Polarization Imaging and Lidar

Effects of wildfire smoke on atmospheric polarization (Proc. SPIE 2014)

Wavelength dependence of the degree of polarization in cloud-free skies: simulations of real environments (Optics Express 2012) [pdf 0.8 MB]

Icy wave-cloud lunar corona and cirrus iridescence (Applied Optics, Oct. 2011) [pdf 562 kB]
Measurements from a dual-polarization lidar and radiosonde are used to show that a corona-producing wave cloud contains tiny ice crystals, not the usually expected liquid water droplets.

Comparison of full-sky polarization and radiance observations to radiative transfer simulations which employ AERONET products, (Optics Express, Sep. 2011) [pdf 925 kB]
All-sky polarization images obtained at Montana State University are compared with a radiative transfer model to show evidence that AERONET solar radiometer retrievals of the aerosol real refractive index may be too low.

Effects of surface reflectance on skylight polarization measurements at the Mauna Loa Observatory, (Optics Express, Aug. 2011) [pdf 1.6 MB]
All-sky polarization images obtained at the Mauna Loa Observatory on the island of Hawaii are used with satellite images of clouds below the observatory to quantify the amount that skylight polarization is reduced by an underlying surface of variable brightness.

Comparison of skylight polarization measurements and MODTRAN-P calculations, (J. Applied Remote Sensing, 2011) [pdf 955 kB]
All-sky polarization imaging measurements are used to assess the accuracy and shortcomings of the MODTRAN-P polarized radiative transfer model.

Observational studies of atmospheric aerosols over Bozeman, Montana using a two color lidar, a water vapor DIAL, a solar radiometer, and a ground based nephelometer over a 24 hour period(J. Atmos. Oceanic Technology, March 2011) [pdf 3.1 MB]
Multi-sensor measurements of aerosols in dry (RH<60%) conditions with incursion of forest fire smoke from fires on the Pacific coast.

Development of a widely tunable amplified diode laser differential absorption lidar for profiling atmospheric water vapor (J. Applied Remote Sensing, March 2010) [pdf 571 kB]
Design of a prototype diode-laser differential absorption lidar for measuring atmospheric water vapor.

Digital all-sky polarization imaging in partly cloudy skies (Applied Optics, 1 Dec. 2008) [pdf 1.98 MB]
All-sky polarization imaging in partly cloudy skies: explanation of why the angle of polarization remains constant beneath many clouds but changes beneath some; demonstration that fluctuations in the observed degree of skylight polarization precede the formation of visible clouds by up to several hours ("twilight zone" effect); and experimental confirmation of theories of halo polarization.

Airborne lidar measurements of invasive lake trout in Yellowstone Lake (International Laser Radar Conference, June 2008) [pdf 480 kB]
A conference paper talking about initial results from airborne fish lidar for locating invasive lake trout that threaten the native cutthroat trout in Yellowstone Lake (at Yellowstone National Park). 

Range-resolved optical detection of honeybees by use of wingbeat modulation of scattered light for locating land mines (Applied Optics, 20 May 2007) [pdf 975 kB]. 
Description of a pulsed lidar using wingbeat modulation to isolate honeybees from other scattering objects. 

Polarization in Remote Sensing - Introduction (Applied Optics, Aug. 2006) [pdf 769 kB]
Introduction to the special issue of Applied Optics in Polarization Imaging in Remote Sensing (1 Aug., 2006).

Review of passive imaging polarimetry for remote sensing applications (Applied Optics, Aug. 2006) [pdf 769 kB]
A review paper in the special issue of Applied Optics on Polarization Imaging in Remote Sensing (1 Aug., 2006).

Dual-field imaging polarimeter using liquid crystal variable retarders (Applied Optics, Aug. 2006) [pdf 769 kB]
An imaging spectro-polarimeter in the 450-700 nm spectral band is described. The system is based on liquid crystal variable retarders and has front-end optics that can be switched between a 300-mm telephoto and fisheye lenses. We show all-sky measurements of polarization that show that clear-sky degree of polarization increases with wavelength except when a cloud is present somewhere in the sky. 

Dual-polarization lidar using a liquid crystal variable retarder (Optical Engineering, Oct. 2006) [pdf 997 kB]
A dual-polarization lidar is described that provides polarization-ratio measurements at 15 Hz rate with a Nd:Yag laser transmitter and a receiver based on a liquid crystal variable retarder. The system has a variable field of view (up to 8.8 mrad). We show measurements of clouds and aerosols to demonstrate the polarization measurement capability, including a measurement of possible Asian dust over Bozeman, Montana in March 2005.  

Optical detection of honeybees by use of wing-beat modulation of scattered laser light for locating explosives and landmines (Applied Optics, Mar. 2006) [pdf 727 kB]
An optical sensor is described that senses flying honey bees in the presence of clutter through the use of wing-beat modulated cw diode laser light. 

Polarization lidar measurements of honey bees in flight for locating land mines (Optics Express, Aug. 2005) [pdf 291 kB]
Describes scanning lidar measurements of honey bee spatial density to locate buried land mines through smell. 

The effect of instrument polarization sensitivity on sea-surface remote sensing with infrared spectroradiometers (J. Atm. Ocean. Technol. 2002)  [pdf 184 kB] 
Discussion of how measurements with partially polarization-sensitive FTIR spectrometers are affected when measuring the ocean surface or other partially polarized scene; includes discussion of the use of FTIRs as polarimeters in military surveillance, etc.

Polarimetric measurements of long-wave infrared spectral radiance from water (Applied Optics 2001)  [pdf 114 kB]

The first spectrally resolved measurements reported in the open literature of water polarization in the long-wave infrared; the first comparison of measured polarization spectra with calculations using the model described by Shaw (Appl. Opt. 1999).

Polarized infrared emissivity for a rough sea surface (Optics Express 2000)  [pdf 162 kB]
Provides user-interactive graph and tables of polarized infrared sea-surface emissivity for a variety of wind speeds and viewing angles.

Degree of linear polarization for water in the infrared (Applied Optics 1999)  [pdf 1011 kB] 
First comprehensive, quantitative model of thermal infrared polarization from water.

Instrument effects in polarized infrared images (Optical Engineering 1995)  [pdf 252 kB] 
Identifies undesirable effects of narcissus, reflected background radiation, and self-emission in thermal-infrared polarization imaging.

Infrared and Multi-spectral Radiometric Sensing (and misc.) 

Infrared moon imaging for remote sensing of atmospheric smoke layers (Applied Optics 2015) [pdf 1.1 MB]

Visible and invisible mirages: comparing inferior mirages in the visible and thermal infrared (Applied Optics 2015) [pdf 0.7 MB]

Comparison of long-wave infrared imaging and visible/near-infrared imaging of vegetation for detecting leaking CO2 gas (IEEE J. Sel. Topics Appl. Earth Obs. Rem. Sens. 2014) [pdf 1.0 MB]

Radiometric calibration of infrared imagers using an internal shutter as an equivalent external blackbody (Optical Engineering 2014) [pdf 0.9 MB]

Correcting for focal plane array temperature dependence in microbolometer infrared cameras lacking thermal stabilization (Optical Engineering 2013) [pdf 1.9 MB]

Physics principles in radiometric infrared imaging of clouds in the atmosphere (European J. Physics 2013) [pdf 1.1 MB]

The physics of near-infrared photography (European J. Physics 2013) [pdf 3 MB]

Infrared cloud imager development for atmospheric optical communication characterization, and measurements at the JPL Table Mountain Facility (IPN Prog. Rep. 2013) [pdf 3.4 MB]

Radiometry and the Friis transmission equation (Am. J. Physics 2012) [pdf 0.6 MB]
Optical radiometry is used in combination with simple scalar diffraction theory to derive the Friis transmission equation, frequently used in wireless communications. This paper can be useful for learning either radiometry in a practical context OR the Friis transmission equation in a simple and novel manner.

Long-wave infrared imaging of vegetation for detecting leaking CO2 gas (J. Appl. Rem. Sens. 2012) [pdf 4.3 MB]

Multispectral imaging systems on tethered balloons for optical remote sensing education and research (J. Appl. Rem Sens. 2012) [pdf 3.9 MB]

Low-cost multispectral vegetation imaging system for detecting leaking CO2 gas (Applied Optics 2012) [pdf 0.8 MB]

Detection of leaking CO2 gas with vegetation reflectances measured by a low-cost multispectral imager (IEEE JSTARS, June 2012) [pdf 1.3 MB]
CO2 gas leaks are located by detecting plant stress with a custom-designed red-and-NIR imaging system.

Analyzing change in Yellowstone's terrestrial emittance with Landsat imagery (GIScience & Remote Sensing, 2012) [pdf 9.3 MB]
Landsat imagery is used to analyze geothermal activity in Yellowstone National Park.

Long-wave infrared imaging for non-invasive beehive population assessment (Optics Express, Jan. 2011). [pdf 1.4 MB]
Radiometrically calibrated infrared images are used to estimate the population of beehives; the best results were obtained just before sunrise.

Experimental observation of signature changes in bulk soil electrical conductivity in response to engineered surface CO2 leakage (Int. J. Greenhouse Gas Control, 2011) [pdf 1.3 MB]
Soil electrical conductivity changes were caused by CO2 gas leaking from underground.

Multi-spectral imaging of vegetation for detecting CO2 leaking from underground (Environmental Earth Sciences - 2 March 2010). [pdf 521 kB].
Application of a scaffold-mounted multi-spectral imager to detect CO2 gas leaking from an underground reservoir through the use of vegetation indices.

A shallow subsurface controlled release facility in Bozeman, Montana, USA, for testing near surface CO2 detection techniques and transport models (Environmental Earth Sciences - 22 Dec 2009). [pdf 980 kB].
Discussion of the design of a field facility designed for testing methods of detecting CO2 leaking from under ground.

Correcting calibrated infrared sky imagery for the effect of an infrared window (J. Atmos. Oceanic Technology - Nov. 2009) [pdf 1.3 MB].
This paper describes a correction for the optical effects of an infrared window on a calibrated long-wave infrared sky imager. Data are shown to demonstrate the validity of the correction, using side-by-side measurements from imagers with and without a window.

Infrared cloud imaging in support of Earth-space optical communications (Optics Express 2009) [pdf 260 kB].
Description of the compact 2nd-generation Infrared Cloud Imager system (ICI-2) and its application to measuring cloud statistics for optical communications. This is the first report in the literature of a passive IR imager used to retrieve cloud optical depth.  

Cloud statistics measured with the Infrared Cloud Imager (ICI) (IEEE Transactions on Geoscience and Remote Sensing 2005) [pdf 452 kB].
Measurements of cloud statistics with the ICI system in Alaska and Oklahoma. 

Radiometric cloud imaging with an uncooled microbolometer thermal infrared camera (Optics Express 2005) [302 kB].
Evaluation of the radiometric calibration of the Infrared Cloud Imager and demonstration of its use in cloud imaging and retrieving cloud emissivity.

Radiosonde humidity soundings and microwave radiometers during Nauru99 (J. Atmospheric & Oceanic Technology 2003)  [pdf 1075 kB] 

Infrared atmospheric spectral radiance measurements at Mauna Loa, Hawaii (Geophysical Research Letters 1999)  [pdf 125 kB] 
Measurements of the radiative effect of upper-tropospheric drying during the 1997-1998 ENSO event.  An exciting measurement that shows that during El Nino periods, the subtropical atmosphere opens a thermal window; we hypothesize that the El Nino phenomenon might be acting as a natural climate-control mechanism.

Modeling infrared lunar radiance (Optical Engineering 1999)  [pdf 32 kB] 
Identifies and corrects a serious limitation of the lunar radiance model in the widely used Modtran and Fascode programs (shows that longwave infrared lunar radiance is primarily thermal emission, not reflected sunlight).

Ground-based remote sensor observations during PROBE in the Tropical Western Pacific (Bulletin Am. Meteorological Society 1999)  [pdf 614 kB] 
First tropical Pacific multi-sensor deployment (1993), prototype for the DoE Atmospheric Radiation Measurement Program tropical sites; source of the IR radiance measurements on which a significant water vapor continuum adjustment was based.  Awarded the 2000 Vaisala Prize by the World Meteorological Organization.

Infrared atmospheric spectral radiance measurements in the tropical Pacific (J. Geophysical Research 1997)  [pdf 232 kB] 
First field validation of a significant water vapor continuum model modification made from earlier measurements by our group.

Multi-wavelength observations of a developing cloud system (J. Atmos. Sci. 1995)  [pdf 1500 kB] 
Radar, lidar, passive infrared observations to study clouds in the FIRE 2 program in Coffeyville, Kansas in 1991.

Comparison of IR brightness temperatures from FTIR & filter radiometer (J. Atmospheric & Oceanic Technology 1995)  [pdf 387 kB] 
Comparison of clear and cloudy atmospheric measurements from a Fourier transform infrared spectrometer and a filter radiometer during the 1991 FIRE 2 program in Coffeyville, Kansas.

Air-Sea Interaction and ocean sensing

Airborne lidar detection and characterization of internal waves in a shallow fjord (J. Appl. Rem. Sens. 2012) [pdf 3.6 MB]

A visual demonstration of three-scale sea-surface roughness under light wind conditions (IEEE Trans. Geoscience & Remote Sensing 2005)  [pdf 2699 kB] 
A fun use of video imagery of the ocean surface viewed from an airplane for evaluating sea-surface roughness. 

Air-temperature profile and air-sea temperature difference measurements by infrared and microwave scanning radiometers (Radio Science 2003)  [pdf 1578 kB] 
Retrievals of vertical air-temperature profiles and air-sea temperature differences from scanning microwave and infrared radiometers near Nauru Island.

Scanning infrared radiometer for measuring the air-sea temperature difference (Applied Optics 2001)  [pdf 287 kB]
Describes a novel scanning IR radiometer and shows measurements of air-sea temperature data from the Tropical Western Pacific.  These data show clearly a strong diurnally varying difference between bulk and skin water temperatures.
Laser-glint measurements of sea-surface slope statistics (Applied Optics 1997)  [pdf 327 kB]
Uses laser-glint data to derive a probability density function of sea-surface slope; identifies a stability correction required for the widely used slope statistics of Cox and Munk (1954).  Awarded the 1998 NOAA Outstanding Scientific Paper Award.

Fractal laser glints from the ocean surface (J. Optical Society of America - A 1997)  [pdf 266 kB]
Determines fractal dimensions for two-scale sea-surface roughness using laser-glint data.

Optics in Nature

Colors of thermal pools in Yellowstone National Park (Applied Optics 2015) [pdf 1.7 MB]

Visible and invisible mirages: comparing inferior mirages in the visible and thermal infrared (Applied Optics 2015) [pdf 0.7 MB]

Das farbenpr√§chtige glitzern frischen schnees (Physik in Unserer Zeit 2014) [0.3 MB] - in German

Brilliant colours from a white snow cover (European J. Physics 2013) [pdf 2.4 MB]

The physics of near-infrared photography (European J. Physics 2013) [pdf 1.1 MB]

Icy wave-cloud lunar corona and cirrus iridescence (Applied Optics, Oct. 2011) [pdf 562 kB]
Measurements from a dual-polarization lidar and radiosonde are used to show that a corona-producing wave cloud contains tiny ice crystals, not the usually expected liquid water droplets.

Light and color in the open air: introduction to the feature issue (Applied Optics, 1 Oct. 2011) [pdf 44 kB] 
Introduction to the light and color in the open air feature issue containing primarily papers from the 10th International Meeting on Light and Color in Nature, held during June 2010 at St. Mary's College of Maryland.

Night-shining clouds (Optics and Photonics News, June 2010) [pdf 433 kB] 
Discussion of noctilucent clouds and associated observing and photographing techniques. Includes photographs of relatively rare mid-latitude noctilucent clouds observed in Bozeman, Montana. 

Light and color in the open air: introduction to the feature issue (Applied Optics, 1 Dec. 2008) [pdf 41 kB] 
Introduction to the light and color in the open air feature issue that arose primarily from the 9th International Meeting on Light and Color in Nature, held during 25-29 June 2007 in Bozeman, Montana.

The digital blue sky at night (Optics and Photonics News, Nov. 2005)  [pdf 408 kB] 
Digital photography of the moonlit sky reveals the blue sky created by Rayleigh-scattered moonlight. Our eyes are not sensitive enough to capture the color, but a digital camera can. Film cameras also see the blue, but capture it with longer exposures because of film reciprocity failure.

Coronas and iridescence in mountain wave clouds over northeastern Colorado  (Bulletin of the American Meteorological Society, Oct. 2003)  [pdf 7593 kB] 
Meteorologically oriented analysis of optical diffraction phenomena in mountain wave clouds at a review level.  Uses same example photographs as Shaw & Neiman, Applied Optics 2003, but adds discussion on wave-cloud physics and Mie scattering analysis that demonstrates that blue rings exist in coronas only when the cloud particle size distribution is narrow and the cloud optical depth is low.  

Coronas and iridescence in mountain wave clouds  (Applied Optics, Jan. 2003 )  [pdf 3121 kB]
Optical analysis of photographs of coronas and iridescence in orographic mountain wave clouds in Colorado, suggesting that small quasi-spherical ice particles in these clouds can produce particularly vivid optical displays; identifies preference for blue (rather than green) as the dominant short-wavelength color as a possible unique feature of coronas in mountain wave clouds.  Part of the January 2003 Special Issue on Light and Color in the Open Air.

Coronas and iridescence (Optics and Photonics News 2002)  [pdf 1580 kB] 
Description and photographic analysis of coronas and iridescence formed by diffraction of sunlight or moonlight by cloud droplets (popular version of the Applied Optics 2003 paper listed above).

What we see in the aurora  (Optics & Photonics News 1999)  [pdf 980 kB] 
What causes the aurora, where and when to see it, and how to photograph it.

Glittering light on water  (Optics & Photonics News 1999)  [pdf 150 kB] 
Explanation of optical glitter patterns on water, and how we use laser glitter patterns to study sea-surface roughness.

The Christmas corona (Optics & Photonics News 1997)  [pdf 374 kB] 
Discussion of diffraction coronas in clouds, based on the photograph of a beautiful corona seen on Christmas night 1996.

What color is the night sky?  (Optics & Photonics News 1996)  [html or pdf 298kB
How Rayleigh scattered moonlight prod