scholarly journals Technical Note: A novel parameterization of the transmissivity due to ozone absorption in the <i>k</i>-distribution method and correlated-<i>k</i> approximation of Kato et al. (1999) over the UV band

2015 ◽  
Vol 15 (1) ◽  
pp. 1027-1040
Author(s):  
W. Wandji Nyamsi ◽  
A. Arola ◽  
P. Blanc ◽  
A. V. Lindfors ◽  
V. Cesnulyte ◽  
...  
Keyword(s):  
Solar Spectrum ◽  
Ground Level ◽  
Maximum Error ◽  
Technical Note ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectral Interval ◽  
Computationally Efficient ◽  
Ozone Absorption ◽  
Distribution Method

Abstract. The k-distribution method and the correlated-k approximation of Kato et al. (1999) is a computationally efficient approach originally designed for calculations of the broadband solar radiation at ground level by dividing the solar spectrum in 32 specific spectral bands from 240 to 4606 nm. Compared to a spectrally-resolved computation, its performance in the UV band appears to be inaccurate, especially in the spectral intervals #3 [283, 307] nm and #4 [307, 328] nm because of inaccuracy in modelling the transmissivity due to ozone absorption. Numerical simulations presented in this paper indicate that a single effective ozone cross section is insufficient to accurately represent the transmissivity over each spectral interval. A novel parameterization of the transmissivity using more quadrature points yields maximum error of respectively 0.0006 and 0.0041 for interval #3 and #4. How to practically implement this new parameterization in a radiative transfer model is discussed for the case of libRadtran.

scholarly journals Technical Note: A novel parameterization of the transmissivity due to ozone absorption in the <i>k</i>-distribution method and correlated-<i>k</i> approximation of Kato et al. (1999) over the UV band

2015 ◽  
Vol 15 (13) ◽  
pp. 7449-7456 ◽  
Author(s):  
W. Wandji Nyamsi ◽  
A. Arola ◽  
P. Blanc ◽  
A. V. Lindfors ◽  
V. Cesnulyte ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Solar Spectrum ◽  
Ground Level ◽  
Technical Note ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectral Interval ◽  
Computationally Efficient ◽  
Ozone Absorption ◽  
Distribution Method

Abstract. The k-distribution method and the correlated-k approximation of Kato et al. (1999) is a computationally efficient approach originally designed for calculations of the broadband solar radiation at ground level by dividing the solar spectrum in 32 specific spectral bands from 240 to 4606 nm. Compared to a spectrally resolved computation, its performance in the UV band appears to be inaccurate, especially in the spectral intervals #3 [283, 307] nm and #4 [307, 328] nm because of inaccuracy in modeling the transmissivity due to ozone absorption. Numerical simulations presented in this paper indicate that a single effective ozone cross section is insufficient to accurately represent the transmissivity over each spectral interval. A novel parameterization of the transmissivity using more quadrature points yields maximum errors of respectively 0.0006 and 0.0143 for intervals #3 and #4. How to practically implement this new parameterization in a radiative transfer model is discussed for the case of libRadtran (library for radiative transfer). The new parameterization considerably improves the accuracy of the retrieval of irradiances in UV bands.

scholarly journals Technical Note: A new discrete ordinate first-order rotational Raman scattering radiative transfer model – implementation and first results

2011 ◽  
Vol 11 (20) ◽  
pp. 10471-10485 ◽  
Author(s):  
A. Kylling ◽  
B. Mayer ◽  
M. Blumthaler
Keyword(s):  
Radiative Transfer ◽  
Raman Scattering ◽  
Solar Spectrum ◽  
Technical Note ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Discrete Ordinate ◽  
First Order ◽  
Spectral Interpolation ◽  
First Results

Abstract. Rotational Raman scattering in the Earth's atmosphere explains the filling-in of Fraunhofer lines in the solar spectrum. A new model including first-order rotational Raman scattering has been developed, based on a reimplementation of the versatile discrete ordinate radiative transfer (DISORT) solver in the C computer language. The solver is fully integrated in the freely available libRadtran radiative transfer package. A detailed description is given of the model including the spectral resolution and a spectral interpolation scheme that considerably speeds up the calculations. The model is used to demonstrate the effect of clouds on top and bottom of the atmosphere filling-in factors and differential optical depths. Cloud effects on vertical profiles of the filling-in factor are also presented. The spectral behaviour of the model is compared against measurements under thunderstorm and aerosol loaded conditions.

scholarly journals A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere

2021 ◽  
Vol 13 (2) ◽  
pp. 270
Author(s):  
Adrian Doicu ◽  
Dmitry S. Efremenko ◽  
Thomas Trautmann
Keyword(s):  
Trace Gases ◽  
Three Dimensional ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Computational Time ◽  
Transfer Model ◽  
Proof Of Concept ◽  
Discrete Ordinate ◽  
Distribution Method ◽  
Total Column

An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate.

scholarly journals Calibration of Satellite Low Radiance by AERONET-OC Products and 6SV Model

2021 ◽  
Vol 13 (4) ◽  
pp. 781
Author(s):  
Cristiana Bassani ◽  
Sindy Sterckx
Keyword(s):  
Optical Sensors ◽  
Atmospheric Correction ◽  
Solar Spectrum ◽  
Water Quality Monitoring ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Blue Band ◽  
Satellite Signal ◽  
Almost All ◽  
User Friendly

For water quality monitoring using satellite data, it is often required to optimize the low radiance signal through the application of radiometric gains. This work describes a procedure for the retrieval of radiometric gains to be applied to OLI/L8 and MSI/S2A data over coastal waters. The gains are defined by the ratio of the top of atmosphere (TOA) reflectance simulated using the Second Simulation of a Satellite Signal in the Solar Spectrum—vector (6SV) radiative transfer model, REF, and the TOA reflectance acquired by the sensor, MEAS, over AERONET-OC stations. The REF is simulated considering quasi-synchronous atmospheric and aquatic AERONET-OC products and the image acquisition geometry. Both for OLI/L8 and MSI/S2A the measured TOA reflectance was higher than the modeled signal in almost all bands resulting in radiometric gains less than 1. The use of retrieved gains showed an improvement of reflectance remote sensing, Rrs, when with ACOLITE atmospheric correction software. When the gains are applied an accuracy improvement of the Rrs in the 400–700 nm domain was observed except for the first blue band of both sensors. Furthermore, the developed procedure is quick, user-friendly, and easily transferable to other optical sensors.

scholarly journals Local Tilt Optimization of Photovoltaic Solar Panels for Maximum Radiation Absorption

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Mauro Masili ◽  
Liliane Ventura
Keyword(s):  
Solar Radiation ◽  
Tilt Angle ◽  
Spectral Response ◽  
Solar Spectrum ◽  
Weather Conditions ◽  
Solar Irradiation ◽  
Radiation Absorption ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Solar Panels

Incident solar radiation on photovoltaic (PV) solar panels is not constant throughout the year. Besides dependence on the season, solar radiation is reliant on the location and weather conditions. For a given location on Earth, the best-fixed orientation of a PV panel can be determined by achieving the maximum incident solar irradiance throughout the year or for a predetermined period. In this paper, we use a sophisticated atmospheric radiative transfer model to calculate the direct and diffuse solar irradiation (radiant exposure) for the solar spectrum incident on PV solar panels to determine the best tilt angle of the panel in order to maximize absorption of solar radiation for selected periods. We used the Regula-Falsi numerical method to obtain the tilt angle at which the derivative of solar irradiation (concerning the tilt angle) approaches zero. Moreover, the spectral response of typical silicon cells is taken into account. These calculations were carried out in São Carlos (SP), a town in the southeast of Brazil. The best tilt angle was obtained for three selected periods. Additionally, we provide results for Southern latitudes ranging from 0° to −55° in steps of −5° for the meteorological seasons. We have shown that for each period, there is an increase in solar radiation absorption compared to the traditional installation angle based exclusively on the local latitude. These calculations can be extended to any location.

Empirical Polarization Distribution Models for CLARREO-Imager Intercalibration

2016 ◽  
Vol 33 (3) ◽  
pp. 439-451 ◽  
Author(s):  
D. Goldin ◽  
C. Lukashin
Keyword(s):  
Linear Polarization ◽  
Infrared Imaging ◽  
Solar Spectrum ◽  
National Research Council ◽  
Real Data ◽  
Radiative Transfer Model ◽  
Degree Of Polarization ◽  
Transfer Model ◽  
Distribution Models ◽  
Polarization Distribution

AbstractPolarization effects bias the performance of various existing passive spaceborne instruments, such as MODIS and the Visible Infrared Imaging Radiometer Suite (VIIRS), as well as geostationary imagers. It is essential to evaluate and correct for these effects in order to achieve the required accuracy of the total reflectance at the top of the atmosphere.In addition to performing highly accurate decadal climate change observations, one of the objectives of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission recommended by the National Research Council for launch by NASA is to provide the on-orbit intercalibration with the imagers over a range of parameters, including polarization. Whenever the on-orbit coincident measurements are not possible, CLARREO will provide the polarization distributions constructed using the adding–doubling radiative transfer model (ADRTM), which will cover the entire reflected solar spectrum. These ADRTM results need to be validated using real data. To this end the empirical polarization distribution models (PDMs) based on the measurements taken by the Polarization and Anisotropy of Reflectances for Atmospheric Sciences Coupled with Observations from a Lidar (PARASOL) mission were developed. Examples of such PDMs for the degree of polarization and the angle of linear polarization for the cloudless ocean scenes are shown here. These PDMs are compared across the three available PARASOL polarization bands, and the effect of aerosols on them is examined. The PDM-derived dependence of the reflectance uncertainty on the degree of polarization for imagers, such as MODIS or VIIRS, after their intercalibration with the CLARREO instrument is evaluated. The influence of the aerosols on the reflectance uncertainty is examined. Finally, the PDMs for the angle of linear polarization is cross-checked against the single-scattering approximation.

scholarly journals Technical Note: Evaluating a simple parameterization of radiative shortwave forcing from surface albedo change

2013 ◽  
Vol 13 (7) ◽  
pp. 18951-18967 ◽  
Author(s):  
R. M. Bright ◽  
M. M. Kvalevåg
Keyword(s):  
Land Use ◽  
Simple Model ◽  
Impact Assessment ◽  
Surface Albedo ◽  
Climate Impact ◽  
Technical Note ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Model Based ◽  
Albedo Change

Abstract. Land use activities affect Earth's energy balance not only via biogeochemical emissions but also through perturbations in surface albedo, the latter of which is often excluded in impact assessment studies. In this short technical note, we present and compare a simple model for estimating shortwave radiative forcings at the top of Earth's atmosphere to a more sophisticated 8-stream radiative transfer model based on a discrete ordinate method. Outcomes from monthly albedo change simulations for ten globally distributed regions and a single year revealed that the simple model – based on a single exogenously supplied meteorological variable – performed quite well, having a sample correlation coefficient of 0.93 and a normalized root mean square error of 7.2%. Simple models like the one presented here can offer an attractive and efficient means for non-experts to begin including albedo change considerations in climate impact assessment studies enveloping land use activities.

scholarly journals Consistency of dimensional distributions and refractive indices of desert dust measured over Lampedusa with IASI radiances

2016 ◽  
Author(s):  
Giuliano Liuzzi ◽  
Guido Masiello ◽  
Carmine Serio ◽  
Daniela Meloni ◽  
Claudia Di Biagio ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Short Wave ◽  
Radiative Transfer Model ◽  
Refractive Indices ◽  
Transfer Model ◽  
Spectral Interval ◽  
Desert Dust ◽  
Microphysical Properties ◽  
Southern Mediterranean ◽  
The One

Abstract. In the context of the ChArMEx campaign, we present here some results concerning the quantitative comparison between simulated and observed radiances during a dust event occurred between June and July 2013 in the southern Mediterranean basin, involving the airmass above Lampedusa island. In particular, comparisons have been performed between radiances as observed by the Infrared Atmospheric Sounder Interferometer (IASI) and those simulated using the σ-IASI-as radiative transfer model, which takes into account aerosol extinction effect through a set of fast parameterizations. Simulations have been carried on with different sets of input complex refractive indices, which take into account the parent soils of the aerosols, and using the high-quality characterization of desert dust aerosol microphysical properties, achieved through direct measurements in the ChArMEx experiment; on the one hand, this comparison has offered the possibility to test the feasibility of the radiative transfer model. On the other hand, this work goes through a direct validation of different refractive indices sets for desert dust in the thermal infrared. Results show a good consistency between calculations and observations, especially in the spectral interval 800–1000 cm−1; moreover, the comparison between calculations and observations suggests that further efforts are needed to better characterize desert dust optical properties in the short wave (above 2000 cm−1). In any case, we show that it is necessary to properly tune the refractive indices according to the geographical origin of the observed aerosol.

Atmospheric Science with Visible/Near-Infrared Spectra from the Mars 2020 Perseverance Rover

2021 ◽  
Author(s):  
Timothy McConnochie ◽  
Thierry Fouchet ◽  
Franck Montmessin ◽  
Pierre Beck ◽  
Baptiste Chide ◽  
...  
Keyword(s):  
Near Infrared ◽  
Solar Spectrum ◽  
Atmospheric Science ◽  
Tunable Filter ◽  
Radiative Transfer Model ◽  
Discrete Ordinates ◽  
Transfer Model ◽  
Absorption Bands ◽  
Aerosol Scattering ◽  
Remote Sensing Techniques

&lt;p&gt;The Mars 2020 &amp;#8220;Perseverance&amp;#8221; rover&amp;#8217;s SuperCam instrument suite [1,2,3] provides a wide variety of active and passive remote sensing techniques [4, 5, 6, 7] including passive visible &amp; near-infrared (&amp;#8220;VISIR&amp;#8221;) spectroscopy [8]. Here we present our plans to use the VISIR technique for atmospheric science by observing solar radiation scattered by the Martian sky, similar to the &amp;#8220;passive sky&amp;#8221; technique demonstrated with ChemCam on the Mars Science Laboratory (MSL) rover [9]. Our presentation will focus on the objectives and techniques of SuperCam VISIR atmospheric science, but we will also present initial atmospheric science results or relevant instrument performance validation results to the extent that such are available at the time of the conference.&lt;/p&gt;&lt;p&gt;The objectives of VISIR atmospheric science are O&lt;sub&gt;2&lt;/sub&gt;, CO, and H&lt;sub&gt;2&lt;/sub&gt;O vapor column abundances, and aerosol particle sizes and composition. These objectives are motivated by unexpected seasonal and interannual variability in the O&lt;sub&gt;2&lt;/sub&gt;mixing ratio that is argued to be so large as to require O&lt;sub&gt;2&lt;/sub&gt; sources and sinks in surface soils [10], by evidence of surface-atmosphere exchange of H&lt;sub&gt;2&lt;/sub&gt;O [11], by the potential significance of O&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O volatiles as field context for returned samples due to their active exchanges with surface materials, and by the Mars 2020 mission [12] objectives of characterizing dust and validating global atmospheric models to prepare for human exploration&lt;/p&gt;&lt;p&gt;The SuperCam spectrometers used for VISIR mode are a ChemCam-heritage reflection spectrometer covering 385&amp;#8211;465 nm with &lt; 0.2 nm res. [2], an intensified transmission spectrometer covering 536&amp;#8211;853 nm with 0.3&amp;#8211;0.7 nm res. [2], and an acousto-optic-tunable-filter (AOTF) -based IR spectrometer covering 1300&amp;#8211;2600 nm with 20&amp;#8211;30 cm&lt;sup&gt;-1&lt;/sup&gt; res. [1, 8]. Our primary observing strategy is the same approach used for MSL ChemCam &amp;#8220;passive sky&amp;#8221; observations [9]: ratioing instrument signals from the two pointing positions with different elevation angles eliminates solar spectrum and instrument response uncertainties that are ~100x and ~10x larger than signals of interest for the transmission and AOTF IR spectrometers, respectively. We will also make use of single pointings directed at the white SuperCam calibration target for less-resource-intensive water vapor and aerosol monitoring, and of multiple-pointing lower-signal-to-noise sky scans to better constrain aerosol size and shape. &lt;strong&gt;Sky radiance is fit&lt;/strong&gt;&lt;strong&gt; &lt;/strong&gt;&lt;strong&gt;with a &lt;/strong&gt;&lt;strong&gt;discrete ordinates multiple scattering radiative transfer model&lt;/strong&gt;&lt;strong&gt; identical to that of [9].&lt;/strong&gt;&lt;strong&gt; As in [&lt;/strong&gt;&lt;strong&gt;9&lt;/strong&gt;&lt;strong&gt;] gas abundances are made robust to aerosol scattering uncertainties by fitting &lt;/strong&gt;CO&lt;sub&gt;2&lt;/sub&gt; absorption bands with an aerosol vertical profile parameter.&lt;/p&gt;&lt;p&gt;References: [1] Maurice S. et al. (2020) SSR, in press. [2] Wiens R.C. et al. (2021) SSR 217, 4. [3] Manrique J.-A. et al. (2020) SSR 216, 138. [4] Ollila A.M. et al. (2021), this meeting. [5] Ollila A.M. et al. (2018) LPSC 49, 2786. [6] Forni O. et al. (2021), this meeting. [7] Lanza N. L. et al. (2021), this meeting. [8] Johnson J.R et al. (2021), this meeting. [9] McConnochie T.H et al. (2018), Icarus 307, 294. [10] Trainer M.G. et al. (2019), JGR 124, 3000. [11] Savij&amp;#228;rvi H. et al. (2016), Icarus 265, 63. [12] Farley K.A. et al. (2020), SSR 216, 142.&lt;/p&gt;

scholarly journals McClear: a new model estimating downwelling solar radiation at ground level in clear-sky conditions

2013 ◽  
Vol 6 (9) ◽  
pp. 2403-2418 ◽  
Author(s):  
M. Lefèvre ◽  
A. Oumbe ◽  
P. Blanc ◽  
B. Espinar ◽  
B. Gschwind ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Weather Prediction ◽  
Ground Level ◽  
Surface Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Clear Sky ◽  
Sky Conditions ◽  
Aerosol Properties

Abstract. A new fast clear-sky model called McClear was developed to estimate the downwelling shortwave direct and global irradiances received at ground level under clear skies. It is a fully physical model replacing empirical relations or simpler models used before. It exploits the recent results on aerosol properties, and total column content in water vapour and ozone produced by the MACC project (Monitoring Atmosphere Composition and Climate). It accurately reproduces the irradiance computed by the libRadtran reference radiative transfer model with a computational speed approximately 105 times greater by adopting the abaci, or look-up table, approach combined with interpolation functions. It is therefore suited for geostationary satellite retrievals or numerical weather prediction schemes with many pixels or grid points, respectively. McClear irradiances were compared to 1 min measurements made in clear-sky conditions at several stations within the Baseline Surface Radiation Network in various climates. The bias for global irradiance comprises between −6 and 25 W m−2. The RMSE ranges from 20 W m−2 (3% of the mean observed irradiance) to 36 W m−2 (5%) and the correlation coefficient ranges between 0.95 and 0.99. The bias for the direct irradiance comprises between −48 and +33 W m−2. The root mean square error (RMSE) ranges from 33 W m−2 (5%) to 64 W m−2 (10%). The correlation coefficient ranges between 0.84 and 0.98. This work demonstrates the quality of the McClear model combined with MACC products, and indirectly the quality of the aerosol properties modelled by the MACC reanalysis.

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