The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used were obtained from government agencies, mostly at the county level, and some new emission factors (Efs) from local measurements were also used. National and regional summaries of emissions were presented at 0.2°×0.2°resolution. Total BC emission was 1499.4 Gg in 2000, mainly due to the burning of coal and biomass. The BC emission estimated here is higher than those in previous studies, mainly because the emissions from coal burning by rural industries and residences were previously underestimated. More BC aerosols were emitted from eastern China than western China. A strong seasonal dependence was observed for BC emissions, with peaks in January and December and low emissions in July and August; and this seasonality is mainly due to patterns in residential heating and the open burning of crop residues.
The regional climate model (RegCM3) and a tropospheric atmosphere chemistry model (TACM) were coupled, thus a regional climate chemistry modeling system (RegCCMS) was constructed, which was applied to investigate the spatial distribution of anthropogenic nitrate aerosols, indirect radiative forcing, as well as its climatic effect over China. TACM includes the thermodynamic equilibrium model ISORROPIA and a condensed gas-phase chemistry model. Investigations show that the concentration of nitrate aerosols is relatively high over North and East China with a maximum of 29 μg m-3 in January and 8 μg m-3 in July. Due to the influence of air temperature on thermodynamic equilibrium, wet scavenging of precipitation and the monsoon climate, there are obvious seasonal differences in nitrate concentrations. The average indirect radiative forcing at the tropopause due to nitrate aerosols is -1.63 W m-2 in January and -2.65 W m-2 in July, respectively. In some areas, indirect radiative forcing reaches -10 W m-2. Sensitivity tests show that nitrate aerosols make the surface air temperature drop and the precipitation reduce on the national level. The mean changes in surface air temperature and precipitation are -0.13 K and -0.01 mm d-1 in January and -0.09 K and -0.11 mm d-1 in July, respectively, showing significant differences in different regions.
Methane (CH4) is the most important greenhouse gas and reactive trace gas in the atmosphere. Recently, it has been reported that terrestrial plants can emit CH4 under aerobic conditions, which may call for reevaluation of the inventory of CH4 emissions in China. In this paper, those emissions over China and their effects on CH4 concentrations in lower troposphere were investigated. Firstly, based on the work of Keppler et al., the aerobic plant CH4 emission model (PLANTCH4) for China was established. And by using the database of normalized difference vegetation index (NDVI) derived from NOAA/ AVHRR, the distribution of net primary productivity (NPP) over China was simulated, and thereby, for the first time, the amount and distribution of the newly identified source in China were estimated. Secondly, with the aid of the three-dimensional atmospheric chemistry model system (MM5-CALGRID), the effects of the emissions were studied. The results show that the annual aerobic plant CH4 emissions over China amount to 11.83 Tg, i.e. nearly 24% of Chinese total CH4 emissions. And the major fraction (about 43%) comes from forests. When those emissions are considered in modeling, computed countrywide mean surface concentration of CH4 is 29.9% higher than without them, with a maximum increase of 69.61 μg·m-3 in the south of Yunnan Province. In conclusion, to study CH4 emissions from terrestrial plants over China may have important implications for correctly estimating the contribution of China to global CH4 budget, and may call for a reconsideration of the role of CH4 in global and regional environment and climate change.
