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

the 2012-2013 Ice seasonRobert LaPlante

Christopher MelloNOAA/NWS Cleveland, OH

Gregory LangJia Wang

NOAA/GLERL Ann Arbor, MI

9 April 2013

OutlineDescription of the GLIM Comparison of the GLIM to the National

Ice Center analysis for the 2012-2013 ice season

Addition of Vessel Icing parameterFuture 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 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

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 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 & Vessel Icing

http://www.glerl.noaa.gov/res/glcfs/glcfs-ice.php?lake=e&type=N&hr=00

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 Subjectivity of the ice analyst in specifying ice edge

and concentration

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

Winter TemperaturesWhile still above normal, the 2012-13 winter was

colder than the unseasonably mild 2011-2012 winterResultant Great Lakes ice cover increased,

especially on shallow Lake ErieMaximum seasonal ice cover attained by lake

(GLERL) 2011-2012 2012-2013Lake Ontario 3% 15%Lake Superior 7% 38%Lake Erie 16% 85%Lake Michigan 17% 20%Lake Huron 20% 40%

Assessment of the NIC Ice AnalysisNIC ice analysis was notRealistic at times with ice Concentration decreasingWith air temperaturesBelow freezing

Temperature

Assessment of the NIC Ice AnalysisNIC Analysis exhibited Occasional spikes of increasedIce concentration which lastedBut a day or so and were notRealistic. In particular, weWill examine the second, or Day 62 spike on Lake SuperiorWhen the ice cover nearly doubledFor only a day

Lake Superior

Assessment of the NIC Ice AnalysisDay61

Day62

Day63

Ice Concentration

Note the abrupt increase and decrease in ice concentrationFrom Day61 through Day63 overWestern Lake Superior

This High Nowcast, due to the highNIC analysis, produced a high starting forecast

Which, with low air temperatures Leads to these high 1-day, 3-day, and 5-day forecasts

Lake Superior

Change in GLIM forecastIce Concentration vsChange in NIC ice analysis

NIC spikes are apparent in thesex/y plots of the GLIM days 1-3-5 forecasts

Too slow ice growth in GLIM

To fastIce growth

Too fastmelt

Too slowmelt

GLIM tends toGrow or meltIce too slowly inDay 3 and Day 5 forecasts

LakeErie

Summary of the GLERL GLIM2012-2013 ice season on Lake Erie

GLIM was successfully run over all the Great LakesGLIM nowcasts for 2012-2013 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“Spikes” in the daily NIC ice analysis appeared spurious

Compared to NIC analysis, the GLIM 3-day and 5-day forecasts tended to grow and melt ice too slowly on all the Lakes

• Difficult to separate error in NIC analysis and NDFD with error in GLIM

Prediction of Vessel Spray Icing with the Great Lake Ice Model

Sea Spray Icing AlgorithmIn the past we used Nomograms of Icing for

Various water temperatures:

Sea Spray Icing AlgorithmUsing the work of Overland et al. (1986) &

(1990): Icing Predictor: PPR is defined by

GLERL modified the equation for fresh water and used output from the Great Lakes Ice Mode (GLIM) to produce icing classes for all five lakes

Icing ClassesIcing classes are determined with the

assumption that vessels are steaming into the wind and of 20 -75 meters in length

Vessel Icing over Lake Erie

NIC 31 Jan 2013

White area is whereIce has formed

Potential Issues Shoreline affects are not accounted for in

icing potentialFor a given wind, waves and resultant freezing

spray will be less at the start of the fetchThe reduction in freezing spray due to lake

ice cover has not been determined, but at some high percentage of ice cover (>70%), freezing spray may be minimal

Vessel Icing NotesGLERL added the Vessel Icing parameter to

its web site http://www.glerl.noaa.gov/res/glcfs/

The quality of the freezing spray forecast is dependent on the inputs into the GLIM which include the NDFDSurface WindAir Temperature

So pay attention (American Forecasters) to the NDFD grids over the entire lake you forecast for

Future Plans for the GLIM• GLCFS POM (currently running the GLIM) will not be

modified• GLERL is in the process of developing a new model: an

operational FVCOM (Finite Volume Coastal Ocean Model) for Lake Erie• Variable grid and much higher resolution for harbors and bays• Heat fluxes are being calculated and testing of ice dynamics is

expected over the next year• Plan to test the Lake Erie FVCOM this fall at CSDL (Coastal

Survey Development Lab)• By late summer 2014, FVCOM may be delivered to NCEP• Remaining lakes will be modeled by early 2017

Questions ?

Robert.laplante@noaa.gov