1. Modeling a heavy rainfall case in North-East Estonia, August 2003
Modeling a heavy rainfall case in North-East Estonia, August Influence of model resolution.
Andres Luhamaa
University of Tartu
2005

2. Overview of the event
Precipitation amount: in one day 1.5 times more than monthly mean.
High precipitation rates measured only in one (Estonian station)

3. Radar observations, aug 05, 17.00 – aug06, 06.00

4. Forecasts
EMHI – general storm warning for Gulf of Finland, nothing more.
FMI 22km forecast estimates high precipitation at the northern coast of Estonia.

5. Modelling experiment Influence of model resolution HH and NHH
22km, 11km, 5km, 3km
HH and NHH
Reference HIRLAM and non-hydrostatic
Different versions of STRACO cloud scheme
HIRLAM STR1
6.1.2 (last major updates) - STR2
Research version for high resolutions (<5km) called straco031 - STR3

6. 11km STR-1 simulation
FMI 22km forecast

7. STR-2
HH 11km simulation
NHH 11km simulation

8. STR-1
HH 5km simulation
NHH 5km simulation

9. NHH STR-3 5km simulation
HH STR-2 5km simulation
NHH STR-2 5km simulation

10. 3-km simulations
NHH STR-3
NHH STR-1
NHH STR-2

11. Conclusions: Nothing better than 22km HH forecast could be achieved ;(
Significant difference between NHH and HH precipitation amounts already at 11km resolution!
Parameterization tuning for HH->NHH modeling?
As difference is only in amounts, is NHH necessary at coarser resolutions?