Technical note: Implementation of prescribed (OFFLEM), calculated (ONLEM),and pseudo-emissions (TNUDGE) of chemical species in the Modular Earth Submodel System (MESSy)

[摘要] We present the submodels OFFLEM, ONLEM, and TNUDGE for the Modular EarthSubmodel System (MESSy). Prescribed emissions from input files arehandled by OFFLEM. ONLEM deals with online-calculated emissions, i.e.,emissions that are calculated during the simulation. The submodel TNUDGEuses the "tracer nudging" technique for pseudo-sources and -sinks. Forspecies with highly uncertain emission fluxes and/or with sufficiently longlifetimes, e.g., CH₄, it is common to createsuch pseudo-fluxes by prescribing the observed mixing ratio of thespecies at a given boundary (e.g., the mixing ratio of methane at thesurface, or the ozone mixing ratio at the tropopause). All threesubmodels substantially simplify the inclusion of emissions into amodel. Specific emissions can easily be switched on or off. Newprescribed emissions can be included without rewriting any code. Newonline emissions only require one additional subroutine containing thenew parameterization. A major advantage is that input fields at arbitraryresolution can be used. The problem of incompatible grids betweenemission data and model is overcome by utilizing the MESSy data importinterface. To further simplify the creation of new offline emissiondata, the preprocessing program EDGAR2NC is provided. EDGAR2NCtransforms files from the EDGAR format into the netCDF format whichis required by OFFLEM. The presented routines are a part of the communitymodeling project MESSy and can be made available for use to the atmosphericmodeling community.

[学科分类] 大气科学