ABSTRACT

The longest Normalized Difference Vegetation Index (NDVI) time series produced from the National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) has ended in 2017. At some point in the near future, all AVHRR sensors will be retired. To maintain continuity and consistency of this global data set, it is imperative to extend NDVI from other sensors, especially the operational Visible Infrared Imaging Radiometer Suite (VIIRS), which planned to maintain continuity at least through 2038. NDVI could be de-composited into two components: (1) the multi-year climatology and (2) the vegetation condition index (VCI). The former contains climate information and a majority of sensor noise, and the latter contains weather information and residual sensor noise. With the assumption that VCI from different sensors are similar, we re-composited the cross-sensor/cross-production NDVI with original VCI and the cross-sensor/cross-production climatology, and compared various cross-converted datasets with the three base NDVI datasets: two NDVI productions derived from AVHRR observation and another from VIIRS observation. As a result, the re-composited NDVI agrees well with the target base NDVI spatially and temporally, with an accuracy of 0.02 NDVI unit at a global scale. The comparison with several regression approaches distinguish the superiority of the new re-compositing approach.

摘要

美国国家海洋和大气管理局 (NOAA) 高级甚高分辨率辐射计 (AVHRR) 生成的最长归一化植被指数 (NDVI) 时间序列已于 2017 年结束。在不久的将来某个时候，所有 AVHRR 传感器都将退役。为了保持这个全球数据集的连续性和一致性，必须从其他传感器扩展 NDVI，尤其是运行中的可见红外成像辐射计套件 (VIIRS)，它计划至少在 2038 年之前保持连续性。 NDVI 可以分解为两个组成部分：（1）多年气候学和（2）植被状况指数（VCI）。前者包含气候信息和大部分传感器噪声，后者包含天气信息和残余传感器噪声。假设来自不同传感器的 VCI 相似，我们将跨传感器/跨生产 NDVI 与原始 VCI 和跨传感器/跨生产气候学重新组合，并将各种交叉转换数据集与三个基础 NDVI 进行比较数据集：两个 NDVI 产品来自 AVHRR 观测，另一个来自 VIIRS 观测。因此，重新合成的 NDVI 在空间和时间上与目标基础 NDVI 非常吻合，在全球范围内的精度为 0.02 NDVI 单位。与几种回归方法的比较区分了新的重新合成方法的优越性。两个 NDVI 产品来自 AVHRR 观测，另一个来自 VIIRS 观测。因此，重新合成的 NDVI 在空间和时间上与目标基础 NDVI 非常吻合，在全球范围内的精度为 0.02 NDVI 单位。与几种回归方法的比较区分了新的重新合成方法的优越性。两个 NDVI 产品来自 AVHRR 观测，另一个来自 VIIRS 观测。因此，重新合成的 NDVI 在空间和时间上与目标基础 NDVI 非常吻合，在全球范围内的精度为 0.02 NDVI 单位。与几种回归方法的比较区分了新的重新合成方法的优越性。