Uncertainties in surface ozone trend at hohenpeissenberg

Surface-Level Ozone: Climate Change and Evidence for Trends

“…The authors found that if sulfur dioxide interference had occurred during the pre-1976 period, a significant effect could modify the appearance of an upward trend, and possibly lead to an overestimation by a factor of 3 in the trend. Using the uncorrected data, Low et al 36 confirmed their previously reported result 29 for the 1971-1988 period, of a positive trend of 1.02 percent/ yr, significant at the 5 percent level. Correcting the pre-1976 data by adding 3 nbar to the annual mean values, as suggested by Attmannspacher et al, 37 Low et al 36 reported that the 1971-1988 trend was reduced to 0.36 percent/yr, which was not found to be statistically significant.…”

“…Using the uncorrected data, Low et al 36 confirmed their previously reported result 29 for the 1971-1988 period, of a positive trend of 1.02 percent/ yr, significant at the 5 percent level. Correcting the pre-1976 data by adding 3 nbar to the annual mean values, as suggested by Attmannspacher et al, 37 Low et al 36 reported that the 1971-1988 trend was reduced to 0.36 percent/yr, which was not found to be statistically significant. The authors concluded that the results of Hohenpeissenberg for the period 1971-1988 were strongly dependent upon the pre-1976 values, which they believed to be suspect.…”

“…However, by including the years 1989 and 1990 (both high ozone concentration years), Wege and Vandersee 32 have reported, as indicated above, a 1.3 percent/yr increase for the period 1971-1990 and 1977-1990. Using the same correction as applied by Low et al, 36 but including the 1989 and 1990 data, the authors reported an increasing trend of 0.7 percent/year, significant at the 5 percent level. 38 Ozone monitors at Wank and Zugspitze, located in southern Germany, provide an opportunity for investigating changes in ozone concentrations in the planetary boundary layer and free troposphere.…”

“…35 an acidic chromium trioxide filter was added to the coulometric measurement instrument. Low et al 36 investigated the possible effects of sulfur dioxide interference on surface ozone trends at Hohenpeissenberg. The authors found that if sulfur dioxide interference had occurred during the pre-1976 period, a significant effect could modify the appearance of an upward trend, and possibly lead to an overestimation by a factor of 3 in the trend.…”

Uncertainty and bias of surface ozone measurements at selected Global Atmosphere Watch sites

“…Proper evaluation of spatial distribution requires the data to be unbiased while the number of data points necessary to identify a trend is in part controlled by the uncertainty of the individual data points. A review of the more recent literature on ozone trends [ Harris et al , 1997; Low et al , 1991; Marenco et al , 1994; Oltmans and Komhyr , 1986; Oltmans et al , 1998; Pavelin et al , 1999; Staehelin et al , 1994, 1998; Zanis et al , 1999] reveals that the uncertainty of the data used has received relatively little attention up to now. For ozone measurements, GAW has adopted the Standard Reference Photometer 2 (SRP 2), manufactured and maintained by the U.S. National Institute of Standards and Technology (NIST), as the common point of reference.…”