An automated snow-removal device for radiometers

Abstract. Snowmelt is strongly influenced by shortwave radiation from the Sun and longwave radiation from the Earth and the atmosphere. These energy fluxes are typically measured in situ using radiometers equipped with pairs of sensors on the bottom and the top of the housing, which measure upwelling and downwelling radiation respectively. However, measuring under snowy conditions is challenging, as the upper lenses tend to become obstructed by snow. Although heating modules can be integrated into radiometers to prevent frost and dew formation on lenses, they are too energy-intensive for off-grid applications and ineffective against substantial snow build-up. This paper presents a novel snow removal device (SRD) designed to automatically brush snow from radiometers lenses with a per-deployment energy cost equivalent to 17 s of heating. A field campaign over an entire winter season (1 Nov 2024–26 Mar 2025) compared a heated and SRD equipped radiometer to a heated-only radiometer, both installed side by side in a snowy forest gap at Montmorency Forest in Quebec, Canada (47°19′ N, 71°10′ W). Two heating strategies were evaluated during this period: fractional heating (cyclic on/off) and continuous heating. Fractional heating proved to induce noise on the data, while continuously heating systematically left snow around the lenses, resulting in increased longwave measurement (+37.20 MJ m^–2) and a decreased shortwave measurement (−1.79 MJ m^–2) for the winter period. Heating modules alone are insufficient to ensure high-quality data from radiometers in windless, snowy environments; hence solutions such as the SRD should be prioritized.