CHARACTERIZING COLD AIR POOL DYNAMICS USING THERMAL IMAGERY
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Transcript of CHARACTERIZING COLD AIR POOL DYNAMICS USING THERMAL IMAGERY
CHARACTERIZING COLD AIR POOL DYNAMICS USING THERMAL IMAGERY
PRESENTED BY CHRIS JOHNSON
BIOMICROMETEOROLOGY GROUP
Photo Credit: The University of Utah
DESIGN OF EXPERIMENT
SODAR
THERMAL IMAGERY TO MAP COLD AIR POOL DYNAMICS
Each pixel of temperature information will be associated with a position on the Earth and an elevation.
But first the thermal imagery must be filtered, georeferenced, and orthorectified.
GEOREFERENCING THERMAL IMAGERY
• Identify objects in the image
• Obtain accurate locations
• Use known objects as Ground Control Points Ground Control Point
Known Object and Location
ORTHORECTIFICATION
Data Gap
VALIDATION – Temperature ProfileBasic Functions:• Emits a sound pulse• Measures properties of sound backscattered
from turbulent fluctuations• Emitted pulse frequency• Backscattered sound frequency• Intensity of backscattered sound
Relationship to IR Measurements:• Atmospheric Structure Parameters
• Refractive Index Structure Parameter(CN
2)• Temperature Structure Parameter
(CT2)
• Intensity related to CN2
• CN2 related to CT
2
• CT2 directly calculated from
temperature gradient
VALIDATION – Cold Air Pool Depth
Plot Credit: Beyrich, F., 1997. Mixing Height Estimation from SODAR Data. Atmospheric Environment 31, 3941-3953.
Assumption:
The depth of the cold air pool is equal to the inversion height.
ABL Conditions for Plot:
Weak wind, surface radiatively cooling.
Potential Temperature
Backscatter Intensity
DESIGN OF EXPERIMENT
SODAR