A comprehensive inventory of perennial snow and ice in Glacier National Park in 2005

These polygon features represent a comprehensive inventory of perennial snow and ice on the landscape in Glacier National Park (GNP) in 2005. The imagery used to delineate perennial snow and ice was taken late season, therefore, all snow and ice present on the landscape is assumed to be perennial. Whether each polygon is "perennial snow and ice" or "active glacial ice" is included. Active glacial ice is defined as perennial ice patches that exhibit characteristics such as bergschrunds and extensive crevassing. This release does not include the 2005 extent of the 37 named glaciers in GNP, which have been previously published. Polygons were digitized based on National Agricultural Imagery Program (NAIP) imagery acquired in 2005, imagery acquired by the National Park Service in 2004 to assess the extent of 2003 wildfires, and border Imagery from the Department of Homeland Security acquired in 2009. Digitization was completed by Adam Clark (USGS) and Kevin Jacks (USGS). Perennial snow and ice was digitized at 1:2000 scale.

本多边形要素数据集为2005年冰川国家公园（Glacier National Park, GNP）范围内地表常年积雪与冰川的综合清查名录。用于勾绘常年积雪与冰川的影像采集于季末时段，因此地表现存的所有积雪与冰川均被认定为常年性积雪与冰川。每个多边形要素均标注为“常年积雪与冰川”或“活动冰川冰”两类，其中活动冰川冰被定义为具备冰斗缝（bergschrund）及大范围冰裂隙等特征的常年性冰体斑块。本数据集未包含冰川国家公园内37座已命名冰川2005年的分布范围，该范围已于此前公开发布。多边形要素的数字化基于三类影像：2005年获取的美国国家农业影像计划（National Agricultural Imagery Program, NAIP）影像、2004年美国国家公园管理局（National Park Service）为评估2003年野火范围而采集的影像，以及2009年美国国土安全部（Department of Homeland Security）获取的边境影像。本次数字化工作由美国地质调查局（United States Geological Survey, USGS）的Adam Clark与Kevin Jacks完成。常年积雪与冰川要素的数字化比例尺为1:2000。