AOSN-II August 2003

ESSE Uncertainty Forecasts

ESSE uncertainty initialization and forecast procedure

The ESSE forecast for August 14, 0000 GMT was initialized from an error nowcast for August 12, 0000 GMT. The background ocean field on August 12, 0000 GMT is a HOPS forecast simulation which assimilates all calibrated data up to 1300 GMT on August 11. The results linked to below illustrate the nowcast on Aug 12, 0000 GMT; the 2-day central forecast for Aug 14, 0000 GMT (deterministic model simulation starting from the nowcast) and the mean of the 272-member ensemble forecast for Aug 14, 0000 GMT (the ensemble mean). The error standard deviation estimates computed from the spread of the ensemble members from their mean are shown in the Aug 12 product.

Error Subspace Statistical Estimation (ESSE) Results
Full Domain
Temperature Salinity
Monterey Bay Zoom
Temperature Salinity

U and V velocities are the two components of the internal velocity (i.e. total velocity - vertically averaged velocity) along the domain coordinate system (zonal is 29.4 degrees northeast from a latitude, meridional is 29.4 degrees northwest from a longitude)

Analyses of ESSE Results

The ESSE ensemble mean is smoother than the central forecast and, at several locations, it contains less numerical noise. The skill of the ensemble mean is usually superior to that of a single forecast. However, the features of the ensemble mean can be less realistic that these of a single forecast. It is therefore sometimes useful to utilize the ensemble member closest to the ensemble mean as the best forecast.



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