THE INFLUENCE OF OUTLIERS ON RESULTS OF WET DEPOSITION MEASUREMENTS AS A FUNCTION OF MEASUREMENT STRATEGY

被引:12
作者
SLANINA, J
MOLS, JJ
BAARD, JH
机构
[1] Netherlands Energy Research Foundation, ECN, 1755 ZG Petten
来源
ATMOSPHERIC ENVIRONMENT PART A-GENERAL TOPICS | 1990年 / 24卷 / 07期
关键词
networks; outlier detection; sampling strategy; statistical analysis; trends; Wet deposition;
D O I
10.1016/0960-1686(90)90517-Q
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The results of a wet deposition monitoring experiment, carried out by eight identical wet-only precipitation samplers operating on the basis of 24 h samples, have been used to investigate the accuracy and uncertainties in wet deposition measurements. The experiment was conducted near Lelystad, The Netherlands over the period 1 March 1983-31 December 1985. By rearranging the data for one to eight samplers and sampling periods of 1 day to 1 month both systematic and random errors were investigated as a function of measuring strategy. A Gaussian distribution of the results was observed. Outliers, detected by a Dixon test (a = 0.05) influenced strongly both the yearly averaged results and the standard deviation of this average as a function of the number of samplers and the length of the sampling period. The systematic bias in bulk elements, using one sampler, varies typically from 2 to 20% and for trace elements from 10 to 500%, respectively. Severe problems are encountered in the case of Zn, Cu, Cr, Ni and especially Cd. For the sensitive detection of trends generally more than one sampler per measuring station is necessary as the standard deviation in the yearly averaged wet deposition is typically 10-20% relative for one sampler. Using three identical samplers, trends of, e.g. 3% per year will be generally detected in 6 years. © 1990.
引用
收藏
页码:1843 / 1860
页数:18
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