Analysis of katabatic flow using infrared imaging
Abstract
We present a novel high-resolution IR method which is developed, tested and used for the analysis of katabatic flow. Modern thermal imaging systems allow for the recording of infrared picture sequences and thus the monitoring and analysis of dynamic processes. In order to identify, visualize and analyze dynamic air flow using infrared imaging, a highly reactive 'projection' surface is needed along the air flow. Here, a design for these types of analysis is proposed and evaluated. Air flow situations with strong air temperature gradients and fluctuations, such as katabatic flow, are particularly suitable for this new method. The method is applied here to analyze nocturnal cold air flows on gentle slopes. In combination with traditional methods the vertical and temporal dynamics of cold air flow are analyzed. Several assumptions on cold air flow dynamics can be confirmed explicitly for the first time. By observing the cold air flow in terms of frequency, size and period of the cold air fluctuations, drops are identified and organized in a newly derived classification system of cold air flow phases. In addition, new flow characteristics are detected, like sharp cold air caps and turbulence inside the drops. Vertical temperature gradients inside cold air drops and their temporal evolution are presented in high resolution Hovmöller-type diagrams and sequenced time lapse infrared videos.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A53G..04G
- Keywords:
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- 3307 ATMOSPHERIC PROCESSES Boundary layer processes;
- 3315 ATMOSPHERIC PROCESSES Data assimilation;
- 3359 ATMOSPHERIC PROCESSES Radiative processes;
- 3379 ATMOSPHERIC PROCESSES Turbulence