Sea ice algae play an important role in the Arctic Ocean ecosystem, driving primary production in the spring and sequestering carbon to the deep ocean. Up to 45% of Arctic Ocean primary production occurs in ice-covered areas; photosynthetically active radiation (PAR) is fundamental to driving this production. Sea ice, and particularly snow, strongly scatter and reflect light, reducing the amount of PAR transmitted to the ice-ocean interface. The effect that varying thicknesses of sea ice (0.2–3.5 m) and snow (0.01–1 m) have on the value of PAR transmittance at the ice-ocean interface are considered for a Winter, Spring, and Summer scenario. When characteristic Arctic Ocean conditions (2 m sea ice and ∼0.2 m snowpack) are modeled, there is roughly a two-fold difference in PAR transmittance at the ice-ocean interface between the Winter (0.003) and Spring (0.007) scenarios and an order of magnitude difference with the Summer scenario (0.04). The modeled values correlate within one standard deviation of measured values and show good agreement with extended pan-Arctic Ocean field campaign measurements. The results also indicate that simple exponential decay methods may lead to inaccurate results, and radiative-transfer modeling is required to accurately predict PAR transmittance at the ice-ocean interface. Therefore, this study offers a novel mathematical technique to predict the value of PAR transmittance at the ice-ocean interface. Coupled with year-round near-real-time sea ice and snow thickness remote sensing data, this technique may improve understanding of primary production and carbon budgets in the changing Arctic Ocean.

中文翻译：

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北极冰海界面光合有效辐射（PAR）透射率值的计算

海冰藻在北冰洋生态系统中发挥着重要作用，推动春季初级生产并将碳封存在深海。北冰洋高达 45% 的初级生产发生在冰雪覆盖的地区；光合有效辐射（PAR）是推动这种生产的基础。海冰，尤其是雪，会强烈散射和反射光线，从而减少传输到冰海界面的 PAR 量。在冬季、春季和夏季情景中考虑了不同厚度的海冰 (0.2–3.5 m) 和雪 (0.01–1 m) 对冰海界面处 PAR 透射率值的影响。当对北冰洋特征条件（2 m 海冰和 ∼0.2 m 积雪）进行建模时，冬季 (0.003) 和春季 (0.007) 情景之间冰海界面处的 PAR 透射率大约有两倍的差异，并且与夏季情景 (0.04) 存在数量级差异。建模值与测量值的一个标准偏差内相关，并且与扩展的泛北冰洋现场活动测量结果具有良好的一致性。结果还表明，简单的指数衰减方法可能会导致结果不准确，需要辐射传输模型来准确预测冰海界面的 PAR 透射率。因此，本研究提供了一种新颖的数学技术来预测冰海界面处的 PAR 透射率值。结合全年近实时的海冰和雪厚度遥感数据，该技术可以提高对不断变化的北冰洋初级生产和碳预算的了解。