Visible to near-infrared spectral reflectance along the NGEE-Arctic tram transect, Utqiagvik (Barrow), Alaska, 2015-2018

DOI: https://doi.org/10.5440/1183993
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NGEE Arctic Record ID: NGA106
Data Version: 1.0
Abstract

Canopy spectral reflectance collected measured in 2015–2018 along the NGEE-Arctic tram located on the Barrow Environmental Observatory (BEO), Barrow, Alaska. Measurements were made using a PP-Systems UniSpec-DC spectrometer mounted on an automatically operated instrument cart. Spectra were collected at 137 stop points at 0.5 m intervals along the tram transect. Transect runs were collected daily, or multiple times per day, from April or May through to August or September each year. Downwelling radiance was measured using a 2 meter fiber optic cable connected to a cosine diffuser. Upwelling (i.e. reflected) radiance was measured using a 2 meter cable connected to a 12 degree field-of-view (FOV) lens. Canopy reflectance was calculated using the ratio of upwelling to downwelling radiance measured over a 99.99% reflectance Spectralon standard measured at the start of each measurement set. Unprocessed spectral data are presented in .spu files. Metadata are provided in csv files, and the instrument manual (pdf).

The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was a 15-year research effort (2012-2027) to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research.

The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska.

Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

Authors
Shawn Serbin (sserbin@bnl.gov) 0000-0003-4136-8971
Andrew McMahon (amcmahon@bnl.gov) 0000-0001-8836-6645
Keith Lewin (lewin@bnl.gov) 0000-0003-3501-4085
Oriana Chafe (oechafe@lbl.gov) 0000-0002-8407-284X
Bryan Curtis (Curtis@colorado.edu)
Kim Ely (kely@bnl.gov) 0000-0002-3915-001X
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Dataset Citation
Shawn Serbin, Andrew McMahon, Keith Lewin, Oriana Chafe, Bryan Curtis, Kim Ely. 2024. Visible to near-infrared spectral reflectance along the NGEE-Arctic tram transect, Utqiagvik (Barrow), Alaska, 2015-2018. Next Generation Ecosystem Experiments Arctic Data Collection, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, USA. Dataset accessed on [INSERT_DATE] at https://doi.org/10.5440/1183993.
Dates
2015-05-15 - 2018-09-05
Geographic Location
NGEE Arctic Utqiagvik (Barrow), Alaska
North71.35
South71.2
East-156.4
West-156.7
Place Keywords:
Barrow | Alaska | Utqiagvik
Subject Keywords:
ESS-DIVE CSV File Formatting Guidelines Reporting Format | ESS-DIVE File Level Metadata Reporting Format | Earth Remote Sensing Instruments > Passive Remote Sensing > Spectrometers/Radiometers > Hyperspectral Spectrometers/Radiometers |
GCMD Keywords
EARTH SCIENCE > BIOSPHERE > VEGETATION > CANOPY CHARACTERISTICS
EARTH SCIENCE > LAND SURFACE > SURFACE RADIATIVE PROPERTIES > REFLECTANCE
Methodology
A PP-Systems UniSpec-DC spectrometer was set up to acquire spectra at each of the tram’s 137 stops in addition to a spectralon reference scanned three times at the start of each run. In 2017 and 2018 a reference scan was also added to the end on each run. Reference plates at the start of each run are designated by the stop number “_000” in the file name while references at the end of a run are designated by “_end”. Due to operational issues with the tram, days and times of operation are not always consistent, including some periods where stops were skipped resulting in mismatched reference numbers. While there is no straightforward method for validating data during periods of inconsistency, some information can be inferred from timestamps and it is apparent when operations were proceeding as expected. The .spu files generated are ASCII text files containing 10 header lines followed by 256 rows of tab separated values corresponding to each of the optical channel's wavelength bins and measured values. To convert these to reflectance values, each spectra should be corrected for dark current, the wavelengths should be interpolated to a single set of bins and then ratioed and normalized using the corresponding reference spectra. Preliminary code to accomplish this is presented in this repository https://github.com/TESTgroup-BNL/UniSpec_Processing/, with the 2018_Improvements branch being the most complete.
Related References
Margaret Torn, Baptiste Dafflon, Sigrid Dengel, Bryan Curtis, Oriana Chafe, Andrew Moyes, Shawn Serbin, Keith Lewin, Amy Breen, Terri Velliquette, Les Hook, Stan Wullschleger. 2019. NGEE Arctic Tram: Overview of Tram-mounted Instruments, Co-located Data, Measurement Position, Elevation and Polygon Characterization, Utqiagvik (Barrow), Alaska, 2014-2018. Next Generation Ecosystem Experiments Arctic Data Collection, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tennessee, USA. https://doi.org/10.5440/1558782.
Related Identifiers
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Metadata Contact
Contact information for the individual or organization that is knowledgeable about the data.
Person: Kim Ely
Organization: Brookhaven National Laboratory
Email: kely@bnl.gov
Point of Contact
Contact information for the individual or organization that is knowledgeable about the data.
Person: Shawn Serbin
Organization: Brookhaven National Laboratory
Email: sserbin@bnl.gov
Dataset Usage Rights
Public Datasets

This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0.

See the NGEE Arctic Data Policies for more details https://ngee-arctic.ornl.gov/data-policies.

Distribution Point of Contact
Contact: Data Center Support
Organization: Next-Generation Ecosystem Experiments (NGEE) Arctic Project, Oak Ridge National Laboratory
Email: support@ngee-arctic.ornl.gov