Enhancements in nocturnal surface ozone at urban sites in the UK.

摘要: Analysis of diurnal patterns surface ozone (O3) at multiple urban sites in the UK shows occurrence prominent nocturnal enhancements during winter months (November-March). Whilst (NSO) enhancement events have been observed other locations, this is first time that such features demonstrated to occur and second location globally. The NSO were found be so prevalent they are clearly discernible monthly cycles averaged over several years data. Long-term (2000-2010) analysis hourly data from 18 background stations a bimodal variation with secondary nighttime peak around 0300 hours along primary daytime peak. For all but one site, daily maxima concentrations exceeded 60 μg/m(3) on >20 % nights. highest value recorded was 118 μg/m(3). During November, December, January, O3 night (0300 h) even those (1300 h). also these can last for regional scale, extending across simultaneously. Interestingly, north exhibited higher than south UK, despite their being similar. In part, seems related typically having lower nitrogen oxides.