Detection of the trend and seasonal variation in tropospheric NO sub(2) over China

• Published in: Journal of Geophysical Research. D. Atmospheres 2006-06, Vol.111 (D12)
• Main Authors: Van der a, RJ, Peters, DHMU, Eskes, H, Boersma, K F, Van Roozendael, M, De Smedt, I, Kelder, H M
• Format: Article
• Language: English
• ISSN: 0148-0227
• DOI: 10.1029/2005JD006594

The results of a trend study on the tropospheric NO sub(2) column over China are presented, on the basis of measurements from the satellite instruments GOME and SCIAMACHY. From these observations, monthly averaged tropospheric NO sub(2) distributions are determined for the period 1996 to 2005 on a 1 degree by 1 degree grid. A linear model with a seasonal component is used to fit these time series. The variance and the autocorrelation of the noise are used to calculate the significance of the trend. The results show a large growth of tropospheric NO sub(2) over eastern China, especially above the industrial areas with a fast economical growth. For instance, Shanghai had a linear significant increase in NO sub(2) columns of 20% plus or minus 6% per year (reference year 1996) in the period 1996- 2005. The seasonal pattern of the NO sub(2) concentration shows a difference between east and west China. In the east a NO sub(2) maximum is found during wintertime, because of chemistry and anthropogenic activity. Contrary to this, in the western part of China the NO sub(2) concentration reaches a maximum in summertime. This spatial difference correlates with the population distribution of China. Since there is negligible anthropogenic activity in west China this difference in seasonality of NO sub(2) is attributed to natural emissions in west China.