The Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC): an experimental facility for studying ocean–sea-ice–atmosphere interactions

Thomas, Max; France, James; Crabeck, Odile; Hall, Benjamin; Hof, Verena; Notz, Dirk; Rampai, Tokoloho; Riemenschneider, Leif; Tooth, Oliver John; Tranter, Mathilde; Kaiser, Jan

Sea ice is difficult, expensive, and potentially dangerous to observe in nature. The remoteness of the Arctic Ocean and Southern Ocean complicates sampling logistics, while the heterogeneous nature of sea ice and rapidly changing environmental conditions present challenges for conducting process studies. Here, we describe the Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC), a laboratory facility designed to reproduce polar processes and overcome some of these challenges. The RvG-ASIC is an open-topped 3.5 minline-formula3 glass tank housed in a cold room (temperature range: inline-formula−55 to inline-formula+30inline-formulaC). The RvG-ASIC is equipped with a wide suite of instruments for ocean, sea ice, and atmospheric measurements, as well as visible and UV lighting. The infrastructure, available instruments, and typical experimental protocols are described.

To characterise some of the technical capabilities of our facility, we have quantified the timescale over which our chamber exchanges gas with the outside, inline-formula M5inlinescrollmathml italic τ normal l = ( normal 0.66 ± normal 0.07 ) 83pt13ptsvg-formulamathimg3b103a1d601997f896a34f882a4ab34e amt-14-1833-2021-ie00001.svg83pt13ptamt-14-1833-2021-ie00001.png  d, and the mixing rate of our experimental ocean, inline-formula M6inlinescrollmathml italic τ normal m = ( normal 4.2 ± normal 0.1 ) 76pt13ptsvg-formulamathimg816170eaf5673659b6a31f50cf82acfb amt-14-1833-2021-ie00002.svg76pt13ptamt-14-1833-2021-ie00002.png  min. Characterising our light field, we show that the light intensity across the tank varies by less than 10 % near the centre of the tank but drops to as low as 60 % of the maximum intensity in one corner. The temperature sensitivity of our light sources over the 400 to 700 nm range (PAR) is inline-formula(0.028±0.003) W minline-formula−2inline-formulaCinline-formula−1, with a maximum irradiance of 26.4 W minline-formula−2 at 0 inline-formulaC; over the 320 to 380 nm range, it is inline-formula(0.16±0.1) W minline-formula−2inline-formulaCinline-formula−1, with a maximum irradiance of 5.6 W minline-formula−2 at 0 inline-formulaC.

We also present results characterising our experimental sea ice. The extinction coefficient for PAR varies from 3.7 to 6.1 minline-formula−1 when calculated from irradiance measurements exterior to the sea ice and from 4.4 to 6.2 minline-formula−1 when calculated from irradiance measurements within the sea ice. The bulk salinity of our experimental sea ice is measured using three techniques, modelled using a halo-dynamic one-dimensional (1D) gravity drainage model, and calculated from a salt and mass budget. The growth rate of our sea ice is between 2 and 4 cm dinline-formula−1 for air temperatures of inline-formula M22inlinescrollmathml ( - normal 9.2 ± normal 0.9 ) 59pt12ptsvg-formulamathimga44d5e88108d09e85877f9b2f27230bb amt-14-1833-2021-ie00003.svg59pt12ptamt-14-1833-2021-ie00003.png inline-formulaC and inline-formula M24inlinescrollmathml ( - normal 26.6 ± normal 0.9 ) 65pt12ptsvg-formulamathimg49c2ee1ca2e74cc3462b6b3f5c359a9e amt-14-1833-2021-ie00004.svg65pt12ptamt-14-1833-2021-ie00004.png inline-formulaC. The PAR extinction coefficients, vertically integrated bulk salinities, and growth rates all lie within the range of previously reported comparable values for first-year sea ice. The vertically integrated bulk salinity and growthpage1834 rates can be reproduced well by a 1D model. Taken together, the similarities between our laboratory sea ice and observations in nature, as well as our ability to reproduce our results with a model, give us confidence that sea ice grown in the RvG-ASIC is a good representation of natural sea ice.

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Thomas, Max / France, James / Crabeck, Odile / et al: The Roland von Glasow Air-Sea-Ice Chamber (RvG-ASIC): an experimental facility for studying ocean–sea-ice–atmosphere interactions. 2021. Copernicus Publications.

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