Robert LaPlanteNOAA/NWS Cleveland, OH

David SchwabJia Wang

NOAA/GLERL Ann Arbor, MI

21 March 2010

Outline

Motivation for developing the GLIMDescription of the GLIMPreliminary Evaluation of the GLIMFuture plans for the GLIM

MODIS 4-9 March 2010

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

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 outdatedIn 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

Description of the GLIMGLERL 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 resolutionHourly Nowcast runs - ingest surface observationsForecast 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

Description of the GLIMThe 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

Integration of the GLIM and NDFD results in the Forecast Generation of:

Surface Water TemperatureIce ConcentrationIce ThicknessIce 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

Preliminary Evaluation of the GLIMBOIVerify 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

MODIS Satellite 2/4/2010

GLERL GLIM Ice Concentration fcst (%) in BOIVerify

NIC observed IceConcentration (%) in BOIVerify

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

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.

GLIM Evaluation with BOIVerify

NIC displacement increases theNumber of grid points of nil ice cover

Expected value reduced due toNIC excessive # of nil grid points near northern Erie lakeshore

Preliminary Evaluation of the GLIMon Lake Erie

Average Ice Concentration/Coverage (%/100)

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

Erroneous?

Future Plans for the GLIMCorrect NIC ice analysis displacement errorInitialize the GLIM with a NIC ice analysisUpon further development, the GLIM will be

expanded to the other Great LakesAdditional 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

Questions ?

Robert.laplante@noaa.gov