AVHRR Remote Sensing Phenology

The Remote Sensing Phenology (RSP) collection is a set of nine annual phenological metrics for the conterminous United States. Researchers at the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center utilize data gathered by satellite sensors to track seasonal changes in vegetation. The two satellite sensors that provide the raw data for the RSP program are the Advanced Very High Resolution Radiometer (AVHRR) from National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites and the Moderate Resolution Imaging Spectroradiometer (MODIS) carried aboard National Aeronautics and Space Administration (NASA) Terra and Aqua satellites. The satellite data are initially transformed into Normalized Difference Vegetation Index (NDVI) values. AVHRR NDVI and eMODIS NDVI provide the foundation for RSP. Time-series NDVI can be summarized and analyzed to produce nine key phenological indicators that represent a complete growing season. These data represent a powerful tool for documenting plant life-cycle trends over time and detecting the impacts of climate change on ecosystems. Remote Sensing Phenology Products Remote Sensing Phenology products are available in two file formats with geographic coordinates referenced to the Lambert Azimuthal Equal Area mapping grid: Georeferenced Tagged Image File Format (GeoTIFF) is a TIFF file with embedded geographic information. This is a standard image format for GIS applications. Band Sequential (BSQ) image file is a binary raster format with an accompanying header file which describes the layout and formatting of the file. EarthExplorer offers a year-to-year record of AVHRR Phenology data at 1-km resolution dating back to 1989 and eMODIS Phenology data at 250-m resolution dating back to 2001. Nine annual historical Remote Sensing Phenology metrics for the conterminous United States are available for each data set.

遥感物候（Remote Sensing Phenology, RSP）数据集集合包含美国本土的9项年度物候指标。美国地质调查局（U.S. Geological Survey, USGS）地球资源观测与科学（Earth Resources Observation and Science, EROS）中心的研究人员利用卫星传感器采集的数据，追踪植被的季节变化。为RSP项目提供原始数据的两颗卫星传感器分别是：美国国家海洋和大气管理局（National Oceanic and Atmospheric Administration, NOAA）极轨卫星搭载的甚高分辨率辐射计（Advanced Very High Resolution Radiometer, AVHRR），以及美国国家航空航天局（National Aeronautics and Space Administration, NASA）Terra与Aqua卫星搭载的中分辨率成像光谱仪（Moderate Resolution Imaging Spectroradiometer, MODIS）。卫星数据首先会被转换为归一化差分植被指数（Normalized Difference Vegetation Index, NDVI）数值，AVHRR NDVI与eMODIS NDVI构成了RSP数据集的核心基础。通过对时间序列NDVI数据进行汇总与分析，可生成表征完整生长季的9项核心物候指标。该数据集是记录植物生命周期长期变化趋势、探测气候变化对生态系统影响的有力工具。

遥感物候产品
遥感物候产品采用两种文件格式，其地理坐标参考于兰伯特方位等面积（Lambert Azimuthal Equal Area）投影网格：地理标记图像文件格式（Georeferenced Tagged Image File Format, GeoTIFF）是嵌入了地理信息的TIFF文件，是地理信息系统（Geographic Information System, GIS）应用中的标准图像格式。波段顺序（Band Sequential, BSQ）图像文件是一种二进制栅格格式，附带用于描述文件布局与格式的头文件。

地球探索者（EarthExplorer）平台提供了可追溯至1989年的1公里分辨率AVHRR物候数据逐年记录，以及可追溯至2001年的250米分辨率eMODIS物候数据逐年记录。两类数据集均包含美国本土的9项年度历史遥感物候指标。