2023 |
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1. | Sara Herrero-Anta; Roberto Román; David Mateos; Ramiro González; Juan Carlos Antuña-Sánchez; Marcos Herreras-Giralda; Antonio Fernando Almansa; Daniel González-Fernández; Celia Herrero del Barrio; Carlos Toledano; Victoria Eugenia Cachorro; Ángel Máximo de Frutos Retrieval of aerosol properties from zenith sky radiance measurements Journal Article In: Atmospheric Measurement Techniques, vol. 16, no. 19, pp. 4423–4443, 2023. Abstract | Links | BibTeX | Tags: aerosol inversion, AOD, GRASP, zenith sky radiance @article{Herrero-Anta2023, This study explores the potential to retrieve aerosol properties with the GRASP algorithm (Generalized Retrieval of Atmosphere and Surface Properties) using as input measurements of zenith sky radiance (ZSR), which are sky radiance values measured in the zenith direction, recorded at four wavelengths by a ZEN-R52 radiometer. To this end, the ZSR measured at 440, 500, 675 and 870?nm by a ZEN-R52 (ZSRZEN), installed in Valladolid (Spain), is employed. This instrument is calibrated by intercomparing the signal of each channel with coincident ZSR values simulated (ZSRSIM) at the same wavelengths with a radiative transfer model (RTM). These simulations are carried out using the GRASP forward module as RTM and the aerosol information from a co-located CE318 photometer belonging to AERONET (AErosol RObotic NETwork) as input. The dark signal and the signal dependence on temperature are characterized and included in the calibration process. The uncertainties for each channel are quantified by an intercomparison with a co-located CE318 photometer, obtaining lower values for shorter wavelengths; they are between 3?% for 440?nm and 21?% for 870?nm. The proposed inversion strategy for the aerosol retrieval using the ZSRZEN measurements as input, i.e. so-called GRASP-ZEN, assumes the aerosol as an external mixture of five pre-calculated aerosol types. A sensitivity analysis is conducted using synthetic ZSRZEN measurements, pointing out that these measurements are sensitive to aerosol load and type. It also assesses that the retrieved aerosol optical depth (AOD) values in general overestimate the reference ones by 0.03, 0.02, 0.02 and 0.01 for 440, 500, 675 and 870?nm, respectively. The calibrated ZSRZEN measurements, recorded during 2.5 years at Valladolid, are inverted by the GRASP-ZEN strategy to retrieve some aerosol properties like AOD. The retrieved AOD shows a high correlation with respect to independent values obtained from a co-located AERONET CE318 photometer, with determination coefficients (r2) of 0.86, 0.85, 0.79 and 0.72 for 440, 500, 675 and 870?nm, respectively, and finding uncertainties between 0.02 and 0.03 with respect to the AERONET values. Finally, the retrieval of other aerosol properties, like aerosol volume concentration for total, fine and coarse modes (VCT, VCF and VCC, respectively), is also explored. The comparison against independent values from AERONET presents r2 values of 0.57, 0.56 and 0.66 and uncertainties of 0.009, 0.016 and 0.02?µm3?µm?2 for VCT, VCF and VCC, respectively |
2. | S. Herrero-Anta; R. Román; D. Mateos; R. González; J. C. Antuña-Sánchez; M. Herreras-Giralda; A. F. Almansa; D. González-Fernández; C. Herrero del Barrio; C. Toledano; V. E. Cachorro; Á. M. Frutos Retrieval of aerosol properties from zenith sky radiance measurements Conference European Aerosol Conference 2023, Málaga, Spain, 2023. BibTeX | Tags: aerosol inversion, AOD, GRASP, sky radiance @conference{Herrero-Anta2023c, |
3. | S. Herrero-Anta; R. Román, D. Mateos, J.C. Antuña-Sánchez, C. Toledano, F. Almansa, R. González, M. Herreras-Giralda, D. González-Fernández, C. Herrero del Barrio, V.E. Cachorro; A.M. de Frutos Retrieval of aerosol properties from zenith sky radiance measurements Conference Workshop on “Recent advancements in remote sensing and modeling of aerosols, clouds and surfaces” GRASP ACE Summer school, Lille, France, 2023. BibTeX | Tags: aerosol inversion, AOD, GRASP, sky radiance @conference{Herrero-Anta2023b, |
2021 |
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4. | AE Bedoya-Velásquez; M Herreras-Giralda; R Román; M Wiegner; S Lefebvre; C Toledano; T Huet; R Ceolato Ceilometer inversion method using water-vapor correction from co-located microwave radiometer for aerosol retrievals Journal Article In: Atmospheric Research, pp. 105379, 2021. Abstract | Links | BibTeX | Tags: aerosol inversion, Ceilometer data pre-processing, Microwave radiometry, Vaisala ceilometer @article{bedoya2021ceilometer, Recent ceilometer models are more sensitive to aerosols, which is increasing the interest in these instruments to retrieve aerosol optical and microphysical properties. In this paper, a new methodology is proposed to retrieve aerosol vertical extinction and backscatter profiles from a Vaisala ceilometer CL51 model. This methodology is based in two parts: first, a signal pre-processing with a suppression of the dark current and background noises, and a correction of the water vapor absorption using near-real-time temperature and absolute humidity (AH) profiles from a co-located Microwave radiometer (MWR). The measured dark current shows a height-dependence from 11?km agl to the end of the profile. From the water vapor correction, it was seen that the raw ceilometer signal overestimates the water vapor corrected one, mainly below 1?km agl. Second part is based on an iterative Klett-based algorithm making use of AERONET (AErosol RObotic NETwork) AOD (Aerosol Optical Depth) and ceilometer profiles as inputs to retrieve the extinction and backscatter profiles. The sensitivity of the aerosol retrievals to the use of modelled temperature and absolute humidity from HYSPLIT to correct water vapor absorption, instead of MWR measurements, is studied. The absolute errors found in temperature and AH profiles leads to errors in the pre-processed range corrected signals up to 9%, and then in particle backscatter (?p) and particle extinction (?p) coefficients up to 2.2 % and 25 %, respectively. |
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2023 |
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1. | Retrieval of aerosol properties from zenith sky radiance measurements Journal Article In: Atmospheric Measurement Techniques, vol. 16, no. 19, pp. 4423–4443, 2023. |
2. | Retrieval of aerosol properties from zenith sky radiance measurements Conference European Aerosol Conference 2023, Málaga, Spain, 2023. |
3. | Retrieval of aerosol properties from zenith sky radiance measurements Conference Workshop on “Recent advancements in remote sensing and modeling of aerosols, clouds and surfaces” GRASP ACE Summer school, Lille, France, 2023. |
2021 |
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4. | Ceilometer inversion method using water-vapor correction from co-located microwave radiometer for aerosol retrievals Journal Article In: Atmospheric Research, pp. 105379, 2021. |