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-l20-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-persistance forecasts. Compared to persistence, 24-h forecast was found to be skillful (>0.2) for all months studied except during the freezing up months of December 2000 and January 2001. Relative to the combined reference field, the 24-h forecast was also positive for the non-freeze up months; however, the skill scores were lower (^0.1). During the poorly performing freeze-up months, a linear combination of persistence (^95% weight) and climatology (^5% weight) appears to provide the best available sea ice forecast.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 30, 2003
- Accession Number
- ADA428859
Entities
People
- Cheng-zhi Zou
- Michael L. Van Woert
- Philip D. Hovey
- Ruth H. Preller
- Walter N. Meier
Organizations
- United States Naval Research Laboratory