Long-term trend of surface ozone at a regional background station in eastern China 1991–2006: enhanced variability

Abstract

Abstract. Information about the long-term trends of surface and tropospheric ozone is important for assessing the impact of ozone on human health, vegetation, and climate. Long-term measurements from East Asia, especially China's eastern provinces, are urgently needed to evaluate potential changes of tropospheric ozone over this economically rapid developing region. In this paper, surface ozone data from the Linan Regional Background Station in eastern China are analyzed and results about the long-term trends of surface ozone at the station are presented. Surface ozone data were collected at Linan during 6 periods between August 1991 and July 2006. The seasonality and the long-term changes of surface ozone at the site are discussed, with focus on changes in the diurnal variations, the extreme values, and the ozone distribution. Some long-term trends of surface ozone, e.g. decrease in the average concentration, increase in the daily amplitude of the relative diurnal variations, increase in the monthly highest 5% of the ozone concentration, decrease in the monthly lowest 5% of the ozone concentration, increase in the frequencies at the high and low ends of the ozone distribution have been uncovered by the analysis. All the trends indicate that the variability of surface ozone has been enhanced. Possible causes for the observed trends are discussed. The most likely cause is believed to be the increase of NO x concentration.

Ozone concentrations, flux and potential effect on yield during wheat growth in the Northwest-Shandong Plain of China

“…This is caused by the extremely low levels of O 3 precursors in the closed natural background condition (Ma et al, 2002;Wang et al, 2006). The difference in O 3 concentration during the day and night showed that O 3 was produced by local photochemical reactions at this site (Crutzen et al, 1999;Xu et al, 2008). Fig.…”

Impacts of the East Asian summer monsoon on interannual variations of summertime surface-layer ozone concentrations over China

“…Wang et al, 2006aT. Wang et al, , 2009Takami et al, 2006;Tu et al, 2007;Ding et al, 2008;Lin et al, 2008;Xu et al, 2008;Zhang et al, 2008;Y. Wang et al, 2011) and episodic concentrations of exceeding 100 ppbv (T. Wang et al, 2006b; Z.…”

Observations of relative humidity effects on aerosol light scattering in the Yangtze River Delta of China

“…A 5-week field campaign was carried out in the early winter of 1999 at Lin'an, a background station in the Yangtze River Delta (Xu et al, 2002). However, since then the physical and chemical properties of gas and particulate pollutants have changed dramatically with the rapidly developing economy and fast growing population, e.g., from 1999 to 2013, the sulfate mass concentration decreased from 21.2 ± 11.5 to 8.1 ± 4.1 (mean ± SD) (Qi et al, 2012;Xu et al, 2008;ZEPB, 1999ZEPB, , 2013. In order to better understand the aerosol light scattering properties and their dependency on relative humidity in the Yangtze River Delta, both the scattering and backscattering coefficients under dry (RH < 40 %) conditions and controlled, elevated relative humidity were measured, along with the chemical composition and particle number size distribution.…”