Bias corrections of precipitation measurements across experimental sites in different ecoclimatic regions of western Canada

Abstract

This study assesses a filtering procedure on accumulating precipitation gauge measurements and quantifies the effects of bias corrections for wind-induced undercatch across four ecoclimatic regions in western Canada, including the permafrost regions of the subarctic, the Western Cordillera, the boreal forest, and the prairies. The bias corrections increased monthly precipitation by up to 163 % at windy sites with short vegetation and sometimes modified the seasonal precipitation regime, whereas the increases were less than 13 % at sites shielded by forest. On a yearly basis, the increase of total precipitation ranged from 8 to 20 mm (3-4 %) at sites shielded by vegetation and 60 to 384 mm (about 15-34 %) at open sites. In addition, the bias corrections altered the seasonal precipitation patterns at some windy sites with high snow percentage (> 50 %). This study highlights the need for and importance of precipitation bias corrections at both research sites and operational networks for water balance assessment and the validation of global/regional climate-hydrology models.