A bias-corrected Siberian regional precipitation climatology

A methodology for correcting the Tretyakov gauge-measured daily precipitation for wind-induced undercatch and trace amounts of precipitation is presented and applied at 61 climate stations in Siberian regions for 1986 to 1992. It is found that wind-induced gauge undercatch is the greatest error, and a trace amount of precipitation is also a significant bias, particularly in the low-precipitation regions. Monthly correction factors (corrected divided by measured precipitation) differ by location and by type of precipitation. Considerable interannual variation of the corrections exists in Siberian regions because of the fluctuation of wind speed, air temperature, and frequency of snowfall. More important, annual precipitation has been increased by 30-330 mm because of the bias corrections for the seven years (about 10%-65% of the gauge-measured yearly total). This result suggests that annual precipitation in Siberia is much higher than previously reported, particularly in the northwest sectors of high precipitation; the latitudinal precipitation gradient may also be greater over Siberian regions. An improved regional precipitation "climatology,'' or description of mean annual precipitation, is derived based on the bias-corrected data and is compared with other existing climatologies. The results of this study will be useful to hydrological and climatic studies in the high-latitude regions.