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CIMMSE TC Wind Group Conference Call

CIMMSE TC Wind Group Conference Call. Wednesday, July 10 th , 2013 11:00 AM. Agenda. Modified Rankine error function (MREF) survey results Modeling Update First WRF-LES simulation problems Potential solutions suggested by collaborators. MREF Survey Results.

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CIMMSE TC Wind Group Conference Call

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  1. CIMMSE TC Wind GroupConference Call Wednesday, July 10th, 2013 11:00 AM

  2. Agenda • Modified Rankine error function (MREF) survey results • Modeling Update • First WRF-LES simulation problems • Potential solutions suggested by collaborators

  3. MREF Survey Results • Collaborators were asked to submit comments based on the images posted at: https://sites.google.com/a/ncsu.edu/modified-_rankine_improvements/ • Two NWS WFOs provided comments based on the supplied images (at least four forecasters within the two WFOs)

  4. MREF Survey Results • Consensus that the MREF interpolated winds were better than the currently used MR winds • MREF: Strong reduction in wind speeds in the left storm quadrants consistent with forecaster experiences for storms paralleling the coastline • MREF: Improvements in right front quadrant (strong reduction in wind speeds just outside the eye wall; larger radius of moderate wind field near storm periphery are consistent with forecaster experiences) • In general, MREF decreases wind speeds for much of storm—consistent with NDFD verification results as a necessary measure • “Improvements in WFO-to-WFO consistency while also retaining the intent of NHC forecasters”

  5. MREF Survey Results • There were a few storms that MR performed better than MREF • Sometimes MR does better in the 40-60 km distance from storm center area (Felix, Paloma, Rina) • Typically storms with “atypical” storm/wind structure have MREF failing • Examples: Felix (2007), Earl (2010) • Suggestion: incorporate into TCMWindTool and then allow WFOs in region to collaborate and decide which interpolation method to use for the given storm)

  6. Modeling Setup • 5 Domains, with innermost two domains having no PBL scheme • Use of 1/16° daily SST analyses, 0.5° six hourly GFS analyses for boundary conditions • Grid Spacing (consistent with Zhu et al. 2008): • D1: 8.1 km D3: 900 m D5: 100 m • D2: 2.7 km D4: 300 m

  7. 10-m wind speeds (knots) for domain 2

  8. Initial WRF-LES Simulation Problem • After a few hours, an anomalous, unphysical wind maximum develops within the WRF-LES domain 4 • Potential causes (after discussing with Dr. Sukanta Basu) • Two-way nesting used—NCAR does not recommend for WRF-LES domains—use one-way nesting for WRF-LES domains and two-way for WRF-mesoscale domains • WRF-LES domain was situated over the land-sea interface (suggested to use WRF-LES domain only over ocean or land)

  9. Modeling Goals/Focuses • Use Irene (2011) as a first case study • Conducted 24 hour WRF-LES simulation near location of landfall beginning at 0000 UTC 27 August • Examine large eddy circulations within the boundary layer • Conduct TKE budget to explore relative magnitude of contributions of the various terms • Examine gust factors at various locations within inner domain (compare to the climatology analysis we have conducted) • Sensitivity studies • Lower level stability • Storm intensity

  10. DiscussionNext Conference Call: Wednesday, August 14th, 2013 11 AM

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