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

Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Data_Organization_Information
• Spatial_Reference_Information
• Entity_and_Attribute_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: University of Alaska Fairbanks

Publication_Date: 20051231

Title:

Seaward Landfast Ice Edge 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 vector 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:

The files names associated with the landfast ice shapefiles 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 vector based landfast ice extent derived from 2001 Radarsat mosaics covering a 16 day period would be "r01_279_295shape".

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: -160.813048

East_Bounding_Coordinate: -133.824195

North_Bounding_Coordinate: 72.620297

South_Bounding_Coordinate: 68.714097

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

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 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)

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:

+/- 3 pixels based on co-location techniques of source imagery.

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. 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 and then to a Shapefile. 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. The data sets were then bundled (and compressed) with Winzip for posting to the web.

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: Vector

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: FID

Attribute_Definition: Feature ID of shapefile

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: FID

Enumerated_Domain_Value_Definition: Feature ID of shapefile

Enumerated_Domain_Value_Definition_Source: ESRI

Attribute:

Attribute_Label: Shape

Attribute_Definition: Feature Class

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: Shape

Enumerated_Domain_Value_Definition: Feature Class = Polygon

Enumerated_Domain_Value_Definition_Source: ESRI

Attribute:

Attribute_Label: Area

Attribute_Definition: Area of polygon

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: Area

Enumerated_Domain_Value_Definition: Area of polygon

Enumerated_Domain_Value_Definition_Source: Automatically calculated by ArcGIS

Attribute:

Attribute_Label: Perimeter

Attribute_Definition: perimeter of polygon

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: Perimeter

Enumerated_Domain_Value_Definition: perimeter of polygon

Enumerated_Domain_Value_Definition_Source: Automatically calculated by ArcGIS

Attribute:

Attribute_Label: r###_###_

Attribute_Definition: Internal Feature Number

Attribute_Definition_Source: ESRI / UAF

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: r###_###_

Enumerated_Domain_Value_Definition:

r = derived from Radarsat; # = represents day of year where each file is comprised of a date from a range of dates

Enumerated_Domain_Value_Definition_Source: ESRI / UAF

Attribute:

Attribute_Label: r###_###_ID

Attribute_Definition: Internal Identifier

Attribute_Definition_Source: ESRI / UAF

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: r###_###_ID

Enumerated_Domain_Value_Definition:

Internal Identifier where r = derived from Radarsat; # = represents day of year where each file is comprised of a date from a range of dates; appended by ID for Identifier

Enumerated_Domain_Value_Definition_Source: ESRI / UAF

Attribute:

Attribute_Label: GRID_CODE

Attribute_Definition: Grid code for cell value

Attribute_Definition_Source: ESRI

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: Value = 255

Enumerated_Domain_Value_Definition: landfast ice

Enumerated_Domain_Value_Definition_Source: Derived from Radarsat imagery

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: 0.631

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: 20051020

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