Derivation of midinfrared (5–25 μm) optical constants of some silicates and palagonite

Roush, T. L.; Pollack, James B.; Orenberg, J. B.

doi:10.1016/0019-1035(91)90150-r

Cited by 111 publications

(71 citation statements)

References 26 publications

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“…While we have not found another source for illite refractive index data, we have compared the Querry (1987) optical constant data sets for montmorillonite and kaolinite with results from other independent measurements (Roush et al 1991), and they show excellent agreement with the Querry (1987) data in the silicate stretch region. (In addition, the errors in the Mie theory simulation shown here are not unique to illite; we will present similar results in forthcoming publications for several other common constituents of mineral dust aerosol including kaolinite, montmorillonite, quartz, calcite, and others (Hudson et al 2007). )…”

Section: Comparison Of Experimental Ir Data and Mie Simulationsupporting

confidence: 51%

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

Hudson

Gibson

Young

et al. 2007

Aerosol Science and Technology

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Although atmospheric particles are often non-spherical, Mie theory is commonly used to acquire aerosol optical depth, composition, and transport information from satellite retrievals. In the infrared (IR) region, the radiative effects of aerosols, usually modeled with Mie theory, are subtracted from satellite spectral data to determine key atmospheric and oceanic properties. To gain a better understanding of the infrared radiative effects of aerosols and the methods used to model them, an instrument has been designed to simultaneously measure infrared extinction spectra and particle size distributions obtained from a scanning mobility particle sizer (SMPS) and an aerodynamic particle sizer (APS). Infrared extinction spectra are simulated with Mie theory using the measured particle size distributions and available literature optical constants. As a result, the errors associated with using Mie theory to model the infrared extinction of mineral dust aerosol can be quantitatively examined. Initial results for this instrument are presented here. For ammonium sulfate, the Mie theory simulation is in good agreement with our measured extinction spectrum. This is in accordance with the nearly spherical shape of ammonium sulfate particles. However, for illite, an abundant clay mineral, there is poor agreement between the experimental spectrum and the Mie simulation. This result is attributed to particle shape effects.

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Section: Comparison Of Experimental Ir Data and Mie Simulationsupporting

confidence: 51%

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

Hudson

Gibson

Young

et al. 2007

Aerosol Science and Technology

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“…The plume is covered very well by the IASI observations, although there are hardly any observations directly above the volcano. It is obvious that some lower mineral AOD observations over northern parts of Chile are not related to the PCCE plume Roush et al (1991) (especially on 6 June). These may well be observations of airborne desert dust.…”

Section: The Svd Based Volcanic Ash Retrieval Methods From Iasimentioning

confidence: 99%

Observation of volcanic ash from Puyehue–Cordón Caulle with IASI

2013

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Abstract. On 4 June 2011 an eruption of the Chilean volcano complex Puyehue-Cordón Caulle injected large amounts of volcanic ash into the atmosphere and affected local life as well as hemisphere-wide air traffic. Observations of the Infrared Atmospheric Sounding Interferometer (IASI) flown on board of the MetOp satellite have been exploited to analyze the evolution of the ash plume around the Southern Hemisphere. A novel singular vector-based retrieval methodology, originally developed for observation of desert dust over land and ocean, has been adapted to enable remote sensing of volcanic ash.Since IASI observations in the 8-12 µm window are applied in the retrieval, the method is insensitive to solar illumination and therefore yields twice the observation rate of the ash plume evolution compared to solar backscatter methods from polar orbiting satellites. The retrieval scheme, the emission characteristics and the circumpolar transport of the ash are examined by means of a source-receptor analysis.

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“…This absorption will affect the albedo only for the very largest effective path lengths, approaching the maximum seasonal cap thickness of 1-1.5 m of solid CO 2 ice. There are also competent estimates of the optical properties of Martian dust [Clancy et al, 1995], using the properties of palagonite (Roush et al [1991] for the infrared, extrapolated beyond 25 lam; and Clark et al [1990], based on the measurements of Singer [1982], for the visible). For water ice, there is more uncertainty, since the spectral structure is not opaque enough in the infrared to be measured accurately using only thin films.…”

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confidence: 99%

Control of the radiative behavior of the Martian polar caps by surface CO₂ ice: Evidence from Mars Global Surveyor measurements

Hansen¹

1999

J. Geophys. Res.

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Abstract. The seasonal polar caps of Mars are composed primarily of solid CO 2, and their growth and decay play a large part in the planer's atmospheric CO 2 cycle. The thermodynamic temperature of the caps is ~ 145 K, in equilibrium with the •-6 mbar atmosphere. The optical properties of CO 2 ice require that pure snow with a sufficiently small particle size has a high visible/near-infrared albedo and a low infrared emissivity in parts of the thermal infrared, particularly in the region between 20 and 50 gm. Dust mixed into or on top of the CO 2 ice will lower the visible albedo and bring the thermal infrared emissivity closer to 1. Water ice mixed with the CO 2 will have little effect in the visible and near-infrared to 1.4 gm but can raise the 20-50 gm emissivity if the particle size is >50 gm. Observations of both seasonal polar caps during two of the assessment orbits of the Mars Global Surveyor spacecraft are used to show that there is a strong correlation between visible brightness and low 20-50 gm emissivity. The infrared spectra from the Thermal Emission Spectrometer from regions with low 20-50 gm brightness temperature are consistent with surface deposits of CO 2 with millimeter-sized grains and containing varying small amounts of dust, and they are not consistent with the expected signature of water ice or clouds. Large regions of low emissivity in the spring seasonal caps have not been observed previously. They are correlated with visible bright regions which are known to become brighter as the spring progresses. The visible brightness of the south polar deposits examined is inferred from historical observations, while the brightness of the north polar region is determined from Mars Orbiter Laser Altimeter measurements at 1.06 gm. The model of seasonal CO 2 caps with bright, low-emissivity regions agrees with previous visible observations of bright crater rims, streaks, and other bright areas within the polar caps, some of which may evolve in time from dark, high-emissivity sheet ice to brighter, fractured, loweremissivity ice layers. It is also in agreement with models of the CO 2 cycle, which require average polar cap emissivities <0.9.

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Derivation of midinfrared (5–25 μm) optical constants of some silicates and palagonite

Cited by 111 publications

References 26 publications

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

Observation of volcanic ash from Puyehue–Cordón Caulle with IASI

Control of the radiative behavior of the Martian polar caps by surface CO₂ ice: Evidence from Mars Global Surveyor measurements

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Derivation of midinfrared (5–25 μm) optical constants of some silicates and palagonite

Cited by 111 publications

References 26 publications

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

A Newly Designed and Constructed Instrument for Coupled Infrared Extinction and Size Distribution Measurements of Aerosols

Observation of volcanic ash from Puyehue–Cordón Caulle with IASI

Control of the radiative behavior of the Martian polar caps by surface CO2 ice: Evidence from Mars Global Surveyor measurements

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Product

Resources

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Control of the radiative behavior of the Martian polar caps by surface CO₂ ice: Evidence from Mars Global Surveyor measurements