Evaluation of Great Lakes Ice Model (GLIM) Real-time Ice Forecasts for

the 2011-2012 Ice seasonRobert LaPlante

NOAA/NWS Cleveland, OH

David SchwabJia Wang

NOAA/GLERL Ann Arbor, MI

15 March 2012

OutlineDescription 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

Description of the GLIMGLIM 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 observationsForecast 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

GLIM resolution for the Great Lakes

10 km

2 km

2km

5 km

2km

2011-2012 ice season

Description of the GLIMGLIM 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

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

GLIM Ice Concentration is nudged toward the NIC ice concentration field

which is updated daily

GLIMNIC

GLERL GLIM included in the GLCFSGreat Lakes Coastal Forecasting System

http://www.glerl.noaa.gov/res/glcfs/

Select “Ice”

Integration of the GLIM and NDFD results in the Forecast Generation of:Surface Water Temperature

Ice ConcentrationIce ThicknessIce Drift

http://www.glerl.noaa.gov/res/glcfs/glcfs-ice.php?lake=h&type=F&hr=01

Sources of Error in the GLIM Ice Concentration Forecast

Error in the daily NIC ice concentration analysisNIC 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

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

2011-2012 GLIM PerformanceThis 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 minimalMaximum seasonal ice cover attained by lake

(GLERL)Lake Ontario 3%Lake Superior 7%Lake Erie 16%Lake Michigan 17%Lake Huron 20%

2011-2012 GLIM PerformanceLack 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 12for ice growth &thaw

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 growingIce along the Michigan shore and Too fast in eastern Georgian Bay

Too little ice forecast Too much ice forecast

%

NIC Ice Analysis25 Jan 2012 (%)

GLIM Ice Cover120 hr fcst valid 25 Jan 2012 (%)

GLIM - NIC (%)

Ice Free

Ice covered

Too little ice forecast

Too much ice forecast

GLIM 120 hr fcst had too littleIce concentration in northern Georgian Bay, western Lake Erie, northern Lake MI, & swLake Superior

Too little ice forecast

Too much ice forecast

NIC Ice Analysis25 Jan 2012 (%)

GLIM Ice Cover120 hr fcst valid 25 Jan 2012 (%)

GLIM - NIC (%)

Over Lake Huron the120 hr GLIM forecast either grew too littleIce early in the forecast or melted it tooQuickly near the end in most shallow areasExcept Saginaw Bay

Summary of the GLERL GLIM2010-2011 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

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

Questions ?

Robert.laplante@noaa.gov