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Robert LaPlante NOAA/NWS Cleveland, OH David Schwab Jia Wang NOAA/GLERL Ann Arbor, MI

Evaluation of Great Lakes Ice Model (GLIM) Real-time Ice Forecasts for Lake Erie during the 2009-2010 Ice season. Robert LaPlante NOAA/NWS Cleveland, OH David Schwab Jia Wang NOAA/GLERL Ann Arbor, MI 21 March 2010. Outline. Motivation for developing the GLIM Description of the GLIM

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Robert LaPlante NOAA/NWS Cleveland, OH David Schwab Jia Wang NOAA/GLERL Ann Arbor, MI

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  1. Evaluation of Great Lakes Ice Model (GLIM) Real-time Ice Forecasts for Lake Erie during the 2009-2010 Ice season Robert LaPlante NOAA/NWS Cleveland, OH David Schwab Jia Wang NOAA/GLERL Ann Arbor, MI 21 March 2010

  2. Outline • Motivation for developing the GLIM • Description of the GLIM • Preliminary Evaluation of the GLIM • Future plans for the GLIM MODIS 4-9 March 2010

  3. Motivation for the Great Lakes Ice Model (GLIM) • Since the 1980’s a rather primitive method has been employed for forecasting ice on the Great Lakes which has been based on a simple regression method between temperature trends and ice formation for specific points around the lakes • Extended temp guidance was used to run the regression with the resultant subjective, general 5 day forecast trend of ice formation/growth/deterioration that has been produced three times a week in text version only

  4. Motivation for the Great Lakes Ice Model (GLIM) • Since the regression method was only applied to a few points around the lakes, it did not account for other areas of the lakes. • The method was woefully simple and outdated • In December 2006, NWS Cleveland approached GLERL about developing a quantitative method of forecasting Great Lakes ice with data from the NDFD (National Digital Forecast Database) or NWP model data with the intent to improve the accuracy and specificity of ice forecasts & outlooks, and open and near shore forecasts

  5. Description of the GLIM • GLERL developed the GLIM from 2007-2010 • GLIM is a combination of the Princeton Ocean Model for hydrodynamics and the Combined Ice Ocean Model tailored for the Great Lakes • GLIM which has two modules runs twice a day for Lake Erie as part of the Great Lakes Coastal Forecast system (GLCFS) at NOAA/GLERL at 2 km resolution • Hourly Nowcast runs - ingest surface observations • Forecast runs from 00 to 12o hours – driven by the NDFD • The GLCFS with the GLIM is run using the latest surface forecast meteorological grids from the NWS National Digital Forecast Database (NDFD) out to 5 days

  6. Description of the GLIM • The initial conditions for the forecast module are based on nowcast runs which use observed meteorological data for atmospheric forcing • Nowcasts produce a lake ice state which is used as the initial condition for the forecast module • Model output for the GLIM is posted to the web • NWS CLE retrieves via ftp the GLIM for AWIPS and GFE

  7. Integration of the GLIM and NDFD results in the Forecast Generation of: Surface Water Temperature Ice Concentration Ice Thickness Ice Drift http://www.glerl.noaa.gov/res/glcfs/erie-ice.php?lake=e&type=F&hr=01 For both the nowcast and forecast components of the GLIM

  8. Preliminary Evaluation of the GLIM • BOIVerify is a statistical analysis application that is run at many NWS offices to help verify locally produced gridded forecasts from the NDFD • BOIVerify was modified at NWS CLE to ingest the GLERL GLIM forecasts of ice concentration and ice cover analysis from the National Ice Center (NIC) to help evaluate the GLIM

  9. MODIS Satellite 2/4/2010 GLERL GLIM Ice Concentration fcst (%) in BOIVerify NIC observed Ice Concentration (%) in BOIVerify

  10. Observed NIC Ice concentrationDisplacement error NIC ice concentration analysis is displaced about 10 miles to the southeast. So for Lake Erie, ice cover is shifted on to the lakeshore of OH, PA, & NY

  11. NIC displacement affects on BOIVerify • Verification statistics generated by BOIVerify have been compromised with this displacement of the NIC analysis. • The NIC has been notified of the error and will hopefully address it soon.

  12. GLIM Evaluation with BOIVerify NIC displacement increases the Number of grid points of nil ice cover Expected value reduced due to NIC excessive # of nil grid points near northern Erie lakeshore

  13. Preliminary Evaluation of the GLIMon Lake Erie Average Ice Concentration/Coverage (%/100) Erroneous? GLIM IC Julian Day 2010 • Seasonal Change to average ice concentration was well simulated • Realistic spatial coverage with initial freezing of Lake Erie in January • Changes in observed spatial coverage not well once lake was mostly frozen

  14. Future Plans for the GLIM • Correct NIC ice analysis displacement error • Initialize the GLIM with a NIC ice analysis • Upon further development, the GLIM will be expanded to the other Great Lakes • Additional NDFD fields may be used by the GLIM – snowfall and QPF to make the model more realistic • Output from the GLIM may be added to the NDFD

  15. Questions ? Robert.laplante@noaa.gov

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