Oscillations in the Inversion and Drainage Flows in and around Arizona's Meteor Crater

The Meteor Crater is an almost circular and approximately 1.2-km wide and 170-m deep crater basin, which is located on a gently sloping 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, which took place at the Meteor Crater in October 2013, was specifically designed 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 along the southwest inner sidewall, as well as to the formation of a deep lee wave in the southwest part of the crater basin. The nighttime development of the crater inversion is strongly influenced by these intrusions over the upstream, southwest crater rim. The typical vertical temperature structure consists of a strong but shallow surface-based inversion, which is topped by a near-isothermal layer that extends almost to the top of the crater.

Periodic oscillations in the nocturnal surface temperature, wind, and pressure fields have been observed within the crater-floor inversion during several nights, with a typical periodicity of about 15-20 min. The phase shift between these oscillations over the southwest sidewall and the opposite northeast sidewall suggests the presence of a sloshing of the crater-floor inversion. In this presentation, we will show an analysis of the characteristics and the possible formation mechanisms of this sloshing, including the possible connection to oscillations with a similar periodicity that occur in the upstream katabatic flow.