PhD graduate student).

C) Gas Profiler for Real-Time CO₂, N₂ and O₂ Measurements (NOAA-OGP-43111630685, 06/01/05-05/31/06)

This system is being built around a Seabird Electronics SBE19plus profiling CTD with model 43 O₂ probe, a newly developed fast response gas tension device (GTD), and a newly developed fast response NDIR pCO2 sensor.

D) 2004 ANZ-SOLAS SAGE Study (NSF prime, subcontract with Dr. David Ho, LDEO, 10/01/03-09/30/06)

This project, in collaboration with David Ho (LDEO), funded Dave Katz (MS student) to participate in the SAGE experiment off New Zealand. The experiment involved releasing tracers (3He/SF6) and Fe (a micro-nutrient) into the ocean. The patch was then tracked, and the biological response and effects on the air-sea gas flux was determined.

E) Better Techniques to Understand Coastal Carbon Fluxes (URI-Council for Research, 7/1/02-12/31/02)

The goal of this project was to investigate the use of N2 measurements to identify the air-sea gas exchange component from CO2/O2 budgets in a coastal environment.  This led to the field experiment MIGEX (Mini-Intensive Gas Exchange Experiment) at the Martha's Vineyard Observatory. The results were published in Continental Shelf Research. Some preliminary SBE 43 O2 probe data are shown below with comparisons to the lab's Winkler titration measurements:

F) Coastal Benthic Denitrification Studies (NSF Prime, subcontract with Dr. Mark Altabet, UMass Dartmouth, 07/01/07-06/29/09)

We will evaluate the use of the GTD to detect denitrification signatures in Long Island Sound in conjunction with high precision mass spectrometry dissolved gas measurements. Field work is planned for summer of 2007.

G) Station Papa Mooring in the NE Pacific

This work is in collaboration with Dr. Svein Vagle (IOS, Sidney, BC, Canada) and part of the Canadian SOLAS effort. The deep sea mooring includes 4 GTD's, O2 sensors, and upward looking sonars for bubble measurements. The mooring is providing new information on the role of bubbles in air-sea gas transfer and a detailed view of the seasonal cycle of dissolved gases in the upper ocean.