Ground-Truthing Satellite Imagery with Phenological Observations: Visual Observations from Grasslands at the Sevilleta National Wildlife Refuge, New Mexico (2007-2008)

Phenology is the study of recurring natural phenomena. The seasonal "greening-up" and "greening-down" of dominant vegetation can be used as a predictor for a variety of processes and variables at local to global scales. The use of satellites to monitor land surface phenology is important for understanding local and regional ecosystem variability, identifying change over time, and potentially predicting ecosystem response to short and long-term changes in climate. However, the relationship between how phenology is expressed on the ground and how it is interpreted from satellites is poorly understood because phenological stages do not always correspond well to changes in spectral reflectance. In this study, we explored the relationship between greenness as measured by digital camera, the human eye, and ASTER imagery in two perennial grasslands at the Sevilleta National Wildlife Refuge in central New Mexico.

物候学（Phenology）是研究周期性自然现象的学科。优势植被的季节性“返青”与“枯黄”，可作为从局地到全球尺度下各类过程与变量的预测因子。利用卫星监测陆地表面物候，对于理解局地与区域生态系统变异性、识别随时间推移的变化，以及潜在预测生态系统对气候短期与长期变化的响应均具有重要意义。然而，地面物候的实际表达与卫星遥感解译结果之间的关联尚不明确，因物候阶段并不总能与光谱反射率的变化较好对应。本研究以新墨西哥州中部塞维莱塔国家野生动物保护区内的两处多年生草原为研究对象，探究了数码相机测量的绿度、人眼观测结果与ASTER影像之间的关联。