Global snow season length and trends in snow season length using MOD10A2, US snow season and trends using MOD10A1

Snow season length (SS), reported in days, is the length of time that snow is present on the ground on an annual basis. It is determined by finding the first and last snow occurrence for any given water year (Oct 1 - Sep 30 NH, Jan 1 - Dec 31 SH), and then finding the difference between these two dates. SS was calculated on a pixel by pixel basis using MODIS/Terra Snow Cover 8-Day L3 Global 500m Grid, Collection 6 obtained from the National Snow and Ice Data Center (NSIDC) for global calculation and MOD10A1 for US calculation. Spatial coverage is for MODIS tiles h08v04, h08v05, h09v04, h09v05, and h10v04 for water years 2001 - 2015. Files are provided in the "USA Contiguous Albers Equal Area Conic USGS" projection. Funding provided by NSF grant EAR-1446870.

雪季长度（Snow season length, SS）以天为计量单位，指单年度内地表存在积雪的总时长。其计算方法为：针对任意指定的水文年（北半球为10月1日至次年9月30日，南半球为1月1日至12月31日），确定该时段内首次与末次出现积雪的日期，再计算二者的时间差，即可得到雪季长度。本数据集采用逐像素方式计算雪季长度：全球范围计算使用取自美国国家冰雪数据中心（National Snow and Ice Data Center, NSIDC）的MODIS/Terra积雪8天合成L3级全球500米网格第六版（Collection 6）产品；美国本土计算则采用MOD10A1产品。空间覆盖范围为2001至2015水文年的MODIS瓦片h08v04、h08v05、h09v04、h09v05及h10v04。数据文件采用"USA Contiguous Albers Equal Area Conic USGS"投影格式存储。本研究资助由美国国家科学基金会（National Science Foundation, NSF）项目EAR-1446870提供。