Design and validation of a calibration system for arctic spectroradiometers

Accurate radiometric calibration is essential for ground-based spectral measurements of atmospheric radiance, particularly in polar environments where harsh conditions can affect instrument performance and limited access to laboratory facilities makes regular calibrations impractical. This work presents the development of an affordable field calibration system for spectroradiometers, designed to enable reliable and repeatable calibration. The methodology was applied to a TriOS RAMSES spectrometer (UV–VIS–NIR) and a custom SWIR spectrometer based on the Zeiss PGS 2.2, both calibrated using the same device layout setup. The robustness of the calibration system was evaluated by testing geometric variations of its components, with observed deviations below 0.2%. Additionally, by modifying lamp-panel distance, the inverse-square law was confirmed (0.3% average error). Temperature effects were identified as the main source of uncertainty, with the RAMSES exhibiting residual variations up to 0.4%/°C, while the SWIR system showed more stability due to shutter-based dark acquisition. These results highlight the importance of both periodic calibration and characterization of the instrument response to environmental conditions, particularly in harsh environments such as the Arctic.