## 4 Conclusions  
Understanding interactions of ecosystem functions and climate across varying spatial and temporal scales could improve climate forecasting capability. However, determining the linkage between very different scales (e.g., global and local) is particularly difficult because key processes at each scale operate at different rates and create complex heterogeneity and dynamics. Recognizing that existing instrumentation would not fully support the type of data collection needed to investigate the interaction of two extreme scales, we developed a tower-based remote sensing system to automatically collect a range of optical and infrared measurements of land surface across the visible to TIR spectral region throughout the day over the growing season. While many existing near-surface remote sensing systems continuously collect measurements in an automated manner over an extended period of time, the uniqueness of the EcoSpec system includes the following:  
1. Collection of measurements from 12 locations spanning a 300 degree rotation of the platform to account for heterogeneity of the land surface. 2. Integration of five optical and infrared sensors to collect a suite of measurements that complements hyperspectral reflectance measurements, enabling various modeling approaches, such as surface and sky temperature, direct and diffused sunlight, incoming and outgoing albedo, and RGB photos of the land surface. 3. Custom software to control synchronized movements and functions of the system components so that every sensor collects measurements properly without interference of other sensors. This software manages a specific order or timing of actuator movement, reference reflectance measurement, target reflectance measurement, and platform movement in a compact package. 4. Portability of the system as being powered by a relatively compact power generating system, such as the solar power system evaluated during the entire testing period, which allows for deployment at a range of sites, including existing research stations/observatories, short-term/temporary locations, remote locations, and agricultural fields. When examining the measurements collected using the system, temporal trajectories between narrow-band spectral vegetation indices--NDVI, NDWI, and PRI--and a biophysical variable directly correlated with the primary production--fPAR--were strongly correlated. TIR temperature that correlates with the MSI at the diurnal scale appeared to correspond to soil moisture across the season. These patterns suggest that hyperspectral reflectance and simultaneously collected complementary optical and infrared measurements could provide valuable observations for investigating ecosystem functions, such as photosynthesis or gross primary production and possibly ecosystem respiration  
Figure 6: Seasonal trajectories of TIR temperature with (**a**) soil moisture and (**b**) NDVI of the 2015 growing season. in response to environmental changes, which would provide critical information to understand interactions between biosphere and atmosphere at its interfaces. Optical and infrared measurements of land surface--plants and surface soils--properties would provide critical data for understanding ecosystem functions and their responses and contributions to environmental changes and variability. Instrumentation that allows measurements from multiple locations at high temporal frequency would enable experiments and modeling with great flexibility by providing replicates of samples and options for temporal aggregation. This type of near-surface remote sensing system can be used to complement existing science observatories to validate satellite remote sensing observations, link local- and regional/global-scale phenomena, and ultimately improve our ability to forecast ecosystem functions and climate. When applying this system for precision agriculture, measurements would be useful for studying crop growth, detecting disease and pests, and comparing traits of breeds or cultivars to improve our future food security.