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 ◽  
Vol 20 (21) ◽  
pp. 12889-12903 ◽  
Author(s):  
Richard J. Bantges ◽  
Helen E. Brindley ◽  
Jonathan E. Murray ◽  
Alan E. Last ◽  
Jacqueline E. Russell ◽  
...  
Keyword(s):  
Far Infrared ◽  
Radiative Properties ◽  
Atmospheric Measurements ◽  
Mid Infrared ◽  
Infrared Observations ◽  
Ice Cloud ◽  
Spectral Flux ◽  
Infrared Frequency Range ◽  
Infrared Radiances ◽  
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 property models. Through use of a minimization approach, we find that the simulations can reproduce the observed spectra in the mid-infrared to within measurement uncertainty, but they are unable to simultaneously match the observations over the far-infrared frequency range. When both mid- and far-infrared observations are used to minimize residuals, first-order estimates of the spectral flux differences between the best-performing simulations and observations indicate a compensation effect between the mid- and far-infrared such that the absolute broadband difference is < 0.7 W m−2. However, simply matching the spectra using the mid-infrared (far-infrared) observations in isolation leads to substantially larger discrepancies, with absolute differences reaching ∼ 1.8 (3.1) W m−2. These results show that simulations using these microphysical models may give a broadly correct integrated longwave radiative impact but that this masks spectral errors, with implicit consequences for the vertical distribution of atmospheric heating. They also imply that retrievals using these models applied to mid-infrared radiances in isolation will select cirrus optical properties that are inconsistent with far-infrared radiances. As such, the results highlight the potential benefit of more extensive far-infrared observations for the assessment and, where necessary, the improvement of current ice bulk optical models.

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

scholarly journals Can downwelling far-infrared radiances over Antarctica be estimated from mid-infrared information?

2018 ◽  
Author(s):  
Christophe Bellisario ◽  
Helen E. Brindley ◽  
Simon F. B. Tett ◽  
Rolando Rizzi ◽  
Gianluca Di Natale ◽  
...  
Keyword(s):  
Far Infrared ◽  
Mid Infrared ◽  
Infrared Radiances

Abstract. Far-infrared (FIR: 100 cm−1 

scholarly journals Can downwelling far-infrared radiances over Antarctica be estimated from mid-infrared information?

2019 ◽  
Vol 19 (11) ◽  
pp. 7927-7937
Author(s):  
Christophe Bellisario ◽  
Helen E. Brindley ◽  
Simon F. B. Tett ◽  
Rolando Rizzi ◽  
Gianluca Di Natale ◽  
...  
Keyword(s):  
Climate Models ◽  
Far Infrared ◽  
Mid Infrared ◽  
Spectral Bands ◽  
Noise Characteristics ◽  
Infrared Spectral ◽  
Infrared Radiances ◽  
Spectrally Resolved ◽  
Spectral Ranges ◽  
The Impact

Abstract. Far-infrared (FIR: 100cm-1<wavenumber, ν<667 cm−1) radiation emitted by the Earth and its atmosphere plays a key role in the Earth's energy budget. However, because of a lack of spectrally resolved measurements, radiation schemes in climate models suffer from a lack of constraint across this spectral range. Exploiting a method developed to estimate upwelling far-infrared radiation from mid-infrared (MIR: 667cm-1<ν<1400 cm−1) observations, we explore the possibility of inferring zenith FIR downwelling radiances in zenith-looking observation geometry, focusing on clear-sky conditions in Antarctica. The methodology selects a MIR predictor wavenumber for each FIR wavenumber based on the maximum correlation seen between the different spectral ranges. Observations from the REFIR-PAD instrument (Radiation Explorer in the Far Infrared – Prototype for Application and Development) and high-resolution radiance simulations generated from co-located radio soundings are used to develop and assess the method. We highlight the impact of noise on the correlation between MIR and FIR radiances by comparing the observational and theoretical cases. Using the observed values in isolation, between 150 and 360 cm−1, differences between the “true” and “extended” radiances are less than 5 %. However, in spectral bands of low signal, between 360 and 667 cm−1, the impact of instrument noise is strong and increases the differences seen. When the extension of the observed spectra is performed using regression coefficients based on noise-free radiative transfer simulations the results show strong biases, exceeding 100 % where the signal is low. These biases are reduced to just a few percent if the noise in the observations is accounted for in the simulation procedure. Our results imply that while it is feasible to use this type of approach to extend mid-infrared spectral measurements to the far-infrared, the quality of the extension will be strongly dependent on the noise characteristics of the observations. A good knowledge of the atmospheric state associated with the measurements is also required in order to build a representative regression model.

Antarctic cloud detection and classification from far and mid infrared downwelling radiance spectra: performances optimization and results

2020 ◽  
Author(s):  
Davide Magurno ◽  
Tiziano Maestri ◽  
William Cossich ◽  
Gianluca Di Natale ◽  
Luca Palchetti ◽  
...  
Keyword(s):  
Machine Learning ◽  
Far Infrared ◽  
Mixed Phase ◽  
Radiative Properties ◽  
High Spectral Resolution ◽  
Ice Clouds ◽  
Mid Infrared ◽  
Clear Sky ◽  
Threat Score ◽  
Mixed Phase Clouds

&lt;p&gt;This work aims at determining the best performing mid and far-infrared (MIR and FIR) joint spectral interval to identify and classify clouds in the Antarctic region by mean of a machine learning algorithm.&lt;/p&gt;&lt;p&gt;About 1700 spectral-resolved radiances, collected during 2013 by the ground based Radiation Explorer in the Far InfraRed-Prototype for Applications and Development, REFIR-PAD (Palchetti et al., 2015) at Dome C, Antarctic Plateau, are selected in coincidence with the co-located with backscatter and depolarization profiles derived from a tropospheric lidar system (Ricaud et al., 2017) to pre-classify clear sky, ice clouds, or mixed phase clouds.&lt;/p&gt;&lt;p&gt;A machine learning cloud identification and classification algorithm named CIC (Maestri et al., 2019), trained with a pre-selected set of REFIR-PAD spectra, is applied to this dataset by assuming that no other information than the spectrum itself is known.&lt;/p&gt;&lt;p&gt;The CIC algorithm is applied by considering different spectral intervals, in order to maximize the classification results for each class (clear sky, ice clouds, mixed phase clouds). A CIC &quot;threat score&quot; is defined as the classification true positives divided by the sum of true positives, false positives, and false negatives. The maximization of the threat score is used to assess the algorithm performances that span from 58% to 96% in accordance with the selected interval. The best performing spectral range is the 380-1000 cm&lt;sup&gt;-1&lt;/sup&gt;. The result, besides suggesting the importance of a proper algorithm calibration in accordance with the used sensor, highlights the fundamental role of the FIR part of the spectrum.&lt;/p&gt;&lt;p&gt;The calibrated CIC algorithm is then applied to a larger REFIR-PAD dataset of about 90000 spectra collected from 2012 to 2015. Some results of the full dataset cloud classification are also presented.&lt;/p&gt;&lt;p&gt;The present work contributes to the preparatory studies for the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission that has recently been selected as ESA&amp;#8217;s 9&lt;sup&gt;th&lt;/sup&gt; Earth Explorer mission, scheduled for launch in 2026.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;&lt;span&gt;Maestri, T., Cossich, W., and Sbrolli, I., 2019: Cloud identification and classification from high spectral resolution data in the far infrared and mid-infrared, Atmos. Meas. Tech., 12, pp. 3521 - 3540&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Palchetti, L., Bianchini, G., Di Natale, G., and Del Guasta, M., 2015: Far infrared radiative properties of water vapor and clouds in Antarctica. Bull. Amer. Meteor. Soc., 96, 1505&amp;#8211;1518, doi: http://dx.doi.org/10.1175/BAMS-D-13-00286.1.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;&lt;span&gt;Ricaud, P., Bazile, E., del Guasta, M., Lanconelli, C., Grigioni, P., and Mahjoub, A., 2017: Genesis of diamond dust, ice fog and thick cloud episodes observed and modelled above Dome C, Antarctica, Atmos. Chem. Phys., 17, 5221&amp;#8211;5237, https://doi.org/10.5194/acp-17-5221-2017.&lt;/span&gt;&lt;/p&gt;

scholarly journals PAH features in Infrared Luminous Galaxies: Results from Michelle

2004 ◽  
Vol 217 ◽  
pp. 216-217
Author(s):  
M. S. Clemens ◽  
B. Nikolic ◽  
P. Alexander ◽  
G. Cotter ◽  
M. S. Longair
Keyword(s):  
Narrow Band Imaging ◽  
Far Infrared ◽  
Infrared Emission ◽  
Radio Continuum ◽  
Energy Output ◽  
Mid Infrared ◽  
Infrared Observations ◽  
Relative Contribution ◽  
Polycyclic Aromatic ◽  
Continuum Data

We present recent results from mid-infrared observations of a sample of nearby, infrared luminous starbursts and AGN made with the new mid-infrared instrument, “Michelle”, on UKIRT. Narrow band imaging in the 7-13 micron range with sub-arcsec resolution has been used to study the spatial distribution of polycyclic aromatic hydrocarbon (PAH) features. The comparison of these sub-arcsecond resolution data with radio continuum data at similar resolution can be used to determine, 1) the sources of excitation required for PAH emission, and 2) whether PAH features are a measure of the relative contribution of star formation and AGN to the bolometric energy output of a galaxy. Unlike the far-infrared emission from dust, that in the mid-infrared can be used to discriminate between different heating sources.

Recent Mid-Infrared Through Submillimeter Observations of Uranus and Neptune

2021 ◽  
Author(s):  
Glenn Orton ◽  
James Sinclair ◽  
Leigh Fletcher ◽  
Naomi Rowe-Gurney ◽  
Michael Roman ◽  
...  
Keyword(s):  
Thermal Emission ◽  
Far Infrared ◽  
Space Observatory ◽  
Infrared Space Observatory ◽  
Mid Infrared ◽  
Infrared Observations ◽  
Spatially Resolved ◽  
James Webb Space Telescope ◽  
Imaging And Spectroscopy ◽  
Auroral Emissions

&lt;p&gt;Observations of thermal emission from Uranus and Neptune have been made over a broad wavelength range from ground-based platforms, airborne observatories, Earth-proximal spacecraft and from the Voyager-2 flybys in the 1980s.&amp;#160; Observations since the Voyager flybys have included long-wavelength observations of disk-averaged radiances from the Infrared Space Observatory and the Herschel Space Observatory covering the far-infrared to millimeter range. We present recent airborne spectra from SOFIA covering 17-35 &amp;#181;m, together with Akari and Spitzer spectroscopy at wavelengths extending down to 7 &amp;#181;m, below which contributions from reflected sunlight and potential auroral emissions may confuse the signature of thermal emission.&amp;#160; We also show how these disk-averaged spectra are complemented by ground-based filtered imaging and spectroscopy at 8-10m telescopes, which have enabled spatially resolved measurements, complementing those of Voyager IRIS from several decades ago. The critical insights into the structure, chemistry and dynamics of the atmospheres of these Ice Giants attest to the need for significant parts of this spectral region to be included in the instrument complement to be assigned to spacecraft sent to these planets.&amp;#160; A vigorous program of Earth-based observations in the accessible spectral range should accompany the spacecraft capability in order to track potential seasonal and non-seasonal variability of these planets, as is evident in the atmospheres of both Jupiter and Saturn. The latter would include mid-infrared observations from the James Webb Space Telescope.&lt;/p&gt;

Spaceborne Middle‐ and Far‐Infrared Observations Improving Nighttime Ice Cloud Property Retrievals

2020 ◽  
Vol 47 (18) ◽  
Author(s):  
Masanori Saito ◽  
Ping Yang ◽  
Xianglei Huang ◽  
Helen E. Brindley ◽  
Martin G. Mlynczak ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Observations ◽  
Cloud Property ◽  
Ice Cloud

scholarly journals Cirrus Cloud Identification from Airborne Far-Infrared and Mid-Infrared Spectra

2020 ◽  
Vol 12 (13) ◽  
pp. 2097 ◽  
Author(s):  
Davide Magurno ◽  
William Cossich ◽  
Tiziano Maestri ◽  
Richard Bantges ◽  
Helen Brindley ◽  
...  
Keyword(s):  
Evaluation System ◽  
Far Infrared ◽  
Classification Performance ◽  
Mid Infrared ◽  
Additional Information ◽  
Temporal And Spatial Variability ◽  
Sensitivity Studies ◽  
Infrared Radiances ◽  
Theoretical Sensitivity ◽  
Infrared Data

Airborne interferometric data, obtained from the Cirrus Coupled Cloud-Radiation Experiment (CIRCCREX) and from the PiknMix-F field campaign, are used to test the ability of a machine learning cloud identification and classification algorithm (CIC). Data comprise a set of spectral radiances measured by the Tropospheric Airborne Fourier Transform Spectrometer (TAFTS) and the Airborne Research Interferometer Evaluation System (ARIES). Co-located measurements of the two sensors allow observations of the upwelling radiance for clear and cloudy conditions across the far- and mid-infrared part of the spectrum. Theoretical sensitivity studies show that the performance of the CIC algorithm improves with cloud altitude. These tests also suggest that, for conditions encompassing those sampled by the flight campaigns, the additional information contained within the far-infrared improves the algorithm’s performance compared to using mid-infrared data only. When the CIC is applied to the airborne radiance measurements, the classification performance of the algorithm is very high. However, in this case, the limited temporal and spatial variability in the measured spectra results in a less obvious advantage being apparent when using both mid- and far-infrared radiances compared to using mid-infrared information only. These results suggest that the CIC algorithm will be a useful addition to existing cloud classification tools but that further analyses of nadir radiance observations spanning the infrared and sampling a wider range of atmospheric and cloud conditions are required to fully probe its capabilities. This will be realised with the launch of the Far-infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission, ESA’s 9th Earth Explorer.

scholarly journals Accretion and Outflow Activity in the Earliest Phases of Star-Formation: CO, Sub-mm Continuum, and Near-Infrared Observations

1997 ◽  
Vol 163 ◽  
pp. 725-726
Author(s):  
K.-W. Hodapp ◽  
E. F. Ladd
Keyword(s):  
Near Infrared ◽  
Spectral Energy Distribution ◽  
Far Infrared ◽  
Point Sources ◽  
Spectral Energy ◽  
Infrared Observations ◽  
Circumstellar Material ◽  
Dense Cores ◽  
Wavelength Radiation ◽  
Main Component

Stars in the earliest phases of their formation, i.e., those accreting the main component of their final mass, are deeply embedded within dense cores of dust and molecular material. Because of the high line-of-sight extinction and the large amount of circumstellar material, stellar emission is reprocessed by dust into long wavelength radiation, typically in the far-infrared and sub-millimeter bands. Consequently, the youngest sources are strong submillimeter continuum sources, and often undetectable as point sources in the near-infrared and optical. The most deeply embedded of these sources have been labelled “Class 0” sources by André, Ward-Thompson, & Barsony (1994), in an extension of the spectral energy distribution classification scheme first proposed by Adams, Lada, & Shu (1987).

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