Testing bulk parameterization of microphysics in ALARO 10 Tomislav Kovacic DHMZ, Croatia

ALARO 10 ALADIN dynamics + MNH physics Hydrostatic version of AROME + parameterization of convection Prototype Leader: Gwenaelle Hello

Gard case Date: 2002-09-08 start time 2002-09-09 12 validity time=2002-09-09 00 Domain: A specific domain for this case 192x192 (smaller than aladin oper)

GARD 2002-09-08 TSTEP=30 s

GARD 2002-09-08 TSTEP=120 s

GARD 2002-09-08 TSTEP=360 s

Time splitting for microphysical scheme Time step used in operational version of the model is to long for microphysics and the consequence is to few precipitation. Time splitting for microphysical scheme has to be introduced in the model. Iterations of microphysics: microphysical scheme is performed several times in one time step of the model

Method Maximal amount of precipitation on the ground Time steps: 30, 60, 120, 180, 240, 300, 360 and 400 s Iterations: 1,2,3,6 and 9

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

GARD 2002-09-08 TIME=12 h

An other consequence Geographical position of the precipitation area is changing It moves upstream

GARD 9-8-2002 TSTEP=120 s ITERATIONS=1

GARD 9-8-2002 TSTEP=120 s ITERATIONS=3

GARD 9-8-2002 TSTEP=120 s ITERATIONS=3

Conclusions The amount of precipitation increases with decreasing time step It is converging for all studied cases Time splitting doesn’t converge always and when it does it is not the same value as for the same time step of the model Shorter time step must be used