Optical constants of ice from the ultraviolet to the microwave: A revised compilation

Warren, Stephen G.; Brandt, Richard E.

doi:10.1029/2007jd009744

Cited by 1,028 publications

(1,003 citation statements)

References 44 publications

Supporting

Mentioning

976

Contrasting

Unclassified

Order By: Relevance

“…At 1550 nm, the optical constant used was n 1550 =1.2907+i4.586×10 −4 . The real part is that of Warren and Brandt (2008). For the imaginary part, Gosse et al (1995) recommend 4.26×10 −4 at −22 • C, with an error of 3% and a temperature dependence of 0.6% K −1 (Warren and Brandt, 2008), so that our value is within the acceptable range.…”

Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 84%

“…In all cases we used a log-normal distribution with σ =1.6, as observed in Antarctica by Grenfell and Warren (1999), and which resolves all sizes between 0.2 and 5 r eff , where r eff =3/(ρ ice SSA) is the effective radius. At 1310 nm, the ice optical constant used was n 1310 =1.29584+i1.302×10 −5 , based on the compilation of Warren and Brandt (2008). The real part used is that of the compilation.…”

Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 99%

“…Another advantage to work in the SWIR is that ice absorption is greater (Warren and Brandt, 2008), so that the effect of absorbing impurities such as mineral dust and soot decreases as wavelength is increased for values 900, 1030, 1310, 1550 nm. For example, we calculate with DISORT that adding 500 ppb of soot particles (100 nm in diameter, density 1800 kg m −3 and of optical properties 1.73077+ i0.612288) to snow of SSA=30 m 2 kg −1 changes its bihemispherical reflectance from 0.850 to 0.827 at 900 nm, from 0.701 to 0.693 at 1030 nm, from 0.483 to 0.481 at 1310 nm and remained unchanged at 0.0475 at 1550 nm.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

et al. 2009

View full text Add to dashboard Cite

Abstract. Even though the specific surface area (SSA) and the snow area index (SAI) of snow are crucial variables to determine the chemical and climatic impact of the snow cover, few data are available on the subject. We propose here a novel method to measure snow SSA and SAI. It is based on the measurement of the hemispherical infrared reflectance of snow samples using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement). DUFISSS uses the 1310 or 1550 nm radiation of laser diodes, an integrating sphere 15 cm in diameter, and InGaAs photodiodes. For SSA<60 m 2 kg −1 , we use the 1310 nm radiation, reflectance is between 15 and 50% and the accuracy of SSA determination is 10%. For SSA>60 m 2 kg −1 , snow is usually of low density (typically 30 to 100 kg m −3 ), resulting in insufficient optical depth and 1310 nm radiation reaches the bottom of the sample, causing artifacts. The 1550 nm radiation is therefore used for SSA>60 m 2 kg −1 . Reflectance is then in the range 5 to 12% and the accuracy on SSA is 12%. We propose empirical equations to determine SSA from reflectance at both wavelengths, with that for 1310 nm taking into account the snow density. DUFISSS has been used to measure the SSA of snow and the SAI of snowpacks in polar and Alpine regions.

show abstract

Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 84%

Section: Reflectance Modeling At 1310 Nmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

et al. 2009

View full text Add to dashboard Cite

show abstract

“…2. The small imaginary component of the ice refractive index at millimetre-wavelengths (Warren and Brandt, 2008) makes scattering the key mechanism for attenuation, even at small masses (compare the yellow and cyan lines in Fig. 3).…”

Section: Hydrometeor Attenuationmentioning

confidence: 99%

G band atmospheric radars: new frontiers in cloud physics

et al. 2014

View full text Add to dashboard Cite

Abstract. Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals.The present work discusses the potential of G band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.

show abstract

“…The optical properties, extinction coefficient (β e ) and single-scattering albedo depend on complex refractive index, particle size, particle shape and wave number. The real and imaginary parts of the complex refractive indices of ice (Warren and Brandt, 2008), volcanic ash (Volz, 1973), volcanic ash components (andesite, basalt, basaltic glass, and obsidian Pollack et al, 1973) and sulfate aerosol (Hummel et al, 1988) are shown in Fig. 1a and b for MIPAS band A.…”

Section: From Optical Properties To Infrared Limb Spectramentioning

confidence: 99%

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

Grießbach¹,

Hoffmann²,

Spang³

et al. 2014

Atmos. Meas. Tech.

View full text Add to dashboard Cite

Abstract. Small volcanic ash particles have long residence times in the troposphere and the stratosphere so that they have significant impact on the Earth's radiative budget and consequently affect climate. For global long-term observations of volcanic aerosol, infrared limb measurements provide excellent coverage, sensitivity to thin aerosol layers, and altitude information. The optical properties of volcanic ash and ice particles, derived from micro-physical properties, have opposing spectral gradients between 700 and 960 cm −1 for small particle sizes. Radiative transfer simulations that account for single scattering showed that the opposing spectral gradients directly transfer to infrared limb spectra. Indeed, we found the characteristic spectral signature, expected for volcanic ash, in measurements of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) after the eruption of the Chilean volcano Puyehue-Cordón Caulle in June 2011. From these measurements we derived an ash detection threshold function. The empirical ash detection threshold was confirmed in an extensive simulations study covering a wide range of atmospheric conditions, particle sizes and particle concentrations for ice, volcanic ash and sulfate aerosol. From the simulations we derived the upper detectable effective radius of 3.5 µm and the detectable extinction coefficient range of 5 × 10 −3 to 1 × 10 −1 km −1 . We also showed that this method is only sensitive to volcanic ash particles, but not to volcanic sulfate aerosol. This volcanic ash detection method for infrared limb measurements is a fast and reliable method and provides complementary information to existing satellite aerosol products.

show abstract

Optical constants of ice from the ultraviolet to the microwave: A revised compilation

Cited by 1,028 publications

References 44 publications

Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

Measurement of the specific surface area of snow using infrared reflectance in an integrating sphere at 1310 and 1550 nm

G band atmospheric radars: new frontiers in cloud physics

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

Contact Info

Product

Resources

About