Regional high-resolution Downscaling of Climate Change in the Antarctic (REDOCCA)

南极气候系统的变化与大气-海洋-海冰的相互作用密切相关。南极的韦德尔海是一个关键区域，在那里AOI过程，如沿海冰川的海冰产生和相关的高盐度陆架水的形成，强烈影响海洋和冰冻圈。该项目的总体目标是通过高分辨率大气/海洋/海冰模拟，研究21世纪中叶和末期韦德尔海大气条件的变化及其对海洋环流的影响。将使用大气区域气候模式CCLM(南极分辨率为15公里，拉森-C冰架区域分辨率为2公里)和高分辨率海冰/海洋模型FESOM(分辨率降至3公里)，对全球CMIP6模拟进行动态下尺度模拟。与对21世纪中叶和末期近期气候和未来气候的粗尺度CMIP6模拟相比较，将研究大气强迫的中尺度过程将如何影响海洋环流以及它们在未来如何变化。波尼亚海的海冰生产和相关的致密水形成是威德尔海南部的关键过程。多尼雅是费尔奇纳-罗恩冰架下海洋环流的主要驱动力，在目前的气候下，这种环流使冰架变得稳定。还特别侧重于南极半岛拉森-C冰架区域的地形效应，它可以影响冰架表面的融化以及冰架下的海洋环流和底部融化。由于全球气候模型不能解决南极半岛地区多尼雅尺度上的影响和地形影响，该项目将对更好地了解南极气候变化框架的变化作出重要贡献。

Changes in the Antarctic climate system are strongly related to atmosphere-ocean-sea ice inter-actions. The Weddell Sea in the Antarctic represents a key area, where AOI processes such as sea ice production in coastal polynyas and associated formation of high-salinity shelf water strongly influence ocean and cryosphere. The overall goal of the project is to study changes of the atmospheric conditions and their impact on the ocean circulation in the Weddell Sea for the mid and end of the 21st century by means of high-resolution atmosphere/ocean/sea ice modelling. A dynamical downscaling of global CMIP6 simulations will be performed using the regional climate model CCLM for the atmosphere (with 15km resolution for the Antarctic and 2km resolution for the region of the Larsen-C ice shelf), and simulations of the high-resolution sea-ice/ocean model FESOM (down to 3km resolution). In comparison with coarse-scale CMIP6 simulations for the recent climate and the future climate for the mid and end of the 21st century it will be studied how mesoscale processes of the atmospheric forcing will impact ocean circulations and how they change in the future. The sea ice production in polynyas and associated dense water formation are key processes for the southern Weddell Sea. Polynyas are a main driver of the ocean circulation beneath the Filchner-Ronne Ice Shelf, which is stabilized by this circulation in the present climate. A special focus lies also on topographic effects in the region of the Larsen-C ice shelf at the Antarctic Peninsula, which can influence melting at the surface of the ice shelf as well as the ocean circulation and basal melting beneath the ice shelf. Since global climate models cannot resolve effects on the scale of polynyas and topographic effects in the region of the Antarctic Peninsula, the project will yield an important contribution to a better understanding of changes in the frame of climate change in the Antarctic.