Effects of Wind-Induced Errors on Winter Snowfall and Its Trends

Datasets of daily precipitation, wind speed, and weather phenomena of 71 stations during 1960-2009 and experimental observations of precipitation from three stations are used to estimate wind-induced errors in winter snowfall records over northeastern China, and to analyze the effects of wind-induced under-catch on long-term winter snowfall trends. The results show that winter snowfall is generally undervalued. Although the region’s average annual snowfall was measured at 15.1 mm, the corrected snowfall was 22.5 mm, which indicates an average error of 7.5 mm, or relative error of approximately 34.1%. In recent years, the gauge catch rate has increased due to the weakening of surface wind speed resulting from urbanization and micro-environmental change surrounding the stations, which have led to an overestimate of winter snowfall trends in the study region. This analysis shows a 50-year linear trend of winter snowfall of 0.4 mm/10 a when original precipitation data are included and a long-term trend of winter snowfall at 0.1 mm/10 a when adjusted data are used. The effect of wind-induced error on the estimates of winter snowfall trends is particularly significant in the southern part of the study region, with an overestimate for long-term trends reaching ?1 mm/10 a, or approximately 64.3% in terms of relative bias.