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).

中文翻译：

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UV-Indien 网络：用于监测西印度洋紫外线辐射的地面测量

在 UV-Indien 网络框架内，9 个地面站配备了紫外宽带辐射计，其中 5 个还配备了全天空摄像机，Saint-Denis de la Réunion 主站也配备了光谱仪。这些台站在空间上分布广泛，覆盖了西印度洋地区五个国家（科摩罗、法国、马达加斯加、毛里求斯和塞舌尔）的广泛纬度、经度、海拔和环境条件。到目前为止已经进行了测量。站的分布基于研究紫外线辐射的科学兴趣，不仅与大气过程有关，而且为了提供与生物学、健康（预防皮肤癌）、和农业。该网络的主要科学目标是研究该地区紫外线 (UV) 辐射的年度和年际变化，验证数值模型的输出和地面紫外线测量的卫星估计值，并监测紫外线辐射在气候变化和该地区预计的臭氧消耗的背景下。校准程序包括三种类型的校准，以应对维持网络的各种限制，并建立了一个数据处理链来控制发送到各个数据中心的文件的质量和格式。还应用了数据的晴空过滤方法。在这里，我们展示了与其他数据集的比对，以及紫外线指数 (UVI) 和云量数据的每日或每月表示，以讨论数据质量及其旧站（安塔那那利佛、安塞基托尔、马埃和圣丹尼斯）的值范围。UVI 的地面测量用于验证卫星估计值 – 臭氧监测仪器 (OMI)、对流层监测仪器 (TROPOMI) 和全球臭氧监测实验 (GOME) – 以及 UVI 的模型预测 – 对流层排放监测互联网服务(TEMIS) 和哥白尼大气监测服务 (CAMS)。卫星或模型估计值与晴空 UVI 的地面测量值之间的中值相对差异范围介于 和圣丹尼斯）。UVI 的地面测量用于验证卫星估计值 – 臭氧监测仪器 (OMI)、对流层监测仪器 (TROPOMI) 和全球臭氧监测实验 (GOME) – 以及 UVI 的模型预测 – 对流层排放监测互联网服务(TEMIS) 和哥白尼大气监测服务 (CAMS)。卫星或模型估计值与晴空 UVI 的地面测量值之间的中值相对差异范围介于 和圣丹尼斯）。UVI 的地面测量用于验证卫星估计值 – 臭氧监测仪器 (OMI)、对流层监测仪器 (TROPOMI) 和全球臭氧监测实验 (GOME) – 以及 UVI 的模型预测 – 对流层排放监测互联网服务(TEMIS) 和哥白尼大气监测服务 (CAMS)。卫星或模型估计值与晴空 UVI 的地面测量值之间的中值相对差异范围介于 和全球臭氧监测实验 (GOME) – 以及 UVI 模型预报 – 对流层排放监测互联网服务 (TEMIS) 和哥白尼大气监测服务 (CAMS)。卫星或模型估计值与晴空 UVI 的地面测量值之间的中值相对差异范围介于 和全球臭氧监测实验 (GOME) – 以及 UVI 模型预报 – 对流层排放监测互联网服务 (TEMIS) 和哥白尼大气监测服务 (CAMS)。卫星或模型估计值与晴空 UVI 的地面测量值之间的中值相对差异范围介于− 34.5 % 和 15.8 %。在晴朗的天空下，卫星或模型估计值与地面仪器测量值之间的最小 UVI 中值差异为 0.02 (TROPOMI)、0.04 (OMI)、- 0.1 (CAMS) 和- 0.4 (CAMS)在圣但尼，塔那那利佛，分别是 Anse Quitor 和 Mahé。对 UVI 和云比例的日变化以及 UVI 的月变化进行评估，以确保数据集的质量。本研究中使用的数据可从 https://doi.org/10.5281/zenodo.4811488（Lamy和 Portafaix，2021a）获得。