scholarly journals Spectral signature of ice clouds in the far-infrared region: Single-scattering calculations and radiative sensitivity study

2003 ◽  
Vol 108 (D18) ◽  
Author(s):  
Ping Yang
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Single Scattering ◽  
Sensitivity Study ◽  
Spectral Signature ◽  
Ice Clouds

Bulk Scattering Properties for the Remote Sensing of Ice Clouds. Part III: High-Resolution Spectral Models from 100 to 3250 cm−1

2007 ◽  
Vol 46 (4) ◽  
pp. 423-434 ◽  
Author(s):  
Bryan A. Baum ◽  
Ping Yang ◽  
Shaima Nasiri ◽  
Andrew K. Heidinger ◽  
Andrew Heymsfield ◽  
...  
Keyword(s):  
Interpolation Method ◽  
Spline Interpolation ◽  
Far Infrared ◽  
Single Scattering ◽  
Asymmetry Factor ◽  
Effective Diameter ◽  
Size Distributions ◽  
Regional Study ◽  
Ice Clouds ◽  
Spectral Models

Abstract This study reports on the development of bulk single-scattering models for ice clouds that are appropriate for use in hyperspectral radiative transfer cloud modeling over the spectral range from 100 to 3250 cm−1. The models are developed in a manner similar to that recently reported for the Moderate-Resolution Imaging Spectroradiometer (MODIS); therefore these models result in a consistent set of scattering properties from visible to far-infrared wavelengths. The models incorporate a new database of individual ice-particle scattering properties that includes droxtals, 3D bullet rosettes, hexagonal solid and hollow columns, aggregates, and plates. The database provides single-scattering properties for each habit in 45 size bins ranging from 2 to 9500 μm, and for 49 wavenumbers between 100 and 3250 cm−1, which is further interpolated to 3151 discrete wavenumbers on the basis of a third-order spline interpolation method. Bulk models are developed by integrating various properties over both particle habit and size distributions. Individual bulk models are developed for 18 effective diameters Deff, ranging from Deff = 10 μm to Deff = 180 μm. A total of 1117 particle size distributions are used in the analyses and are taken from analysis of the First International Satellite Cloud Climatology Project Regional Experiment (FIRE)-I, FIRE-II, Atmospheric Radiation Measurement Program intensive operation period (ARM-IOP), Tropical Rainfall Measuring Mission Kwajalein Experiment (TRMM-KWAJEX), and Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida-Area Cirrus Experiment (CRYSTAL-FACE) data. The models include microphysical and scattering properties such as median mass diameter, effective diameter, single-scattering albedo, asymmetry factor, and scattering phase function. The spectral models are appropriate for applications involving the interpretation of the radiometric measurements of ice clouds acquired by infrared spectrometers such as the Atmospheric Infrared Sounder (AIRS) on the NASA Aqua satellite and the Cross-Track Infrared Sounder (CrIS) on the upcoming National Polar-Orbiting Environmental Satellite System (NPOESS) platforms.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

scholarly journals A model sensitivity study of the impact of clouds on satellite detection and retrieval of volcanic ash

2015 ◽  
Vol 8 (5) ◽  
pp. 1935-1949 ◽  
Author(s):  
A. Kylling ◽  
N. Kristiansen ◽  
A. Stohl ◽  
R. Buras-Schnell ◽  
C. Emde ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Liquid Water ◽  
Volcanic Ash ◽  
Spectral Band ◽  
Sensitivity Study ◽  
Transfer Model ◽  
Mass Loading ◽  
Ice Clouds ◽  
Medium Range Weather Forecast ◽  
The Impact

Abstract. Volcanic ash is commonly observed by infrared detectors on board Earth-orbiting satellites. In the presence of ice and/or liquid-water clouds, the detected volcanic ash signature may be altered. In this paper the sensitivity of detection and retrieval of volcanic ash to the presence of ice and liquid-water clouds was quantified by simulating synthetic equivalents to satellite infrared images with a 3-D radiative transfer model. The sensitivity study was made for the two recent eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011) using realistic water and ice clouds and volcanic ash clouds. The water and ice clouds were taken from European Centre for Medium-Range Weather Forecast (ECMWF) analysis data and the volcanic ash cloud fields from simulations by the Lagrangian particle dispersion model FLEXPART. The radiative transfer simulations were made both with and without ice and liquid-water clouds for the geometry and channels of the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The synthetic SEVIRI images were used as input to standard reverse absorption ash detection and retrieval methods. Ice and liquid-water clouds were on average found to reduce the number of detected ash-affected pixels by 6–12%. However, the effect was highly variable and for individual scenes up to 40% of pixels with mass loading >0.2 g m−2 could not be detected due to the presence of water and ice clouds. For coincident pixels, i.e. pixels where ash was both present in the FLEXPART (hereafter referred to as "Flexpart") simulation and detected by the algorithm, the presence of clouds overall increased the retrieved mean mass loading for the Eyjafjallajökull (2010) eruption by about 13%, while for the Grímsvötn (2011) eruption ash-mass loadings the effect was a 4% decrease of the retrieved ash-mass loading. However, larger differences were seen between scenes (standard deviations of ±30 and ±20% for Eyjafjallajökull and Grímsvötn, respectively) and even larger ones within scenes. The impact of ice and liquid-water clouds on the detection and retrieval of volcanic ash, implies that to fully appreciate the location and amount of ash, hyperspectral and spectral band measurements by satellite instruments should be combined with ash dispersion modelling.

Hagen-Rubens relation beyond far-infrared region

2010 ◽  
Vol 90 (4) ◽  
pp. 44004 ◽  
Author(s):  
F. E. M. Silveira ◽  
S. M. Kurcbart
Keyword(s):  
Far Infrared ◽  
Infrared Region

scholarly journals Graphene-Based Plasmonic Tunable Dual-Band Bandstop Filter in the Far-Infrared Region

2018 ◽  
Vol 10 (6) ◽  
pp. 1-9 ◽  
Author(s):  
Yijun Cai ◽  
Kai Da Xu ◽  
Rongrong Guo ◽  
Jinfeng Zhu ◽  
Qing Huo Liu
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Dual Band ◽  
Bandstop Filter

Reflection Spectra of Calcite in Far-Infrared Region

1971 ◽  
Vol 31 (6) ◽  
pp. 1837-1837 ◽  
Author(s):  
Mitsukazu Onomichi ◽  
Keiei Kudo ◽  
Toshihiro Arai
Keyword(s):  
Far Infrared ◽  
Infrared Region ◽  
Reflection Spectra

scholarly journals A test of the ability of current bulk optical models to represent the radiative properties of cirrus cloud across the mid-and far-infrared

2020 ◽  
Author(s):  
Richard J. Bantges ◽  
Helen E. Brindley ◽  
Jonathan E. Murray ◽  
Alan E. Last ◽  
Cathryn Fox ◽  
...  
Keyword(s):  
Compensation Effect ◽  
Far Infrared ◽  
Single Scattering ◽  
Radiative Properties ◽  
Cirrus Cloud ◽  
Atmospheric Measurements ◽  
Infrared Observations ◽  
Ice Cloud ◽  
Infrared Frequency Range ◽  
The Uk

Abstract. Measurements of mid- to far-infrared nadir radiances obtained from the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft during the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) are used to assess the performance of various ice cloud bulk optical (single-scattering) property models. Through use of a minimisation approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty but are unable to simultaneously match the observations over the far-infrared frequency range. When both mid and far-infrared observations are used to minimise residuals, first order estimates of the flux differences between the best performing simulations and observations indicate a strong compensation effect between the mid and far infrared such that the absolute broadband difference is

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