Forecast Verification of the Polar Ice Prediction System (PIPS) Sea Ice Concentration Fields

Abstract The National Ice Center relies upon a coupled ice–ocean model called the Polar Ice Prediction System (PIPS) to provide guidance for its 24–120-h sea ice forecasts. Here forecast skill assessments of the sea ice concentration (C) fields from PIPS for the period 1 May 2000–31 May 2002 are presented. Methods of measuring the sea ice forecast skill are adapted from the meteorological literature and applied to locations where the forecast or analysis sea ice fields changed by at least ±5%. The forecast skill referenced to climatology was high (>0.85, relative to a maximum score of 1.0) for all months examined. This is because interannual variability in the climatology, which is used as a reference field, is much greater than the day-to-day variability in the forecast field. The PIPS forecasts were also evaluated against persistence and combined climatological–persistence forecasts. Compared to persistence, the 24-h forecast was found to be skillful (>0.2) for all months studied except during the freez...

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