We have presented a new operational model for the
evolution of search areas for drifting objects. A
taxonomy of common SAR objects has been set up
based on the field experiments conducted to date.
A new method for decomposing and perturbing the
leeway of the object in downwind and cross-wind
components has been employed, yielding more robust
computations at low winds and more realistic ensemble
perturbations. It is found that this new method makes
search areas inflate at approximately 25–50% of the rate
found using older methods. The stochastic particle
trajectory approach employed for this model thus leads
to a significantly lower rate of expansion of search areas
compared with other models.
The ensemble trajectory model is operational and can
forecast search areas up to 60 h ahead in time. A seven day
archive of wind and current fields allows simulations to be
started as early as one week ago. This is important, as
incidents are not always reported immediately.
It is found that particles are dispersed primarily
through the perturbation of leeway properties, as these