Controlling factors of interannual variability of downward particle fluxes on a NW Mediterranean continental margin
Abstract
Downward transfer of particulate matter, currents and water temperature have been measured on the Gulf of Lions margin since October 1993, at 500 and 1000 m depth within two submarine canyons. At the global scale, principal component and cross-correlation analysis of the long term time series underlines two features: (i) transfer of particulate matter to the deep ocean is neither correlated with atmospheric inputs nor forced by the wave induced bottom stress on the continental shelf; (ii) mass fluxes are likely controlled by the meandering of the alongslope current (Northern Current) and by dense water formation in winter. At the local scale, i.e. when each canyon is considered separately, statistical analysis reveals the influence of Rhône river inputs at intermediate depth on the slope (500 m) and of intense dense water formation that occurred during winter in 1999 and 2000. Numerical simulations have been carried out to answer the questions of particulate transfer of riverine origine down to 500 m as well as of the frequency and location of the Northern Current intrusions and dense water formation events. This modelling approach examines the impact of local atmospheric forcing (wind stress, heat fluxes, precipitation - evaporation budget) on the variability of the alongslope circulation and of total mass fluxes within the canyons. Preliminary results show a positive correlation between anomalies of dense water formation rates and interannual variability of total mass fluxes.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....10888G