Average monthly air temperature (T) and precipitation (P) are 'traditionally' interpolated and
mapped at a 0.5-degree resolution from 7135 T and 6877 P stations contained in the Legates and
Willmott (1990a and b) climatology (Figures 1 and 2).  These maps illustrate the considerable
spatial and seasonal variability in Pan-Arctic T and P, as well as the station networks'
difficulty in resolving these average-monthly fields.  A marked east-to-west gradient is
apparent in January T over both Asia and North America.  The regionally sparse network also
contributes to an unconvincing depiction of T and P over Greenland and the mountainous regions of
eastern Asia and western North America. 

Spatially interpolated and averaged annual air temperature (T) and precipitation (P), from the
Global Historical Climatology Network version 1 (GHCN v.1: Vose et. al., 1992), are plotted for
the years 1955 through 1989 (Figures 3 and 4).  Solid lines represent seven-point linear filters
of the Pan-Arctic basin averages.  Annual T shows a slightly increasing trend through the 1970s,
and the western Arctic (west of the Greenwich meridian) is generally warmer than the eastern
Arctic basin.  Spatial averages of annual P indicate that the western Arctic also has higher mean
precipitation rates than the eastern Arctic.  In addition, there appears to be less year-to-
year variability in P between the eastern and western Arctic from 1970 through the 1980s, than
prior to 1970.  This may, however, be due to the relative paucity of observation stations earlier
in the GHCN archive.  There seems to be no long-term increase or decrease in spatially averaged
P from 1955 through 1989. 

Work is ongoing to improve the spatial resolution and reliability of our Pan-Arctic monthly P
and T fields, as well as our basin-scale spatial averages of T and P.  Several available
station-record archives (including some previously unavailable records from Russia) are being
merged into a composite archive which will provide much better weather-station coverage of Pan-
Arctic T and P.  A refined version of Willmott and Matsuura's (1995) DEM-assisted air-temperature
interpolation algorithm also is being implemented.  Its new spatially and seasonally variable lapse-
rate function should improve both the spatial resolution of interpolated (gridded) T fields, as well
as reduce the warm bias inherent in Arctic weather-station networks.  Improvements in interpolated
(gridded) Pan-Arctic P also are expected from the spatially higher-resolution P-station networks
contained within the composite archive, as well as through "smart" refinements in the spatial 
interpolation of P, such as "modeling" the topographic influences on P from a DEM.  Our smartly 
interpolated (gridded) P fields should better resolve topographically rugged environments, as well
as underestimates of Pan-Arctic P arising from the use of most available raingage (station-record)
archives. 

Legates, D. R. and C. J. Willmott (1990a) Mean Seasonal and Spatial Variability in Global Surface 
    Air Temperature.  Theoretical and Applied Climatology, 41:11-21. 

Legates, D. R. and C. J. Willmott (1990b) Mean Seasonal and Spatial Variability in Gauge-Corrected,
    Global Precipitation.  International Journal of Climatology, 10:111-127. 
 
Vose et. al. (1992) The Global Historical Climatology Network: long-term monthly temperature,
    precipitation, sea level pressure, and station pressure data.  ORNL/CDIAC-53, NDP-041.
    Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. 

Willmott, C.J. and K. Matsuura (1995) Smart interpolation of annually averaged air temperature in 
    the United States.  Journal of Applied Meteorology, 34:2577-2586.