Figure 4 shows CRPSS scores of the 2-m temperature for 2008 summer, verified over the Northern Hemisphere. Values added from the bias correction are noticeable for both NCEP/GEFS and CMC/GEFS. Figure 5 shows the RPSS of 850-hPa temperature for fall 2009. Both the NCEP/GEFS and CMC/GEFS are improved due to calibration. Overall, the bias reductions globally FIG. 6. NCEP/GEFS CRPSS of 1000-hPa height averaged from 1 Dec 2007 to 29 Feb 2008 for the Northern Hemisphere. E20s is for the raw ensemble forecast and E20sb is for the biascorrected ensemble forecast.
APRIL 2012 C U I E T A L . 405 (absolute value) after calibration can reach up to 75% for days 0–3, 60% for days 2–8, and 45% for days 8–15 for the 500-hPa height field (not shown). More evaluation results such as PAC and relative economic value (Zhu et al. 2002) are also examined. These results are available online (http://www.emc.ncep.noaa.gov/gmb/ yzhu/html/opr/naefs.html) and are updated seasonally. In general, there are skill gains for forecast days 1–6 due to bias correction.