Preliminary test for the development of a 2.8km ensemble over Italy Chiara Marsigli, Andrea Montani, Tiziana Paccagnella ARPA-SIMC, Bologna, Italy Servizio IdroMeteoClima

Outline Aim of the work Description of the ensemble The meteorological events Results Hymex implementation Future plans

Aim of this work Study the impact of initial state and boundary condition perturbations from global models Study the impact of model perturbations at 2.8km Have a reference ensemble against which comparing future developments

The 7 km ensembles COSMO-LEPS: initial and boundary conditions from 16 members selected from the ECMWF EPS COSMO-SREPS: initial and boundary conditions from 3 operational global models (IFS, GME, GFS) -> 16 members Parameter perturbations applied to the 7km COSMO runs

The convection-permitting ensemble COSMO model run at 2.8km, 45 levels Downscaling of COSMO-LEPS and COSMO-SREPS 7km ensembles, providing IC and BCs perturbations Model perturbations applied to COSMO run at 2.8 km (perturbed parameters)

The meteorological events Liguria Cinque Terre - 25/10/2011 Genova – 04/11/2011

25th October 2011

2.8km ensemble on COSMO-LEPS i.t. 24/10/2011 12UTC +12-36h 50 100 200 1500 1

Probability of tp>100mm/24h 24h observed precipitation – 25/10/2011 ens 24/10 12UTC +12-36h 10 30 60 90 100 ens 23/10 12UTC +36-60h best member ens 24/10 12UTC +12-36h

Probability of tp>100mm/24h - 25/10/2011 00UTC +24h COSMO-SREPS (7km) 2.8 km ensemble on COSMO-SREPS 10 30 60 90 100 24h observed precipitation – 25/10/2011

IFS driven tp24h distribution m1 m2 m3 m4 m5 m16

GME driven tp24h distribution m6 m7 m8 m9 m10

GFS driven tp24h distribution m11 m12 m13 m14 m15

Verification 25/11/2011 00UTC +24h nearest point average 0.2 x 0.2 maximum 0.2 x 0.2

4th November 2011

2.8km on COSMO-SREPS i.t. 04/11/2011 00UTC +24h 10 30 60 90 100 24h tp 04/11/11 prob tp>100mm/24h 10 50 100 200 1500 1 IFS driven GME driven GFS driven 7km 2.8km

tp 24h distribution - 04/11/2011 00UTC - member 1 7km 2.8km

Summary of the results Some gain in skill from simple downscaling of the 7km ensembles at 2.8km Significant dependence of the small-scale precipitation structure on the driving model (influence of large scale perturbations) Strong impact of the error of the model run at high resolution -> importance of the modelisation of the small-scale phenomena “reasonable” effect of the parameter perturbations

Hymex implementation Hymex SOP: 6th Sept – 5th Nov 2012 Many models available, among which AROME-EPS 2.5km Many observations available (and many deployed on IOPs) COSMO-H2-EPS set-up: 2.8 km, 50 levels 10 members IC and BC COSMO-LEPS 1 run daily at 12 UTC 36h forecast range

Plans Provide IC perturbations based on KENDA to the 2.8km ensemble Re-run the ensemble on the Hymex period with the perturbed ICs (use of high density observations) Test the perturbation of the physics tendencies in the 2.8km ensemble Implement a suite over an italian domain