The TRIMREX Field Project: An OSSE Study Shu-Hua Chen /UC Davis This work is supported by NTFRI and...
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Transcript of The TRIMREX Field Project: An OSSE Study Shu-Hua Chen /UC Davis This work is supported by NTFRI and...
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 http://sivo.gsfc.nasa.gov/OSSE)
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
D02
D03
D04
D01
Domain Grid points Resolution
1 141 x 121 x 31 27 km
2 331 x 271 x 31 9 km
3 721 x 541 x 31 3 km
4 901 x 961 x 31 1 km
Simulated observations
Nature Run – Physics Schemes
RadiationRRTM long waveGSFC short wave
CumulusGrell-Devenyi ensemble (domains 1 and 2 only)
PBL MYJ TKE
Microphysics Purdue
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
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, 2003 Z = 3 km, June 07/00Z, 2003
Nature Run – Simulated Radar Echo
Simulated observations
List of Simulated Observations
Existing observations:
Additional observations:
Radar radial velocityRadiosondesSurface stationsEPS wind profiler
S-POL radar radial velocityTEAM-R radial velocityNCU ISS wind profilerRadiosondesDropsondes
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 :22.75 lat, 120.47 long
22.88 lat, 120.64 long
22.88 lat, 120.21 long
Simulated observations
Potential position for TEAM-R
Position for S-POL
Existing radar
Simulated Doppler Radar Locations
Simulated observations
x
y
zVr1
Vr2
Vr3
u
wv
αβ
βsin/)βcosVV(v
αsin/)αcosVV(u
Vw
βcoswβsinvV
αcoswαsinuV
wV
rr
rr
r
r
r
r
13
12
1
3
2
1
Simulated Wind Profiler Winds
Simulated observations
Data taken every 20 Seconds Wb = 5 m/s
x
y
z
u
v
w
wb
ft
tb dt )ww(vu S
0
222
Simulated Radiosondes
Radiosonde track
Simulated observations
Regular sites:Ban-ChiaoHua-LianMa-Kung Green-IslandDong-Sa
Additional sites:Tai-ChungTai-NanPeng-DongHeng-ChunISSShip
Simulated Radiosonde Locations
Simulated observations
z
x
y
u
vw
-wd
ft
td dt )ww(vu S
0
222
Simulated Dropsondes
Wd
Hock and Frnaklin (BAMS, 1999)
Dropsonde track
Numerical Experiments - Configuration
Domain Grid points Resolution
1 133 x 115 x 31 27 km
2 241 x 181 x 31 9 km
3 271 x 250 x 31 3 km
Experiment design
D02
D03
D01
Same physics were chosen as the nature run
Experiment design
Numerical Experiments
WRF Var cycling WRF integration
6 h 1.5 days
Time (h)
0 36 -3-6 -5 -4 -1-2
Obs Obs Obs Obs Obs ObsObs
Case WRF Var data cycling WRF simulation
2003 18Z/06 – 00Z/07 00Z/07 – 12Z/08
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_NORAD3 hourly radiosondes (existing + additional)Hourly surface stationsHourly Wind profiler
NONE No observation
Experiment design
Nature run BEST_NORAD NONE
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 run BEST_NORAD NONE
00Z/06/07/2003 (After WRF Var cycling)
Experiment design
Nature run BEST_NORAD NONE
00Z/06/07/2003 (After WRF Var cycling)
Wind Speed at the 1st Half Model Level