Bluff-Body Flow Separation in Arizona's Meteor Crater

The Meteor Crater, an almost circular and approximately 1.2-km wide and 170-m deep crater basin, is located on a gently sloping, mesoscale plain in northern Arizona. During quiescent, clear-sky nights a southwesterly katabatic flow forms over the plain, which interacts with the crater basin and with the upstream, southwest crater rim, which extends approximately 30-50 m above the surrounding plain. The Second Meteor Crater Experiment (METCRAX II) field campaign took place at the Meteor Crater in October 2013, with the goal to study these terrain-flow interactions. As the mesoscale katabatic wind flows over the southwest crater rim it can lead to the drainage of cold and negatively buoyant air into the crater basin, as well as to the formation of a deep lee wave with downslope-windstorm-type flows (DWFs) in the southwest part of the crater basin.

In this presentation, we will look at the formation of bluff-body flow separation in the immediate lee of the crater rim that occurs together with DWFs during relatively strong upstream winds. The wake formed by the flow separation results in a wind sheltering effect in the upper part of the crater sidewall, while the lower part of the sidewall experiences comparatively high wind speeds as a consequence of the DWFs. Data collected during METCRAX II are analyzed to show that the observations are consistent with the concept of bluff-body flow separation, with the goal to further our understanding of the complex terrain-flow interactions in the Meteor Crater during DWFs.