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| Titel |
The Arctic Cap Nowcast Forecast System |
| VerfasserIn |
R. Allard, P. Posey, R. Preller, D. Hebert, E. J. Metzger, A. Wallcraft, S. Piacsek, O. M. Smedstad, M. Phelps |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060167
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| Zusammenfassung |
| The Naval Research Laboratory has developed a two-way coupled Arctic Cap Nowcast
Forecast System (ACNFS) which consists of the Los Alamos Community Ice Code (CICE),
the Hybrid Coordinate Ocean Model (HYCOM) and the Navy Coupled Ocean
Data Assimilation (NCODA) system. Model fields are exchanged using the Earth
System Modeling Framework (ESMF). The ACNFS has a horizontal resolution of
3.5 km in the central Arctic that increases to approximately 7 km at the model’s
southern boundary at 40Ë N. CICE has state-of-the-art ice thermodynamics, snow
layers, ridging and melt pond parameterizations and the ability to forecast multiple
categories of ice thickness according to World Meteorological Organization definitions.
HYCOM is designed with a generalized vertical coordinate. It is isopycnal in the
open stratified ocean, reverts to a terrain-following coordinate in shallow coastal
regions, and uses z-levels near the surface in the mixed-layer where the water column
is weakly stratified. The ACNFS data assimilation is performed using the Navy
Coupled Ocean Data Assimilation (NCODA) system where the model forecast is
used as a first guess. NCODA assimilates available satellite altimeter observations,
satellite ice concentration, satellite and in situ sea surface temperature, in situ vertical
temperature and salinity profiles for xbt’s, Argo floats and moored buoys using a
3-Dimenionsal VARiational analysis (3DVAR) scheme. The ACNFS is forced with
the Navy Operational Global Atmospheric Prediction System (NOGAPS) 0.5 deg
atmospheric forcing. Ocean boundary conditions are provided by the Navy’s 1/12 deg
global HYCOM. The ACNFS has been validated by examining ice extent, ice drift,
ice thickness, and ice draft versus observational data. The ACNFS is running in
real-time at the Naval Oceanographic Office (NAVOCEANO) and produces a daily
nowcast and 5-day forecasts of ice concentration, ice thickness, ice drift, ocean
currents, ocean temperature and ocean salinity. The National Ice Center is evaluating
ice products from ACNFS while NAVOCEAN is evaluating the ocean products.
The ACNFS is expected to be declared “operational” during the first half of 2012. |
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