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

AbstractThe spatial and temporal characters of tropospheric NO2 column over Yangtze River Delta (YZD) are analyzed using monthly averaged tropospheric NO2 column densities from GOME (1996-2002) and SCIAMACHY (2003-2010) measurements. In addition, with the NO2 column densities data and the land cover maps 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 characteristics. It has the highest concentration in winter while lowest in summer. It also presents zonal distribution and decreasing along the Yangtze River from eastern to western. Under the influence of the urbanization process, the highest NO2 column densities appeared at cities and metropolis which are located in the Shanghai, Nanjing as well as Hangzhou. Moreover the lowest column densities appeared at the forest areas which are in the south and west of Zhejiang province. The sharp increasing of appeared in water bodies, followed urban area and water bodies. The lowest increasing of NO2 column appeared in grassland. Furthermore, we inferred the ground-level NO2 concentration from the GOME and SCIAMACHY data in this paper. We compared with the dry plus of N deposition which inferred from the remote sensing data and the mass concentration of N dry deposition from the control experiments, they performed significant correlation (P<0.001), and have the high R value (R2=0.86)