Abstract

An accurate precipitation climatology and time-series are needed to document and quantify potential changes in the hydrology of the Arctic. Unfortunately precipitation is underestimated, particularly in the Arctic, due to the deleterious effect of wind on snowfall. Bias adjustments were applied to almost 2800 precipitation recording stations in the Arctic (above 50°N). These gage-specific adjustments took into account (1) the effect of wind, (2) wetting losses on the walls of the gage, (3) evaporation from the gage (minor in the Arctic), and (4) the treatment of trace precipitation events in determining in precipitation totals.

The research presented here assesses the spatial variability of the bias adjustments, which is dependent on the type of precipitation collected at the gage site and the type of gage used. Bias-adjustments were applied to precipitation values from two temporal resolutions (daily and monthly) so to evaluate the extra uncertainty introduced when adjusting monthly totaled data as opposed to daily totaled data. Qualifying the extra uncertainty is needed since data are most commonly available on a monthly time scale. The sensitivity of the most influential variable, wind speed at gage height during the time of precipitation, required for adjustment calculations was also investigated. For instances where the finest resolution of wind data is only available on a monthly basis, new coefficients for the calculation of the solid precipitation wind adjustment coefficient from monthly wind speed have been developed. In addition, new coefficients are provided to calculate the fraction of precipitation that was solid from average monthly temperature.