Our understanding is encapsulated in atmospheric model component models forming part of the CESM modeling ecosystem. The development and support of these models through the CESM Atmospheric Model Working Group (AMWG) and Software Engineering Working Group (SEWG) is a key community activity of the section, and close collaboration between software engineers and scientists enables us to provide the most robust and usable models for research. We work across NCAR labs to develop versions of CAM with a high top (WACCM) and chemistry enabled capabilities (CAM-CHEM). We are also building a model hierarchy within CAM that spans complexities from the most simple of configurations through to the fully coupled CESM. Section staff is also an integral part of the development of the NCAR System Integrated for Modeling of the Atmosphere (SIMA); an activity to streamline interoperable atmosphere modeling, with applications requiring resolutions at the km scale. As part of all these model development and validation activities, we collaborate routinely with MMM (MPAS), RAL, ACOM, and HAO.