Campaign: D320

The overall aim of the UKSOLAS project DOGEE-SOLAS is the parameterization of air-sea gas exchange, which is a currently a major uncertainty in global modelling. RRS Discovery cruise D320 thus was primarily concerned with the measurement of air-sea gas transfer velocities and some of the important physical parameters that influence them through contributing to near surface turbulence, and other processes. In brief, specific cruise objectives were:

1. Determine open ocean gas transfer velocities through a number of dual-tracer releases (3He & SF6).
2. Investigate the role of surfactant in gas exchange through a targeted surfactant release in conjunction with (1).
3. Determine CO2 fluxes and transfer velocities, and make associated hydrographic and turbulence related measurements from autonomous ASIS (Air-Sea Interaction Spar) buoys.
4. Measure air-sea fluxes of CO2, sensitive heat, latent heat and momentum using the AUTOFLUX automated sensor array
5. Measure, total gas tension, dissolved O2, and CO2 to obtain independent air-sea gas exchange estimates.
6. Make covariance and gas budgeting estimates of air-sea gas exchange using intelligent profiling Lagrangian floats.
7. Independently determine DMS fluxes and gas transfer velocities for comparison with CO2 to examine the role of gas solubility in gas transfer.
8. Deploy a spar buoy (NOC) for measurement of wave heights and bubble properties
9. Record and measure whitecap coverage and wave breaking coincident with the air-sea flux measurements using ship mounted cameras
10. Record key meteorological variables
11. Quantify flow distortion biases in the direct flux measurements via the use of established models.
12. Make biogas, surfactant and bacterial measurements in the surface microlayer and in the uppermost meters of the ocean using surface microlayer samplers, a remotely operated catamaran, and a near surface sampler.
13. Deploy an autonomous powered profiler (ASIP) for turbulence-related measurements in the mixed layer.

Objectives 1-12 were all met. Unfortunately, due to mechanical failure and loss of ASIP, objective 13 was not realized.