Progress Update of Numerical Simulation for OSSE Project Yongzuo Li 11/18/2008

ECMWF T799 nature run Simulated squall line is focus of regional-scale nature run

Regional-scale Nature Run with MM5 9-km domain 521 × 553 × 30 3-km domain 511 × 661 × 30 One-way nesting from 9- to 3-km grid Initial and boundary conditions from ECMWF T799 NR Integration period: 00 UTC 02 May to 00 UTC 04 May Parameterizations: – simple ice microphysics – Blackadar PBL – Kain-Fritsch cumulus (9-km domain) – no cumulus scheme (3-km domain) MM5 /WRF 3 km MM5 9 km

Simulation Results of MM5 9-km Grid Run 10 M windPrecipitation

Simulation Results of MM5 3-km Grid Run 10 M windPrecipitation

Sensitivity experiments with WRF (cold start) 3-km domain 511 × 661 × 30 Initial and boundary conditions from MM5 9-km [ regional-scale NR ] One-way nesting from MM5 9-km grid Integration period: 00 UTC 02 May to 00 UTC 04 May Parameterizations: – no cumulus scheme – simple ice microphysics – YSU PBL MM5 /WRF 3 km MM5 9 km Synthetic observations assimilated using WRF-VAR

WRF 3DVAR Background Error 1) Use NMC method to calculate WRF 3DVAR BE. Starting at 00Z and 12Z respectively, 24 hour forecast using WRF model are performed from 12 April to 14 May hrs fcst 00Z12 12Z12 00Z13 perturbation 1 at 00Z13 24 hrs fcst 12 hrs fcst 12Z12 00Z13 12Z13 perturbation 2 at 12Z13 24 hrs fcst

WRF 3DVAR Cycling and Simulation Synthetic observations are extracted from MM5 3-km grid simulation (section 4). 36 hours 00Z02 03Z02 06Z02 09Z03 12Z02 00Z 04 WRF 3DVAR cycling WRF simulation From 00Z 02 to 12Z 02 WRF 3DVAR cycling is made to assimilate “true data” of synthetic observation from MM5 3-km.

Data assimilation Synthetic observations are taken from MM5 3-km grid. 02 May 02 May 02 May 02 May 02 May 00 UTC 03 UTC 06 UTC 09 UTC 12 UTC SFC SFC SFC SFC SFC UA SAT UA WRF 3DVAR cycling every 3 hrs Sites of synthetic UA soundings 5-minute ATMS / CrIS swath Sites of synthetic surface obs Synthetic satellite coverage

Current work: Satellite data assimilation Synthetic satellite observations of T and T d are taken from MM5 3-km grid. 02 May 02 May 02 May 02 May 02 May 00 UTC 03 UTC 06 UTC 09 UTC 12 UTC SFC SFC SFC SFC SFC UA SAT UA WRF 3DVAR cycling every 3 hrs 5-minute ATMS / CrIS swath Synthetic satellite coverage Procedure : Synthetic ATMS / CrIS data available within 3-km grid area from 0730 UTC to 1000 UTC on 02 May Synthetic ATMS / CrIS data are thinned to closely match MM5 3-km grid points MM5 T and T d are matched to ATMS / CrIS swath points in horizontal space and vertical space New synthetic satellite observation dataset is assimilated at 0900 UTC in WRF 3DVAR, with appropriate errors added: T (± 1K) T d (± 2K)

Comparison of MM5 and WRF Simulations Comparison of simulation results from MM5, WRF cold start, and WRF data assimilation is made in this section. The results are very close to each other though very subtle difference is seen between MM5 and WRF results. Precipitation, sea level pressure, and 2 meter dew point temperature are compared in following slides.

At beginning, 00Z 02, sea level pressure fields of MM5 and WRF are almost identical as they are interpolated from the same MM5 9-km fields. MM5WRF

At beginning, 00Z 02, 2 meter dew point temperature fields of MM5 and WRF are also very clso as they are interpolated from the same MM5 9-km fields. MM5WRF

At 18Z 02, locations of WRF and MM5 rainfall are close. But obvious difference of rainfall patterns are found between WRF and MM5. MM5WRF 3DVAR WRF

At 21Z 02, locations of WRF and MM5 rainfall are close. But obvious difference of rainfall patterns are found between WRF and MM5. MM5WRF 3DVAR WRF

At 00Z 03, mean sea level pressure fields of MM5 and WRF are very similar whereas MSL pressure fields from WRF cycling run are closer to WRF cold start run than to MM5 run. It means that model similarity affects results at this moment more than data assimilation during first 12 hours does. MM5WRF 3DVAR WRF

At 00Z 03, precipitation fields of MM5 and WRF are close. Rainfall band of MM5 moves a little faster than that of WRF. Rainfall pattern of WRF cycling is closer to that of WRF cold start than to that of MM5. MM5WRF 3DVAR WRF

At 03Z 03, precipitation fields of MM5 and WRF are close. Rainfall band of MM5 still moves a little faster than that of WRF. Rainfall pattern of WRF cycling is closer to that of WRF cold start than to that of MM5. MM5WRF 3DVAR WRF