Circumpolar Arctic Lake Cover data theme, used in the
creation of the Circumpolar Arctic Vegetation Map.
Lake cover strongly affects the albedo, or reflectance,
of the land surface over large areas of the Arctic and is useful for
delineating extensive wetlands. Lake cover was based on the
number of AVHRR water pixels in each mapped polygon,
divided by the total number of pixels in the polygon. Since the
imagery has a pixel size of 1 km2, lake cover is
underestimated for areas with many small lakes. No pixels were
sampled within two pixels (2 km) of the coastline to avoid including
ocean pixels.
Integrated Landscape Units (ILUM) used to create the Circumpolar
Arctic Vegetation Map (CAVM). The ILUM is the union of all individual
data themes used to create the CAVM. The Circumpolar Arctic Vegetation
Map shows the types of vegetation that occur across the Arctic, between
the ice-covered Arctic Ocean to the north and the northern limit of
forests to the south. The CAVM team grouped over 400 described plant
communities into 16 different physiognomic units based on plant growth
forms. An international team of arctic vegetation scientists
representing the six countries of the Arctic (Canada, Greenland,
Iceland, Norway, Russia, and the United States) prepared the map.
Detailed descriptions of the methods used to create the map can be found
at: http://www.geobotany.uaf.edu/cavm/