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Initial and Lateral Boundary Condition Perturbations DET Module 2

Initial and Lateral Boundary Condition Perturbations DET Module 2. Isidora Jankov Acknowledgements: Joseph B. Olson, Steven Albers, Jun Du, Mozeheng Wei, Brian Etherton, Adam Clark, Cliff Mass, Yuejian Zhu and the rest of the DET team. Overview. Objectives Current Status

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Initial and Lateral Boundary Condition Perturbations DET Module 2

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  1. Initial and Lateral Boundary Condition Perturbations DET Module 2 Isidora Jankov Acknowledgements: Joseph B. Olson, Steven Albers, Jun Du, Mozeheng Wei, Brian Etherton, Adam Clark, Cliff Mass, Yuejian Zhu and the rest of the DET team

  2. Overview • Objectives • Current Status • Community Examples • Options for the first year activities • Options for testing • Tentative timeline • Preliminary results

  3. Objective • Create infrastructure that allows for testing of different methods to capture analysis uncertainty. • Porting NCEP/EMC SREF system as a benchmark for testing. • Testing of various community developed methods for creation of Initial Condition (IC) and Lateral Boundary Condition (LBC) perturbations. • Working with NCEP and other agencies on transition of selected methods to operations.

  4. Current International Status • Different centers use different approaches to ICs and LBCs problem. • Usually the initial and LBC question for regional EFS is addressed by using the corresponding global EFS. • UK Met Office: • The initial condition perturbations for global EFS are generated by using the Ensemble Transform Kalman Filter (ETKF) approach (Bishop et al. 2001). • Originally the global EFS was used to provide ICs and LBCs to the regional EFS by simple interpolation to LAM higher resolution grid (dynamical downscaling). • Regional ETKF used for a while. Based on the Bowler and Mylne 2009 study decision was reversed back to use of simple interpolation. • Environment Canada: • The initial condition perturbations for global EFS generated by using the Ensemble Kalman Filter (EnKF) approach. • Simple interpolation currently in place. An effort on producing regional EnKF initial condition perturbations has started.

  5. Current NCEP/EMC Status • Breeding technique for Global Ensemble Forecasting System (GEFS) – 1992 • Breeding technique for Regional EFS – 2000 • Ensemble Transform with Rescaling (ETR) for GEFS - 2006 • ETR has not been implemented for the regional EFS yet (this option will be explored). Currently there is an inconsistency between Global and Regional EFS. P1 forecast Rescaling P2 forecast ETR with Rescaling P1, P2, P3, P4are orthogonal vectors To centralize all perturbed vectors (simplex approach: sum of all vectors are equal to zero) Scaling down by applying climatologically fixed mask The direction of vectors is tuned by ETR. P3 forecast P4 forecast t=t0 t=t1 t=t2 Courtesy of Yuejian Zhu, Richard Wobus, Mozheng Wei, Bo Cui and Zoltan Toth

  6. Some of the community examples

  7. Options Year 1 • Set up basic infrastructures for using global EFS to drive regional EFS (initial perturbations created by using the Ensemble Transform with Rescaling (ETR))… e.g. UK Metoffice and Environment Canada simple interpolation technique • Create infrastructure and test cycling approach when using GEFS as a step beyond the simple interpolation. • Work on getting ETR ESMF compatible. For the sake of compatibility between Global and Regional EFS simple interpolation approach will be compared to the cycling approach The upgraded version of the regional EFS (SREF) will be Placed on the DTC systems

  8. DET IC/LBC Perturbation Module

  9. Candidates for Testing • Regional EnKF • Regional ETKF • Use of quasi-orthogonal perturbations for both global and regional components of the current NCEP/EMC system • Regional ETR • Suggestions are welcome ! • Collaboration with the NCAR GSI group on data assimilation issues

  10. Tentative timeline • Year 1 – Detailed plan for infrastructure and preliminary testing of the cycling approach. • Year 2 – Implementation of additional perturbation methods and testing of user’s community requests. • Year 3 – Continuation of testing community-developed techniques and transitioning of promising techniques to NCEP for operational consideration.

  11. Cycling Initial Perturbations Perturbation Legend Global Model Analysis interpolated on LAM grid Global Model Forecast LAM Forecast 00Z 06Z Forecast Time

  12. HMT Ensemble Integration Domains • Nested domain: • Outer/inner nest grid spacing • 9 and 3 km, respectively • IC perturbations applied only • to the outer domain using the • GFS control run.

  13. Wind Speed July 30 2010 00UTC 00hr LAPS CYC NOCYC 03hr 06hr

  14. 12hr ~25kt 500mb Wind July 30 2010 12UTC ~25kt ~15kt CYC

  15. 12hr ~25kt 500mb Wind July 30 2010 12UTC ~30kt ~15kt NOCYC

  16. Cloud Coverage July 30 2010 00UTC LAPS CYC NOCYC 00hr 03hr 06hr

  17. Questions for the Community • How should the infrastructure be organized to accommodate testing of various IC and LBC perturbation approaches? • What options for IC and LBC perturbations would the community suggest to be developed/tested?

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