--------------------------------------------------------------------- DATASET OVERVIEW Dataset Title: Tower-based solar-induced fluorescence and vegetation index data for Southern Old Black Spruce forest Investigators: Zoe Pierrat, zpierrat@g.ucla.edu, ORCID: 0000-0002-6726-2406, and Jochen Stutz, jochen@atmos.ucla.edu, ORCID: 0000-0001-6368-7629 Point of Contact: Zoe Pierrat, zpierrat@g.ucla.edu, University of California Los Angeles Summary: Data includes remote sensing products from PhotoSpec (a scanning spectrometer) from September 2019-December 2020 at the Southern Old Black Spruce site in Saskatchewan Canada. We provide half-hourly averaged vegetation indices (NIRv, NDVI, PRI, CCI) and solar-induced fluorescence (SIF) and for a stand-representative mix of black spruce and larch. Additionally, we provide photosynthetically active radiation (PAR), absorbed photosynthetically active radiation (APAR), and the escape fraction of SIF photons (fesc). Keywords: remote-sensing, solar-induced fluorescence, vegetation reflectance, boreal forest, diurnal and seasonal dynamics Acknowledgments: Earth Science Division grant numbers 80NSSC17K0108 and 80NSSC17K0110. ABoVE grant number 80NSSC19M0130. National Science Foundation Graduate Research Fellowship under Grant No. DGE-1650604 and DGE-2034835 Related Publication: Pierrat, Z., Magney, T., Parazoo, N., Grossmann, K., Bowling, D., Seibt, U., Johnson, B., Helgason, W., Barr, A., Bortnik, J., Norton, A., Maguire, A., Frankenberg, C., Stutz, J. Diurnal and seasonal dynamics of solar-induced chlorophyll fluorescence, vegetation indices, and gross primary productivity in the boreal forest. Journal of Geophysical Research: Biogeosciences. --------------------------------------------------------------------- DATASET CHARACTERISTICS Spatial Resolution: Instrument field of view is 0.7 degrees atop a 26m tower and takes a canopy representative average over a 30-minute window. Temporal Resolution: PhotoSpec target measurements are made approximately every 20 seconds, and the revisit time for each target is approximately 30-minutes so that all canopy targets are retrieved within 30-minutes and averaged together. Temporal Coverage: 2018-Sep-08 to 2020-Dec-31 Data Dictionary for Pierrat_JGRB_2022_PhotoSpec.csv: Time, 30-minute timestamp for measurements SIF, far-red (745-758nm) solar-induced chlorophyll fluorescence, [Wm^-2sr^-1microm^-1] NDVI, normalized difference vegetation index, unitless NIRv, near-infrared reflectance from vegetation, unitless PRI, photochemical reflectance index, unitless CCI, chlorophyll-carotenoid index, unitless PAR, photosynthetically active radiation in [micromol m^-2 s^-1] APAR, absorbed photosynthetically active radiation in [micromol m^-2 s^-1] fesc, escape fraction of SIF photons, unitless --------------------------------------------------------------------- APPLICATION & DERIVATION Data is used to explore the diurnal and seasonal dynamics among SIF, vegetation indices, and GPP in the boreal forest. --------------------------------------------------------------------- QUALITY ASSESSMENT Estimate of Uncertainty: Details of measurement uncertainty can be found in Grossmann, K., Frankenberg, C., Magney, T. S., Hurlock, S. C., Seibt, U., & Stutz, J. (2018). PhotoSpec: A new instrument to measure spatially distributed red and far-red Solar-Induced Chlorophyll Fluorescence. Remote Sensing of Environment, 216(November 2017), 311–327. https://doi.org/10.1016/j.rse.2018.07.002 We excluded low-quality retrievals where the SIF retrieval error was > 0.2 Wm^-2sr^-1microm^-1 and where SIF < -0.1 Wm^-2sr^-1microm^-1 or SIF > 10 Wm^-2sr^-1microm^-1. We only considered observations where the solar zenith angle was < 80 degrees and where PAR conditions changed significantly (PARstd > 0.2*PARavg) over the PhotoSpec integration time. --------------------------------------------------------------------- DATA ACQUISITION, MATERIALS & METHODS The study site (Southern Old Black Spruce, SOBS, Fluxnet ID CA-Obs) is located near the southern limit of the boreal forest ecotone in Saskatchewan, Canada (53.98 ◦N, 105.12◦W). It is a mixed forest stand with stem density predominantly (90%) black spruce (Picea mariana), and scattered (10%) larch (Larix laricina). Average canopy height at the site is ∼16 m with a canopy leaf area index of ∼3.8 m2m-2. Long-term (1981-2010) mean annual air temperature and total precipitation in the area are 1.4◦C and 427.7mm respectively. There is an average of 146 days with a snow depth of 1cm or more. The site is equipped with a 26 m above ground level (agl) twin scaffold tower, approximately twice the height of the forest canopy. We collected co-located remotely sensed products (SIF, NDVI, NIRv, PRI, CCI) as well as PAR using PhotoSpec (see Grossmann et al. (2018) for detailed instrument description) from September 2018 to December 2020. PhotoSpec was installed at the top of the 26m scaffolding tower facing due north. It has a narrow field of view (0.7 degrees) and a 2-D scanning capability which permits canopy representative scanning. Additional details of measurement procedure can be found in the aforementioned citations. Instruments: PhotoSpec --------------------------------------------------------------------- REFERENCES: Pierrat, Z., Magney, T., Parazoo, N., Grossmann, K., Bowling, D., Seibt, U., Johnson, B., Helgason, W., Barr, A., Bortnik, J., Norton, A., Maguire, A., Frankenberg, C., Stutz, J. Diurnal and seasonal dynamics of solar-induced chlorophyll fluorescence, vegetation indices, and gross primary productivity in the boreal forest. Journal of Geophysical Research: Biogeosciences. Grossmann, K., Frankenberg, C., Magney, T. S., Hurlock, S. C., Seibt, U., & Stutz, J. (2018). PhotoSpec: A new instrument to measure spatially distributed red and far-red Solar-Induced Chlorophyll Fluorescence. Remote Sensing of Environment, 216(November 2017), 311–327. https://doi.org/10.1016/j.rse.2018.07.002