1. Robert LaPlante NOAA/NWS Cleveland, OH David Schwab Jia Wang NOAA/GLERL Ann Arbor, MI 15 March 2012

2. Outline Description of the expansion of the GLIM to all five Great Lakes for the 2011-2012 ice season Comparison of the GLIM to the National Ice Center analysis for the 2011-2012 ice season Future plans for the GLIM MODIS 4-9 March 2010

3. Description of the GLIM GLIM has been under development by GLERL since 2007 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 all five Great Lakes this year as part of the Great Lakes Coastal Forecast system (GLCFS) at NOAA/GLERL Hourly Nowcast runs - ingest surface meteorological and daily NIC ice concentration observations Forecast runs from 00 to 12o hours – driven by the NDFD The GLIM is run using the latest surface forecast meteorological grids from the NWS National Digital Forecast Database (NDFD) out to 5 days

4. GLIM resolution for the Great Lakes 10 km 2 km 5 km 2km 2011-2012 ice season

5. Description of the GLIM GLIM Nowcasts of ice concentration are “nudged” towards the daily NIC ice concentration field and form the initial conditions 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

6. GLIM Nudge Procedure GLIM Nowcast nudging procedure was added in the 2010-2011 ice season GLIM ice concentration are “nudged” or modified to be close to the daily National Ice Center ice concentration analysis

7. GLIM Ice Concentration is nudged toward the NIC ice concentration field which is updated daily GLIM NIC

8. GLERL GLIM included in the GLCFS Great Lakes Coastal Forecasting System http://www.glerl.noaa.gov/res/glcfs/ Select “Ice”

9. 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/glcfs- ice.php?lake=h&type=F&hr=01

10. Sources of Error in the GLIM Ice Concentration Forecast Error in the daily NIC ice concentration analysis NIC analysis data sources are lagged: ~00 and ~12 UTC RADARSAT passes & previous day ~18 UTC MODIS imagery and current day ~18 UTC MODIS imagery are combined and posted about 00 UTC the next day Variable observation times add uncertainty due to advective changes and growth and decay of ice cover Error in the NDFD parameters (wind, temperature, or dewpoint) over the entire Great Lakes Error within the GLIM: nudging procedure, vertical mixing, or wave mixing

11. Comparison of the GLIM to the NIC Analysis 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 GraADS software was also used to create difference fields between the NIC and GLERL GLIM

12. 2011-2012 GLIM Performance This winter has been quite mild near the lakes with temperatures averaging in the warmest 10% of winters since records began Resultant Great Lakes ice cover has been minimal Maximum seasonal ice cover attained by lake (GLERL) Lake Ontario 3% Lake Superior 7% Lake Erie 16% Lake Michigan 17% Lake Huron 20%

13. 2011-2012 GLIM Performance Lack of sustained cold prevented much ice growth this winter across the lakes and limited evaluation of GLIM ice forecasts Just a few, brief cold spells produced a slight increase in ice cover Examine 17-25 Jan 12 for ice growth & thaw

14. NIC ice cover (%) 19 Jan 2012 GLIM ice cover (%) 72 hr valid 19 Jan 2012 GLIM –NIC (%) 19 Jan2012 Ice Cover/Concentration (%) Comparison GLIM was too slow in growing Ice along the Michigan shore and Too fast in eastern Georgian Bay Too little ice forecast Too much ice forecast %

15. NIC Ice Analysis 25 Jan 2012 (%) GLIM Ice Cover 120 hr fcst valid 25 Jan 2012 (%) GLIM - NIC (%) Ice FreeIce covered Too little ice forecast Too much ice forecast GLIM 120 hr fcst had too little Ice concentration in northern Georgian Bay, western Lake Erie, northern Lake MI, & sw Lake Superior

16. Too little ice forecast Too much ice forecast NIC Ice Analysis 25 Jan 2012 (%) GLIM Ice Cover 120 hr fcst valid 25 Jan 2012 (%) GLIM - NIC (%) Over Lake Huron the 120 hr GLIM forecast either grew too little Ice early in the forecast or melted it too Quickly near the end in most shallow areas Except Saginaw Bay

17. Summary of the GLERL GLIM 2010-2011 ice season on Lake Erie Expansion of the GLIM to the Great Lakes was successfully implemented GLIM nowcasts for 2011-2012 closely matched the NIC ice concentration analysis with daily nudging across all the lakes Since the NIC analysis is not a snap shot of the observed ice cover…some uncertainty is introduced into the GLIM Lack of sustained cold air this winter allowed only minimal ice growth that was confined to the shallow portions of the lakes Little ice formation allowed only a cursory examination of the GLIM on just a few forecasts Difficult to separate error in NIC analysis and NDFD with error in GLIM

18. Future Plans for the GLIM Assuming normal winter weather returns to the Great Lakes… a more thorough evaluation of the GLIM is planned for the 2012-2013 ice season Forecasters need to be aware that the GLIM uses NDFD data over the entire lakes including the Canadian waters 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

19. Questions ? Robert.laplante@noaa.gov