水科学进展2017，Vol.28Issue(5)：662-670,9.DOI:10.14042/j.cnki.32.1309.2017.05.003
风场变形误差对北京降水记录及变化趋势的影响
Effects of gauge under-catch on precipitation observation and long-term trend estimates in Beijing area
摘要
Abstract
Among all of the uncertainties of precipitation records, the gauge under catch effect is one of the most im-portant error sources. It not only affects the accuracy of the observational value and area-averaged precipitation calcula-tion, but also leads to a false estimate of the long-term trends of the precipitation for any sites and regions. An accurate evaluation of the gauge under-catch effect is thus of great significance for understanding long-term change of precipita-tion and its possible causes and impacts. Based on observational data of daily precipitation and daily mean wind speed from 20 meteorological stations in Beijing area during the period 1976—2015, the effects of gauge under-catch on pre-cipitation records and the estimates of the long-term precipitation trends were evaluated, and the urbanization effect on near-surface mean wind speed change was also discussed. The results showed that the mean values of precipitation catch rate ranged from 90% to 95% over last 40 years, but they had a significant upward trend and a heterogeneous spatial distribution with larger catch rates in urban area than in rural area. The urbanization process, which led to a lower wind speed in urban area, was the main reason for the observed difference of the under catch rates between the urban and rural stations especially after 2006. The effects of under catch differed among years and seasons significant-ly. In the past 40 years, the measured area-averaged annual precipitation was 552. 2 mm, while the under catch adjus-ted area-averaged annual precipitation was 575. 3 mm, with an average absolute error of 23. 1 mm and an average rela-tive error of 4. 0%. The area-averaged precipitation intensity before and after the under catch adjustment were 7. 9 mm/d and 8. 3 mm/d respectively. The downward trends of the area-averaged annual precipitation for the past 40 years changed from -34. 4 mm/10 a for the pre-adjusted data to -37. 0 mm/10 a for the aft-adjusted data. Therefore, the original observed values underestimated the daily precipitation intensity by about 4. 8% and the decreasing trend by 7. 0%. Larger under catch errors occurred for the more intense precipitation processes, and the inter-annual varia-tions of the under catch effects were generally greater at urban stations than those at rural stations. There existed a clear underestimate of precipitation record for the weak precipitation process at rural sites, but the underestimate was more significant for the intense precipitation process at urban sites.关键词
风速/捕获/测量误差/降水记录/变化趋势/北京Key words
wind speed/under catch/error/precipitation record/change trend/Beijing city分类
天文与地球科学引用本文复制引用
郑祚芳,任国玉..风场变形误差对北京降水记录及变化趋势的影响[J].水科学进展,2017,28(5):662-670,9.基金项目
国家自然科学基金资助项目( 41575010 （）
41505102) The study is financially supported by the National Natural Science Foundation of China ( No. 41575010 （）
No. 41505102) . （）
