Analysis of katabatic flow using infrared imaging at micro...

Martina Grudzielanek, Roland Vogt, Jan Cermak | [email protected] | www.climate.rub.de | AMS - Boundary Layers and Turbulence 10/06/2014

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


Martina Grudzielanek Jan Cermak Ruhr-Universität Bochum, Germany Roland Vogt University of Basel, Switzerland

[email protected] www.climate.rub.de

AMS - Boundary Layers and Turbulence 06/10/2014



Infrared imaging at microscale

Adapted from BENDIX 2004

Cold air pool

Cold air drops

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Experimental setup

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

- microscale -

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Special feature: identification of new and only supposed phenomena

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

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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

hei

ght

ove

r gr

ou

nd

[cm

]

IR t

emp

erat

ure

[°C

]

time [hours]

Analysis as: - visualization - statistical time series analysis

- microscale -

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8 Hovmöller diagram for exemplary 10 minutes at cold air flow phase

hei

ght

ove

r gr

ou

nd

[cm

]

hei

ght

ove

r gr

ou

nd

[IR

-Pix

el]

IR t

emp

erat

ure

[°C

]

IR temperature [°C] cold air drop peak

time [hours]

Observation of passing cold air drops and analysis of their vertical temperature gradients

Classification of cold air drops in different types based on size, period, frequency and vertical temperature gradient is possible!

- micro scale -

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METCRAX II - The Meteor Crater Experiment II http://www.inscc.utah.edu/~whiteman/metcrax2/

Barringer Meteor Crater, Arizona: meteorological measurements in Oct. 2013 cold air flow into the crater dynamic processes in and around the

crater

Dave Whiteman (PI, University of Utah) and Team of international scientists

Infrared imaging at meso scale

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).

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

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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

3. Warm air intrusion (WAI) and resulting turbulence at the crater´s ground WAI

Cold air pool

- mesoscale -

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Turbulence in the crater, no steady inversion

- mesoscale -

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Warm Air Intrusion at stable inversion at 10/22/2013 from 3 to 4 UTC

- mesoscale -

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IR profile and Infrared profile diagram for the animated period

- mesoscale -

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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

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Thanks for your attention!

Sunrise after a really cold night

Analysis of katabatic flow using infrared imaging at micro...

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