MEASUREMENTS OF REACTIVE NITROGEN SPECIES IN THE EASTERN CHINA DURING THE EXPERIMENT PEM-WEST A

Measurements of NOx(NO+NO2),HNO3,particulate nitrate,and total odd nitrogen NOy were made at Lin'an atmosphere regional background station during the NASA GTE/PEM-WEST A in the fall of 1991.NOx and NOy were measured using chemiluminescence detectors.HNO3 and aerosol nitrate(NO3-) were collected by a filter system. NOx concentration exhibits a significant diurnal variation:maximum occurring in the evening and postsunrise weak peak occurring following sunrise.Unlike NOx,NOy does not show distinct diurnal variations.From the ratios of day/night NOx concentration and the diurnal cycles of two kinds of weather conditions,it is clear that the photochemical production of NOx varies with solar radiation.NOx is the major component of total odd nitrogen NOy and NO2 is the major portion of NOx as well.The regional background concentrations of NOx,NOy,aerosol intrate(NO3-) and HNO3 range from 4.77 to 7.02 ppb,9.24 to 10.95 ppb,0.33 to 2.38 ppb and 0.31 to 0.97 ppb in a day on average,respectively.In the eastern China,the biomass burning is an important local emission source of nitrogen species.The ratios of NO/NO2,NOx/NOy,HNO3/NOy,NO3-/NOy and HNO3/NOx are also discussed in our paper.