College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China; State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China.
Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of the Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Beijing, China; CAS Center for Excellence in the Tibetan Plateau Earth Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
Sci Total Environ. 2020 Jul 1;724:138156. doi: 10.1016/j.scitotenv.2020.138156. Epub 2020 Mar 23.
Accurate spatiotemporal information of snow cover not only is important for investigating the mechanisms of climate change but also greatly contributes to hydrological modelling in mountainous regions. The Suomi-National Polar-orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) (referred to as VNP) daily snow cover product is recently released and expected to take place of Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products in near future. As an important addition to the widely used MODIS products, there is also an urgent need for a reliable accuracy evaluation and comparison of VNP for future large-scale daily snow cover mapping. This study for the first time evaluates the accuracy of VNP daily snow cover data in China using daily snow depth observations from 330 stations. The accuracy of VNP data is generally good with the averaged CK (Cohen's Kappa) and FS (F-Score) as high as 0.72 and 0.75, respectively, but considerably decreases to 0.50 and 0.52 for the Tibetan Plateau. VNP shows slightly better accuracy than MODIS TERRA for stations outside the Tibetan Plateau owing to its higher spatial resolution, but its accuracy is lower than TERRA for those within the Tibetan Plateau possibly due to its longer time interval between ground observation and satellite overpass time. By contrast, VNP shows much better accuracy than MODIS AQUA in China including both outside and within the Tibetan Plateau. This study provides important implications for optimal use of VNP and MODIS daily snow cover products in China, which may further contribute to more accurate snow variation information for climate analysis and cryospheric hydrological modelling.
积雪时空信息不仅对气候变化机制的研究至关重要，而且对山区水文模型也有重要贡献。苏美国家极地轨道伙伴关系（Suomi-National Polar-orbiting Partnership，S-NPP）可见近红外成像辐射计套件（Visible Infrared Imaging Radiometer Suite，VIIRS）（简称 VNP）的积雪日覆盖产品最近发布，预计将在不久的将来取代中分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer，MODIS）积雪覆盖产品。作为广泛使用的 MODIS 产品的重要补充，迫切需要对 VNP 进行可靠的精度评估和比较，以实现未来大规模的积雪日覆盖制图。本研究首次利用 330 个站点的每日积雪深度观测数据，评估了 VNP 积雪日覆盖数据在中国的精度。VNP 数据的精度总体较好，平均 CK（科恩 Kappa）和 FS（F-Score）分别高达 0.72 和 0.75，但对于青藏高原，精度分别下降到 0.50 和 0.52。由于 VNP 的空间分辨率较高，对于青藏高原以外的站点，其精度略优于 MODIS TERRA，但对于青藏高原内的站点，其精度低于 TERRA，可能是由于其与地面观测的时间间隔较长。相比之下，VNP 在包括青藏高原内外的中国地区的精度明显优于 MODIS AQUA。本研究对优化使用 VNP 和 MODIS 积雪日覆盖产品在中国具有重要意义，这可能有助于为气候分析和冰冻圈水文模型提供更准确的积雪变化信息。
