Evaluation of long-term tropospheric NO2 columns and the effect of different ecosystem in Yangtze River Delta

The spatial and temporal characters of NO₂ over Yangtze River Delta (YZD) are analyzed using monthly averaged tropospheric & column densities from GOME (1996-2002) and SCIAMACHY (2003-2010) measurements. In addition, with the land cover map of YZD, the characters of NO₂ concentration over different ecosystem have been analyzed. The results indicated that the tropospheric NO₂ column densities in YZD increased distinctly from 1996 to 2010 and it showed distinct regional and seasonal variation. It has the highest concentration in winter while lowest in summer. Under the influence of the urbanization process, the highest NO₂ column densities appeared at cities and metropolis while the lowest column densities appeared in forest. The sharp increasing of tropospheric NO₂ column appeared in water bodies, followed urban land and woodland. Furthermore, we compared with the NO₂ column and the mass concentration of N dry deposition from the control experiments, they performed significant correlation and the high R value (R2=0.86, P<;0.001).