HEMCO: a versatile software component for calculating and validating emissions in atmospheric models

Abstract:

Accurate representation of emissions is essential in global models of atmospheric composition. New and updated emission inventories are continuously being developed by research groups and agencies, reflecting both improving knowledge and actual changes in emissions. Timely incorporation of this new information into atmospheric models is crucial but can involve laborious programming.

Here, we present the Harvard–NASA Emission Component version 1.0 (HEMCO), a stand-alone software component for computing emissions in global atmospheric models. HEMCO determines emissions from different sources, regions, and species on a user-defined grid and can combine, overlay, and update a set of data inventories and scale factors, as specified by the user through the HEMCO configuration file. New emission inventories at any spatial and temporal resolution are readily added to HEMCO and can be accessed by the user without any preprocessing of the data files or modification of the source code. Emissions that depend on dynamic source types and local environmental variables such as wind speed or surface temperature are calculated in separate HEMCO extensions.

By providing a widely applicable framework for specifying constituent emissions, HEMCO is designed to ease sensitivity studies and model comparisons, as well as inverse modeling in which emissions are adjusted iteratively. So far, we have implemented HEMCO in the GEOS-Chem chemical transport model and in the NASA Goddard Earth Observing System Model (GEOS-5) along with its integrated data assimilation system.