Gas transfer velocities in a tropical reservoir and its river downstream. Wind speed and rainfall effect

Fabien Guérin (1) , Gwenaël Abril (2) , Dominique Serça (1) , Claire Delon (1) , Sandrine Richard (3) , Robert Delmas (1) , Alain Tremblay (4) , Louis Varfalvy (4)

1 LAERO - Laboratoire d'aérologie
2 EPOC - Environnements et Paléoenvironnements OCéaniques
3 HYDRECO
4 Hydro-Québec

We have measured simultaneously the methane (CH4) and carbon dioxide (CO2) surface concentrations and fluxes in the Petit-Saut reservoir (French Guiana) and its tidal river (Sinnamary River) downstream the dam, during two field experiments in wet (May 2003) and dry season (December 2003). Gas fluxes were measured with floating chambers (FC) on the artificial lake and on the river, and with the eddy covariance (EC) technique for CO2 during a 24h experiment on the lake. For each chamber measurement, wind speed was measured at 1m above the water surface and recalculated at 10 m using the formulation proposed by Amorocho et DeVrie (1980). During the 24h EC experiment the wind speed at 10m (U10) and the rainfall rates were recorded by a meteorological station. For each flux measurement the gas transfer velocity normalized for a Schmidt Number of 600 was computed.

Domaines: Physique Atmosphérique et Océanique [physics.ao-ph]

Fabien Guérin, Gwenaël Abril, Dominique Serça, Claire Delon, Sandrine Richard, et al.. Gas transfer velocities in a tropical reservoir and its river downstream. Wind speed and rainfall effect. 37th International Liège Colloquium on Ocean Dynamics, May 2005, Liège, Belgium. ⟨hal-00143014⟩