Application of collected data
Presentations at the DBCP Technical Workshop
Buenos Aires, Argentina, 17-18 October 2005
Theme 2: Operational enhancements and practices
12. A Simple Model for Drifting Buoy Life-Times, and a Method for Estimating Evolution of a Network's Size
Authors: Etienne Charpentier, Mathieu Belbéoch, Julien Bourcier
Abstract: Using
JCOMMOPS database, and series of actual drifter life-times, it was shown
that survivability of a drifting buoy network fits very well with an
exponential model N(t)=N0 e-αt. Using
regression method, α coefficient can be estimated. This coefficient
is directly linked to the theoretical network half life L1/2:
α=ln(2)/L1/2. Assuming a constant deployment rate of Rx
drifters per day, it is therefore possible to estimate evolution with time
of the size of a network of consistent buoys: N(t)= (N0 - Rx/
α) e-αt+Rx/ α. Network size will
eventually tend towards theoretical limit of Rx/ α buoys.
In order to maintain a buoy network at a target level of Nt
units, it is therefore recommended to deploy buoys at a rate of Nt
α units per day. A higher deployment rate will be needed in case the
initial number of buoys is substantially lower than the target. New
JCOMMOPS web page permits to query the database in order to make quick
estimation of α coefficient and to simulate network evolution based
on provided criteria. This works, of course provided that buoy deployment
information, and particularly deployment date is made available to
JCOMMOPS. Recently developed buoy metadata collection system and
deployment notification scheme permits to collect required information and
to assist buoy operators in managing their networks.
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