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Although the primary objectives for PACE are directed toward the study of atmospheric and oceanic processes, by providing frequent global moderate-resolution hyperspectral observations PACE is producing a new generation of remotely sensed products that can address key science questions on terrestrial ecosystem productivity, function, and biodiversity. PACE OCI terrestrial products include surface reflectance and10 different indices: greenness indices (EVI & NDVI), snow index (NDSI), foliar water indices (NDWI & NDII), foliar pigment indices (for chlorophyll, carotenoids, and anthocyanins), and vegetation stress indices (PRI & CCI). Foliar pigment concentrations play an important role in plant photosynthesis and protection and can be inferred from the PACE indices. Chlorophyll controls potential photosynthesis, carotenoids have both photosynthetic and photoprotective functions, and anthocyanins can alter the light environment within a leaf and regulating photosynthesis and limiting photoinhibition and photobleaching, while the Photochemical Reflectance Index (PRI) is related to the xanthophyll cycle pigments and an indicator of photosynthetic downregulation and photosynthetic light use efficiency.

We will use the PACE products to illuminate aspects of terrestrial ecosystems highlighting spatial patterns of seasonal and shorter term changes in spectral reflectance and vegetation indices as they relate to gross primary productivity.

PACE, with its frequently collected continuous high spectral resolution imagery, provides an opportunity to describe dynamics of key terrestrial vegetation biochemical and functional characteristics. Frequent observations of leaf pigment contents provide information on vegetation seasonal activity and stress responses that are related to photosynthetic rates and ecosystem primary productivity. Spectral reflectance can also identify vegetation functional type coverage, related to biodiversity, which further constrains physiological responses. Thus, taken together, PACE measurements can describe factors determining plant productivity, stress responses, and resource allocations, providing new insights into global patterns of the function of terrestrial ecosystems and their response to environmental conditions.

The potential uses of PACE data for terrestrial applications are demonstrated in a variety of studies using data from combinations of MODIS ocean and land bands, HICO and Hyperion imaging spectrometers, AVIRIS imagery from aircraft, ground measurements, and vegetation canopy models.