Snow and ice broadband albedo from Sentinel-3 OLCI measurements and empirical regression

This dataset contains: snow and ice broadband albedo mosaics over Greenland for years 2018 and 2019 computed from a simple empirical approach (Wehrlé et al, 2021). This approach consists of a fit between 4729 hourly PROMICE albedo measurements and the nearest in time and space OLCI Top of Atmosphere (TOA) reflectances spanning 3 years (2017–2019). We then defined the broadband albedo from a fit to the average of four OLCI TOA reflectances: A = α (R400 nm+ R560 nm+ R865 nm + R1020 nm) / 4+ β where α corresponds to the slope of the linear regression between OLCI TOA and PROMICE albedo measurements (1.003), and β is its intercept (0.058). Clouds were detected and thereafter masked in Sentinel-3 imagery using the Simple Cloud Detection Algorithm (SCDA) version 2.0 (Metsämäki et al. 2015; Wehrlé & Box 2021). This algorithm consists of up to six tests on Sea and Land Surface Temperature Radiometer (SLSTR) TOA reflectances (550 and 1600 nm) and brightness temperatures (3.7, 11 and 12 μm). Processing scripts: https://github.com/AdrienWehrle/SICE_tools Related studies: - Wehrlé A.; Box J.E.; Niwano M.; Anesio A.M.; Fausto R.S., Greenland bare ice albedo from PROMICE automatic weather station measurements and Sentinel-3 satellite observations, GEUS bulletin, in press 2021 - Wehrlé, A. & Box, J., SICE implementation of the Simple Cloud Detection Algorithm (SCDA) v2.0, GEUS Dataverse, 2021 https://doi.org/10.22008/FK2/N0XWSJ - Metsämäki, S.; Pulliainen, J.; Salminen, M.; Luojus, K.; Wiesmann, A.; Solberg, R.; Böttcher, K.; Hiltunen, M.;Ripper E, Introduction to globSnow snow extent products with considerations for accuracy assessment. Remote Sensing of Environment, 2015

本数据集包含2018年与2019年格陵兰地区的冰雪宽带反照率镶嵌图，该数据由Wehrlé等人2021年提出的简易经验方法计算得到。该方法通过将4729组逐时PROMICE反照率测量值，与时间和空间维度上最邻近的、覆盖2017至2019年三年的海洋陆地颜色仪器（Ocean and Land Colour Instrument, OLCI）大气顶层（Top of Atmosphere, TOA）反射率进行拟合构建。随后通过对四组OLCI TOA反射率的平均值拟合得到宽带反照率公式：A = α*(R400 nm + R560 nm + R865 nm + R1020 nm)/4 + β，其中α为OLCI TOA反射率与PROMICE反照率测量值之间线性回归的斜率（取值为1.003），β为其截距（取值为0.058）。

本研究采用2.0版本简易云检测算法（Simple Cloud Detection Algorithm, SCDA v2.0，Metsämäki等，2015；Wehrlé & Box，2021）对Sentinel-3影像进行云检测，并对云区进行掩膜去除。该算法基于海陆表面温度辐射计（Sea and Land Surface Temperature Radiometer, SLSTR）的TOA反射率（550 nm与1600 nm波段）以及亮温（3.7、11和12 μm波段）开展最多六项测试实现。

处理脚本可访问：https://github.com/AdrienWehrle/SICE_tools

相关研究如下：
- Wehrlé A.; Box J.E.; Niwano M.; Anesio A.M.; Fausto R.S. 《基于PROMICE自动气象站测量与Sentinel-3卫星观测的格陵兰裸冰反照率》，《GEUS通报》，2021年待刊
- Wehrlé, A. & Box, J. 《简易云检测算法（SCDA）v2.0的SICE实现》，GEUS数据仓库，2021，https://doi.org/10.22008/FK2/N0XWSJ
- Metsämäki, S.; Pulliainen, J.; Salminen, M.; Luojus, K.; Wiesmann, A.; Solberg, R.; Böttcher, K.; Hiltunen, M.; Ripper E. 《globSnow积雪范围产品介绍及精度评估考量》，《遥感环境》，2015