Physical Characteristics and Basic Climatic Features - The Arctic Climate System - page 61

Figure 2.27. Mean cloud cover (%) from the APP-x data set (1982-1999) for: January,
April, July, and October (courtesy of J. Key, NOAA, Madison, WI).
particularly over the Canadian Arctic Archipelago, the Greenland Ice Sheet and
the Arctic Ocean, making it difficult to obtain accurate regional precipitation esti-
mates. The station density problem has become more severe as fiscal constraints in
Canada and Russia have led to the closure of many stations. In recognition of net-
work deficiencies, various techniques have been explored to compile Arctic-specific
data sets that make use of output from numerical weather prediction models (e.g.,
Chen, Bromwich, and Bai, 1997 ; Serreze, Clark, and Bromwich, 2003b ). A number
of gridded global data sets providing Arctic coverage have been developed based
on satellite retrievals or blending satellite retrievals with station gauge data and
numerical weather model output (e.g., Xie and Arkin, 1997 ; Huffman et al., 1997 ,
Huffman et al., 2001 ). Arctic results, however, are of questionable value; although
satellite retrievals are confounded by snow-covered surfaces, there is an ongoing