Analysis of katabatic flow using infrared imaging at micro and meso scale

Air flow situations with strong air temperature gradients and fluctuations, such as katabatic flow, are particularly suitable for the application of infrared thermography. We present results from two experiments where thermal cameras were used to observe and visualize flow patterns on different spatial and temporal scales.

As a first example, micro-scale cold air flow on sloping grassland is analyzed using continuous infrared measurements at 60 Hz. An artificial projection screen is designed to retrieve information on vertical temperature gradients and temporal flow patterns. The screen is oriented along the direction of air flow and maps air temperature via quickly adapting surface temperatures. Cold air flow features are identified and organized in a new classification system of cold air flow phases.

A second example focuses on applications of the IR method on meso-scale processes at the Meteor Crater Experiment II (METCRAX II) conducted in October 2013 at Barringer Meteor Crater, Arizona, USA. High resolution IR measurements were taken in addition to a wide range of other measurements, observing the crater from different perspectives.

Based on both examples it is suggested that IR thermography has a great potential for analyzing dynamic and surface exchange processes, including advances in process understanding.