Analysis of katabatic flow using infrared imaging at micro- and mesoscale

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1 AMS - Boundary Layers and Turbulence 06/10/2014 Analysis of katabatic flow using infrared imaging at micro- and mesoscale Analysis of katabatic flow using infrared imaging at micro- and mesoscale Martina Grudzielanek Jan Cermak Roland Vogt Ruhr-Universität Bochum, Germany University of Basel, Switzerland martina.grudzielanek@rub.de

2 Infrared imaging at microscale Cold air drops Cold air pool Adapted from BENDIX

3 Experimental setup Analysis of katabatic flow using infrared imaging at micro- and mesoscale - microscale - Setup design on sloping grassland Infrared-Camera: VarioCam 384x288 IR pixel; 7,5 14 μm Evaluation of the Infrared (IR) method by cross-correlation of Infrared temperatures and sensor temperatures at almost identical locations 2

4 Special feature: identification of new and only supposed phenomena 3

5 - microscale - 4

6 height over ground [cm] IR temperature [ C] Analysis of katabatic flow using infrared imaging at micro- and mesoscale - microscale - IR data analysis Observation of near ground inversion in time response Hovmöller diagram for IR_Profil1 for two hours of measurement at cold air flow phase Analysis as: - visualization - statistical time series analysis time [hours] 5

7 height over ground [cm] IR temperature [ C] height over ground [IR-Pixel] Analysis of katabatic flow using infrared imaging at micro- and mesoscale - micro scale - Observation of passing cold air drops and analysis of their vertical temperature gradients Hovmöller diagram for exemplary 10 minutes at cold air flow phase 8 time [hours] cold air drop peak IR temperature [ C] Classification of cold air drops in different types based on size, period, frequency and vertical temperature gradient is possible! 6

8 Infrared imaging at meso scale METCRAX II - The Meteor Crater Experiment II Dave Whiteman (PI, University of Utah) and Team of international scientists Barringer Meteor Crater, Arizona: meteorological measurements in Oct cold air flow into the crater dynamic processes in and around the crater 5 Infrared Cameras: VarioCams; 7,5 14 μm 384x288 IR pixel, 640 x 480 IR pixel 1022 x 766 IR-Pixel Thanks for technical support and additional IR cameras to Matthias Krauß (InfraTec), Andrea Pitacco (University of Padova and Christian Bernhofer (University of Dresden). 7

9 - mesoscale - 8

10 - mesoscale - Exemplary research questions at METCRAX II, which are additionally analyzed with the IR method: 1. Identification and dynamics of the cold and warm air inflow into the crater s south rim 2. Thickness of the cold air pool in the crater over the night and at special flow situations Cold air pool 3. Warm air intrusion (WAI) and resulting turbulence at the crater s ground WAI 9

11 - mesoscale - Turbulence in the crater, no steady inversion 10

12 - mesoscale - Warm Air Intrusion at stable inversion at 10/22/2013 from 3 to 4 UTC 11

13 - mesoscale - IR profile and Infrared profile diagram for the animated period 12

14 Conclusions: IR method for the analysis of dynamic air processes like catabatic flows What is possible? - Analysis of air mass processes, which are attended by air temperature changes - Analysis in different scales - Data collection as time sequenced IR data - Combination with other data are possible - Data analysis as 1. visualization 2. time series statistical analysis What has to be considered? - The recorded surfaces have fit in order to heat capacity and thermal conductivity the surface has to react fast with air temperature changes - surface properties can be different in one recorded IR investigation area emissivity, angle of IR Cam view, humidity (near ground condensation), temperature reactivity and heat storage - Big benefit for understanding dynamic air processes by additional IR method 13

15 Thanks for your attention! Sunrise after a really cold night