High-Resolution Orthorectified Imagery for the Coastal Areas of Bering Land Bridge NP (BELA) and Cape Krusenstern NM (CAKR), Northwest Alaska

ABSTRACT

This data series consists of orthorectified digital photography for the coastal and nearshore areas of Bering Land Bridge National Preserve (BELA), Cape Krusenstern National Monument (CAKR), and nearby portions of northwestern Alaska. The series consists of three timeslices: from 2003, approximately 1980, and approximately 1950. The orthoimages were completed as part of a study on coastal erosion in collaboration between the University of Colorado (Institute of Arctic and Alpine Research) and the National Park Service (Arctic Network Inventory and Monitoring Program). Each high-resolution image has the qualities of a photograph and the functionality of a map layer for use in Geographic Information Systems (GIS) or remote sensing software. The 2003 orthophoto mosaic was created by Aero-Metric Inc., and consists of 103 tiles derived from 1:24,000-scale, natural-color aerial photographs acquired for NPS and NOAA. The tiles have a pixel resolution of 0.6 m, an absolute horizontal accuracy of 1.1 m, and cover a total of 4,330 km². This imagery is the highest resolution for this large of an area in Alaska to date. The 57 orthorectified frames for 1978 to 1985 are derived from 1:64,000-scale, color-infrared (CIR) photographs acquired by the USGS and NOAA, as part of the Alaska High Altitude Photography (AHAP) program. They have a pixel resolution of 1.0 m, a relative horizontal accuracy of 1.5 m, and cover a total of 8,800 km². The 108 orthorectified frames for 1949 to 1956 are derived from 1:43,000-scale, black and white photographs acquired by the US Air Force. They have a pixel resolution of 1.0 m, a relative horizontal accuracy of 2.0 m, and cover a total of 6,990 km². Digital scans of the photographs from ca. 1950 and ca. 1980 were fully orthorectified in ERDAS Imagine using air-photo camera models, a Digital Elevation Model (DEM), information from calibration reports, and image-to-image control points linked to the 2003 base imagery. Each of the 268 image files is in georeferenced .tif (GeoTIFF) format, accompanied by a pyramid file (.rrd) generated by ArcGIS. The 2003 tiles are also provided in .sid (MrSID) format. Accessory shapefiles consist of extent map layers and attributed index map layers. All of the data layers share a UTM zone 3 projection and NAD83 datum, and are provided with FGDC-compliant metadata (in .html, .txt, and .xml formats). Also provided are a README file and a PowerPoint visual overview of the data series. Together, the three datasets make up a total of 2032 files and 162 GB of data. The imagery is available through an unrestricted public license, and can be obtained on a hard drive by request (see Distributor contact information in the metadata).

The high-resolution imagery will be of interest to land managers, scientists, and others for observation and analysis of natural features and ecosystems. Beyond investigation of coastal erosion for >600 km of shoreline, the three timeslices will be helpful to assess the status of environmental features, and to detect change in: 1) cultural resources and archeological sites; 2) ecosystem components such as geology, soils, permafrost, lake and stream hydrology, and vegetation assemblages; and 3) marine, terrestrial, and freshwater habitats for a variety of animals. The imagery assists the goals of the NPS Arctic Network Inventory and Monitoring Program, which has a mission to "collect, compile, and synthesize scientific information about the arctic network of parks to facilitate their preservation, unimpaired, for future generations."

METADATA AND CITATIONS

PLEASE READ the FGDC-compliant metadata files that are available for each image (in .html, .txt, and .xml formats). These files provide numerous details that may be of interest. Also, please cite the three datasets as indicated under "Other Citation Details".

FILE LIST

CONTACT US

RELEVANT LINKS

• NPS Arctic Network Inventory and Monitoring Program
• INSTAAR QGIS Lab: Coastal Erosion of Alaska's Arctic Parks
• NPS Alaska Region Geographic Information Systems