Forecast Performance Verification of the ECMWF Model over the Northeast Hemisphere

Using climatological methods, the forecast performance of the ECMWF model over the Northeast Hemisphere is discussed through analytic comparison between the ECMWF daily analysis and its seven-day forecast products. The results show that: 1) the time series verification indicates that the ECMWF’s daily forecast exhibits a seasonal trend, that is the forecast performance for summer was worse than those for the other seasons and the forecast accuracy decreased to its minimum in July. 2) The prediction ability differed among the various meteorological fields. In general, the analysis showed good correlation with the seven-day forecast 850-hPa temperature and 500-hPa geopotential height while the correlation with the 850-hPa relative humidity was poor. The forecast bias increased with extended prediction time. 3) The seven-day forecast temperature was higher than the ECMWF analysis over the land and lower over the tropical area; the forecast performance over the nearby area of the equator was weaker than over the higher latitude region, showing similar behavior to some degree in other meteorological prediction fields. 4) There was a remarkable OKJ wave chain in the 500-hPa geopotential height or a 500-hPa wind difference between the seven-day forecast and the analysis. 5) The zonal wind forecast was better than the meridional wind forecast field, and showed a high correlation with the analysis near 30°N. 6) Overall, the ECMWF model has better forecasting capability at the high level fields than at the lower level ones, with the exception of the 700-hPa wind fields.