2005和2015年中国近海氮沉降的时空分布特征及影响因子的比较OA北大核心CSTPCD

Based on the results of the GEOS-Chem model,the spatial and temporal distribution charac-teristics of nitrogen deposition and the influencing factors of nitrogen deposition in the coastal waters of China in 2005 and 2015 are compared and analyzed.The results show that the total nitrogen deposition in the Yellow Sea and Bohai Sea is the highest in summer(about 2.2 kg·m-2)and the lowest in win-ter(0.6 kg·m-2).The total nitrogen deposition in the East China Sea is the highest(1.3 kg·m-2)in winter and the lowest(0.5 kg·m-2)in summer.The total nitrogen deposition in the South China Sea is the highest in autumn(1.5 kg·m-2)and the lowest in summer(0.8 kg·m-2)and the wet ni-trogen deposition in most regions accounts for more than 55%of the total nitrogen deposition.Com-pared to 2005,In 2015,the total nitrogen deposition in spring,summer and autumn decreases by 0.3,0.7 and 0.2 kg·m-2,and increases by 0.4 kg·m-2 in winter.In the East China Sea,the total nitro-gen deposition decreases by 0.1 and 0.3 kg·m-2 in spring and winter and increases by 0.1 kg·m-2 in summer and autumn.The total nitrogen deposition in the South China Sea increases by 0.1 kg·m-2 in both summer and winter and decreases by 0.1 and 0.4 kg·m-2 in spring and autumn.Compared with the anthropogenic source emissions in 2005,the change in the meteorological field in offshore China in 2015 has a greater impact on the change of total nitrogen deposition and the change of different meteoro-logical conditions in 2015 results in different changes in dry and wet nitrogen deposition in offshore China in 2015.In terms of dry deposition of nitrogen,the average winter wind speed in the Yellow Sea and Bohai Sea area decreases by 23.9%in 2015 compared with 2005,which results in increased dry deposition of nitrogen.In terms of wet deposition of nitrogen,compared with 2005,the average wind speed over the Yellow Sea and the Bohai Sea in summer and the South China Sea in autumn in 2015 decreass by 38.8%and 42.3%respectively,while the precipitation decreased by 2.4 and 0.9 mm respectively,resulting in the decrease of wet deposition of nitrogen over the Yellow Sea and the Bohai Sea in summer and the South China Sea in autumn in 2015.Therefore,In 2015,the decrease of wet nitrogen deposition in summer over the Yellow Sea and Bohai Sea and the increase of wet nitrogen depo-sition in autumn over the South China Sea and the increase of wet nitrogen deposition in winter over the South China Sea are the result of the combined changes of wind transport and precipitation.The changes of winter wind field in the Yellow Sea and Bohai Sea in 2015 increases the total nitrogen concentration in winter,while the winter precipitation remains basically unchanged.Therefore,the changes of winter wet nitro-gen deposition in the Yellow Sea and Bohai Sea in 2015 are mainly related to the changes of the wind field.The decrease range of the total nitrogen concentration in summer,autumn and winter of the East China Sea is less than 1.0 ppbv,and the change of nitrogen wet deposition is mainly dominated by the change of precipitation.