1. WRF model runs of 2 and 3 August
Yahui Huang, Alan Blyth

2. Model configuration and set-up of simulations
Advanced Research WRF Version 3.2
Three nested domains with horizontal grid spacing of 400 m for the inner domain
61 levels in vertical direction & dz ~ 70 m (surface) to 240 m (500 hPa)
Initiated at 06:00 UTC using the GFS analysis data
Physical processes included: radiation, surface physics, PBL parameterization, and microphysics (Morrison’s scheme)
Set: Nc=400 cm¯³ for the simulations

3. Model configuration and set-up of simulations
06:00 UTC on 03 August
06:00 UTC on 02 August

4. Case 1: 3 August 2013

5. Radar observations
10:14 UTC
11:26 UTC
15:13 UTC
13:45 UTC

7. From 15 dBZ to 30 dBZ in just one min at 3 km
Cloud top is at T ~ -17 °C
Melting level is around 2.4 km
Most of ice and graupel stayed in the air

8. Raindrops fell from 2.4 km to ground in 5 min
Only a few of graupel fell below 2.4 km and melted

9. Warm rain is dominant for the production of precipitation in this cell

10. Brighter band in the melting level
Cloud top is at T ~ -23 °C

11. The increase of raindrops below the melting level is likely due to melted graupel

12. Cold rain may be dominant for the rain production in this cell

13. Case 2: 2 August 2013

14. 14:00
15:00
16:00
17:00

16. Summary
On 3 August, the warm rain process dominated the production of precipitation for the cell with a moderate top temperature; the cold rain process took over when the cell rose higher up with a colder temperature.
The performance for the 2 August case is not as good as for the 3 August case.

17. Future work
Analysis of microphysics data (03/08 case, 02/08 case, and 18/07 case)
Modelling studies with WRF and MAC3; comparing the results
focusing on the warm rain: comparing the modelled formation with radar analysis and possible aircraft data to see the capabilities and limitations of the parameterization in the models; the role in the formation and development of ice; which one is more important for the precipitation, warm rain or cold rain?