5 . 1 BIAS ADJUSTMENTS TO ARCTIC PRECIPITATION : A COMPARISON OF DAILY VERSUS MONTHLY BIAS ADJUSTMENTS

In the Arctic, gage-based measurements of precipitation contain significant systematic biases. These biases include wind-induced undercatch, wetting losses, and evaporative losses. In addition, trace amounts of precipitation are not routinely counted in daily precipitation totals although they can contribute significantly to precipitation in dry locations in the high latitudes. Thus, gage-based measurements of Arctic precipitation substantially underestimate actual (true) precipitation. Accurate precipitation data from the Arctic are required to realistically simulate runoff from Arctic watersheds and model the global water balance (Serreze et al. 2003). This study addresses the need for accurate Arctic precipitation data by applying the systematic bias adjustments that have been developed from experimental studies (e.g., Sevruk 1982; Groisman et al. 1991; Goodison et al. 1998) to gagemeasured precipitation. Bias adjustments were applied to 9 years of daily data (1994–2002) from nearly 2800 stations north of 50°N to 1) determine the impact that applying the bias adjustments on a daily versus monthly basis has on monthly and annual precipitation totals, and 2) examine the temporal variability of the bias adjustments.