The TRIMREX Field Project: An OSSE Study Shu-Hua Chen /UC Davis This work is supported by NTFRI and NSC in Taiwan Other contributors: Jhih-Ying Chen (NCU), Wei-Yu Chang (NCU), Wen-Yih Sun (NTFRI),Pay-Liam Lin (NCU), Po-Hsiung Lin (NTU), Tai-Chi Chen (NCU), Yu-Chieng Liou (NCU)

Introduction  Where and when should we use additional instruments to obtain better analysis and forecasts ? Location of the TEAM-R? Location of ISS wind profiler? Frequency of radiosondes? Pattern and frequency of dropsondes? Motivation  Use OSSE to investigate better use of additional instruments during TIMREX.

Introduction Observing System Simulation Experiments Def: An observing system experiment in which synthetic meteorological observations are used as a surrogate for real observations. The assimilation of these observations and subsequent free forecasts are conducted the same as with real observations. The synthetic observation are usually extracted from a long forecast from a high resolution, state- of-the art model, known as a “nature run”, which acts as a proxy atmosphere specifically for the OSSE. (from OSSE

OSSE Flow Chart Introduction Nature run: High-resolution (1km) WRF simulations Simulate existing & additional observations WRF Var first guess (NCEP reanalysis) Assimilate simulated observations Perform WRF runs and evaluate simulated observations Applied to TIMREX project

Nature Run – Configuration DomainGrid pointsResolution 1141 x 121 x 3127 km 2331 x 271 x 319 km 3721 x 541 x 313 km 4901 x 961 x 311 km Simulated observations

Nature Run – Physics Schemes Radiation RRTM long wave GSFC short wave Cumulus Grell-Devenyi ensemble (domains 1 and 2 only) PBLMYJ TKE MicrophysicsPurdue Simulated observations WRF integrates from 00Z June 6 to 12Z June 9, 2003

Z = 3 km, June 06/00Z – 09/12Z, 2003, interval – 6h Nature Run – Simulated Radar Echo Simulated observations

WRF domain 4 simulation with the 1 km resolution from 18Z June 6 to 00Z June 7, 2003 was use to simulate existing and additional observations. These observations will then be assimilated in WRF numerical experiments for evaluation. Z = 3 km, June 06/18Z, 2003Z = 3 km, June 07/00Z, 2003 Nature Run – Simulated Radar Echo

Simulated observations List of Simulated Observations Existing observations: Additional observations: Radar radial velocity Radiosondes Surface stations EPS wind profiler S-POL radar radial velocity TEAM-R radial velocity NCU ISS wind profiler Radiosondes Dropsondes

Simulated observations Maximum distance ~ 250 km Gate resolution – 1 km Beam resolution – 1 degree Existing radar & SPOL Simulated Radar Data Strategy Scanning angles : 0.5, 1.5, 2.4, 3.3, 4.3, 6.0, 9.9, 14.6, 19.5 degree Maximum distance ~ 40 km Gate resolution – 1 km Beam resolution – 1 degree TEAM-R Three potential sites : lat, long lat, long lat, long

Simulated observations Potential position for TEAM-R Position for S-POL Existing radar Simulated Doppler Radar Locations

Simulated observations x y z V r1 V r2 V r3 u w v Simulated Wind Profiler Winds

Simulated observations ISS wind profiler EPA Wind profiler Simulated Wind Profiler Locations

Simulated observations  Data taken every 20 Seconds  W b = 5 m/s x y z u v w wbwb Simulated Radiosondes Radiosonde track

Simulated observations Regular sites: Ban-Chiao Hua-Lian Ma-Kung Green-Island Dong-Sa Additional sites: Tai-Chung Tai-Nan Peng-Dong Heng-Chun ISS Ship Simulated Radiosonde Locations

Simulated observations 33 CWB surface stations Simulated Surface Station Locations

Simulated observations z x y u v w -w d Simulated Dropsondes WdWd Hock and Frnaklin (BAMS, 1999) Dropsonde track

Simulated observations Simulated Flight Patters

Simulated observations Simulated Flight Patters

Numerical Experiments - Configuration DomainGrid pointsResolution 1133 x 115 x 3127 km 2241 x 181 x 319 km 3271 x 250 x 313 km Experiment design Same physics were chosen as the nature run

Experiment design Numerical Experiments WRF Var cyclingWRF integration 6 h1.5 days Time (h) Obs CaseWRF Var data cyclingWRF simulation Z/06 – 00Z/0700Z/07 – 12Z/08

Experiment design Assimilated observationsTimes Radar windsEvery hour Wind profiler windsEvery hour RadiosondesEvery three hours Surface stationsEvery hour DropsondesEvery hour Numerical Experiments – Var Data Cycling

Experiment design Temperature at the 1st Half Model Level First Guess (NCEP reanalysis) 18Z/06/06/2003 Nature run (18h simulation)

Experiment design Moisture at the 1st Half Model Level 18Z/06/06/2003 Nature run (18h simulation)First Guess (NCEP reanalysis)

Experiment design Wind Speed at the 1st Half Model Level 18Z/06/06/2003 Nature run (18h simulation)First Guess (NCEP reanalysis)

Experiment design Numerical Experiment Design EXPERIMENT Assimilated OBs BEST_NORAD 3 hourly radiosondes (existing + additional) Hourly surface stations Hourly Wind profiler NONE No observation

Experiment design Nature runBEST_NORADNONE 00Z/06/07/2003 (After WRF Var cycling) Temperature at the 1st Half Model Level

Experiment design Moisture at the 1st Half Model Level Nature runBEST_NORADNONE 00Z/06/07/2003 (After WRF Var cycling)

Experiment design Nature runBEST_NORADNONE 00Z/06/07/2003 (After WRF Var cycling) Wind Speed at the 1st Half Model Level

Experiment design  Still work on the assimilation of simulated radar winds (close to finish)  Still work on the assimilation of dropsondes (close to finish)  Keep evaluating the OSSE system and hopefully will finish before the TIMREX starts. On Going