The De-Icing Comparison Experiment (D-ICE): a study of broadband radiometric measurements under icing conditions in the Arctic

Abstract. Surface-based measurements of broadband shortwave (solar) and longwave (infrared) radiative fluxes using thermopile radiometers are made regularly around the globe for scientific operational environmental monitoring. The occurrence ice on sensor windows in cold environments – whether snow, rime, or frost is a common problem that difficult to prevent as well correct post-processing. Baseline Surface Radiation Network (BSRN) community recognizes radiometer icing major outstanding measurement uncertainty. Towards constraining this uncertainty, De-Icing Comparison Experiment (D-ICE) was carried out at NOAA Atmospheric Observatory Utqiaġvik (formerly Barrow), Alaska, from August 2017 July 2018. purpose D-ICE evaluate existing ventilation heating technologies developed mitigate icing. consisted 20 pyranometers 5 pyrgeometers operating various ventilator housings alongside systems part NOAA's Barrow BSRN station US Department Energy Measurement (ARM) program North Slope Alaska Oliktok Point observatories. To detect icing, were monitored continuously cameras, with total more than 1 million images domes archived. Ventilator ventilator–heater performance overall skillful average mitigating formation 77 % (many >90 %) time during which conditions present. Ventilators without elements also effective capable providing heat through roughly equal contributions waste energy fan adiabatic downstream fan. This provided ∼0.6 ∘C warming, enough subsaturate air up relative humidity (with respect ice) ∼105 %. Because mitigation performed well, near complete record verified ice-free radiometric assembled duration campaign. well-characterized data set suitable model evaluation, particular Year Polar Prediction (YOPP) first Special Observing Period (SOP1). We used calculate short- long-term biases iced sensors, finding can be +60 W m−2 (longwave) −211 +188 (shortwave). However, because frequency by ventilators, cloud conditions, timing available sunlight, monthly means generally less aggregate uncertainty attributed other conventional sources both longwave.