This dataset includes 446 hemispherical-conical reflectance factors at wavelengths from 350 to 2500 nm measured on 13 hemiboreal, boreal, sub-Arctic and Arctic peatland sites in Finland and Estonia. The measurements were made during growing seasons of 2022 and 2023, on 1 m × 1 m plots under diffuse illumination conditions. The dataset includes also the site ID, country of the measurement, name of the peatland site, date of the measurement, coordinates of the plot, Finnish peatland type for the measurements done in Finland and tree-covert type for the measurements done in Estonia, basal area of the dead and alive standing trees by species, and vegetation fractional cover of the plot, as well as the quality class of the SWIR data on wavelengths 2025–2310 nm. For more elaborate description of the contents, see Data_description.pdf. Furthermore, a detailed description of the data acquisition and preprocessing is provided in Salko et al. [1]. The spectra are reported in two versions: as raw data (“_raw”) and as smoothed with Savitzky-Golay smoothing (_smoothed). The Savitzky-Golay smoothing was applied using a second order polynomial and a window size of 15 nm in the 350 to 1000 nm region, 39 nm in the 1001 to 2000 nm region and 75 nm in the 2001–2500 nm region. The atmospheric water absorption regions with high levels of noise are present at 1330–1549 nm, 1761–2024 nm, and 2311–2500 nm. In the _raw version, there reflectance factors on the water absorption regions are included in the data, and in the _smoothed version, they are omitted.

2024