The Significance of the Melt-Pond Scheme in a CMIP6 Global Climate Model
The Significance of the Melt-Pond Scheme in a CMIP6 Global Climate Model
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CMIP6 全球气候模型中融化池方案的意义
DOI：
10.1175/jcli-d-22-0902.1
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发表时间：
2024
影响因子：
4.9
通讯作者：
Diamond R
中科院分区：
文献类型：
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作者：
Diamond R
已经观察和记录了融化池塘对海冰反照率的影响。在大气环流模型中，池塘现在通过间接诊断治疗(“隐式”方案)或预测熔池参数化(“显式”方案)来解释。然而，缺乏显示这些计划对模拟北极气候的影响的研究。我们在这里着重于使用大气环流模型HadGEM3来纠正这一点，该模型是为数不多的具有详细显式池塘方案的模型之一。我们确定了融化池塘对海冰和气候的影响，以及相关的冰-海-气相互作用。我们在三个不同的时期运行了一组恒定的强迫模拟，并首次表明，使用机械上不同的池塘方案可以导致非常显著的不同的海冰和气候状态。在近期条件下，隐式方案永远不会产生无冰的夏季北极，而显式方案在35%的年内产生无冰的北极，并使秋季北极气温升高5°~8°C。我们发现，对气候和海冰的影响取决于冰态：在近期和末次间冰期条件下，薄的海冰对池塘的形成和参数化非常敏感，而在工业化前时期，较厚的海冰对池塘方案的选择不那么敏感。这两种常用的海冰反照率参数在工业化前条件下产生类似的结果，但在较温暖的气候条件下导致北冰洋海冰以及海洋和大气温度截然不同。因此，海冰模式中物理参数的变化可能会对模拟的海冰、海洋和大气产生很大的影响。意义陈述本研究利用HadGEM3-GC3.1-LL大气环流模式，研究了不同气候条件下融化池塘对北极海冰的影响。此外，我们还研究了改变所使用的池塘方案类型的影响。我们发现，在近期和更温暖的古气候条件下，改变池塘方案会导致GCM模拟北极海冰、海洋和大气的方式有很大不同。这些巨大的差异以前没有发现过，因为这是第一次进行这种类型的GCM研究。我们的结果证明了融化池塘的重要性，以及它们对海洋和大气的更广泛影响。此外，他们还提出，更好地评估海冰过程的代表性，对于对未来气候变化的有力预测至关重要。
The impact of melt ponds on sea ice albedo has been observed and documented. In general circulation models, ponds are now accounted for through indirect diagnostic treatments (“implicit” schemes) or prognostic melt-pond parameterizations (“explicit” schemes). However, there has been a lack of studies showing the impacts of these schemes on simulated Arctic climate. We focus here on rectifying this using the general circulation model HadGEM3, one of the few models with a detailed explicit pond scheme. We identify the impact of melt ponds on the sea ice and climate, and associated ice–ocean–atmosphere interactions. We run a set of constant forcing simulations for three different periods and show, for the first time, that using mechanistically different pond schemes can lead to very significantly different sea ice and climate states. Under near-future conditions, an implicit scheme never yields an ice-free summer Arctic, while an explicit scheme yields an ice-free Arctic in 35% of years and raises autumn Arctic air temperatures by 5° to 8°C. We find that impacts on climate and sea ice depend on the ice state: under near-future and last-interglacial conditions, the thin sea ice is very sensitive to pond formation and parameterization, whereas during the preindustrial period the thicker sea ice is less sensitive to the pond scheme choice. Both of these two commonly used parameterizations of sea ice albedo yield similar results under preindustrial conditions but in warmer climates lead to very different Arctic sea ice and ocean and atmospheric temperatures. Thus, changes to physical parameterizations in the sea ice model can have large impacts on simulated sea ice, ocean, and atmosphere.Significance StatementThis study investigates the impacts of melt ponds on Arctic sea ice under different climate conditions, using the HadGEM3-GC3.1-LL general circulation model (GCM). Additionally, we study the impact of changing the type of pond scheme used. We find that changing the pond scheme causes large differences to how a GCM simulates Arctic sea ice, the ocean, and the atmosphere, for both near-future and warmer paleoclimate conditions. These large differences have not been found previously, because this is one of the first GCM studies of this type. Our results demonstrate the importance of melt ponds, and their wider impacts on ocean and atmosphere. Furthermore, they suggest that better evaluation of the representation of sea ice processes is vital for the robust projection of future climate change.