NOAA G-IV AIRCRAFT TRACK AROUND HURRICANE IVAN.

ETKF PLANNED FLIGHT

ACTUAL G-IV FLIGHT

Testing the Ensemble Transform Kalman Testing the Ensemble Transform Kalman Filter strategy for targeted observations Filter strategy for targeted observations

during the 2004 Atlantic Hurricane Season during the 2004 Atlantic Hurricane Season (JHT 03-05)(JHT 03-05)

Dr Sharanya J. Majumdar (University of Dr Sharanya J. Majumdar (University of Miami)Miami)

Dr Sim D. Aberson (NOAA/AOML/HRD),Dr Sim D. Aberson (NOAA/AOML/HRD),Dr Brian J. Etherton (UNC Charlotte),Dr Brian J. Etherton (UNC Charlotte),Mr Paul Leighton (NOAA/AOML/HRD),Mr Paul Leighton (NOAA/AOML/HRD),

Dr Zoltan Toth (NOAA/NWS/NCEP/EMC).Dr Zoltan Toth (NOAA/NWS/NCEP/EMC).

TPC/NHC Point of Contact: Mr James Franklin.TPC/NHC Point of Contact: Mr James Franklin.

59th Interdepartmental Hurricane Conference, Jacksonville, FL. March 9th

2005.

Targeted ObservationsTargeted Observations

• Motivation: Motivation: To improve tropical cyclone track To improve tropical cyclone track and intensity forecasts by selective and intensity forecasts by selective deployments of observations in the storm’s deployments of observations in the storm’s environment.environment.

• NOAA G-IV Synoptic Surveillance missions use NOAA G-IV Synoptic Surveillance missions use targeted GPS dropwindsondes.targeted GPS dropwindsondes.

• Present strategy: drop sondes in locations in which Present strategy: drop sondes in locations in which the “spread” of the NCEP GFS ensemble forecast 850-the “spread” of the NCEP GFS ensemble forecast 850-200hPa deep layer mean wind is large at the 200hPa deep layer mean wind is large at the observation time.observation time.

Ensemble Transform Kalman Filter Ensemble Transform Kalman Filter (ETKF)(ETKF)

•Used annually by NWS for Winter Storm Reconnaissance since 2001.

ttiittoo tt

vv

Initialization timeInitialization time Observing timeObserving time Verification timeVerification time

tt

2 days 1-3 days

Sq = Pr – Pq = M Pr(to) HqT (Hq Pr(to) HqT+Rq)-1 Hq Pr(to) MT

2004 Hurricane Season2004 Hurricane Season

ETKF maps of “reduction in wind forecast error ETKF maps of “reduction in wind forecast error variance” for all feasible deployments of targeted variance” for all feasible deployments of targeted observations were produced in real-time.observations were produced in real-time.

• A combination on A combination on uniform samplinguniform sampling, , ensemble ensemble spreadspread and and ETKF ETKF were used to design G-IV were used to design G-IV synoptic surveillance tracks.synoptic surveillance tracks.

• ETKF and Ensemble Spread maxima were ETKF and Ensemble Spread maxima were traversed by “travelling salesman” flight planner traversed by “travelling salesman” flight planner code (Aberson and Leighton, prior JHT) to plot code (Aberson and Leighton, prior JHT) to plot coordinates.coordinates.

Hurricane Frances: September 2 2004, 00Z

SPREAD ETKF

SPREAD ETKF

Hurricane Jeanne: September 24 2004, 00Z

Evaluation of Targeted Evaluation of Targeted ObservationsObservations

• 4 PARALLEL CYCLES:4 PARALLEL CYCLES:– AVNO:AVNO: operational cycle with all dropwindsonde data operational cycle with all dropwindsonde data– AVNN:AVNN: no dropwindsonde data are assimilated no dropwindsonde data are assimilated – AVTG:AVTG: only those dropwindsonde data that meet the only those dropwindsonde data that meet the

targeting requirements of Aberson (2003) are targeting requirements of Aberson (2003) are assimilatedassimilated

– AVET:AVET: as in AVTG, but with targets selected by the ETKF as in AVTG, but with targets selected by the ETKF

• The removal of between one-third and one-half of the The removal of between one-third and one-half of the dropwindsonde data from the data assimilation did not dropwindsonde data from the data assimilation did not appreciably change the errors of the forecasts.appreciably change the errors of the forecasts.

• Testing with the remainder of the 31 cases from the 2004 Testing with the remainder of the 31 cases from the 2004 season is proceeding.season is proceeding.

TIME 12h 24h 36h 48h 60h 72h AVNN 89. 289. 519. 844. 1234. 1620.AVNO 46. 67. 214. 368. 562. 655.AVET 46. 78. 243. 427. 642. 754.AVTG 46. 59. 184. 372. 641. 751.

Data Impact: Charley 12th Aug Data Impact: Charley 12th Aug 0404

All 3 runs with dropwindsonde data provided All 3 runs with dropwindsonde data provided dramatically better forecasts than the run without.dramatically better forecasts than the run without.Small differences exist between these 3 forecasts.Small differences exist between these 3 forecasts.

Data Impact: Frances 30Data Impact: Frances 30thth Aug Aug 0404

TIME 12 h 24 h 36 h 48 h 60 h 72 h 84 h 96 h AVNN 69. 94. 124. 91. 46. 61. 137. 188. AVNO 25. 44. 33. 64. 62. 114. 153. 203. AVET 39. 56. 30. 59. 70. 124. 155. 213.

AVTG 31. 56. 35. 64. 70. 124. 155. 213.

Errors for all 4 runs << those of the Charley case. Errors for all 4 runs << those of the Charley case.

ExtensionsExtensions

• 1. Guidance on DOTSTAR typhoon 1. Guidance on DOTSTAR typhoon surveillance (Chun-Chieh Wu, National surveillance (Chun-Chieh Wu, National Taiwan University)Taiwan University)

• 2. Comparison with targeted Singular 2. Comparison with targeted Singular Vectors from ECMWF and NOGAPSVectors from ECMWF and NOGAPS

A comparison between targeted observing strategies for tropical A comparison between targeted observing strategies for tropical cyclonescyclonesS. J. Majumdar (RSMAS/MPO, U. Miami), S. D. Aberson (NOAA/AOML/HRD), C. H. Bishop (NRL Monterey), R. Buizza (ECMWF), M. S. Peng (NRL Monterey), C. A. Reynolds (NRL Monterey)

SummarySummary

ETKF provides a theoretical improvement ETKF provides a theoretical improvement over ensemble spread as an objective over ensemble spread as an objective targeted observing strategy.targeted observing strategy.

In practice, ETKF guidance is often very In practice, ETKF guidance is often very similar to ensemble spread guidance (70% similar to ensemble spread guidance (70% of cases)of cases)

End-to-end product has been created, from End-to-end product has been created, from input of surveillance time to output of ETKF input of surveillance time to output of ETKF sensitivity map and automated flight track.sensitivity map and automated flight track.

To be completedTo be completed• Continued evaluation of data impact from 2004 Continued evaluation of data impact from 2004

season. Preliminary results are promising.season. Preliminary results are promising.

• Quantitative testsQuantitative tests of ETKF’s ability to predict of ETKF’s ability to predict signal variance and reduction in forecast error signal variance and reduction in forecast error variance.variance.

• Automate ETKF at EMC for use in 2005 season.Automate ETKF at EMC for use in 2005 season.

• Investigation of problems with Ivan forecasts.Investigation of problems with Ivan forecasts.

• Results will continue to be disseminated on Results will continue to be disseminated on http://www.aoml.noaa.gov/hrd/data_sub/assessment.htmhttp://www.aoml.noaa.gov/hrd/data_sub/assessment.htmll and and http://orca.rsmas.miami.edu/~majumdar/tc/http://orca.rsmas.miami.edu/~majumdar/tc/