The terrestrial component of the Earth system has witnessed considerable changes in the past decades due to anthropogenic action. Throughout this period, the NASA Terra mission has been constantly monitoring the surface with the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. When combined with the MODIS instrument on-board of the Aqua platform, we obtain a hyper-frequent revisit capability providing sub-daily observations globally at a moderate resolution of ~250 m, but with a strong multi-angular variation of the observation footprint. Here we propose to exploit this particular configuration provided by the combined Terra + Aqua constellation to infer spatial homogeneity from the temporal stability of the observation time series. We thus designed a Temporal Coherence Index (TCI) based on the concept of information entropy. We test it on both synthetic and real landscapes showing its capacity to isolate which time series correspond to homogeneous targets based only on the MODIS measurements themselves. The index is calculated annually for the entirety of emerged surfaces for the period 2003–2020 by leveraging on the scaling capacity of the cloud computing Google Earth Engine (GEE). We foresee multiple practical applications for this index as a novel information layer that should foster the integration of surface data with satellite records, a practice that is increasingly necessary in Earth System Science.

在过去的几十年中，由于人类活动，地球系统的陆地部分发生了巨大变化。在此期间，NASA Terra任务一直使用中分辨率成像光谱仪（MODIS）仪器持续监控表面。当与Aqua平台上的MODIS仪器结合使用时，我们获得了超频繁的重访功能，可以以〜250 m的中等分辨率在全球范围内提供次日观测，但是观测足迹具有很大的多角度变化。在这里，我们建议利用由Terra + Aqua组合星座提供的特定配置，从观测时间序列的时间稳定性推断空间均匀性。因此，我们基于信息熵的概念设计了时间相干指数（TCI）。我们在合成景观和真实景观上对其进行了测试，显示了仅基于MODIS测量本身就能够确定哪些时间序列对应于同类目标的能力。利用云计算的Google Earth Engine（GEE）的缩放能力，每年对2003-2020年期间出现的整个表面进行计算。我们预见到该索引的多种实际应用将作为一种新颖的信息层，应促进将地面数据与卫星记录集成在一起，这种做法在“地球系统科学”中变得越来越必要。利用云计算的Google Earth Engine（GEE）的缩放能力，每年对2003-2020年期间出现的整个表面进行计算。我们预见到该索引的多种实际应用将作为一种新颖的信息层，应促进将地面数据与卫星记录集成在一起，这种做法在“地球系统科学”中变得越来越必要。利用云计算的Google Earth Engine（GEE）的缩放能力，每年对2003-2020年期间出现的整个表面进行计算。我们预见到该索引的多种实际应用将作为一种新颖的信息层，应促进将地面数据与卫星记录集成在一起，这种做法在“地球系统科学”中变得越来越必要。