Particle Fluxes at the Edge of the Ross Ice Shelf:
the Rôle of Physical Forcing
A. Accornero1, A. Bergamasco2, A. Monaco3 and S. Tucci4
1 Istituto di Meteorologia e Oceanografia, Istituto Universitario Navale, Via A. De Gasperi 5,
80133 Napoli, Italy
2Istituto per lo Studio délia Dinamica delle Grandi Masse, Consiglio Nazionale delle
Ricerche, San Polo 1364,30125 Venezia, Italy
3Centre de Formation et de Recherche sur l'Environnement Marin, Université de
Perpignan, Avenue de Villeneuve 52,66860 Perpignan cedex, France
4Dipartimento di Scienze délia Terra, Université di Genova, Corso Europa 26, 16132
Genova, Italy
Abstract
In this paper we présent the seasonal variation of downward particle flux, as
expressed by total mass flux and its main biogenic components (organic matter,
biogenic silica and carbonate) in a site located at the edge of the Ross Ice Shelf.
The focus of this study is on data from mooring site named F, located at 77°59'.998
S, 177°01'.623 W in the framework of the C.L.I.M.A. Project (Climatic Long-term
Interaction for the Mass Balance in Antarctica) during the deployment period
January 28,1995 - January 21,1996. Total mass flux shows a clear seasonal trend,
with the austral summer months (December-March) accounting for about 93% of
the total annual flux and the prédominance of the biogenic (55-99 % of the total)
versus the lithogenic fraction through the whole considered period. In order to
understand the rôle of physical forcing on sédimentation processes (as recorded
by the moored trap) we construct a simple Montecarlo model of particle downfall that takes into account both the intrinsic sinking velocity of particles and the
actual vertical displacement of the water layer in wich they are contained. On the
basis of the potential density anomaly évolution, vertical displacement of the
isopycnal surfaces ranging from 27.69 to 27.77 are computed and updated every
day. This numerical experiment puts in evidence the great importance of the
water column stability and density variability as forcing factors for sédimentation
processes. Dynamical constraints are observed to play a crucial rôle, even in the
presence of high production rates.
1 Introduction
Particle fluxes affect a number of important processes in the water column,
including nutrient recycling, supply of food to deep-water and benthic communities, sédiment composition and stratification. They resuit from the interaction of
ail processes that produce, introduce, transform and destroy particulate matter in
the Rôle of Physical Forcing
A. Accornero1, A. Bergamasco2, A. Monaco3 and S. Tucci4
1 Istituto di Meteorologia e Oceanografia, Istituto Universitario Navale, Via A. De Gasperi 5,
80133 Napoli, Italy
2Istituto per lo Studio délia Dinamica delle Grandi Masse, Consiglio Nazionale delle
Ricerche, San Polo 1364,30125 Venezia, Italy
3Centre de Formation et de Recherche sur l'Environnement Marin, Université de
Perpignan, Avenue de Villeneuve 52,66860 Perpignan cedex, France
4Dipartimento di Scienze délia Terra, Université di Genova, Corso Europa 26, 16132
Genova, Italy
Abstract
In this paper we présent the seasonal variation of downward particle flux, as
expressed by total mass flux and its main biogenic components (organic matter,
biogenic silica and carbonate) in a site located at the edge of the Ross Ice Shelf.
The focus of this study is on data from mooring site named F, located at 77°59'.998
S, 177°01'.623 W in the framework of the C.L.I.M.A. Project (Climatic Long-term
Interaction for the Mass Balance in Antarctica) during the deployment period
January 28,1995 - January 21,1996. Total mass flux shows a clear seasonal trend,
with the austral summer months (December-March) accounting for about 93% of
the total annual flux and the prédominance of the biogenic (55-99 % of the total)
versus the lithogenic fraction through the whole considered period. In order to
understand the rôle of physical forcing on sédimentation processes (as recorded
by the moored trap) we construct a simple Montecarlo model of particle downfall that takes into account both the intrinsic sinking velocity of particles and the
actual vertical displacement of the water layer in wich they are contained. On the
basis of the potential density anomaly évolution, vertical displacement of the
isopycnal surfaces ranging from 27.69 to 27.77 are computed and updated every
day. This numerical experiment puts in evidence the great importance of the
water column stability and density variability as forcing factors for sédimentation
processes. Dynamical constraints are observed to play a crucial rôle, even in the
presence of high production rates.
1 Introduction
Particle fluxes affect a number of important processes in the water column,
including nutrient recycling, supply of food to deep-water and benthic communities, sédiment composition and stratification. They resuit from the interaction of
ail processes that produce, introduce, transform and destroy particulate matter in