HR: 1340h
AN: B53B-1178    [Abstracts]
TI: Is Convectively Driven air-sea CO2 Exchange Important When Evaluating Regional and Global Estimates?
AU: * Jeffery, C D
EM: cdj200@noc.soton.ac.uk
AF: National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom
AU: Woolf, D K
EM: david.woolf@thurso.uhi.ac.uk
AF: Environmental Research Institute, North Highland College - UHI, Castle Street, Thurso, Caithness, KW14 7JD, United Kingdom
AU: Robinson, I S
EM: isr@noc.soton.ac.uk
AF: National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom
AU: Barciela-Fernandez, R M
EM: rosa.barciela@metoffice.gov.uk
AF: Met Office, Fitzroy Road, Exeter, EX1 3PB, United Kingdom
AU: Donlon, C J
EM: craig.donlon@metoffice.gov.uk
AF: Met Office, Fitzroy Road, Exeter, EX1 3PB, United Kingdom
AB: Present estimates of air-sea carbon dioxide (CO₂) transfer during low wind speeds and strong solar heating underestimate the net amount of gas exchanged, as they fail to consider the response of the near surface ocean to diurnal temperature variability and subsequent buoyancy-driven convective overturning. We present results that aim to assess the significance of this missing term for regional and global calculations of CO₂ exchange. A two equation k-ε turbulence closure model served as a 1-d test-bed for evaluating a modified version of the National Oceanic and Atmospheric Administration/Coupled-Ocean Atmospheric Response Experiment (NOAA/COARE) air-sea gas transfer parameterization. The improved parameterization includes a new term based on a water-side convective velocity scale (w_*w), to better represent convective gas transfer. Meteorological data from the PIRATA mooring located at 10°S10°W in the Tropical Atlantic was used, in conjunction with cloud cover estimates from Meteosat-7, to calculate fluxes of longwave, latent and sensible heat along with a heat budget and temperature profiles during February 2002. Results from twin model experiments, representing idealistic and realistic conditions showed a 20% enhancement to the instantaneous gas transfer velocity, and when integrated over a week; CO₂ exchange was increased by approximately 3%. In addition we present results from simulations utilizing the UK Met Office FOAM-HadOCC system (Forecasting Ocean Assimilation Model with Hadley Centre Ocean Carbon Cycle Model biogeochemistry). We aim to highlight the spatial and temporal variability of enhanced low wind speed CO₂ exchange and ultimately assess its global importance.
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0428 Carbon cycling (4806)
DE: 4255 Numerical modeling (0545, 0560)
DE: 4504 Air/sea interactions (0312, 3339)
DE: 4954 Sea surface temperature
SC: Biogeosciences [B]
MN: 2007 Fall Meeting