Post on 28-Jan-2016
Effects of Humidity on Atmospheric Transmission in
the Thermal Region
What is the Problem?
• Sponsored by (Herb Mitchell) describes the problem– Atmospheric Transmission Anomaly Observed
• Scenario:– Remote Sensing Experiment
• Multiple airborne sensors collecting coincidently– Visible and Longwave Imagery (spectral)
• Decision made to collect imagery– Based on observation of clear sky condition
• Resulting Thermal Imagery with regions of low transmission
• Data Not Useful (Avoid in the future)
What are the clues and conditions?
• Experiment was collected in high humidity conditions
• Observed over land and water scenes
• Degraded Transmission across LWIR region (8-14 um)
• Rarely occurring event
The Hypothesis
• High concentration of aerosols < 200 [nm] diameter
• Aerosols coated by thin layer liquid water
• Size small enough to not scatter in the visible region, but…
• Absorb in LWIR because of the water coating resulting in lower transmission
Primary Approach
• Image Analysis & Modeling– Get smart/review topics of humidity, aerosols, and
LWIR– Study the observed phenomenon in the previously
collected imagery– Radiometric model these effects (MODTRAN)– Tool development for analysis/visualization of
simulations
Secondary Approach
• Instrumentation & Field Experiments– Ground-based observation of these effects
• Develop Instrumentation• Measure Environmental Condition• Simultaneous imaging in VIS-LWIR
Most Figures and Facts are stolen from
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Basic Concepts
• Water in the atmosphere– Water Vapor– Hydrometeors– Part of Aerosol
• Measures of Moisture– Mixing ratio
• [g/cm^3]
– Dew Point• Temperature to which air is cooled to reach saturation
– Relative Humidity • Ratio of partial pressure of water vapor to partial pressure of
saturated air at a given temperature
Surface Spectral Measurements
What are typical atmospheric water vapor values?
• Tropical Atmosphere - 3.55517 GM / CM2
• Mid-latitude Summer - 2.50788 GM / CM2• Mid-latitude Winter - 0.74752 GM / CM2
• Subarctic Summer - 1.81400 GM / CM2• Subartctic Winter - 0.37745 GM / CM2
• 1976 US Standard - 1.24007 GM / CM2
Water as a particle
• Difficult for Pure Water to become particles
Water condenses on other particles
Possible for particles to be in a Haze State
• R=microns
Log-normal Distribution
Sample Diameters of Particles
Electro-physics IR Camera and Sony Camcorder
Electrophysics EZ-Therm
• Pros– More portable– IR camera meant for field
work
• Cons– Separate Cameras Difficult
to Manage– Visible Camera unreliable in
high humidity conditions– Conventional Video
recording limited to 2 hours max
– Not meant for persistent surveillance
BAE Bolometer Sensor Head
• Attempted use in MDCT Project
• Conclusion: Not really packaged properly
• Requires Rube-goldberg setup of PC, power, recording setup
• Multiple copies of camera
What about humidity measurements?
• Off the shelf weather station (mostly stationery)
• Kestral - mobile, but not suitable for long term monitoring
Enter Bob Kremens Fire Weather Stations
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Weather Station Features
• Basic Met Data• Customizable• *RF-enabled• Need to modify for
GPS capability…• Easier said than
done.
Hardware Advice - Make Multiple Copies
• Remember, there was a backup mirror for the Hubble.
When I broke hardware, I attended Seminars
• Continued attempt to procrastinate
• IS&T (Rich Hailstone) - nanoparticles!
• Research Computing
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Summary of RC Seminar• Use of computational fluid
dynamics– Aerosol and Particle
Deposition in Lungs
• Lab setup for imaging air flow– Use laser fluorescence of
micron size particle (30 microns?)
• Effects of Tobacco byproduct deposition
Followup Discussion
• Discussed experiments using <200 nm particles– Dr. Robinson Currently not setup of this– Aerosol equipment company called TSI
• Check out Rich Hailstone’s lab– Can fabricate nanoparticles [nm], but typically in solution or
substrate.– No means to aerosolize
Grand Opening Celebration
Hardware Advice - Make Multiple Copies
• Remember, there was a backup mirror for the Hubble.
Conesus Tracks with Humidity
Relative Humidity vs Time/Position
0
10
20
30
40
50
60
70
80
90
100
1 25 49 73 97 121 145 169 193 217 241 265
Time/Position
Relative Humidity
Series1
Tested again on the Last MISI/LANDSAT Collect
Relative Humidity vs. Time/Position
0
10
20
30
40
50
60
70
80
1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103 109
Time/Position
Relative Humidity
Series1
Ready for next year’s collection season
While the snow is flying and our airborne sensors are not…
Deploying the MDCT Weather Heads
Currently Repackaging IR & VIS Camera
• Need to figure out trigering based on meteorologial parameters
• Simultaneous video recording of imagery
• Work in Progress…
When the ladder is too short…
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What is the relationship to humidity?
• Thank you Frank Padula and Jason Faulring
• (www.weatherunderground.com)
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Wind DataQuickTime™ and a
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What constituent has spectral features?
• Use Odonnell and Pogorzala techniques to possibly identify?– Statistics based
• Apply Topology-based techniques as alternative
• More to come…
Crazy Thought!
• Can Land feature anomaly be caused by the imaging aircraft exhaust plume?
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Meanwhile… Back at the Google Ranch
• Described lab setup to generate hydrocarbon aerosol particles in the 1x10e6 concentration.
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• PASTE DIAGRAM OF VERANTH SETUP HERE
• Turns out Veranth is no longer at UR
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What is it?
HUCAPS
More Work To Do…
• MODTRAN v2 r11 simulations– Topological Tool Analysis
• Camera Package Integration• <200 [nm] Imaging Lab Experiment• Spectral Image Analysis• Matt’s Cooling Tower Experiment• Field Imaging and Instrumentation
Experiment (Spring overflight)
Wants
• Weather Station for the HUCAPS
• Persistent Imaging of the Surround
Deploying the MDCT Weather Heads