Abstract. We publish and describe a surface spectral reflectance data record
of seasonal snow (dry, wet, shadowed), forest ground (lichen, moss) and
forest canopy (spruce and pine, branches) constituting the main elements of
the boreal landscape. The reflectances are measured with
spectro(radio)meters covering the wavelengths from visible (VIS) to
short-wave infrared (SWIR) (350 to 2500 nm). In this paper, we describe the
instruments used and how the spectral observations at different scales along
with the concurrent in situ reference data have been collected, processed
and archived. Information on the quality of the data and factors causing
uncertainty are discussed. The main experimental site is located in
the Sodankylä Arctic Space Centre in northern Finland (67.37∘ N,
26.63∘ E; 179 m a.s.l) and the surrounding region. The collection
includes highly controlled snow and conifer branch laboratory spectral
measurements, portable field spectroradiometer observations of snow and
snow-free ground at different locations, and continuous mast-borne
reflectance time series data of a pine forest and forest opening. In
addition to the surface level spectral reflectance, data from airborne
imaging spectrometer campaigns over the Sodankylä boreal forest and
Saariselkä fell region at selected spectral bands are included in the
collection. All measurements of the data record correspond to a typical
polar-orbiting satellite observation event in the high-latitude spring season
regarding their Sun or illumination source (calibrated lamp) zenith angle
and close-to-nadir instrument viewing angle. For all measurement geometries,
observations are given in surface reflectance quantity corresponding to the
typical representation of a satellite observation quantity to facilitate
their comparison with other data sources. The openly accessible spectral
reflectance data at multiple scales are suitable to climate and
hydrological research and remote sensing model validation and development.
To facilitate easy access to the data record the four datasets described
here are deposited in a permanent data repository
(http://www.zenodo.org/communities/boreal_reflectances/)
(Hannula et al., 2019). Each dataset of a distinct scale has its own unique
DOI – laboratory: https://doi.org/10.5281/zenodo.3580078 (Hannula and Heinilä, 2018a);
field: https://doi.org/10.5281/zenodo.3580825 (Heinilä et al., 2019a); mast-borne:
https://doi.org/10.5281/zenodo.3580096 (Hannula and Heinilä, 2018b); and airborne:
https://doi.org/10.5281/zenodo.3580451 (Heinilä, 2019a) and https://doi.org/10.5281/zenodo.3580419
(Heinilä, 2019b).