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Forecast Sensitivity from new Models and Special Observations
Jan Paegle (U. of Utah), Lee A. Byerle (USAF) Celeste Saulo, Juan Ruiz (U. Buenos Aires)
Julia Nogues-Paegle (U. of Utah)
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
OUTLINE.Previous work by Gonzalo Miguez-Macho
.Recent work by
Jan Paegle, Lee Byerle, Juan Ruiz,
Celeste Saulo, Julia Paegle
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
BACKGROUND• Gonzalo estimated initial state uncertainty
from the difference of two equally credible analyses (EC and NCEP)
• He initialized the Utah P.E. model with each analysis => 2 forecasts of same case
• And studied the differences of these forecasts
• Next 4 slides from his dissertation
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
“predictability” curves are useful to determine fcst sensitivity to new analyses or observing systems
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Gonzalo:
• Area integrated results for N. America suggest that:
• Enhanced obs over N. America more valuable than those outside N. America until about 30h
• After 30h enhanced obs outside N. America are more important
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Remaining questions
.Do results: depend on forecast model?
. on initial state uncertainty estimate?
. on region and season?
Present talk employs
.newer models (regional WRF, Utah global)
.and special observations to get obs uncertainty
.Over a relative data void (S. America, summer)
.Use time evolution of area integrated results
OUTLINE.Much previous work has emphasized the
impact of init. state changes over N.H.
.Most of the testing done with PE models
.Here we discuss forecast sensitivity to special
obs over S. America
.Use recent Euler models
WRF
New Global Euler
Operational S. American radiosonde network pre-SALLJEX
S. American radiosonde network (pre-SALLJEX) positioned over N. America
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
An example of radiosonde coverage at 00UTC
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Example of Aircraft coverage
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
SALLJEX obs enhancement (blue) Upper air enhancement 12/02-2/03
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Dirceu and Kousky (2007) assimilated SALLJEX obs usingOperational NCEP GDAS system: EXPERIMENT
control GDAS assimilations w/o SALLJEX obs: CONTROL
The subsequent slides show impact of these obs inForecast models that are initialized with both analyses
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
|V(exp)-V(con)| at 500 mb, 24 Jan 2003, 00UTC (analyses)
10 m/s
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Area ave RMS diff (exp-con) at 500 mbArea rms |V(exp)-V(con)|, 500mb Analysis
2 m/s
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
WRF Euler model forecast response
res: 50 kmRegional dmn
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
(48h response)/(00h response) for WRF Euler model < 2 at all times Ave response amplifies byAbout 20% in 48h
2
1
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Utah Global Euler Model
Our Euler model runs stably without horiz diffusion (KH) in troposphere
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Evolution of |V(exp)-V(con)| at 500 mb for Utah Euler model 16 Jan -31 Jan 2003
Day 0 Day 4
Day 9 Day 14
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Area average of globalEuler model sensitivityvs fcst day for selecteddomains
Much more sensitive (400% growth in 48h)than WRF model(20% growth in 48h)Why?
16m/s
0 m/s
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Tools: uniform resolution global model• Uniform resolution grid in Euler model:
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Tools: rotated, uniform res, global model• Mathematical pole rotation and variable resolution in Euler model:
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Tools: stretched grid, rotated, global model• Increased resolution over the area of interest in Euler model:
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Selected Case• Mesoscale convective system observed on January 17th 2003
January 17 at 17:45 UTCJanuary 17 at 17:45 UTC January 17 at 23:45 UTCJanuary 17 at 23:45 UTC
January 18 at 05:45 UTCJanuary 18 at 05:45 UTC January 18 at 17:45 UTCJanuary 18 at 17:45 UTC
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
|V(exp)-V(con)| 500 mb for Variable res. Utah Euler model (S. Am)
w. diff,w. precip
no diff,no precip
no diffusion,with precip
Uniform res
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
INTERIM CONCLUSIONS
Moist, non diffusive variable resolution Euler model most responsive
Dry, non-diffusive case less responsive
Moist, diffusive case also less responsive
But all are more responsive than WRF or PE models
Could it be that the moist non-diffusive Euler model simply generates noise?
Next examine forecast accuracy of Euler cases
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Anomaly correlation Euler model no diffusion with precip.S. H. skillful for 144h
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
• ,
Anomaly correlationEuler model with diffusion with precipSH skillful for 130h
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
Anomaly correlationEuler model no diffusion no precipSH skillful for 126h
1020 April 2004 Intercomparison of Global Research and Operational Models Jennifer C. Roman
CONCLUSIONS
.fcst. response to obs depends on model
.Utah PE model least responsive
.Var. res. global Euler model most responsive
.Regional WRF intermediate
.Precip processes, diffusion are important
.Most responsive global model is most accurate
.More study needed on FCST ERROR