The Ross Ice Shelf Air Stream (RAS) flows to the north adjacent to the Transantarctic Mountains, is a persistent feature of daily weather over the Ross Ice Shelf in West Antarctica, and is an important mechanism by which mass is transported off of the Antarctic continent. Equally as common are the katabatic winds that flow down from the high plateau of Antarctica into the valleys of the Transantarctic Mountains and out over the Ross Ice Shelf. Satellite imagery of the RAS and katabatic flows supports a close connection where by the katabatic flows act as tributaries flowing into the river that is the RAS. The lack of observations over the Ross Ice Shelf has made it difficult to qualify and quantify the interaction between these two features. While the RAS is primarily a barrier wind, it is unknown how much of the mass transported by the RAS has katabatic origins. The University of Wisconsin-Madison Nonhydrostatic Modeling System (UW-NMS) has been employed for high-resolution simulations that capture both the RAS and the katabatic flows. The role of the katabatic mass flux in supporting the RAS was compared to that of just the barrier effect. This was accomplished by a sensitivity experiment in which the glacier valleys leading down to the Ross Ice Shelf were numerically filled in a manner that would stop the katabatic flows.