Sea ice physical properties were determined at 21 first‐year ice (FYI) and 20 multiyear ice (MYI) stations in the Pacific sector of the Arctic during summer in 2008–2018. The bulk ice temperature was between −2.7 and −0.3 °C for FYI and between −1.7 and −0.2 °C for MYI. The bulk salinity was 0.4–3.2 practical salinity unit (psu) for FYI and 0.4–2.4 psu for MYI. A low‐salinity layer and an almost fresh layer were always present at the top of FYI and MYI, respectively. The bulk density was 600.3–900.1 kg/m³ for FYI and 686.1–903.3 kg/m³ for MYI. The upper layer density was less than the lower layer density due to higher gas content. Salinity and density were less than previously reported values of summer sea ice, and their parameterization formulae were updated. The brine and gas volume fractions were determined based on the measured ice temperature, salinity, and density. The average bulk brine and gas volume fractions were 11.3 ± 6.2% and 14.9 ± 7.9% for FYI and 9.5 ± 11.0% and 13.5 ± 12.7% for MYI. Typical brine and gas volume fraction profiles were identified and parameterized using regression analysis. The large brine and gas content of sea ice affects the sea ice melting. The energy used to melt a unit volume of summer Arctic sea ice was estimated as (2.26 ± 0.29) × 10⁵ kJ for FYI and (2.36 ± 0.24) × 10⁵ kJ for MYI. This study shows that the current physical state of the Arctic summer sea ice is different from earlier sea ice climatology, and the results will guide further research and modeling of Arctic sea ice.

中文翻译：

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2008-2018年北极太平洋太平洋夏季海冰的物理性质

在2008-2018年夏季，在北极太平洋地区的21个第一年冰（FYI）和20个多年冰（MYI）站确定了海冰的物理特性。FYI的大冰温度在-2.7至-0.3°C之间，而MYI在-1.7至-0.2°C之间。FYI的总盐度为0.4–3.2实用盐度单位（psu），MYI的总盐度为0.4–2.4 psu。在FYI和MYI的顶部始终始终存在一个低盐度层和一个几乎新鲜的层。FYI的堆积密度为600.3–900.1 kg / m ³，FYI的堆积密度为686.1–903.3 kg / m ³对于MYI。由于较高的气体含量，上层密度小于下层密度。盐度和密度小于以前报道的夏季海冰值，并且更新了它们的参数化公式。根据测得的冰温，盐度和密度确定盐水和气体的体积分数。FYI的平均散装盐水和气体体积分数分别为11.3±6.2％和14.9±7.9％，MYI为9.5±11.0％和13.5±12.7％。使用回归分析确定了典型的盐水和天然气体积分数分布并进行了参数化。海冰中大量的盐水和气体会影响海冰融化。 FYI用于融化单位体积的夏季北极海冰的能量估计为（2.26±0.29）×10 ⁵ kJ和（2.36±0.24）×10 ⁵ MYI的kJ。这项研究表明，北极夏季海冰的当前物理状态不同于早期的海冰气候学，其结果将为北极海冰的进一步研究和建模提供指导。