BCC-ESM1 Model Datasets for the CMIP6 Aerosol Chemistry Model Intercomparison Project (AerChemMIP)

BCC-ESM1 is the first version of the Beijing Climate Center’s Earth System Model,and is participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6).The Aerosol Chemistry Model Intercomparison Project(AerChemMIP)is the only CMIP6-endorsed MIP in which BCC-ESM1 is involved.All AerChemMIP experiments in priority 1 and seven experiments in priorities 2 and 3 have been conducted.The DECK(Diagnostic,Evaluation and Characterization of Klima)and CMIP historical simulations have also been run as the entry card of CMIP6.The AerChemMIP outputs from BCC-ESM1 have been widely used in recent atmospheric chemistry studies.To facilitate the use of the BCC-ESM1 datasets,this study describes the experiment settings and summarizes the model outputs in detail.Preliminary evaluations of BCC-ESM1 are also presented,revealing that:the climate sensitivities of BCC-ESM1 are well within the likely ranges suggested by IPCC AR5;the spatial structures of annual mean surface air temperature and precipitation can be reasonably captured,despite some common precipitation biases as in CMIP5 and CMIP6 models;a spurious cooling bias from the 1960s to 1990s is evident in BCC-ESM1,as in most other ESMs;and the mean states of surface sulfate concentrations can also be reasonably reproduced,as well as their temporal evolution at regional scales.These datasets have been archived on the Earth System Grid Federation(ESGF)node for atmospheric chemistry studies.

Updated Simulation of Tropospheric Ozone and Its Radiative Forcing over the Globe and China Based on a Newly Developed Chemistry–Climate Model

This study evaluates the performance of a newly developed atmospheric chemistry–climate model,BCCAGCM_CUACE2.0(Beijing Climate Center Atmospheric General Circulation Model_China Meteorological Administration Unified Atmospheric Chemistry Environment)model,for determining past(2010)and future(2050)tropospheric ozone(O_(3))levels.The radiative forcing(RF),effective radiative forcing(ERF),and rapid adjustments(RAs,both atmospheric and cloud)due to changes in tropospheric O_(3)are then simulated by using the model.The results show that the model reproduces the tropospheric O_(3)distribution and the seasonal changes in O_(3)surface concentration in 2010 reasonably compared with site observations throughout China.The global annual mean burden of tropospheric O_(3)is simulated to have increased by 14.1 DU in 2010 relative to pre-industrial time,particularly in the Northern Hemisphere.Over the same period,tropospheric O_(3)burden has increased by 21.1 DU in China,with the largest increase occurring over Southeast China.Although the simulated tropospheric O_(3)burden exhibits a declining trend in global mean in the future,it increases over South Asia and Africa,according to the Representative Concentration Pathway(RCP)4.5 and 8.5 scenarios.The global annual mean ERF of tropospheric O_(3)is estimated to be 0.25 W m^(−2)in 1850−2010,and it is 0.50 W m^(−2)over China.The corresponding atmospheric and cloud RAs caused by the increase of tropospheric O_(3)are estimated to be 0.02 and 0.03 W m^(−2),respectively.Under the RCP2.6,RCP4.5,RCP6.0,and RCP8.5 scenarios,the annual mean tropospheric O_(3)ERFs are projected to be 0.29(0.24),0.18(0.32),0.23(0.32),and 0.25(0.01)W m^(−2)over the globe(China),respectively.