Abstract. Projections of global climate change and Arctic amplification are sensitive to the representation of low-level cloud phase in climate models. Ice-nucleating particles (INPs) are necessary for primary cloud ice formation at temperatures above approximately -38 °C, and thus significantly affect cloud phase and cloud radiative effect. Due to their complex and insufficiently understood variability, INPs constitute an important modelling challenge, especially in remote regions with few observations, such as the Arctic. In this study, INP observations were carried out at Andenes, Norway in March 2021. These observations were used as a basis for an Arctic-specific and purely temperature-dependent INP parameterization, and implemented into the Norwegian Earth System Model. This implementation results in an annual average increase in cloud liquid water path (CLWP) of 70 % for the Arctic, and improves the representation of cloud phase compared to satellite observations. The change in CLWP in boreal autumn and winter is found to likely be the dominant contributor to the annual average increase in net surface cloud radiative effect of 2 W m^-2. This large surface flux increase brings the simulation into better agreement with Arctic ground-based measurements. Despite that the model cannot respond fully to the INP parameterization change due to fixed sea surface temperatures, Arctic surface air temperature increases with 0.7 °C in boreal autumn. These findings indicate that INPs could have a significant impact on Arctic climate, and that a region-specific INP parameterization can be a useful tool to improve cloud representation in the Arctic region.

中文翻译：

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使用特定区域的冰核粒子参数化可以改善北极云在全球气候模型中的代表性


摘要。全球气候变化和北极放大的预测对气候模型中低层云相的表示很敏感。冰核颗粒（INP）对于温度高于约-38°C的初级云冰形成是必需的，因此显着影响云相和云辐射效应。由于 INP 的复杂性和未充分理解的变异性，INP 构成了重要的建模挑战，特别是在北极等观测很少的偏远地区。在这项研究中，INP 观测于 2021 年 3 月在挪威安德内斯进行。这些观测被用作北极特定且纯粹与温度相关的 INP 参数化的基础，并实施到挪威地球系统模型中。这一实施导致北极云液态水路径 (CLWP) 年平均增加 70%，并与卫星观测相比改善了云相的表征。研究发现，北半球秋季和冬季 CLWP 的变化可能是净表面云辐射效应年平均增加 2 W m ^-2 的主要贡献者。这种巨大的表面通量增加使模拟与北极地面测量结果更加一致。尽管由于海面温度固定，该模型无法完全响应 INP 参数化变化，但北半球秋季北极表面气温仍增加了 0.7 °C。这些发现表明，INP 可能对北极气候产生重大影响，并且特定区域的 INP 参数化可以成为改善北极地区云代表性的有用工具。