Atmospheric Composition Studies with the GEOS Models

Atmospheric trace gases and aerosols are key environmental quantities that impact the physical forcing of the climate system and the quality of the environment that we inhabit.  For about a decade, the Goddard Earth Observing System (GEOS) model has included a number of options to represent gaseous chemistry and aerosol processes.  Early versions of the “finite-volume” dynamical core, developed by Lin and Rood at NASA GSFC, were the basis of off-line chemistry-transport models (CTMs) used to study stratospheric ozone and global aerosols.  As the FV core was adopted in the GEOS circulation models, it was a natural extension to include the chemical and aerosol processes.  This presentation will focus on highlights of this work, including:

• Studies of ozone-climate interactions using the GEOS CCM (Chemistry-Climate Model), which on the basis of several metrics was one of the best-performing models in the international “CCM Val” model evaluation;
• Early introduction of ozone assimilation into the GEOS models and the subsequent development of that capability, using increasingly complex chemical modules, to introduce NASA’s ozone observations into weather prediction and reanalysis;
• Use of simple measures of pollution chemistry in the GEOS models, beginning with carbon monoxide and its use in guiding NASA’s airborne campaigns that study atmospheric chemistry, and the subsequent introduction of atmospheric aerosols into this system;
• Forefront progression to Earth System Analysis, with MERRA-2 being the first global reanalysis to include interactive aerosols and ozone chemistry, using a wide variety of research-quality observations from NASA’s EOS mission.

These examples demonstrate the evolution of constituent modeling in the context of the Earth System, the success of which is strongly linked to the use of the FV core in the GEOS models.  The results support the continued development of atmospheric composition components in the GEOS models, with a range of applications from radiative forcing of climate change to the impacts of air quality on human health.