1. AGREPS – ACCESS Global and Regional Ensemble Prediction System
Michael Naughton, David Smith,
Asri Sulaiman
Bureau of Meteorology
CAWCR Earth System Modelling Program
GIFS-TIGGE WG Meeting, June 2013
UK Met Office

2. AGREPS – ACCESS ensemble prediction system
24-member ensemble designed for medium-range and short-range forecasting
Based on UKMO MOGREPS
Global ensemble to 10 days
Regional ensemble over Australian Region to 3 days
Global ETKF for initial condition perts
Stochastic model perturbations
ACCESS-G 40km (N320) – 25km (N512) AGREPS-G 80km (N144) – 60km (N216)
ACCESS-R 12 km AGREPS-R 24 km
HI-RES 4km
Currently running at 60 km & 37.5 km

3. AGREPS current status
APS0 AGREPS global and Australian regional systems at 80km (N144) & 37.5km L50 based on UM 6.4 ran from Jan 2011 to Mar 2013 (without model perturbations)
APS1 AGREPS global system at 60km (N216) L70 based on UM 7.6 has been from start of 2012, running daily since November 2012 (includes SKEB2 model perturbations)
APS1 AGREPS has been compared with APS0 version and overseas ensemble systems
Operational implementation of AGREPS is planned, timing still dependent on resourcing

4. AGREPS plans
Ensembles will be key element of data assimilation through provision of capability for flow-dependent error covariances; we plan to incorporate Met Office hybrid DA approach into future ACCESS NWP suites
Ensembles for high resolution ACCESS systems are also planned

5. Verification – Spread-skill T850
AGREPS N216 v N144
T850
December 2012

6. Verification – Spread-skill T850
AGREPS N216 EM cf
ACCESS-G N320
T850
April 2013

7. Verification – Spread-skill c.f. other centres
AGREPS N216
ECMWF
NCEP
JMA
T850
August 2012
Southern Hemisphere