forecast sensitivity from new models and special observations jan paegle (u. of utah), lee a. byerle...

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


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


“predictability” curves are useful to determine fcst sensitivity to new analyses or observing systems


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


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


An example of radiosonde coverage at 00UTC


Example of Aircraft coverage


SALLJEX obs enhancement (blue) Upper air enhancement 12/02-2/03


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


|V(exp)-V(con)| at 500 mb, 24 Jan 2003, 00UTC (analyses)

10 m/s


Area ave RMS diff (exp-con) at 500 mbArea rms |V(exp)-V(con)|, 500mb Analysis

2 m/s


WRF Euler model forecast response

res: 50 kmRegional dmn


(48h response)/(00h response) for WRF Euler model < 2 at all times Ave response amplifies byAbout 20% in 48h

2

1


Utah Global Euler Model

Our Euler model runs stably without horiz diffusion (KH) in troposphere


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


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


Tools: uniform resolution global model• Uniform resolution grid in Euler model:


Tools: rotated, uniform res, global model• Mathematical pole rotation and variable resolution in Euler model:


Tools: stretched grid, rotated, global model• Increased resolution over the area of interest in Euler model:


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


|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


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


Anomaly correlation Euler model no diffusion with precip.S. H. skillful for 144h


• ,

Anomaly correlationEuler model with diffusion with precipSH skillful for 130h


Anomaly correlationEuler model no diffusion no precipSH skillful for 126h


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

forecast sensitivity from new models and special observations jan paegle (u. of utah), lee a. byerle...

Documents

utah euler model

obs uncertainty

obs inforecast models

h enhanced obs

new models

forecast sensitivity

variable resolution

newer models regional