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 Rubegoldberg setup of PC,
power, recording setup
• Multiple copies of
camera
What about humidity
measurements?
• Off the shelf weather • Kestral - mobile, but
station (mostly
not suitable for long
stationery)
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
100
Relative Humidity
90
80
70
60
50
Series1
40
30
20
10
0
1
25 49 73 97 121 145 169 193 217 241 265
Time/Position
Tested again on the Last
MISI/LANDSAT Collect
Ready for
next year’s
collection
season
Relative Humidity vs. Time/Position
80
Relative Humidity
70
60
50
40
Series1
30
20
10
0
1
7
13
19
25
31
37
43
49
55
61
67
Time/Position
73
79
85
91
97 103 109
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)
Wind Data
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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
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• Described lab setup to generate hydrocarbon aerosol
particles in the 1x10e6 concentration.
• PASTE DIAGRAM OF VERANTH SETUP
HERE
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• 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