Preprints
https://doi.org/10.5194/tc-2019-154
https://doi.org/10.5194/tc-2019-154

  17 Jul 2019

17 Jul 2019

Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.

Presentation and evaluation of the Arctic sea ice forecasting system neXtSIM-F

Timothy Williams, Anton Korosov, Pierre Rampal, and Einar Ólason Timothy Williams et al.
  • Nansen Environmental and Remote Sensing Center, Thormøhlensgate 47, 5006 Bergen, Norway and the Bjerknes Center for Climate Research, Bergen, Norway

Abstract. The neXtSIM-F forecast system consists of a stand-alone sea ice model, neXtSIM, forced by the TOPAZ ocean forecast and the ECMWF atmospheric forecast, combined with daily data assimilation. It was tested for the northern winter of 2018–2019 with different data being assimilated and was found to perform well. Despite drift not being assimilated in our system, we obtain quite good agreement between observations, comparing well to more sophisticated coupled ice-ocean forecast systems. The RMSE in drift speed is around 3 km/day for the first three days, climbing to about 4 km/day for the next day or two; computing the RMSE in the total drift adds about 1 km/day to the error in speed. The drift bias remains close to zero over the whole period from Nov 2018–Apr 2019. The neXtSIM-F forecast system assimilates OSISAF sea ice concentration products (both SSMI and AMSR2) and SMOS sea ice thickness by modifying the initial conditions daily and adding a compensating heat flux to prevent removed ice growing back too quickly. This greatly improved the agreement of these quantities with observations for the first 3–4 days of the forecast.

Timothy Williams et al.

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Timothy Williams et al.

Timothy Williams et al.

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Short summary
neXtSIM (neXt-generation Sea Ice Model) includes a novel and extremely realistic way of modeling sea ice dynamics – i.e. how the sea ice moves and deforms in response to the drag from winds and ocean currents. It has been developed over the last few years for a variety of applications, but this paper represents its first demonstration in a forecast context. We present results for the Arctic winter of 2018–2019, and show that it agrees well with satellite observations.