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Robert LaPlante Christopher Mello NOAA/NWS Cleveland, OH Gregory Lang Jia Wang NOAA/GLERL Ann Arbor, MI 9 April 2013.

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Presentation on theme: "Robert LaPlante Christopher Mello NOAA/NWS Cleveland, OH Gregory Lang Jia Wang NOAA/GLERL Ann Arbor, MI 9 April 2013."— Presentation transcript:

1 Robert LaPlante Christopher Mello NOAA/NWS Cleveland, OH Gregory Lang Jia Wang NOAA/GLERL Ann Arbor, MI 9 April 2013

2 Outline Description of the GLIM Comparison of the GLIM to the National Ice Center analysis for the ice season Addition of Vessel Icing parameter 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 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

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

7 GLERL GLIM included in the GLCFS Great Lakes Coastal Forecasting System Select “Ice”

8 Integration of the GLIM and NDFD results in the Forecast Generation of: Surface Water Temperature Ice Concentration Ice Thickness Ice Drift & Vessel Icing ice.php?lake=e&type=N&hr=00

9 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 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

10 Winter Temperatures While still above normal, the winter was colder than the unseasonably mild winter Resultant Great Lakes ice cover increased, especially on shallow Lake Erie Maximum seasonal ice cover attained by lake (GLERL) Lake Ontario 3%15% Lake Superior7%38% Lake Erie 16%85% Lake Michigan17%20% Lake Huron20%40%

11 Assessment of the NIC Ice Analysis NIC ice analysis was not Realistic at times with ice Concentration decreasing With air temperatures Below freezing Temperature

12 Assessment of the NIC Ice Analysis NIC Analysis exhibited Occasional spikes of increased Ice concentration which lasted But a day or so and were not Realistic. In particular, we Will examine the second, or Day 62 spike on Lake Superior When the ice cover nearly doubled For only a day Lake Superior

13 Assessment of the NIC Ice Analysis Day61 Day62 Day63 Ice Concentration Note the abrupt increase and decrease in ice concentration From Day61 through Day63 over Western Lake Superior

14 This High Nowcast, due to the high NIC analysis, produced a high starting forecast Which, with low air temperatures Leads to these high 1-day, 3-day, and 5-day forecasts

15 Lake Superior Change in GLIM forecast Ice Concentration vs Change in NIC ice analysis NIC spikes are apparent in these x/y plots of the GLIM days forecasts

16 Too slow ice growth in GLIM To fast Ice growth Too fast melt Too slow melt GLIM tends to Grow or melt Ice too slowly in Day 3 and Day 5 forecasts Lake Erie

17 Summary of the GLERL GLIM ice season on Lake Erie GLIM was successfully run over all the Great Lakes GLIM nowcasts for 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

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19 Sea Spray Icing Algorithm In the past we used Nomograms of Icing for Various water temperatures:

20 Sea Spray Icing Algorithm Using 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

21 Icing Classes Icing classes are determined with the assumption that vessels are steaming into the wind and of meters in length

22 Vessel Icing over Lake Erie NIC 31 Jan 2013 White area is where Ice has formed

23 Potential Issues Shoreline affects are not accounted for in icing potential For a given wind, waves and resultant freezing spray will be less at the start of the fetch The 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

24 Vessel Icing Notes GLERL added the Vessel Icing parameter to its web site The quality of the freezing spray forecast is dependent on the inputs into the GLIM which include the NDFD Surface Wind Air Temperature So pay attention (American Forecasters) to the NDFD grids over the entire lake you forecast for

25 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

26 Questions ?


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