## 2 Historical Data
### Aerial Photography in the Polar Regions
#### 2.1.1 The Arctic  
This section is a concise summary of aerial photography coverage for various regions in the Arctic. Note, the listings are limited to areas where data are known to be available, which will limit the coverage in some regions (e.g., Arctic Russia).  
Norway/Svalbard: Norway compiled a series of 1:100,000 scale maps of Svalbard from 1936 onwards, beginning with oblique photography acquired in 1936, 1938 and 1956. Vertical aerial photography campaigns at 1:50,000 scale in the 1960s and 1970s, notably 1966, when almost complete coverage was achieved, ensured that all areas were covered at least once by the 1970s. There is almost complete systematic coverage at 1:50,000 scale with color infrared (CIR) film acquired in 1990 and further photography from 1995 and 2000 for selected areas [11, 12].  
Similarly, aerial photography was being flown for topographic mapping on the Norwegian mainland, including systematic photography of the Norway/Sweden border in 1957 ([[http://www.norgeibilder.no/](http://www.norgeibilder.no/)]([http://www.norgeibilder.no/](http://www.norgeibilder.no/))).  
Iceland: Systematic topographic map compilation from aerial photography for Iceland began in 1937 from oblique photos flown in 1937 and 1938 [13, 14]. Earlier mapping efforts were then superseded by 1:50,000 scale maps with more accurate contours on glaciers in 1948-1949, produced by the U.S. Army Map Service from vertical aerial photography flown in 1946-1947.  
Greenland: In Greenland, parts of the east coast had been mapped from aerial photography as early as 1937, with much mapping activity in the late 1940s and 1950s, and the far north was mapped after WWII by the U.S. Army Map Service [15]. Aerial photography cover for accurate topographic mapping of even the ice-free areas in north Greenland was not completed until a campaign by the Danish Geodetic Institute in 1978, with mapping beginning in the 1980s. In addition, oblique aerial photos from Greenland expeditions are available from collections in Denmark, at the Scott Polar Research Institute in Cambridge and elsewhere and have been used to reconstruct, for example, 80 years of glacier change in southeast Greenland [16].  
Canadian Arctic and Alaska: Due to the technical challenges of dealing with vast remote areas, national mapping agencies did not undertake extensive aerial photography of the Western hemisphere Arctic (Alaska and Canada) until the 1950s, following further developments in aviation and photogrammetric techniques, particularly aerotriangulation, to deal with the vast geographic areas involved [17, 18, 19, 20].  
The Alaska High Altitude Photography (AHAP) collection, 1978-1986, covers about 95% of the State of Alaska in both 1:60,000 CIR and 1:120,000 black and white photography. Approximately 60,000 frames of photography have been scanned by the USGS EROS data center at medium resolution (400 dpi). Imagery and metadata are available from the Polar Geospatial Center (PGC; [[http://www.pgc.umn.edu/imagery/aerial](http://www.pgc.umn.edu/imagery/aerial)]([http://www.pgc.umn.edu/imagery/aerial](http://www.pgc.umn.edu/imagery/aerial))).  
In addition, over six million aerial photographs over Canada are available for a nominal fee from the National Air Photo Library (NAPL) of Natural Resources Canada. The metadata are freely available and searchable at [[http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/9265](http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/9265)]([http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/9265](http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/9265)). There are also a large number of freely available photographs of Alaskan and Canadian glaciers in the Glacier Photograph Collection ([[https://nsidc.org/data/glacier_photo/](https://nsidc.org/data/glacier_photo/)]([https://nsidc.org/data/glacier_photo/](https://nsidc.org/data/glacier_photo/))) [21].