Landsat-based snow persistence map for northwest Alaska
Landsat-based snow persistence map for northwest Alaska
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DOI：
10.1016/j.rse.2015.02.028
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发表时间：
2015-06
影响因子：
13.5
通讯作者：
M. Macander;C. Swingley;K. Joly;M. Raynolds
中科院分区：
文献类型：
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作者：
M. Macander;C. Swingley;K. Joly;M. Raynolds
1985年至2011年2月1日至8月31日期间阿拉斯加西北部的陆地卫星图像被用来绘制高空间分辨率的积雪持续性地图。我们分析了覆盖 505,800 平方公里的 11,645 个场景，包括五个北极国家公园单位和西北极驯鹿群的范围（85 个 Landsat 路径/行）。使用陆地卫星生态系统干扰自适应处理系统 (LEDAPS) 创建云掩模。地形阴影是根据 ASTER G-DEM2 和太阳入射角计算的。对于非阴影和阴影像素，使用单独的雪图算法来确定积雪的存在。生成的积雪数据被重新格式化为 562 个 30 × 30 km 的图块，每个像素的平均样本大小为 216 个无云观测。使用二元分类树成功确定了一年中最能标志着 99.8% 的研究区域从有雪条件变为无雪条件的日子。评估当天之前的无雪数据或当天之后的雪数据的内部一致性检查表明，98.7% 的土地像素在 ≥ 90% 的时间内一致分类。与 MODIS 雪季结束数据的比较显示平均差异为 4.2 天。积雪持续图与研究区域内的少数 SNOTEL 站密切相关 (r2= 0.856)。总体而言，研究区域的大部分融雪发生在 4 月下旬至 6 月初，向北和海拔较高地区的融雪时间会延迟。在详细的 30 米产品中，许多局部规模的积雪图案很明显。积雪持续性地图被共同注册到 Landsat 土地覆盖绘图中，为生态系统和土地利用分析创建了强大的、公开可用的资源 (https://irma.nps.gov/App/Reference/Profile/2203863)。
Landsat imagery for northwest Alaska from 1 February to 31 August, 1985–2011 was used to map snow persistence at high spatial resolution. We analyzed 11,645 scenes covering 505,800 km2, including five Arctic National Park units and the range of the Western Arctic caribou herd (85 Landsat path/rows). A cloud mask was created using the Landsat Ecosystem Disturbance Adaptive Processing System (LEDAPS). Terrain shadows were calculated from ASTER G-DEM2 and solar incidence angle. The presence of snow cover was determined using separate Snowmap algorithms for non-shadowed and shadowed pixels. Resulting snow cover data were reformatted into 562 30 × 30 km tiles, with an average sample size per pixel of 216 cloud-free observations. A binary classification tree was used to successfully determine the day of the year that best marked the change from snow to snow-free conditions for 99.8% of the study area. An internal consistency check evaluating the occurrence of snow-free data earlier than that day or snow data later than that day, showed that 98.7% of the land pixels were consistently classified ≥ 90% of the time. Comparison with MODIS end of snow season data showed an average difference of 4.2 days. The snow persistence map was strongly correlated with the few SNOTEL stations in the study area (r2= 0.856). Broadly, most snowmelt over the study area occurs from late April through early June, with timing delayed farther north and at higher elevations. Many local-scale snow patterns are evident in the detailed, 30-m product. The snow persistence map was co-registered to Landsat land cover mapping, creating a powerful, publicly available resource for ecosystem and land use analyses (https://irma.nps.gov/App/Reference/Profile/2203863).