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Coupled HWRF-HYCOM (HyHWRF) and Forecast Performance Results

This document outlines the progress and validation of the Coupled HWRF-HYCOM (HyHWRF) hurricane prediction system. It discusses the motivations for transitioning to HYCOM, the progress in NCEP/EMC, validation of ocean simulations, AXBT data assimilation, pre-ops testing results, risks, and a summary. The document also includes information on the GSI statistical interpolation system and computational cost analysis.

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Coupled HWRF-HYCOM (HyHWRF) and Forecast Performance Results

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  1. Coupled HWRF-HYCOM (HyHWRF) and Forecast Performance Results by HYCOM team MMAB/EMC/NWS/NCEP/NOAA and HWRF team EMC/NWS/NCEP/NOAA

  2. Outline: • Introduction to HyHWRF • Motivations • Progress in NCEP/EMC • Validation of Ocean Simulations • AXBT Data Assimilation • HyHWRF Pre-Ops Testing Results • Risks • Summary

  3. The HyHWRF Hurricane Prediction System GSI: Gridpoint Statistical Interpolation

  4. Motivations GFDL-POM and HWRF-POM are proven systems. Why transition to HYCOM? • Scientific / technical issues: • Use operational RTOFS-Atlantic model for IC and BC: • Realistic real-time ocean • Full ocean model: • Separate support community • Solid base for physics based improvement. • Management of NCEP production suite: • No support (at NCEP) for further development of POM based system • Cannot afford to maintain multiple systems

  5. NCEP/EMC progress HYCOM – HWRF (HyHWRF) • System reaching maturity at the end of 2008 • Initial development not with operational HWRF: • Needing H050 baseline for sensible coupling • HR issues • Parallel testing with frozen system for 2009 Atlantic Hurricane Season: • Goal: Show potential impact of POM-HYCOM replacement • Compare to operational HWRF • In pre-op testing for possible 2010 operational implementation • Fully integrated with HWRF development path • Goal: Replacing POM with HYCOM should do no harm • AXBT data assimilation in RTOFS • Pipe line set up from NCO to RTOFS • AXBT data assimilation tested

  6. Loop Current Loop Current Ocean Validation Pre-Storm Survey for Gustav (07L), 2008 • Skin temperature O(0.5oC) • Wentz, et al (2000) • Excellent Agreement in SST • Good Agreement in Spatial Variation

  7. In-Storm Survey for Gustav (07L): August 31 08Z – 13Z, 2008 Ocean Validation (cont’ed) • remote sensing data scarce • We Need Real-Time Data Feed!

  8. AXBT Data Assimilation Using data collected in July 2009 • 27/57 probes accepted thru QC Blue: data Green: w/o Other: w Accepted Accepted Rejected

  9. HyHWRF Pre-Op Testing

  10. No GFS res. incr. HyHWRF Pre-Ops Testing Result TRACK Forecast 25 NM improvement 10 NM improvement Green: Operation 2009 HWRF model. Red: New baseline HWRF model (H050) Purple: 2010 test package (POM) (H054) Orange: 2010 test package (HYCOM) (HYC2)

  11. No GFS res. incr. HyHWRF Pre-Ops Testing Result INTENSITY Forecast 1.5 kt improvement Overall, ~4 kt improvement Green: Operation 2009 HWRF model. Red: New baseline HWRF model (H050) Purple: 2010 test package (POM) (H054) Orange: 2010 test package (HYCOM) (HYC2)

  12. Risks Replacing POM with HYCOM • HYCOM (with RTOFS-Atlantic) is a much more complex system than POM without real-time continuous initialization • Risk: previous issues with quality of RTOFS-Atlantic • Mitigation: New procedures are in place to rapidly resolve spurious behavior in operations • Mitigation: Adding Jason-2 to SSH data to better constrain model • Mitigation: growing support group for RTOFS • Possible mitigation: Fallback to other SST in coupler

  13. Risks (cont’ed) • HYCOM-HWRF coupling is more complex • Risk: Small support group for coupled system • Mitigation: Dedicated group expanded from 1 to 3 • Mitigation: Community support (FSU, AOML, …) • Risk: Complexity of system may make it more prone to failure • Reality: This system will be fully supported in-house, the present POM base system is not • Reality: This system was robust in parallel testing • Possible mitigation: Fallback to other SST in coupler

  14. Computational Cost Analysis • HYCOM runs on more processes than POM, but HYCOM requires resources much less than HWRF (see Table) • HyHWRF takes < 57 min. w/ 2 nodes (same allocated resource) • Same as Operational HWRF!! assigned resources in test setup Done by Utilizing IBM Supercomputer Configuration, e.g., Logical = 64 Procs/Node

  15. Summary: • HYCOM is complex, and HYCOM-HWRF is more complex. However, HYCOM is based on Solid Physics; • HyHWRF has shown Consistent and Persistent Predictions; • In-House Infrastructure for IC and BC, as well as Routes for Real-Time Streamline Data; • In-House Support as well as Community Support. • Computation Time: HYCOM-HWRF = POM-HWRF

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