Aerosol microphysics modules in the framework of the ECHAM5 climate model – intercomparison under stratospheric conditions

[摘要] In this manuscript, we present an intercomparison of three differentaerosol microphysics modules that are implemented in the climatemodel ECHAM5. The comparison was done between the modal aerosolmicrophysics module M7, which is currently the default aerosolmicrophysical core in ECHAM5, and two sectional aerosol microphysicsmodules SALSA, and SAM2. The detailed aerosol microphysical model MAIAwas used as a reference to evaluate the results of the aerosolmicrophysics modules with respect to sulphate aerosol.

The ability of the modules to describe the development of theaerosol size distribution was tested in a zero dimensionalframework. We evaluated the strengths and weaknesses of differentapproaches under different types of stratospheric conditions. Also,we present an improved method for the time integration in M7 andstudy how the setup of the modal aerosol modules affects the evolution ofthe aerosol size distribution.

Intercomparison simulations were carried out with varyingSO₂ concentrations from background conditions to extremevalues arising from stratospheric injections by large volcaniceruptions. Under background conditions, all microphysics moduleswere in good agreement describing the shape of the aerosol size distribution,but the scatter between the model results increased with increasingSO₂ concentrations.In particular in the volcanic case thesetups of the aerosol modules have to be adapted in order to dependablycapture the evolution of the aerosol size distribution, and to perform inglobal model simulations.

In summary, this intercomparison serves as a review of the differentaerosol microphysics modules which are currently available for theclimate model ECHAM5.

[学科分类] 天文学(综合)