Seaward Landfast Ice Edge (100 m cell size) derived from gradient differences of RADARSAT Imagery for the Chukchi and Beaufort Seas, Northern Alaska, USA and Northwest Canada.

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Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: University of Alaska Fairbanks
Publication_Date: 20051231
Title:
Seaward Landfast Ice Edge (100 m cell size) derived from gradient differences of RADARSAT Imagery for the Chukchi and Beaufort Seas, Northern Alaska, USA and Northwest Canada.
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://mms.gina.alaska.edu>
Description:
Abstract:
This gridded data set represents the Seaward Landfast Ice Edge (SLIE) along the coast of Northern Alaska (West of Barrow) and Northwest Canada (East to the Mackenzie Delta) for the study area which ranges from approximately 133 to 160 degrees West and 68 to 72.5 degrees North. Landfast sea ice is a seasonal phenomena in the Alaskan Arctic 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 compiled by the University of Alaska Fairbanks to meet contract requirements for the US Mineral Management Service: Mapping and Characterization of Recurring Spring Leads and Landfast ice in the Beaufort and Chukchi Seas (AK-03-06)
Supplemental_Information:
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: 2004
Currentness_Reference: ground condition
Status:
Progress: Complete
Maintenance_and_Update_Frequency: None planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -160.815145
East_Bounding_Coordinate: -133.825784
North_Bounding_Coordinate: 72.620654
South_Bounding_Coordinate: 68.714535
Keywords:
Theme:
Theme_Keyword_Thesaurus: Aquatic Sciences and Fisheries Thesaurus
Theme_Keyword: raster
Theme_Keyword: landfast
Theme_Keyword: sea ice
Theme_Keyword: grounded ice
Place:
Place_Keyword_Thesaurus: Dictionary of Alaska Place Names
Place_Keyword: Arctic Ocean
Place_Keyword: Chukchi Sea
Place_Keyword: Beaufort Sea
Place_Keyword: North Slope
Place_Keyword: Alaska
Place_Keyword: Canada
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
Contact_Position: Unversity of Alaska Fairbanks
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 Mineral Management Service for Mapping and Characterization of Recurring Spring Leads and Landfast ice in the Beaufort and Chukchi Seas (AK-03-06, MMS-71707)
Native_Data_Set_Environment:
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.0.0.535
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)

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:
+/- 2 pixels based on co-location techniques of source imagery.
Quantitative_Horizontal_Positional_Accuracy_Assessment:
Horizontal_Positional_Accuracy_Value: 200
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. The study area was divided into 10 subregions in order to obtain subscenes from 460 x 460 km RADARSAT scenes that were free from mosaicking edges prior to calculating the gradient fields. 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: 2004
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Andy Mahoney
Contact_Organization: University of Alaska Fairbanks, Geophysical Institute
Contact_Position: PhD Candidate
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: 907-474-5648
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 compiled from the 10 subscenes using ENVI image processing software. Each SLIE delineation is processed and exported to GeoTIFF format using IDL routines. ArcGIS ArcToolbox batch utilities are then used to convert each GeoTiff to a 100 meter cell ArcGIS Grid file. Low resolution browse images (*.bmp format) were generated using ArcCatalog. These browse images were then converted to *.jpg format for display on the LILIFECS web site. Final processing included a batch import of the appropriate FGDC compliant metadata template. Final data sets were exported to ESRI Interchange format (*.e00) and bundled (and compressed) with Winzip for posting to the web to ensure clean data transfer of the *.e00, plus associated metadata record and browse image.
Process_Date: 2004
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: Allison Graves Gaylord
Contact_Organization: Nuna Technologies
Contact_Position: Owner / GIS Specialist
Contact_Address:
Address_Type: mailing address
Address: POB 1483
City: Homer
State_or_Province: AK
Postal_Code: 99603
Country: USA
Contact_Voice_Telephone: 907.235.3476
Contact_Facsimile_Telephone: 907.235.3476
Contact_Electronic_Mail_Address: nunatech@usa.net
Contact_Instructions: Email preferred.

Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Raster
Raster_Object_Information:
Raster_Object_Type: Grid Cell
Row_Count: 3298
Column_Count: 9554
Vertical_Count: 1

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

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 = SLIE)
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

Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: UAF Geographic Information Network of Alaska (GINA)
Contact_Person: Dr. Virgil (Buck) Sharpton
Contact_Position: President's Professor of Remote Sensing
Contact_Address:
Address_Type: mailing and physical address
Address: 903 Koyukuk Drive
City: Fairbanks
State_or_Province: Alaska
Postal_Code: 99775-7320
Country: USA
Contact_Voice_Telephone: 907.474.6663
Contact_Electronic_Mail_Address: buck.sharpton@gina.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: 2004
Format_Specification: ESRI Grid
Transfer_Size: 0.620
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name: <http://mms.gina.alaska.edu>
Access_Instructions: web browser and/or FTP
Fees: None
Ordering_Instructions:
These data will be made available at the request of the US Mineral Management Service via online tools provided by the Geographic Information Network of Alaska (GINA) at the University of Alaska Fairbanks.
Available_Time_Period:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19961015
Ending_Date: 20040715

Metadata_Reference_Information:
Metadata_Date: 20050510
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: Nuna Technologies
Contact_Person: Allison Graves Gaylord
Contact_Position: Owner / GIS Specialist
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_Facsimile_Telephone: 907.235.3476
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

Generated by mp version 2.8.14 on Tue May 10 13:39:59 2005