Sea Ice Trends and Climatologies from SMMR and SSM/I-SSMIS, Version 2

NSIDC provides this data set to aid in the investigations of the variability and trends of sea ice cover. Ice cover in these data are indicated by sea ice concentration: the percentage of the ocean surface covered by ice. The ice-covered area indicates how much ice is present; it is the total area of a pixel multiplied by the ice concentration in that pixel. Ice persistence is the percentage of months over the data set time period that ice existed at a location. The ice-extent indicates whether ice is present; here, ice is considered to exist in a pixel if the sea ice concentration exceeds 15 percent.This data set provides users with data about total ice-covered areas, sea ice extent, ice persistence, and monthly climatologies of sea ice concentrations.美国国家冰雪数据中心（National Snow and Ice Data Center, NSIDC）提供本数据集，以支持海冰覆盖范围的变化性与趋势研究。本数据集以海冰密集度（sea ice concentration）表征海冰覆盖情况，即海洋表面被冰覆盖的百分比。海冰覆盖面积代表区域内冰量的多少，其数值为单个像素的总面积与该像素内海冰密集度的乘积。海冰持续性（ice persistence）指在数据集的时间周期内，某一位置有冰存在的月份占比。海冰范围（ice extent）用于表征冰是否存在：本数据集中，当某一像素的海冰密集度超过15%时，即认为该像素存在海冰。本数据集为用户提供总海冰覆盖面积、海冰范围、海冰持续性以及海冰密集度的月平均气候态数据。