WRF/DART

• Forecasts from Weather Research and Forecasting model, assimilation from Data Assimilation Research Testbed.

• DART is general purpose ensemble filtering system. Easily applied to new models and observations.

• Available to community. See www.image.ucar.edu/DAReS/DART

Open issues

• More frequent cycling and/or use of “time interpolation.” Effects on balance?

• Higher resolution, nests, multiple spatial scales

D1

D2

D3

.

.obs

obs

3DVar EnKF

Initializing “True” State and Ensemble

• Construct N+1 initial states– AVN analysis (1 Jan 03) + perturbations drawn

randomly from 3DVar covariances

• Construct N+1 lateral BC’s– AVN analyses (1-10 Jan 03) + perturbations– Perturbations are deviations from Jan climatology,

scaled by 0.2

• EnKF uses first N initial states and LBCs; true state use N+1st– Ensemble and true state drawn from same pdf