Inter-Comparison Campaign of Solar UVR Instruments under Clear Sky Conditions at Reunion Island (21°S, 55°E)

Cadet, Jean-Maurice; Portafaix, Thierry; Benchérif, Hassan; Lamy, Kévin; Brogniez, Colette; Auriol, Frédérique; Metzger, Jean‐Marc; Boudreault, Louis-Étienne; Wright, Caradee Y.

doi:10.3390/ijerph17082867

Cited by 11 publications

(10 citation statements)

References 30 publications

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“…The diurnal CF profiles show a slightly higher CF over a large part of the day in the JJA season compared to the annual profile or the other seasons. The CF diurnal cycle alone is probably not the only factor involved in triggering UVI enhancement: cloud distributions and type of clouds probably play a role (Sabburg and Wong, 2000;Calbó et al, 2005;Badosa et al, 2014). The measurements proposed here will be fully useful in carrying out this type of study.…”

Section: Seasonal Distribution and Variation In Uvr And Cfmentioning

confidence: 93%

UV-Indien network: ground-based measurements dedicated to the monitoring of UV radiation over the western Indian Ocean

Lamy¹,

Portafaix²,

Brogniez

et al. 2021

Earth Syst. Sci. Data

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Abstract. Within the framework of the UV-Indien network, nine ground stations have been equipped with ultraviolet broadband radiometers, five of them have also been equipped with an all-sky camera, and the main station in Saint-Denis de la Réunion is also equipped with a spectroradiometer. These stations are spatially distributed to cover a wide range of latitudes, longitudes, altitudes, and environmental conditions in five countries of the western Indian Ocean region (Comoros, France, Madagascar, Mauritius, and Seychelles), a part of the world where almost no measurements have been made so far. The distribution of the stations is based on the scientific interest of studying ultraviolet radiation not only in relation to atmospheric processes but also in order to provide data relevant to fields such as biology, health (prevention of skin cancer), and agriculture. The main scientific objectives of this network are to study the annual and inter-annual variability in the ultraviolet (UV) radiation in this area, to validate the output of numerical models and satellite estimates of ground-based UV measurements, and to monitor UV radiation in the context of climate change and projected ozone depletion in this region. A calibration procedure including three types of calibrations responding to the various constraints of sustaining the network has been put in place, and a data processing chain has been set up to control the quality and the format of the files sent to the various data centres. A method of clear-sky filtering of the data is also applied. Here, we present an intercomparison with other datasets, as well as several daily or monthly representations of the UV index (UVI) and cloud fraction data, to discuss the quality of the data and their range of values for the older stations (Antananarivo, Anse Quitor, Mahé, and Saint-Denis). Ground-based measurements of the UVI are used to validate satellite estimates – Ozone Monitoring Instrument (OMI), the TROPOspheric Monitoring Instrument (TROPOMI), and the Global Ozone Monitoring Experiment (GOME) – and model forecasts of UVI – Tropospheric Emission Monitoring Internet Service (TEMIS) and Copernicus Atmospheric Monitoring Service (CAMS). The median relative differences between satellite or model estimates and ground-based measurements of clear-sky UVI range between −34.5 % and 15.8 %. Under clear skies, the smallest UVI median difference between the satellite or model estimates and the measurements made by ground-based instruments is found to be 0.02 (TROPOMI), 0.04 (OMI), −0.1 (CAMS), and −0.4 (CAMS) at Saint-Denis, Antananarivo, Anse Quitor, and Mahé, respectively. The diurnal variability in UVI and cloud fraction, as well as the monthly variability in UVI, is evaluated to ensure the quality of the dataset. The data used in this study are available at https://doi.org/10.5281/zenodo.4811488 (Lamy and Portafaix, 2021a).

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Section: Seasonal Distribution and Variation In Uvr And Cfmentioning

confidence: 93%

UV-Indien network: ground-based measurements dedicated to the monitoring of UV radiation over the western Indian Ocean

Lamy¹,

Portafaix²,

Brogniez

et al. 2021

Earth Syst. Sci. Data

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“…Different thresholds (i.e., 1-2: low, 3-5: moderate, 6-7: high, 8-10: very high, >11: extreme) have been defined depending on the risk to human health and the use of suitable protection [23]. Sea level climatological averages showed that the UVI can reach 8 during winter and 16 during summer on Reunion Island [24,25]. Reunion is a mountainous island where Cadet et al [6] reported a maximum UVI of 20 at~2900 m height.…”

Section: Introductionmentioning

confidence: 99%

Solar UV Radiation in the Tropics: Human Exposure at Reunion Island (21° S, 55° E) during Summer Outdoor Activities

Cadet

Benchérif

Cadet

et al. 2020

IJERPH

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Reunion Island is a popular tourist destination with sandy beaches, an active volcano (Piton de la Fournaise), and Piton des Neiges, the highest and most dominant geological feature on the island. Reunion is known to have high levels of solar ultraviolet radiation (UVR) with an ultraviolet index (UVI) which can reach 8 in winter and 16 in summer (climatological conditions). UVR has been linked to skin cancer, melanoma, and eye disease such as cataracts. The World Health Organization (WHO) devised the UVI as a tool for expressing UVR intensity. Thresholds ranging from low (UVI 1–2) to extreme (UVI > 11) were defined depending on the risk to human health. The purpose of the study was to assess UVR exposure levels over three of the busiest tourist sites on the island. UVR was measured over several hours along popular hiking trails around Piton de la Fournaise (PDF), Piton des Neiges (PDN), and St-Leu Beach (LEU). The results were compared with those recorded by the local UV station at Saint-Denis. In addition, cumulative standard erythemal dose (SED) was calculated. Results showed that UVI exposure at PDF, PDN, and LEU were extreme (>11) and reached maximum UVI levels of 21.1, 22.5, and 14.5, respectively. Cumulative SEDs were multiple times higher than the thresholds established by the Fitzpatrick skin phototype classification. UVI measurements at the three study sites showed that Reunion Island is exposed to extreme UVR conditions. Public awareness campaigns are needed to inform the population of the health risks related to UVR exposure.

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“…This is a portable instrument containing a UV-sensitive photodiode [ 28 ] which allows the UVI to be estimated with an error of 10% (NIST traceable accuracy). The same Solarmeter 6.5 instrument was successfully used in previous works and similar situations [ 10 , 12 ]. Furthermore, as reported by [ 13 ], the Solarmeter instrument was regularly calibrated during side-by-side intercomparison campaigns with the Bentham DTMc spectrophotometer and shows a small discrepancy, with an overestimation of about 12%.…”

Section: Methodsmentioning

confidence: 99%

“…The UVI in the southern Indian Ocean was found to be higher than 10 UVI units almost throughout the year [ 10 ]. Extreme UVI, as high as 15 to 20 UVI units, was also measured at various location in this region such as Antananarivo (Madagascar), Mahé (Seychelles), Plaine Corail (Rodrigues), and Saint–Denis (La Réunion) [ 11 , 12 , 13 ]. This may imply dangerous consequences for the health of the local population.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Solar Radiation UV Exposure in the Comoros

Lamy

Ranaivombola

Benchérif

et al. 2021

IJERPH

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As part of the UV-Indien project, a station for measuring ultraviolet radiation and the cloud fraction was installed in December 2019 in Moroni, the capital of the Comoros, situated on the west coast of the island of Ngazidja. A ground measurement campaign was also carried out on 12 January 2020 during the ascent of Mount Karthala, located in the center of the island of Ngazidja. In addition, satellite estimates (Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument) and model outputs (Copernicus Atmospheric Monitoring Service and Tropospheric Ultraviolet Model) were combined for this same region. On the one hand, these different measurements and estimates make it possible to quantify, evaluate, and monitor the health risk linked to exposure to ultraviolet radiation in this region and, on the other, they help to understand how cloud cover influences the variability of UV-radiation on the ground. The measurements of the Ozone Monitoring Instrument onboard the EOS-AURA satellite, being the longest timeseries of ultraviolet measurements available in this region, make it possible to quantify the meteorological conditions in Moroni and to show that more than 80% of the ultraviolet indices are classified as high, and that 60% of these are classified as extreme. The cloud cover measured in Moroni by an All Sky Camera was used to distinguish between the cases of UV index measurements taken under clear or cloudy sky conditions. The ground-based measurements thus made it possible to describe the variability of the diurnal cycle of the UV index and the influence of cloud cover on this parameter. They also permitted the satellite measurements and the results of the simulations to be validated. In clear sky conditions, a relative difference of between 6 and 11% was obtained between satellite or model estimates and ground measurements. The ultraviolet index measurement campaign on Mount Karthala showed maximum one-minute standard erythemal doses at 0.3 J·m−2 and very high daily cumulative erythemal doses, at more than 80 J·m−2. These very high levels are also observed throughout the year and all skin phototypes can exceed the daily erythemal dose threshold, at more than 20 J·m−2.

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Inter-Comparison Campaign of Solar UVR Instruments under Clear Sky Conditions at Reunion Island (21°S, 55°E)

Cited by 11 publications

References 30 publications

UV-Indien network: ground-based measurements dedicated to the monitoring of UV radiation over the western Indian Ocean

UV-Indien network: ground-based measurements dedicated to the monitoring of UV radiation over the western Indian Ocean

Solar UV Radiation in the Tropics: Human Exposure at Reunion Island (21° S, 55° E) during Summer Outdoor Activities

Monitoring Solar Radiation UV Exposure in the Comoros

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