Project: Surface-Ocean Lower-Atmosphere Studies Air-Sea Gas Exchange (Experiment)

While not officially funded as a U.S. SOLAS project, SAGE included
significant U.S. participation and it's science themes were consistent
with those of the International SOLAS program.

[from http://www.us-solas.org:8080/Plone/projects/the-us-solas-in-the-sage-study (26 may 2008)]
SAGE was a mesoscale Fe addition experiment run after the seasonal autumnal
bloom of the sub-Antarctic showed a small biological response to Fe addition.
The SF6/3He dual-tracer experiment extended the range of gas exchange measurement
into stronger wind regimes typical of the Southern Ocean.

A goal of the SAGE project was to increase understanding of air-water Gas Exchange,
Mixed Layer structure, skin/surface properties, biogenic gases and atmospheric fluxes.
Core measurements included Carbon, N2/O2, noble gas, DMS(P), SO2, N2O, CO, CDOM CN
and aerosol chemistry.

One cruise was conducted aboard the Research Vessel Tangaroa and instrumentation
included CARIOCA pCO2 Buoys, Shipboard Gill R3A Anemometer mast, SAMI pCO2 sensors,
SkinDeep vertical profiler, MAERI, SCAMP/TRAMP temperature microstructure profiler,
sparbuoy, ADCP, S-band radar, FRRF, flow cytometer, primary production, nutrients,
Fe, Meteorology and radiosondes.

from "DSR intro.doc"; by Mike Harvey described as in preparation for Deep Sea Research II
The SOLAS air-sea gas exchange experiment (SAGE) was a combined gas-transfer process
study and iron fertilisation experiment conducted in sub-Antarctic waters of the
south-west Bounty Trough (46.5°S 172.5°E) to the south-east of New Zealand between
mid-March and mid-April 2004.

The experiment was designed as a lagrangian study of air-sea gas exchange processes
of CO2, DMS and other biogenic gases associated with an iron-induced phytoplankton
bloom. In conjunction with the iron fertilisation a dual tracer SF6/3He release
served quantify both patch evolution and air-sea tracer exchange at the 10's of km's
scale. Within this patch local/micrometeorological (100's m scale) gas exchange
process studies quantified physical variables such as near-surface turbulence,
temperature microstructure at the interface, wave properties and wind speed to enable
development of improved gas exchange models for the frequently windy Southern Ocean.

After 15 days and four iron additions totalling 1.1 tonne Fe2+ there was a doubling
in both column chlorophyll-a and primary productivity; a very modest response compared
with other mesoscale iron enrichment. An investigation of factors limiting bloom
development considered co-limitation by light, other nutrients, phyto-plankton seed-stocks
and grazing regulation.

 

Related files

SAGE precruise Science Plan
SAGE precruise Voyage Plan
SAGE Voyage Report
SAGE Release Times
SAGE Surface Physics Metadata Report

SAGE Cruise Track from SST data (.jpg image)
Note:
SAGEtime/Experiment time zero (0.0000) is: 25 March 2004, 19:00 Local Time (NZST) (from SAGE Voyage Report, Voyage Timetable, Pages 5-6)