Impact of rheology on probabilistic forecasts of sea ice trajectories: application for search and rescue operations in the Arctic
We present a sensitivity analysis and discuss the probabilistic forecast capabilities of the novel sea ice model neXtSIM used in hindcast mode. The study pertains to the response of the model to the uncertainty on winds using probabilistic forecasts of ice trajectories. neXtSIM is a continuous L...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-03-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/935/2018/tc-12-935-2018.pdf |
| Summary: | We present a sensitivity analysis and discuss
the probabilistic forecast capabilities of the novel sea ice model
neXtSIM used in hindcast mode. The study pertains to the response of
the model to the uncertainty on winds using probabilistic forecasts of ice
trajectories. neXtSIM is a continuous Lagrangian numerical model that uses an elasto-brittle rheology to simulate the ice response to external
forces. The sensitivity analysis is based on a Monte Carlo sampling of 12
members. The response of the model to the uncertainties is evaluated in terms
of simulated ice drift distances from their initial positions, and from the
mean position of the ensemble, over the mid-term forecast horizon of 10 days.
The simulated ice drift is decomposed into advective and diffusive parts that
are characterised separately both spatially and temporally and compared to
what is obtained with a free-drift model, that is, when the ice
rheology does not play any role in the modelled physics of the ice. The
seasonal variability of the model sensitivity is presented and shows the
role of the ice compactness and rheology in the ice drift response at both
local and regional scales in the Arctic. Indeed, the ice drift simulated by
neXtSIM in summer is close to the one obtained with the
free-drift model, while the more compact and solid ice pack shows a
significantly different mechanical and drift behaviour in winter. For the
winter period analysed in this study, we also show that, in contrast to the
free-drift model, neXtSIM reproduces the sea ice Lagrangian
diffusion regimes as found from observed trajectories. The forecast
capability of neXtSIM is also evaluated using a large set of real
buoy's trajectories and compared to the capability of the
free-drift model. We found that neXtSIM performs
significantly better in simulating sea ice drift, both in terms of forecast
error and as a tool to assist search and rescue operations, although the
sources of uncertainties assumed for the present experiment are not
sufficient for complete coverage of the observed IABP positions. |
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| ISSN: | 1994-0416 1994-0424 |