Error growth and predictability in operational ECMWF forecasts

Predictability error growth of turbulent flows

Recently, alternative viewpoints were suggested that is in contrast to the conventional picture of predictability error growth in the spectral domain. We survey key historical and current literatures and suggest that the traditional perspective has not been invalidated.

The impact of airborne Doppler lidar observations on ECMWF forecasts

Reconciling the Return Predictability Evidence In-sample Forecasts, Out-of-sample Forecasts, and Parameter Instability

Evidence of stock return predictability by financial ratios is still controversial, as documented by inconsistent results for in-sample and out-of-sample regressions and by substantial parameter instability. This paper shows that these seemingly incompatible results can be reconciled if the assumption of a fixed steady-state mean of the economy is relaxed. We find strong empirical evidence in s...

Influence of observations on the operational ECMWF system

Editorial ECMWF regularly reviews the impact that various observing system data has on the forecast. A recent series of such observing system experiments are reported in the first article (page 2). In January 1997, there were severe floods in Greece due to torrential rainfalls over 12/13 J a n u a r y. The ECMWF forecast for that period is discussed on page 9. Three more reports in the ECMWF Te...

Asian summer monsoon prediction in ECMWF System 4 and NCEP CFSv2 retrospective seasonal forecasts

The seasonal prediction skill of the Asian summer monsoon is assessed using retrospective predictions (1982–2009) from the ECMWF System 4 (SYS4) and NCEP CFS version 2 (CFSv2) seasonal prediction systems. In both SYS4 and CFSv2, a cold bias of sea-surface temperature (SST) is found over the equatorial Pacific, North Atlantic, Indian Oceans and over a broad region in the Southern Hemisphere rela...