The Radiative Forcing Of Anthropogenic Particles And Its Interaction With Climate Change

With the aggravation of human activities since the industrial era,especially in recent decades,the content of aerosol particles in the atmosphere has been gradually increasing,they can not only aggravate air pollution and cause potential harm to living environment and human health,but also can affect the global climate change by influencing atmospheric radiation and cloud forming process.In the context of global warming,the interaction between aerosol particles and climate change is a hot and difficult issue in the international and domestic science.Further quantitative research is urgently needed to provide scientific and technological support for national and government departments to formulate scientific emission reduction policies and climate change foreign negotiation policies.Therefore,using an aerosol-climate coupled model BCC?AGCM2.0?CUACE/Aero,developed by China Academy of Meteorological Sciences and National Climate Center,combined with the different emission data of anthropogenic aerosol particles and their precursors,the following research work was carried out.Firstly,we simulated the impacts of changes in anthropogenic fine particles(PM_2.5,aerosol particles with particle diameter less than or equal to 2.5?m)column concentration in the atmosphere on the global climate system since the industrial revolution and under different emission scenarios(RCP4.5and RCP8.5)in future.The important effect of anthropogenic fine particles on climate change is further revealed by comparing the different climatic effects of coarse particles(CPM,aerosol particles with particle diameter greater than 2.5?m)and fine particles.Secondly,the study will go further to reveal the importance of anthropogenic fine particles by comparing different climate effects caused by coarse particles and fine particles emitted by human activities.Secondly,this study also takes China as a typical emission source area of particulate matters,and simulates and analyzes the climate effect of particulate matter over this area.Finally,we further explore how the temporal and spatial distribution of anthropogenic aerosol particles will change under the situation of global warming,in which we compare the temporal and spatial characteristics of aerosol particles produced mainly by natural source emissions,especially the different responses of coarse and fine particles to global warming.The influence of dry and wet deposition on the content and spatial distribution of aerosols in the atmosphere is analyzed from the near surface wind and divergence field,as well as the change of precipitation.The main conclusions are as follows:(1)The simulated anthropogenic PM_2.5 column concentration has increased globally since the Industrial Revolution,especially over East Asia and South Asia.Over the regions of South Asia and the Arabian Peninsula,the column concentration of anthropogenic coarse particles reduced.Since the Industrial Revolution,the average global effective radiative forcing(ERF)caused by anthropogenic PM_2.5 and coarse particles were-1.21 and-0.24 W m^-2,respectively.Globally,the radiative forcing caused by the increase of anthropogenic PM_2.5 is negative globally,but the radiative forcing caused by anthropogenic coarse particles is irregular.Increase in anthropogenic PM_2.5 burden has caused a global cooling,and the most significant reduction are located at high latitudes in the NH,with the global average surface temperature decreased by about 0.94 K.Although the change of surface air temperature caused by varying coarse particles is different,the change of the meridional flow function caused by anthropogenic coarse and fine particles is the same.The Hadley circulation strengthens and move the southern hemisphere(SH),with the precipitation decreases over the tropical regions of the NH decreased,and increases over the tropical regions of the SH due to increase in anthropogenic PM_2.5.(2)Under the green emission scenario(RCP4.5)given by the Fifth Assessment Report(AR5)of the Intergovernmental Panel on Climate Change(IPCC),the column concentration of anthropogenic PM_2.5 from year of 2014 to 2050 reduced over the most regions of the world,especially over East Asia.The column concentration of anthropogenic coarse particles increased over South Asia and the Arabian Peninsula.The reduction of anthropogenic PM_2.5 concentration caused a significant global warming,especially over high latitude regions in the NH,while the surface temperature caused by anthropogenic coarse particles has decreased at high latitudes over North America and Asia.With the reduction of anthropogenic PM_2.5 emissions,the Hadley circulation in the NH weakened and moved northward,while the Hadley circulation in the southern hemisphere was enhanced.(3)In the case of simulation designed in this paper,the cooling is mainly located over some arid region of western China during 1850 to 2014.The changes in the circulation in winter is not conducive to precipitation,leading to a nationwide decrease in precipitation,while the precipitation in southern China increases slightly in summer.Under RCP4.5 scenario,the surface temperature increases over most parts of China.Changes in the circulation in winter is conducive to the precipitation over the East and South Asian monsoon regions,while the precipitation over East Asia has increased slightly in summer.The air currents blown from land to the ocean over South Asia are not conducive to local precipitation.Relative humidity(RH)decreases over arid,semi-arid,and humid regions,while the RH increases over some semi-humid regions.(4)Under the background of global warming caused by four-time carbon dioxide concentration designed in this paper,the surface temperature has increased over most parts of the world,especially over high-latitude regions in NH.The Hadley circulation in the NH weakened,with the circulation in the SH strengthened and moved northward,and the tropical precipitation center moved northward.In the context of this climate change,anthropogenic PM_2.5 is mainly reduced over high latitude regions,especially over the North America and East Asia in the NH,with the max increase of3.2 mg m^-2.The variation of anthropogenic PM_2.5 column concentration is not limited to the vicinity of emission source area,and is mainly related to the variation of precipitation and atmospheric horizontal divergence over this area.However,the natural particles in the atmosphere mainly occur near emission source area,especially over the northern Africa,and the column concentration changes of natural coarse and fine particles are similar in magnitude.The variation of near-ground wind speed and the horizontal divergence of the whole atmosphere are the main factors that affect the variation of the content of natural particulate matter.