1 / 27

WRF-EnKF Lightning Assimilation Real-Observation Experiments Overview

WRF-EnKF Lightning Assimilation Real-Observation Experiments Overview. Cliff Mass, Greg Hakim, Phil Regulski Department of Atmospheric Sciences University of Washington February 12, 2008. Overview. Project Review Lightning Assimilation Technique Review Model Estimate Experiments

annis
Download Presentation

WRF-EnKF Lightning Assimilation Real-Observation Experiments Overview

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. WRF-EnKF Lightning Assimilation Real-Observation ExperimentsOverview Cliff Mass, Greg Hakim, Phil Regulski Department of Atmospheric Sciences University of Washington February 12, 2008

  2. Overview • Project Review • Lightning Assimilation Technique Review • Model Estimate Experiments • Case Studies • December 2002 (Case 1 Review) • October 2004 • November 2006 • In-progress/Future work

  3. Project Review • Review • Two working WRF-EnKF models • LTNG2 – Original • Tested successfully on Dec. 2002 regime • LTNG4 – Minimal counting technique • Tested successfully on Dec. 2002 regime

  4. Project Review • Research Progress • Oct. 2004 Test Case - Analysis • Nov. 2006 Test Case - Analysis • Modifications to LTNG2 and LTNG4 models to improve analysis and forecasts • In-progress • Forecast analysis of Oct. 2004 Test Case • Forecast analysis of Nov. 2006 Test Case • 1-hr assimilation of cumulative convective rain rate data (previously using 6-hr cumulative totals) for LTNG2 and LTNG4 models

  5. Lightning Assimilation TechniquesHow model assimilates lightning: LTNG2 • Original Lightning Experiment (LTNG2) • NLDN/LR lightning strike is detected • Lightning strike is converted into lightning rate from nearby LTNG observations • Lightning rate converted into convective rainfall rate using Pessi/Businger convective rain rate/lightning rate relationship • Relaxed WRF-EnKF quality control accepts more lightning strike convective rainfall values when comparing to background forecasts • Convective rainfall (mm) is assimilated into WRF-EnKF • Successful testing on Dec. 2002 case • Apply to other test case events • Test model adjustments to improve performance

  6. Lightning Assimilation TechniquesHow model assimilates lightning: LTNG4 • Minimal Counting Technique Lightning Experiment (LTNG4) • NLDN/LR lightning strike is detected • Lightning strike is converted into lightning rate from nearby LTNG observations • Once any nearby lightning strikes are used to calculate a lightning density they are no longer available as an assimilation point (although they are still used to calculate LTNG densities) • Lightning rate converted into convective rainfall rate using Pessi/Businger convective rain rate/lightning rate relationship • Relaxed WRF-EnKF quality control accepts more LTNG strike convective rainfall values when comparing to background forecasts • Convective rainfall (mm) is assimilated into WRF-EnKF • Successful testing on Dec. 2002 case • Apply to other test case events • Test model adjustments to improve performance

  7. Model Estimate ExperimentsCan we further improve Dec 2002 performance? • Model-estimate and observations of cumulative convective precipitation calculated by LTNG density occasionally have large innovations leading to large increments in the model’s dynamical fields, possibly leading to locally unbalanced states • Set a upper bound on assimilated cumulative convective precipitation • Minimal Counting Technique Lightning Experiment (LTNG4) w/ modifications (LTNG5) • Same techniques as LTNG4 with upper bound (18mm) • Less improvement in analysis and forecasts • Original LTNG4 still best performing model to test further on new regimes • Original Lightning Experiment (LTNG2) w/ modifications (LTNG6) • Same techniques as LTNG2 with upper bound (18mm) • Less improvement in analysis and forecasts • Original LTNG2 still best performing model to test further on new regimes • Another solution • Reduce cumulative value of convective rain assimilated from 6- to 1-hr block (In-progress)

  8. Case Studies (Case 1 Review) • Case #1: December 16-21, 2002 • Analysis • Extra-tropical cyclone minimum SLP with new modifications • SLP fields • WRF-EnKF v. Observations

  9. Case Study #1 – December 2002Minimum SLP recorded at extra-tropical cyclone’s center Limiting upper bound of cumulative convective precipitation degrades analysis performance (LTNG5/6)

  10. Case Study #1 – December 2002SLP Analysis Fields Correct location and intensity of SLP cyclone center for LTNG assimilations

  11. Case Study #1 – December 2002WRF-EnKF v. Observations: Integrated Error of SLP LTNG assimilation reduces error over control

  12. Case Studies • Case #2: October 4-7, 2004 • Analysis • Extra-tropical cyclone minimum SLP • SLP, H500 fields • WRF-EnKF v. Observations • Number of LTNG strikes during test case is much smaller than Dec. 2002 case

  13. Case Study #2 – October 2004Minimum SLP recorded at extra-tropical cyclone’s center LTNG assimilated from 04/00 – 07/18 LTNG4 more accurately simulates min. SLP depth of extra tropical cyclone

  14. Case Study #2 – October 2004SLP Analysis Fields Correct location and intensity of SLP cyclone center for LTNG assimilations

  15. Case Study #2 – October 2004H500 Analysis Fields Correct location and intensity of H500 center for LTNG assimilations

  16. Case Study #2 – October 2004H500 Analysis Fields LTNG4 pulls location of upper-level cyclone center too close to LTNG observations Reducing to 1-hr cumulative convective rain totals could weigh OBS correctly

  17. Case Study #2 – October 2004WRF-EnKF v. Observations: Integrated Error of SLP LTNG assimilated from 04/00 – 07/18

  18. Case Study #2 – October 2004WRF-EnKF v. Observations: Cloud top temperature v. Satellite LTNG2: 10/08 00

  19. Case Study #2 – October 2004WRF-EnKF v. Observations: Cloud top temperature v. Satellite LTNG4: 10/08 00

  20. Case Studies • Case #3: November 8-12, 2006 • Analysis • Extra-tropical cyclone minimum SLP • SLP, H500 fields • WRF-EnKF v. Observations

  21. Case Study #3 – November 2006Minimum SLP recorded at extra-tropical cyclone’s center Only LTNG assimilated hours

  22. Case Study #3 – November 2006SLP Analysis Fields Correct location and intensity of SLP cyclone center for LTNG assimilations

  23. Case Study #3 – November 2006H500 Analysis Fields Correct location and intensity of H500 center for LTNG assimilations

  24. Case Study #3 – November 2006WRF-EnKF v. Observations: Integrated Error of SLP LTNG assimilated from 08/00 – 11/18

  25. Case Study #3 – November 2006WRF-EnKF v. Observations: Cloud top temperature v. Satellite LTNG2: 11/10 12

  26. Case Study #3 – November 2006WRF-EnKF v. Observations: Cloud top temperature v. Satellite LTNG4: 11/10 12

  27. In-progress/Future Work • In-Progress • Reduce WRF cumulative convective precipitation assimilation from 6- to 1-hr to avoid unbalanced states • 24-hr Forecasts for Oct 2004 Case • 24-hr Forecasts for Nov 2006 Case • Investigate robustness of Pessi/Businger lightning rate/convective rain rate relationship • Future Work • Test Case #4 – December 2006 • Implement UW-ATMS lightning rate/convective rain rate relationship • Investigate lightning/graupel relationship • Questions/Comments?

More Related