Beijing Climate Center Earth System Model version 1 (BCC-ESM1): Model Description and Evaluation

Abstract. BCC-ESM1 is the first version of a fully-coupled Earth System Model with interactive atmospheric chemistry and aerosols developed by Beijing Climate Center, China Meteorological Administration. Major aerosol species (including sulfate, organic carbon, black carbon, dust and sea salt) and greenhouse gases are interactively simulated with a whole panoply of processes controlling emission, transport, gas-phase chemical reactions, secondary aerosol formation, gravitational settling, dry deposition, and wet scavenging by clouds and precipitation. Effects of aerosols on radiation, cloud, and precipitation are fully treated. The performance of BCC-ESM1 in simulating aerosols and their optical properties is comprehensively evaluated as required by the Aerosol Chemistry Model Intercomparison Project (AerChemMIP), covering the preindustrial mean state and time evolution from 1850 to 2014. The simulated aerosols from BCC-ESM1 are quite coherent with CMIP5-recommended data and in-situ measurements from surface networks (such as IMPROVE in the U.S. and EMEP in Europe). A comparison of the aerosol optical depth (AOD) at 550 nm for all aerosols with the satellite AOD observations retrieved from MODIS and MISR and surface AOD observations from AERONET shows reasonable agreement between simulated and observed AOD. However, BCC-ESM1 seems to show weaker upward transport of aerosols from the surface to the middle and upper troposphere, likely reflecting the deficiency of representing deep convective transport of chemical species in BCC-ESM1. With an overall good agreement between BCC-ESM1 simulated and observed aerosol properties, it demonstrates a success of the implementation of interactive aerosol chemistry in BCC-ESM1.