Seaward Landfast Ice Edge (100 m cell size) derived from gradient differences of RADARSAT Imagery

Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: University of Alaska Fairbanks
Publication_Date: 2012
Title:
Seaward Landfast Ice Edge (100 m cell size) derived from gradient differences of RADARSAT Imagery
Geospatial_Data_Presentation_Form: raster digital data
Other_Citation_Details:
See extended abstract on "Landfast sea ice extent and variability in the Alaskan Arctic derived from SAR imagery" presented at the International Geoscience and Remote Sensing Symposium, September 20-24, 2004, Anchorage, Alaska.
Online_Linkage: http://boemre.gina.alaska.edu/
Description:
Abstract:
This gridded data set represents the Seaward Landfast Ice Edge (SLIE).  Landfast sea ice is a seasonal phenomena and throughout its annual existence, between formation in late fall and break-up in late spring, it is shaped by a range of thermodynamic and dynamic forces (Barry et al. 1979; Shapiro and Metzner, 1989). The most apparent changes are those in landfast ice area and extent when floes of ice attach to and break off from its seaward edge. The position of the SLIE over the course of the year generally advances offshore to a stable position in mid-winter before retreating with the onset of spring. However, higher frequency changes in position also occur on timescales of days to weeks, which are generally small but occasionally affect the full width of the landfast ice. The location and stability of the SLIE at any point in time affects the activities of people and wildlife in the coastal arctic as it marks the boundary between stationary, continuous sea ice and drifting deforming pack ice. It is a vital consideration for people hunting or working on the ice in determining where food sources might be or where spilt oil might go. Since landfast ice occupies the shallowest water in the arctic, its presence or absence is also important for coastal process such as erosion and sediment entrainment.
Purpose:
These data were processed to meet contract requirements for the US Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE): Mapping and Characterization of Recurring Spring Leads and Landfast ice in the Beaufort and Chukchi Seas Coastal Marine Institute (CMI/BOEMRE09HQPA0004T).
Supplemental_Information:
Data files have been processed to cover the western and eastern portions of the study area.  The westen portion spans the coast from Russia's Chukotka Peninsula across the Bering Straight to Wainwright, Alaska.  The eastern portion extends from Wainwright, Alaska to Mackenzie Bay, Canada.

The files names associated with the landfast ice grid data derived from Radarsat mosaics are prefixed with an "r".  The year and time period covering each delineation is noted with a range consisting of the day of the year for the first and last Radarsat mosaic used.  For descriptive purposes, the following abbreviations are used as placeholders for real values to illustrate the naming convention:
"d" = day of year 
and "Y" = Year.  
This convention follows as "rYY_ddd_ddd" where the gridded landfast ice extent derived from 2001 Radarsat mosaics covering a 16 day period would be r01_279_295  (ArcGIS grids have a 13 character file naming convention.)

Definition of landfast sea ice:
The seaward landfast ice edge has been delineated from colocated Radarsat SAR imagery based on the following criteria, which are used to define landfast ice
1) The ice is contiguous with the coast
2) The ice exhibits no detectable motion over approximately 20 days

The pixel size of the imagery is 100m, with a stated geolocation accuracy of 200m. The time period for which the ice must remain stationary was chosen to represent a number of synoptic periods and therefore exclude ice that temporarily comes to rest adjacent to the coast without any mechanism to hold it in place while weather patterns change. The exact time period cannot be stated universally, since ice motion, or lack thereof, is determined by examination of 3 consecutive mosaics, the time interval between which is not constant. Furthermore, each mosaic represents a time-span of between 3 and 4 days and so there maybe different time seperations between different points in any two mosaics. A more detailed explanation of the definition and delineation of the seaward landfast ice edge can be found at mms.gina.alaska.edu
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 1996
Ending_Date: 2008
Currentness_Reference:
ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -177.005445
East_Bounding_Coordinate: -159.199921
North_Bounding_Coordinate: 71.710522
South_Bounding_Coordinate: 65.041910
Keywords:
Theme:
Theme_Keyword_Thesaurus: Aquatic Sciences and Fisheries Thesaurus
Theme_Keyword: landfast
Theme_Keyword: sea ice
Theme_Keyword: grounded ice
Place:
Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Arctic Ocean
Place_Keyword: Chukchi Sea
Place_Keyword: Beaufort Sea
Place_Keyword: North Slope
Place_Keyword: Alaska
Place_Keyword: Canada
Place_Keyword: Russia
Access_Constraints: None.
Use_Constraints:
Any hardcopies or published datasets utilizing these data sets shall clearly indicate their source.  If the user has modified the data in any way they are obligated to describe the types of modifications that they have performed.  User specifically agrees not to misrepresent these datasets, nor to imply that any changes that they made were approved by the University of Alaska.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Dr. Hajo Eicken
Contact_Organization: Geophysical Institute, University of Alaska Fairbanks
Contact_Position: Professor
Contact_Address:
Address_Type: mailing and physical address
Address:
903 Koyukuk Dr., P.O. Box 757320
City: Fairbanks
State_or_Province: Alaska
Postal_Code: 99775-7320
Country: USA
Contact_Voice_Telephone: 907-474-7280
Contact_Facsimile_Telephone: 907-474-7290
Contact_Electronic_Mail_Address: hajo.eicken@gi.alaska.edu
Data_Set_Credit:
The funding for this effort was provided by the US Bureau of Ocean Energy Management, Regulation and Enforcement (AK-03-06, MMS-71707) and the Coastal Marine Institute (CMI/BOEMRE09HQPA0004T). Matching funds are provided through support of Shell and Conoco-Phillips.
Native_Data_Set_Environment:
Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4; ESRI ArcCatalog 8.3.0.800
Cross_Reference:
Citation_Information:
Originator: Barry, R, R.E. Moritz and J.C. Rogers,
Publication_Date: 1979
Title:
The Fast Ice Regimes of the Beaufort and Chukchi Sea Coasts, Alaska.
Edition: 1
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: Cold Regions Science and Technology
Issue_Identification: 1, pp129-152
Cross_Reference:
Citation_Information:
Originator: Shapiro, L.H and R.C. Metzner
Publication_Date: 1989
Title:
Nearshore Ice Conditions from Radar Data, Point Barrow Area, Alaska.
Geospatial_Data_Presentation_Form: document
Series_Information:
Series_Name: Geophysical Institute Report
Issue_Identification: UAG-R (132)
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Data_Quality_Information:
Logical_Consistency_Report:
Map projection and datum were confirmed and checked to conform with base data sets and imagery.  

It should be noted that water on the surface of the ice will affect the backscatter, without necessarily affecting the stability of the ice or causing it to move. This situation is common in the Spring.  Thus, if the ice immediately beyond a flooded area exhibits consistency, then the SLIE line is drawn beyond the flooded area. This is consistent with our definition of SLIE (Seaward Landfast Ice Edge.)  As the ice at the mouth of a river becomes unstable during the Spring, a "hole" may develop in the landfast ice which we will not detect with this approach. This will be discussed further in reports associated with this study.
Completeness_Report:
Complete.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Horizonal Positional accuracy is typically between 0-300 m when comparing images with the Alaska coastline (derived from 1:63360 and AlaskaMapped.org data sources) in ArcMap.  Offset larger than 300 m are reported to ASF for investigation.

A few mosaics lacked coverage for Kotzebue.  In these cases, the landfast ice delineation from the previous sequence was used.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 300
Horizontal_Positional_Accuracy_Explanation:
Visual inspection.
Lineage:
Process_Step:
Process_Description:
A combination of automated and manual techiques have been employed to derive the Seaward Landfast Ice Edge (SLIE) shown in this data set.  Custom IDL scripts were utilized to derive the net difference between gradient fields of 3 consecutive, colocated Radarsat subscenes.  The average period between scenes is 10 days.  A semi-automated procedure was developed to consider 3 consecutive mosaics at a time representing an average period of 20 days. From these a magnitude image of the horizontal and vertical components of gradient difference is created.  The landfast ice is characterized by dark regions of low gradient difference adjacent to the land and typically bounded by bright, linear regions of high gradient difference.  The SLIE is identified by bright regions of high gradient difference.  After thresholding the image at a gray value corresponding to a net backscatter gradient difference of 8 dB / km, the SLIE is more easily detected and can be manually delineated. A technique for automatically delineating the SLIE from the gradient difference images proves elusive at this time, since the SLIE can be less distinct in some areas or misidentification of a SLIE, e.g., in areas of ice surface flooding can occur.  For this reason, the SLIE is manually delineated over gradient image mosaics using the corresponding source imagery for interpretation.
Process_Date: 2010
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Andy Mahoney
Contact_Organization: University of Alaska Fairbanks, Geophysical Institute
Contact_Position: Research Assistant Professor of Geophysics
Contact_Address:
Address_Type: mailing and physical address
Address:
903 Koyukuk Dr., P.O. Box 757320
City: Fairbanks
State_or_Province: AK
Postal_Code: 99775-7320
Country: USA
Contact_Voice_Telephone: 907-474-5382
Contact_Facsimile_Telephone: 907-474-7290
Contact_Electronic_Mail_Address: mahoney@gi.alaska.edu
Hours_of_Service: business hours
Contact Instructions:
Email preferred.
Process_Step:
Process_Description:
SLIE is manually delineated over gradient image mosaics using ENVI image processing software.  Each SLIE delineation is processed and exported to GeoTIFF format .  ArcGIS batch utilities are used to convert each GeoTiff to a 100 meter cell ArcGIS Grid file.  Low resolution browse images (*.bmp format) are generated using ArcCatalog.  These browse images are then converted to *.jpg format for display on the project web site.  Final processing includes importing FGDC metadata, export to ESRI Interchange format (*.e00) and bundling with Winzip for posting to the project web site to ensure clean data transfer of the ESRI interchange file (*.e00), plus associated metadata record and browse image.
Process_Date: 2010
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Allison Graves Gaylord
Contact_Organization: Nuna Technologies
Contact_Position: Principal
Contact_Address:
Address_Type: mailing address
Address:
POB 1483
City: Homer
State_or_Province: AK
Postal_Code: 99603
Country: USA
Contact_Voice_Telephone: 907.399-1120
Contact_Electronic_Mail_Address: nunatech@usa.net
Contact Instructions:
Email preferred.
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Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 6271
Column_Count: 6234
Vertical_Count: 1
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Map_Projection:
Map_Projection_Name: Albers Conical Equal Area
Albers_Conical_Equal_Area:
Standard_Parallel: 55.000000
Standard_Parallel: 65.000000
Longitude_of_Central_Meridian: -154.000000
Latitude_of_Projection_Origin: 50.000000
False_Easting: 0.000000
False_Northing: 0.000000
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: row and column
Coordinate_Representation:
Abscissa_Resolution: 100.000000
Ordinate_Resolution: 100.000000
Planar_Distance_Units: meters
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1983
Ellipsoid_Name: Geodetic Reference System 80
Semi-major_Axis: 6378137.000000
Denominator_of_Flattening_Ratio: 298.257222
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Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: Landfast Ice Edge
Entity_Type_Definition:
Band 1
Entity_Type_Definition_Source:
ESRI
Attribute:
Attribute_Label: ObjectID
Attribute_Definition:
Internal feature number.
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: ObjectID
Enumerated_Domain_Value_Definition:
Internal feature number.
Enumerated_Domain_Value_Definition_Source:
ESRI
Attribute:
Attribute_Label: Value
Attribute_Definition:
Cell Value
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Value
Enumerated_Domain_Value_Definition:
Grid cell value (where 255 = landfast ice)
Enumerated_Domain_Value_Definition_Source:
UAF
Attribute:
Attribute_Label: Count
Attribute_Definition:
Cell Count
Attribute_Definition_Source:
ESRI
Attribute_Domain_Values:
Enumerated_Domain:
Enumerated_Domain_Value: Count
Enumerated_Domain_Value_Definition:
Cell Count
Enumerated_Domain_Value_Definition_Source:
ESRI
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: UAF Geographic Information Network of Alaska (GINA)
Contact_Person: Tom Heinrichs
Contact_Position: Associate Director
Contact_Address:
Address_Type: mailing and physical address
Address:
909 Koyukuk Drive
City: Fairbanks
State_or_Province: Alaska
Postal_Code: 99775-7275
Country: USA
Contact_Voice_Telephone: 907.474.6663
Contact_Electronic_Mail_Address: tom.heinrichs@alaska.edu
Hours_of_Service: 8:00 a.m. - 5:00 p.m. AST
Resource_Description: Downloadable Data
Distribution_Liability:
The University of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any users purposes. In no event will the University of Alaska be liable for any incidental, indirect, special, consequential or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products, any failure thereof or otherwise, and in no event will the State of Alaska's liability to the requestor or anyone else exceed the fee paid for the electronic service or product.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ESRI Grid
Format_Version_Date: 2010
Format_Specification:
ESRI Grid
Transfer_Size: 0.631
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: http://boemre.gina.alaska.edu/
Access_Instructions:
web browser and/or FTP
Fees: None
Available_Time_Period:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19961015
Ending_Date: 200805
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Metadata_Reference_Information:
Metadata_Date: 20100929
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nuna Technologies
Contact_Person: Allison Graves Gaylord
Contact_Position: Principal
Contact_Address:
Address_Type: mailing address
Address:
P.O. Box 1483
City: Homer
State_or_Province: AK
Postal_Code: 99723-1483
Country: USA
Contact_Voice_Telephone: 907.399.1120
Contact_Electronic_Mail_Address: nunatech@usa.net
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
Metadata_Access_Constraints: None.
Metadata_Use_Constraints:
If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the University of Alaska.
Metadata_Security_Information:
Metadata_Security_Classification_System: None.
Metadata_Security_Classification: Unclassified
Metadata_Security_Handling_Description:
None.
Metadata_Extensions:
Online_Linkage: http://www.esri.com/metadata/esriprof80.html
Profile_Name: ESRI Metadata Profile
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