Topographic effects on nighttime cooling in a basin and plain atmosphere

The Meteor Crater Experiment (METCRAX), conducted in the Arizona Meteor Crater near Winslow, AZ, aimed to better understand cold pool evolution within the idealized topography of the crater. Throughout the experiment period of October 2006 seven intensive observational periods (IOPs) had supplemental tethersonde and radiosonde launches. Vertical temperature profiles throughout the cold pool formation, maintenance, and break-up periods were taken both within the crater atmosphere and outside on the gently sloping plain. HOBO temperature sensors along the slopes of the crater provided additional information on the structure of the crater atmosphere. The diurnal evolution of the crater and plain atmospheres were both qualitatively compared to determine difference in boundary layer structure and depth, and quantitatively compared utilizing the topographic amplification factor (TAF) to characterize impacts of the crater topography on nighttime cooling. We find that enhanced cooling occurs in the lower levels of the crater atmosphere which contains very little volume compared to the higher levels in the crater, and this strong surface inversion is very susceptible to turbulent mix out. In addition total volume weighted cooling is found to be similar for the crater and plain, however, the effects of advection must be taken into account. Additionally, we will investigate IOPs with strong, moderate, and weak external forcing and compare the inversion structures and strengths between the plain and basin.