scholarly journals Aerosol retrievals from the EKO MS-711 spectral direct irradiance measurements and corrections of the circumsolar radiation

2020 ◽  
Vol 13 (5) ◽  
pp. 2601-2621
Author(s):  
Rosa Delia García-Cabrera ◽  
Emilio Cuevas-Agulló ◽  
África Barreto ◽  
Victoria Eugenia Cachorro ◽  
Mario Pó ◽  
...  
Keyword(s):  
Field Of View ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Mean Square ◽  
Aerosol Scattering ◽  
The World ◽  
Uv Visible ◽  
Sun Photometer ◽  
Comparison Of The Results ◽  
Uv Range

Abstract. Spectral direct UV–visible normal solar irradiance (DNI) has been measured with an EKO MS-711 grating spectroradiometer, which has a spectral range of 300–1100 nm, and 0.4 nm step, at the Izaña Atmospheric Observatory (IZO, Spain). It has been used to determine aerosol optical depth (AOD) at several wavelengths (340, 380, 440, 500, 675, and 870 nm) between April and September 2019, which has been compared with synchronous AOD measurements from a reference Cimel and Aerosol RObotic NETwork (AERONET) sun photometer. The EKO MS-711 has been calibrated at the Izaña Atmospheric Observatory by using the Langley plot method during the study period. Although this instrument has been designed for spectral solar DNI measurements, and therefore has a field of view (FOV) of 5∘ that is twice the recommended amount in solar photometry for AOD determination, the AOD differences compared to the AERONET–Cimel reference instrument (FOV ∼1.2∘) are fairly small. A comparison of the results from the Cimel AOD and EKO MS-711 AOD presents a root mean square (rms) of 0.013 (24.6 %) at 340 and 380 nm, and 0.029 (19.5 %) for longer wavelengths (440, 500, 675, and 870 nm). However, under relatively high AOD, near-forward aerosol scattering might be significant because of the relatively large circumsolar radiation (CSR) due to the large EKO MS-711 FOV, which results in a small but significant AOD underestimation in the UV range. The AOD differences decrease considerably when CSR corrections, estimated from libRadtran radiative transfer model simulations, are performed and obtain an rms of 0.006 (14.9 %) at 340 and 380 nm, and 0.005 (11.1 %) for longer wavelengths. The percentage of 2 min synchronous EKO AOD–Cimel AOD differences within the World Meteorological Organization (WMO) traceability limits were ≥96 % at 500, 675, and 870 nm with no CSR corrections. After applying the CSR corrections, the percentage of AOD differences within the WMO traceability limits increased to >95 % for 380, 440, 500, 675, and 870 nm, while for 340 nm the percentage of AOD differences showed a poorer increase from 67 % to a modest 86 %.

scholarly journals Characterization of an EKO MS-711 spectroradiometer: aerosol retrieval from spectral direct irradiance measurements and corrections of the circumsolar radiation

2019 ◽  
Author(s):  
Rosa Delia García-Cabrera ◽  
Emilio Cuevas-Agulló ◽  
África Barreto ◽  
Victoria Eugenia Cachorro ◽  
Mario Pó ◽  
...  
Keyword(s):  
Field Of View ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Retrieval ◽  
Aerosol Scattering ◽  
Comparison Results ◽  
The World ◽  
Uv Visible ◽  
Uv Range

Abstract. Spectral direct UV-Visible normal solar irradiance (DNI) measured with an EKO MS-711 spectroradiometer at the Izaña Atmospheric Observatory (IZO, Spain) has been used to determine aerosol optical depth (AOD) at several wavelengths (340, 380, 440, 500, 675 and 870 nm) between April and September 2019 that have been compared with synchronous AOD measurements from a reference Cimel-AERONET (Aerosol RObotic NETwork) sunphotometer. The EKO MS-711 has been calibrated at Izaña Observatory using the Langley-Plot method during the study period. Although this instrument has been designed for spectral solar DNI measurements, and therefore has a field of view (FOV) of 5° that is twice that recommended in solar photometry for AOD determination, the AOD differences compared against the AERONET Cimel reference instrument (FOV ∼ 1.2°), are fairly small. The comparison results between AOD Cimel and EKO MS-711 present a root mean square (RMS) of 0.013 (24.6 %) at 340, and 380 nm, and 0.029 (19.5 %) for longer wavelengths (440, 500, 675 and 870 nm). However, under relatively high AOD, near forward aerosol scattering might be significant because of the relatively large circumsolar radiation (CSR) due to the large EKO MS-711 FOV, resulting in a small but significant AOD underestimation in the UV range. The AOD differences decrease considerably when CSR corrections, estimated from LibRadtran radiative transfer model simulations, are performed, obtaining RMS of 0.006 (14.9 %) at 340 and 380 nm, and 0.005 (11.1 %) for longer wavelengths. The percentage of 2-minute synchronous EKO AOD–Cimel AOD differences within the World Meteorological Organization (WMO) traceability limits were ≥ 96 % at 500 nm, 675 nm and 870 nm with no CSR corrections. After applying the CSR corrections, the percentage of AOD differences within the WMO traceability limits increased to > 95 % for 380, 440, 500, 675 and 870 nm, while for 340 nm the percentage of AOD differences showed a poorer increase from 67 % to a modest 86 %.

scholarly journals Description of the Baseline Surface Radiation Network (BSRN) station at the Izaña Observatory (2009–2017): measurements and quality control/assurance procedures

2019 ◽  
Vol 8 (1) ◽  
pp. 77-96 ◽  
Author(s):  
Rosa Delia García ◽  
Emilio Cuevas ◽  
Ramón Ramos ◽  
Victoria Eugenia Cachorro ◽  
Alberto Redondas ◽  
...  
Keyword(s):  
Quality Control ◽  
Research Programme ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
High Mountain ◽  
Total Column Ozone ◽  
The World ◽  
Instantaneous Values

Abstract. The Baseline Surface Radiation Network (BSRN) was implemented by the World Climate Research Programme (WCRP) starting observations with nine stations in 1992, under the auspices of the World Meteorological Organization (WMO). Currently, 59 BSRN stations submit their data to the WCRP. One of these stations is the Izaña station (station IZA, no. 61) that enrolled in this network in 2009. This is a high-mountain station located in Tenerife (Canary Islands, Spain, at 28.3∘ N, 16.5∘ W; 2373 m a.s.l.) and is a representative site of the subtropical North Atlantic free troposphere. It contributes with basic-BSRN radiation measurements, such as global shortwave radiation (SWD), direct radiation (DIR), diffuse radiation (DIF) and longwave downward radiation (LWD), and extended-BSRN measurements, including ultraviolet ranges (UV-A and UV-B), shortwave upward radiation (SWU) and longwave upward radiation (LWU), and other ancillary measurements, such as vertical profiles of temperature, humidity and wind obtained from radiosonde profiles (WMO station no. 60018) and total column ozone from the Brewer spectrophotometer. The IZA measurements present high-quality standards since more than 98 % of the data are within the limits recommended by the BSRN. There is an excellent agreement in the comparison between SWD, DIR and DIF (instantaneous and daily) measurements with simulations obtained with the LibRadtran radiative transfer model. The root mean square error (RMSE) for SWD is 2.28 % for instantaneous values and 1.58 % for daily values, while the RMSE for DIR is 2.00 % for instantaneous values and 2.07 % for daily values. IZA is a unique station that provides very accurate solar radiation data in very contrasting scenarios: most of the time under pristine sky conditions and periodically under the effects of the Saharan air layer characterized by a high content of mineral dust. A detailed description of the BSRN program at IZA, including quality control and quality assurance activities, is given in this work.

scholarly journals Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment

2016 ◽  
Author(s):  
Stelios Kazadzis ◽  
Panagiotis Ι. Raptis ◽  
Natalia Kouremeti ◽  
Vassilis Amiridis ◽  
Antti Arola ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Aerosol Composition ◽  
Data Set ◽  
Aerosol Absorption ◽  
Uv Irradiance ◽  
Band Radiometer ◽  
Uv Range

Abstract. We have used total and diffuse UV irradiance measurements with a multi-filter rotating shadow-band radiometer (UVMFR), in order to calculate aerosol absorption properties (Single Scattering Albedo – SSA) in the UV range, for a 5 years period in Athens, Greece. Τhis data set was used as input to a radiative transfer model and the SSA for 368 nm and 332 nm has been calculated. Retrievals from a collocated CIMEL sun-photometer were used to validate the products and study absorption spectral behavior SSA values at these wavelengths. UVMFR SSA together with synchronous,CIMEL-derived, retrievals at 440 nm, show a mean of 0.90, 0.87 and 0.83, with lowest values (higher absorption) towards lower wavelengths. In addition, noticeable diurnal variations of the SSA in all wavelengths are revealed, with amplitudes in up to 0.05. High SSA wavelength dependence is found for cases of low Ångström exponents and also an SSA decrease with decreasing extinction optical depth, suggesting an effect of the different aerosol composition. Dust and Brown Carbon UV absorbing properties were investigated to understand seasonal variability of the results.

scholarly journals Aerosol absorption retrieval at ultraviolet wavelengths in a complex environment

2016 ◽  
Vol 9 (12) ◽  
pp. 5997-6011 ◽  
Author(s):  
Stelios Kazadzis ◽  
Panagiotis Raptis ◽  
Natalia Kouremeti ◽  
Vassilis Amiridis ◽  
Antti Arola ◽  
...  
Keyword(s):  
Wavelength Dependence ◽  
Single Scattering ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Complex Environment ◽  
Aerosol Composition ◽  
Aerosol Absorption ◽  
Uv Irradiance ◽  
Band Radiometer ◽  
Uv Range

Abstract. We have used total and diffuse UV irradiance measurements from a multi-filter rotating shadow-band radiometer (UVMFR) in order to investigate aerosol absorption in the UV range for a 5-year period in Athens, Greece. This dataset was used as input to a radiative transfer model and the single scattering albedo (SSA) at 368 and 332 nm was calculated. Retrievals from a collocated CIMEL sun photometer were used to evaluate the products and study the absorption spectral behavior of retrieved SSA values. The UVMFR SSA, together with synchronous, CIMEL-derived retrievals of SSA at 440 nm, had a mean of 0.90, 0.87 and 0.83, with lowest values (higher absorption) encountered at the shorter wavelengths. In addition, noticeable diurnal variation of the SSA in all wavelengths is shown, with amplitudes up to 0.05. Strong SSA wavelength dependence is revealed for cases of low Ångström exponents, accompanied by a SSA decrease with decreasing extinction optical depth, suggesting varying influence under different aerosol composition. However, part of this dependence for low aerosol optical depths is masked by the enhanced SSA retrieval uncertainty. Dust and brown carbon UV absorbing properties were also investigated to explain seasonal patterns.

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

<p>The Mars 2020 “Perseverance” rover’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 & near-infrared (“VISIR”) 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 “passive sky” 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.</p><p>The objectives of VISIR atmospheric science are O<sub>2</sub>, CO, and H<sub>2</sub>O vapor column abundances, and aerosol particle sizes and composition. These objectives are motivated by unexpected seasonal and interannual variability in the O<sub>2</sub>mixing ratio that is argued to be so large as to require O<sub>2</sub> sources and sinks in surface soils [10], by evidence of surface-atmosphere exchange of H<sub>2</sub>O [11], by the potential significance of O<sub>2</sub> and H<sub>2</sub>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</p><p>The SuperCam spectrometers used for VISIR mode are a ChemCam-heritage reflection spectrometer covering 385–465 nm with < 0.2 nm res. [2], an intensified transmission spectrometer covering 536–853 nm with 0.3–0.7 nm res. [2], and an acousto-optic-tunable-filter (AOTF) -based IR spectrometer covering 1300–2600 nm with 20–30 cm<sup>-1</sup> res. [1, 8]. Our primary observing strategy is the same approach used for MSL ChemCam “passive sky” 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. <strong>Sky radiance is fit</strong><strong> </strong><strong>with a </strong><strong>discrete ordinates multiple scattering radiative transfer model</strong><strong> identical to that of [9].</strong><strong> As in [</strong><strong>9</strong><strong>] gas abundances are made robust to aerosol scattering uncertainties by fitting </strong>CO<sub>2</sub> absorption bands with an aerosol vertical profile parameter.</p><p>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] Savijärvi H. et al. (2016), Icarus 265, 63. [12] Farley K.A. et al. (2020), SSR 216, 142.</p>

scholarly journals Description of the Baseline Surface Radiation Network (BSRN) station at the Izaña Observatory (2009–2017): measurements and quality control/assurance procedures

2018 ◽  
Author(s):  
Rosa Delia García ◽  
Emilio Cuevas ◽  
Ramón Ramos ◽  
Victoria Eugenia Cachorro ◽  
Alberto Redondas ◽  
...  
Keyword(s):  
Quality Control ◽  
Research Programme ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
High Mountain ◽  
Total Column Ozone ◽  
The World ◽  
Instantaneous Values

Abstract. The Baseline Surface Radiation Network (BSRN) was implemented by the World Climate Research Programme (WRCP) starting observations with 9 stations in 1992, under the auspices of the World Meteorological Organization (WMO). Currently, 59 BSRN stations submit their data to the WRCP. One of these stations is the Izaña station (Station: IZA, #61) that enrolled in this network in 2009. This is a high-mountain station located in Tenerife (Canary Islands, Spain; at 28.3° N, 16.5° W, 2373 m a.s.l.) and is a representative site of the subtropical North Atlantic free troposphere. It contributes with basic-BSRN radiation measurements, such as, global shortwave radiation (SWD), direct radiation (DIR), diffuse radiation (DIF) and longwave downward radiation (LWD) and extended-BSRN measurements, including ultraviolet ranges (UV-A and UV-B), shortwave upward radiation (SWU) and longwave upward radiation (LWU) and other ancillary measurements, such as vertical profiles of temperature, humidity and wind obtained from radiosonde (WMO, station #60018) and total column ozone from Brewer spectrophotometer. The IZA measurements present high quality standards since more than 98 % of the data are within the limits recommended by the BSRN. There is an excellent agreement in the comparison between SWD, DIR and DIF (instantaneous and daily) measurements with simulations obtained with the LibRadtran radiative transfer model. The root mean square error (RMSE) for SWD is 2.28 % for instantaneous values and 1.58 % for daily values, while the RMSE for DIR is 2.00 % for instantaneous values and 2.07 % for daily values. IZA is a unique station that provides very accurate solar radiation data in very contrasting scenarios: most of the time under pristine sky conditions, and periodically under the effects of the Saharan Air Layer characterized by a high content of mineral dust. A detailed description of the BSRN program at IZA, including quality control and quality assurance activities, is given in this work.

scholarly journals A New Method to Calibrate Shortwave Solar Radiation Measurements

2014 ◽  
Vol 31 (6) ◽  
pp. 1321-1329 ◽  
Author(s):  
Jinhuan Qiu ◽  
Xiangao Xia ◽  
Jianghui Bai ◽  
Pucai Wang ◽  
Xuemei Zong ◽  
...  
Keyword(s):  
New Method ◽  
Radiative Transfer Model ◽  
Maximum Deviation ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Calibration Transfer ◽  
The World ◽  
Potential Applications ◽  
Atmospheric Transmittance ◽  
Radiation Measurements

Abstract A method is proposed to simultaneously calibrate shortwave (0.3–4 μm) global, direct, and scattering solar irradiance (GSI, DSI, and SSI, respectively) measurements. The method uses the World Radiation Reference (WRR) as a calibration standard and on-site radiation measurements as inputs. Two simple but effective techniques are used in the calibration. The first is to scale SSI and GSI detection sensitivities under overcast skies, which is based on the assumption that SSI should be equal to GSI if DSI is completely scattered and absorbed. The second is a new method to retrieve aerosol optical thickness (AOT), using the ratio of horizontal DSI (HDSI) to GSI measurements under clear and clean conditions. Thereafter, retrieved AOTs are used to drive a radiative transfer model to calculate atmospheric transmittance and then a ratio of GSI to the transmittance. Deviation of this ratio to the WRR is regarded as an indicator of GSI uncertainty, and the calibration transfer coefficient is derived as the WRR ratio. The method is applied to calibrate radiation measurements at Xianghe, China, during 2005. It is estimated from the derived transfer coefficients on 36 clear and clean days that uncertainties of DSI, GSI, and SSI measurements are within −4.0% to 2.9%, −5.9% to 2.4%, and −6.1% to 4.9%, respectively. The calibration is further validated based on comparisons of AOT at 750 nm retrieved from HDSI/GSI to Aerosol Robotic Network (AERONET) AOT products. The maximum deviation between two AOT products is 0.026. The unique advantage of this method lies in its potential applications in correcting historic radiation measurements and monitoring radiometer performance.

Study on the Inversion of Atmospheric Aerosol Depth in Tianjin Based on the HJ_1_CCD Satellite Products

2014 ◽  
Vol 675-677 ◽  
pp. 1192-1196
Author(s):  
Yan Xu ◽  
Qi Gang Jiang
Keyword(s):  
Global Climate Change ◽  
Satellite Remote Sensing ◽  
Global Climate ◽  
Quantitative Measure ◽  
Radiative Transfer Model ◽  
Inversion Method ◽  
Transfer Model ◽  
Sun Photometer ◽  
Tianjin City

With the global climate change and air quality gradually become today's serious problems that affecting the quality of human survival and people's life, aerosol satellite remote sensing quantitative measure gradually become a trend. Taking Tianjin city as example, This article based on HJ moonlet using dark pixels and combined with 6s radiative transfer model, calculated the aerosol optical thickness on the day of December 26, 2013 of Tianjin. And use the CE-318 sun photometer observations on the inversion results of the verification, found that the inversion method was effective, its error is within 20% on the day.

scholarly journals A Variational Method to Retrieve the Extinction Profile in Liquid Clouds Using Multiple-Field-of-View Lidar

2012 ◽  
Vol 51 (2) ◽  
pp. 350-365 ◽  
Author(s):  
Nicola L. Pounder ◽  
Robin J. Hogan ◽  
Tamás Várnai ◽  
Alessandro Battaglia ◽  
Robert F. Cahalan
Keyword(s):  
Optical Depth ◽  
Vertical Profile ◽  
Global Radiation ◽  
Simulated Data ◽  
Field Of View ◽  
Radiation Budget ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Optimization Schemes ◽  
Multiple Field

AbstractLiquid clouds play a profound role in the global radiation budget, but it is difficult to retrieve their vertical profile remotely. Ordinary narrow-field-of-view (FOV) lidars receive a strong return from such clouds, but the information is limited to the first few optical depths. Wide-angle multiple-FOV lidars can isolate radiation that is scattered multiple times before returning to the instrument, often penetrating much deeper into the cloud than does the single-scattered signal. These returns potentially contain information on the vertical profile of the extinction coefficient but are challenging to interpret because of the lack of a fast radiative transfer model for simulating them. This paper describes a variational algorithm that incorporates a fast forward model that is based on the time-dependent two-stream approximation, and its adjoint. Application of the algorithm to simulated data from a hypothetical airborne three-FOV lidar with a maximum footprint width of 600 m suggests that this approach should be able to retrieve the extinction structure down to an optical depth of around 6 and a total optical depth up to at least 35, depending on the maximum lidar FOV. The convergence behavior of Gauss–Newton and quasi-Newton optimization schemes are compared. Results are then presented from an application of the algorithm to observations of stratocumulus by the eight-FOV airborne Cloud Thickness from Off-Beam Lidar Returns (THOR) lidar. It is demonstrated how the averaging kernel can be used to diagnose the effective vertical resolution of the retrieved profile and, therefore, the depth to which information on the vertical structure can be recovered. This work enables more rigorous exploitation of returns from spaceborne lidar and radar that are subject to multiple scattering than was previously possible.

A vector radiative-transfer model for the Odin/OSIRIS project

2002 ◽  
Vol 80 (4) ◽  
pp. 375-393 ◽  
Author(s):  
C A McLinden ◽  
J C McConnell ◽  
E Griffioen ◽  
C T McElroy
Keyword(s):  
Radiative Transfer ◽  
Infrared Imaging ◽  
Radiative Transfer Equation ◽  
Imaging System ◽  
Scattered Light ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Weighting Functions ◽  
Uv Visible ◽  
Solution Parameters

A vector radiative-transfer code has been developed that is able to accurately and efficiently calculate radiance and polarization scattered from Earth's limb. A primary application of this code will be towards generating weighting functions, based on calculated limb radiances, for the retrieval of trace gases (O3, NO2, BrO, OClO, and O4) from the optical spectrograph and infrared imaging system (OSIRIS). OSIRIS is a UV–visible instrument on board the Odin satellite that measures limb-scattered light. This model solves the vector radiative-transfer equation using an iterative technique simultaneously in both plane-parallel and spherical-shell atmospheres. OSIRIS simulated limb radiance and polarization and OSIRIS weighting functions are presented along with a discussion of the numerical solution parameters, model intercomparisons and timings, and necessary model improvements. Overall agreement with other models was found to be very good and model speed is comparable to a fast finite-difference code. A set of OSIRIS reference atmospheres have been compiled for use with radiative-transfer models. Each of the 216 atmospheres (18 latitudes × 12 months) include profiles of air, pressure, temperature, ozone, NO2, BrO, and stratospheric aerosols.PACS Nos.: 42.68-w, 94.10Gb

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