Monitoring of Eyjafjallajökull volcanic aerosol by the new European Skynet Radiometers (ESR) network

Campanelli, Monica; Estellés, V.; Smyth, Tim; Tomasi, Claudio; Martìnez-Lozano, M.P.; Claxton, B. M.; Müller, Jan-Peter; Pappalardo, G.; Pietruczuk, Aleksander; Shanklin, Jonathan; Colwell, Steve; Wrench, C. L.; Lupi, Angelo; Mazzola, Mauro; Lanconelli, Christian; Vitale, Vito; Congeduti, F.; Dionisi, Davide; Cardillo, F.; Cacciani, Marco; Casasanta, Giampietro; Nakajima, Teruyuki

doi:10.1016/j.atmosenv.2011.09.070

Cited by 55 publications

(29 citation statements)

References 21 publications

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“…Moreover, the advantage of having simultaneous measurements of aerosol characteristics and water vapour columnar content with a high temporal resolution, and obtained by using only standard surface meteorological observation for calibrating the instrument, can be of great interest to the scientific community. The present procedure will in the future be applied to the instruments that are part of the SKYNET (Takamura and Nakajima, 2004; http://atmos.cr.chiba-u.ac.jp/) and ESR (Campanelli et al, 2012; http://www.euroskyrad.net/) networks on which web page the open source software will be released. It will also be tested against AERONET sun-sky radiometer measurements in order to compare the two methodologies.…”

Section: Discussionmentioning

confidence: 99%

Retrieval of characteristic parameters for water vapour transmittance in the development of ground-based sun–sky radiometric measurements of columnar water vapour

et al. 2014

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Abstract. Sun-sky radiometers are instruments created for aerosol study, but they can measure in the water vapour absorption band allowing the estimation of columnar water vapour in clear sky simultaneously with aerosol characteristics, with high temporal resolution. A new methodology is presented for estimating calibration parameters (i.e. characteristic parameters of the atmospheric transmittance and solar calibration constant) directly from the sun-sky radiometer measurements. The methodology is based on the hypothesis that characteristic parameters of the atmospheric transmittance are dependent on vertical profiles of pressure, temperature and moisture occurring at each site of measurement. To obtain the parameters from the proposed methodology some seasonal independent measurements of columnar water vapour taken over a large range of solar zenith angle simultaneously with the sun-sky radiometer measurements, are needed. In this work high time resolution columnar water vapour measurements by GPS were used as independent data set, but also the case when such measurements are not available was considered by developing the surface humidity method (SHM). This methodology makes it possible to retrieve the needed independent data set of columnar water vapour using the standard surface meteorological observations (temperature, pressure and relative humidity) more readily available. The time pattern of columnar water vapour from sun-sky radiometer retrieved using both the methodologies was compared with simultaneous measurements from microwave radiometer, radiosondings and GPS. Water vapour from sun-sky radiometer, obtained using GPS independent measurements, was characterized by an error varying from 1 % up to 5 %, whereas water vapour from SHM showed an error from 1 % up to 11 %, depending on the local columnar water occurring at the site during the year. These errors were estimated by comparing water vapour series from sun-sky radiometer against measurements taken by GPS at a nearby station. The accordance between retrievals from sun-sky radiometer and simultaneous measurements from the other instruments was found always within the error both in the case of SHM and of the GPS independent data set.Water vapour obtained using characteristic parameters of the atmospheric transmittance dependent on water vapour was also compared against GPS retrievals, showing a clear improvement with respect to the case when these parameters are kept fixed.

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Section: Discussionmentioning

confidence: 99%

Retrieval of characteristic parameters for water vapour transmittance in the development of ground-based sun–sky radiometric measurements of columnar water vapour

et al. 2014

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“…Finally, the relatively low cost and easy deployment of sun photometers allowed the establishment of several international networks in the last 30 years worldwide. AErosol RObotic NETwork (AERONET) network (Holben et al, 1998;Smirnov et al, 2004), Global Atmospheric Watching Precision Filter Radiometer (GAW-PFR) network (Wehrli, 2000;Nyeki et al, 2005) and European Skynet Radiometers (ESR-SKYNET) network (Campanelli et al, 2012(Campanelli et al, , 2014 provide operationally free estimation of W or develop algorithms and open-source packages for improving the retrieval of this important atmospheric pa- rameter. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters.…”

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confidence: 99%

Precipitable water vapour content from ESR/SKYNET sun–sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

et al. 2018

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Abstract. The estimation of the precipitable water vapour content (W ) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun-sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration parameters. The objective of this paper is to validate a new methodology based on the hypothesis that the calibration parameters characterizing the atmospheric transmittance at 940 nm are dependent on vertical profiles of temperature, air pressure and moisture typical of each measurement site. To obtain the calibration parameters some simultaneously seasonal measurements of W , from independent sources, taken over a large range of solar zenith angle and covering a wide range of W , are needed. In this work yearly GNSS/GPS datasets were used for obtaining a table of photometric calibration constants and the methodology was applied and validated in three European ESR-SKYNET network sites, characterized by different atmospheric and climatic conditions: Rome, Valencia and Aosta. Results were validated against the GNSS/GPS and AErosol RObotic NETwork (AERONET) W estimations. In both the validations the agreement was very high, with a percentage RMSD of about 6, 13 and 8 % in the case of GPS intercomparison at Rome, Aosta and Valencia, respectively, and of 8 % in the case of AERONET comparison in Valencia.Analysing the results by W classes, the present methodology was found to clearly improve W estimation at low W content when compared against AERONET in terms of % bias, bringing the agreement with the GPS (considered the reference one) from a % bias of 5.76 to 0.52.

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“…Other sun photometers such as precision filter radiometers (PFRs) (Nyeki et al, 2005) have also been used by the Global Atmosphere Watch (GAW) WMO programme to monitor IWV. Furthermore, the SKYNET radiometer network (details at http://atmos2.cr.chiba-u.jp/skynet/) also retrieves IWV using Prede-POM sun photometers at many stations (Campanelli et al, 2012(Campanelli et al, , 2014. Finally, national networks of sun photometers that are installed and operating in some countries also provide integrated water vapour (IWV) retrievals; e.g.…”

Section: Introductionmentioning

confidence: 99%

Water vapour retrieval using the Precision Solar Spectroradiometer

et al. 2018

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Abstract. The Precision Solar Spectroradiometer (PSR) is a new spectroradiometer developed at PhysikalischMeteorologisches Observatorium Davos -World Radiation Center (PMOD-WRC), Davos, measuring direct solar irradiance at the surface, in the 300-1020 nm spectral range and at high temporal resolution. The purpose of this work is to investigate the instrument's potential to retrieve integrated water vapour (IWV) using its spectral measurements. Two different approaches were developed in order to retrieve IWV: the first one uses single-channel and wavelength measurements, following a theoretical water vapour high absorption wavelength, and the second one uses direct sun irradiance integrated at a certain spectral region. IWV results have been validated using a 2-year data set, consisting of an AERONET sun-photometer Cimel CE318, a Global Positioning System (GPS), a microwave radiometer profiler (MWP) and radiosonde retrievals recorded at Meteorological Observatorium Lindenberg, Germany. For the monochromatic approach, better agreement with retrievals from other methods and instruments was achieved using the 946 nm channel, while for the spectral approach the 934-948 nm window was used. Compared to other instruments' retrievals, the monochromatic approach leads to mean relative differences up to 3.3 % with the coefficient of determination (R 2 ) being in the region of 0.87-0.95, while for the spectral approach mean relative differences up to 0.7 % were recorded with R 2 in the region of 0.96-0.98. Uncertainties related to IWV retrieval methods were investigated and found to be less than 0.28 cm for both methods. Absolute IWV deviations of differences between PSR and other instruments were determined the range of 0.08-0.30 cm and only in extreme cases would reach up to 15 %.

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Monitoring of Eyjafjallajökull volcanic aerosol by the new European Skynet Radiometers (ESR) network

Cited by 55 publications

References 21 publications

Retrieval of characteristic parameters for water vapour transmittance in the development of ground-based sun–sky radiometric measurements of columnar water vapour

Retrieval of characteristic parameters for water vapour transmittance in the development of ground-based sun–sky radiometric measurements of columnar water vapour

Precipitable water vapour content from ESR/SKYNET sun–sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe

Water vapour retrieval using the Precision Solar Spectroradiometer

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