2003111618225600FALSE20040914192924002005042912503400{FA1C4FBC-DAB3-427C-98B0-F02EA49099AF}Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 8.3.0.800 This shapefile 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. 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) Following is an operational definition of Landfast ice stability that will be refined as extensive data sets are analyzed for the MMS study area. (1) The general time period of stable landfast ice is bracketed by the first, sustained attachment in fall/winter and the break-up and decay of landfast ice in early summer. Preliminary work suggests that these dates have been shifting somewhat in the past 20 years. Here, the period of first, sustained attachment is defined as that time when a landfast ice cover of more than 1 km width is established that persists in-situ for more than 2 weeks over a given stretch of coastline. Break-up and decay are defined by the removal of substantial portions of the landfast ice to within less than 1 km from the beach, with concurrent substantial reductions in ice thickness through surface and bottom ablation. (2) During the general time period of stable landfast ice, it is the location of the seaward edge of the fast ice that determines stability in any given location. Hence, the simplest assessment of stability would include an indication of the amplitude of oscillations in seaward landfast ice edge during the course of the ice season as a measure of stability. In most cases, however, one can expect such oscillations to subside once the seaward sectors of the landfast ice are grounded by a combination of thick ice floes and pressure ridges. Thus, break-out events as major manifestations of fast-ice unstability could be characterized as breaking off of major sections of the landfast ice (ice fragments larger than 1 x 1 km in size) during this latter, "more stable" period of the landfast ice seasonal cycle. (3) In order to distinguish between full break-out events and the attachment and detachment of "floating extentions" which are often observed in the Beaufort Sea during periods of stagnating ice motion, one would furthermore discriminate between break-out of landfast ice inshore and offshore of the deepest grounded ridges (if present and identifiable) or of the isobath typically associated with the deepest grounded pressure ridges (generally between 20 and 25 m; Reimnitz et al., 1978). For a floating extension to qualify as part of the landfast ice, it would have to be present for two weeks or more. en University of Alaska Fairbanks 20051231 vector digital data http://mms.gina.alaska.edu slie200111See 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. 1996 2004 ground condition Complete None planned -160.813048-133.82419572.62029768.714097-236179.999978719219.9999782180119.0001002509919.000142 Aquatic Sciences and Fisheries Thesaurus raster landfastsea icegrounded ice Dictionary of Alaska Place Names Arctic Ocean Chukchi SeaBeaufort SeaNorth SlopeAlaskaCanada None. 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. Vector DatasetThe 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) Dr. Hajo EickenGeophysical InstituteUnversity of Alaska Fairbanksmailing and physical address

903 Koyukuk Dr., P.O. Box 757320

FairbanksAlaska99775-7320USA907-474-7280907-474-7290hajo.eicken@gi.alaska.edu Barry, R, R.E. Moritz and J.C. Rogers,19791documentCold Regions Science and Technology1, pp129-152Shapiro, L.H and R.C. Metzner1989documentGeophysical Institute ReportUAG-R (132)Microsoft Windows 2000 Version 5.1 (Build 2600) Service Pack 1; ESRI ArcCatalog 8.3.0.800slie200111-236179.999978719219.9999782509919.0001422180119.00011-160.813048-133.82419572.62029768.7140971 20050429 Nuna Technologies Allison Graves Gaylord Owner / GIS Specialist mailing address

P.O. Box 1483

Homer AK 99723-1483 USA 907.399.1120 nunatech@usa.net 907.235.3476 FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time enNone.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.None.UnclassifiedNone.http://www.esri.com/metadata/esriprof80.htmlESRI Metadata Profile ISO 19115 Geographic Information - MetadataDIS_ESRI1.0dataset UAF Geographic Information Network of Alaska (GINA) Dr. Virgil (Buck) Sharpton mailing and physical address

903 Koyukuk Drive

Fairbanks Alaska 99775-7320 USA 907.474.6663 buck.sharpton@gina.alaska.edu President's Professor of Remote Sensing8:00 a.m. - 5:00 p.m. AST Downloadable Data 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. ESRI Grid 2004 ESRI Grid 2.384 2.384 http://mms.gina.alaska.edu web browser and/or FTP None 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. 1993 2003 002file://\\NEWNUNALAP\C$\MMS\SLIE\2001-2002Semi_auto_monthly_averages\ArcShape\slie200111.shpLocal Area Network2.384ShapefileVectorSimplePolygonFALSE1179FALSEFALSEG-polygon1179GCS_North_American_1983NAD_1983_Alberscoordinate pairmeters0.0020480.002048Albers Conical Equal Area55.00000065.000000-154.00000050.0000000.0000000.000000North American Datum of 1983Geodetic Reference System 806378137.000000298.257222NAD_1983_Albers29554100329810011179 polygon polygon ESRI Feature Class1179 FIDFIDOID400Internal feature number.ESRIFIDInternal feature number.ESRIShapeShapeGeometry000Feature geometry.ESRIShapeFeature geometry.ESRICoordinates defining the features.AREAAREANumber93Polygon Area in MetersAREAAREAPolygon Area in MetersAREAPERIMETERPERIMETERNumber93PERIMETER of Polygon in MetersESRIPERIMETERPERIMETER of Polygon in MetersESRISLIEyyyymmSLIE0111_Number9Seaward Landfast Ice Edge Year / MonthUAF / ESRISLIEyyyymmSeaward Landfast Ice Edge Year / MonthUAF / ESRI (this field is a remant of the internal fields associated with the ESRI coverage format which has been truncated in the conversion to shapefile format)SLIEyyyymmSLIE0111_INumber9UAF & ESRI (this field is a remant of the internal fields associated with the ESRI coverage format which has been truncated in the conversion to shapefile format)Seaward Landfast Ice Edge Year / MonthSLIEyyyymmSeaward Landfast Ice Edge Year / MonthUAF / ESRIGRID_CODEGRID_CODENumber9Cell Value Derived from ESRI Grid formatESRIGRID_CODE (where 255 = SLIE)Cell Value Derived from ESRI Grid formatESRI 20050429 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. Complete. A combination of automated and manual techiques have been employed to derive the Seaward Landfast Ice Edge (SLIE) shown in this data set. The MMS study area was divided into 10 subregions in order to obtain subscenes from 500 x 500 km RADARSAT scenes that were free from mosaicking edges prior to calculating the gradient fields. Custom IDL routines were developed to derive the net difference between gradient fields of 3 consecutive colocated Radarsat subscenes. The average period between scenes was 8 days. An automated procedure was developed to consider 3 consecutive mosaics at a time representing an average period of 17 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 in some areas 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 sometimes be less distinct in some areas and bright regions sometimes occur along the coast particularly in springtime when surface flooding from rivers occurs. For this reason, the SLIE is manually delineated over gradient image mosaics compiled from the 10 subscenes. Monthly averages were processed and exported to GeoTIFF format using IDL routines. The final steps included converting GeoTiffs to ArcGIS format, defining the map projection and associating XML based metadata templates in preparation for posting to the project web site. 2004 Andy Mahoney University of Alaska Fairbanks, Geophysical Institute PhD Candidate mailing and physical address

903 Koyukuk Dr., P.O. Box 757320

Fairbanks AK 99775-7320 USA 907-474-5648 Mahoney@gi.alaska.edu business hours Email preferred. 907-474-7290 ENVI 4.0 +/- 3 pixels based on co-location techniques of source imagery.300Visual inspection.