Initial Perturbation for Regional MPAS

JEDI
1

Hi,

We are planning to conduct ensemble forecasts on the regional MPAS using only initial perturbations, without data assimilation.
Is there any recommended system or framework for this purpose?

Thanks.

2

The simplest approach would be to use initial conditions from NOAA’s Global Ensemble Forecast System (GEFS). Data is available from AWS and can be processed to MPAS ICs in the same way as GFS data. You could use this directly as an ensemble of ICs, or you could compute perturbations as deviations from the ensemble mean and add those to the analyis of your choice.

Another approach is to draw random perturbations from a distribution with zero mean and covariance given by the MPAS-JEDI background covariance. This can be done with the ErrorCovarianceToolbox app in SABER, though we don’t have extensive experience with this in MPAS-JEDI.