ABoVE: UAV and Ground-based VNIR/SWIR Spectroscopy Data of Plant Functional Types

This dataset contains 1000 reflectance scans (350-2500 nm, 1nm bands) of 100 vegetation species and orthorectified surface reflectance (400-1000 nm, 326 bands, 4-10 cm GSD) collected around the ABoVE domain. Ground scans were collected with a SpectralEvolution PSR+ spectroradiometer and imagery was collected with a UAV-based Headwall Micro A-series VNIR imaging spectrometer. Both datasets were collected in July and August of 2019 and 2020. Most acquisitions for both sensors occurred during the acquisitions of the NASA AVIRIS-NG sensor so that the plant functional types (PFT) at fine taxonomic resolution (eg. species) within the UAV images can be used to train models using AVIRIS-NG reflectance to generate PFT maps for each AVIRIS-NG scene.

The QA and documentation of this dataset is in progress.

Study area: (These coordinates are the approximate locations of the study sites and may not match the extent of the data files. All latitude and longitude are given in degrees minutes seconds.)

Site	Northern Extent	Western Extent	Eastern Extent	Southern Extent
Birch_Lake	64°55'14.48"N	147°49'35.46"W	147°49'3.90"W	64°55'2.59"N
Little_Lake	64°24'53.09"N	146°54'1.62"W	146°53'28.79"W	64°24'26.36"N
Eight_Mile	63°52'39.62"N	149°15'25.73"W	149°15'2.85"W	63°52'26.48"N
Big Trail Lake	64°55'14.65"N	147°49'35.78"W	147°49'4.24"W	64°55'2.64"N
Twelve_Mile	65°24'10.09"N	145°58'52.59"W	145°58'35.46"W	65°24'3.26"N
Murphy_Dome	64°57'16.31"N	148°26'17.56"W	148°20'36.47"W	64°56'56.73"N
Wickersham_Dome	65°11'23.33"N	148° 4'4.29"W	148° 3'45.12"W	65°11'15.39"N
Vault_Dr	65° 2'10.66"N	147°42'48.57"W	147°42'12.90"W	65° 1'57.88"N
Bison_Gulch	63°48'29.04"N	148°57'14.74"W	148°56'58.41"W	63°48'20.33"N
Chatnika	65° 9'17.82"N	147°29'7.30"W	147°28'34.69"W	65° 9'9.14"N
Clayton_Lake	64°55'14.38"N	147°49'27.53"W	147°49'16.29"W	64°54'41.75"N
Eagle_Summit	65°29'11.33"N	145°25'27.26"W	145°24'44.88"W	65°28'55.51"N
Yukon	62°45'12.56"N	164°40'56.98"W	164°32'55.24"W	62°39'30.95"N

Acknowledgement: 

NASA ABoVE award (Phase 1) and (Phase 2) Grant Number: NNX15AU05A; Maine Economic Improvement Fund - Small Campus Initiative (MEIF-SCI) awards in 2016 and 2018; Polar Studies research award from the Field Museum, Chicago.

Spatial Coverage: Flights over the Alaskan Arctic and boreal zones within the ABoVE Domain

Spatial Resolution: approximately 4-10 centimeters

Temporal Coverage: 07-24-2018 to 08-12-2019

Temporal Resolution: Areas were surveyed once

There are 4 files associated with each of the 175 flight lines included in this dataset. These files are as follows:

ENVI image files - these files have no extension and store reflectance measurements captured by the Headwall Micro A-series VNIR imaging spectrometer.

Header files - accompanying file for the ENVI image files. They should remain in the same directory as the image files for the data to be displayed properly. Header files provide spatial and spectral metadata related to the image file such as the number of lines, samples, channels, etc. Please see the Harris Geospatial reference for the ENVI file format for more detailed information on the header files.

KMLs - these files store the footprint of each flight line.

RGB JPEGs -  these files are RGBs of each flight line stored in a jpeg format.

Each flight line uses a specific base filename prefix: LOC_YYYY_MM_DD_HH_NN_SS_ID_rd_rf_or. The datetime codes outlined below applies to all files for the 175 flight lines.

• LOC: General name of the site (e.g Murphy dome)
• YYYY : Year of flight
• MM : Month of flight
• DD : Day of flight
• HH : UTC hour at start of flight
• NN : UTC minute at start of flight
• SS : UTC second at start of flight
• ID : Headwall ID number
• rd: flight was brought to radiance cube
• rf: flight brought to reflectance cube
• or: cube orthorectified

 

The reflectance measurements of 100 vegetation species were collected under AVIRIS-NG flight lines as close as possible in time, providing on-the-ground reflectance of targets in an area independent of NASA’s sensor. The reflectance measurements have higher spectral resolution but the same bandpass as AVIRIS-NG. This library will be an useful resource for those interested in resolving what vegetation occurs in an AVIRIS-NG pixel.

Moreover, the imaging spectroscopy data collected under AVIRIS-NG using a UAV has lower spectral resolution than AVIRIS-NG but high spatial resolution, which is helpful for classifying or mapping features and then calculating the fraction of each feature within an AVIRIS-NG pixel. The imaging spectroscopy data could also be used to directly compare reflectance to AVIRIS-NG in the VNIR where the two sensor’s bandpasses overlap.

An imagery was generated using a Headwall Micro A-Series sensor push broom imaging spectrometer covering the VNIR (400-1000 nm) in 324 spectral bands with 1004 spatial bands/pixel. This spectrometer is mounted on UAV (DJI Matrice 600) with Trimble APX-15 GPS/IMU. Imagery was orthorectified using the coordinates from the GPS/IMU that were not post-processed. Reflectance of a Spectralon panel taken just before flight under ambient conditions was used as a white reference. Radiometric calibration occurred in the proprietary software SpectralView by Headwall. Orthorectified reflectance products are delivered in GeoTIFF at a spatial resolution of 4-10 cm GSD.

Ground spectra were collected using the PSR+ 3500 Spectroradiometer by Spectral Evolution which cover the range 350-2500 nm in 2151 spectral bands. Values in the data are percent reflectance based on radiometric calibration against a Spectralon panel taken before scanning. Scans were collected using leaf clip or contact probe with tungsten halogen light source that eliminates almost all ambient light. GPS coordinates are included in many of the scans unless they were collected via samples that were taken back to a central location and scanned after field work each day.