Abstract. Concentrations of atmospheric trace species in the United States have changed dramatically over the past several decades in response to pollution control strategies, shifts in domestic energy policy and economics, and economic development (and resulting emission changes) elsewhere in the world. Reliable projections of the future atmosphere require models to not only accurately describe current atmospheric concentrations; but to do so by representing chemical, physical and biological processes with conceptual and quantitative fidelity. Only through incorporation of the processes controlling emissions and chemical mechanisms that represent the key transformations among reactive molecules can models reliably project the impacts of future policy, energy, and climate scenarios. Efforts to properly identify and implement the fundamental and controlling mechanisms in atmospheric models benefit from intensive observation periods (IOPs), during which co-located measurements of diverse, speciated chemicals in both the gas and condensed phases are obtained. The Southeast Atmosphere Studies (SAS, including SENEX, SOAS, NOMADSS and SEAC4RS) conducted during the summer of 2013, provided an unprecedented opportunity for the atmospheric modeling community to come together to evaluate, diagnose, and improve the representation of fundamental climate and air quality processes in models of varying temporal and spatial scales. In the summer of 2015 a group of experimentalists and modelers convened at the NOAA Geophysical Fluid Dynamics Laboratory (GFDL), to discuss use of SAS observations to evaluate, diagnose, and improve air quality and climate modeling over the Southeast US. The effort focused primarily on model representation of fundamental atmospheric processes that are essential to the formation of ozone, secondary organic aerosols (SOA) and other trace species in the troposphere over the Southeastern US, with the ultimate goal of understanding the radiative impacts of these species in the Southeast and elsewhere. The workshop addressed questions surrounding four key themes: gas phase chemistry, aerosol chemistry, regional climate and chemistry interactions, and natural and anthropogenic emissions. This paper serves as a summary from this meeting and more importantly, as guidance for future modeling efforts.;
