Alaska Statewide annual maximum Normalized Difference Vegetation Index (NDVI) values from 1982-2003 at 8km pixel size

Maximum annual NDVI values derived from twice monthly GIMMS-NDVI data, acquired for the period of 1982-2003 were downloaded fry the University of Maryland Global Land Cover Facility (http://www.landcover.org). These data were originally maximum NDVI values for each 64km2 pixel for each 15-day composite period. By selecting the maximum NDVI during each 15-day period, non-vegetation effects such as cloud or smoke contamination, and view geometry effects are reduced. The data had been calibrated by NASA scientists to correct for orbital drift and sensor degradation from a time series of five NOAA AVHRR sensors. The data were also processed by NASA scientists to correct for atmospheric effects resulting from two major volcanic eruptions: El Chichon in 1982, Mt. Pinatubo in 1991.

我们从马里兰大学全球土地覆盖设施（University of Maryland Global Land Cover Facility，http://www.landcover.org）下载了1982—2003年间从双月合成GIMMS-NDVI数据提取得到的年最大归一化差分植被指数（Normalized Difference Vegetation Index，NDVI）。该数据的原始形式为每个15天合成周期内、每幅64平方千米像元对应的最大NDVI值。通过选取每个15天合成周期内的最大NDVI值，可降低云、烟雾污染等非植被影响以及观测几何效应带来的干扰。美国国家航空航天局（National Aeronautics and Space Administration，NASA）的科研人员已针对由5台美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration，NOAA）先进甚高分辨率辐射计（Advanced Very High Resolution Radiometer，AVHRR）组成的时间序列传感器的轨道漂移与传感器性能衰减问题，对该数据完成了校准校正。此外，NASA科研人员还针对1982年埃尔奇琼火山（El Chichon）与1991年皮纳图博火山（Mount Pinatubo）两次大规模火山喷发引发的大气效应，对该数据进行了处理校正。