The Ice-Covered Ocean: the Final Challenge for Climate Models?

极地地区对气候变化的反应最为敏感，并主导着推动这一变化的关键过程。然而，它们是人们所知最少的地区，部分原因是历史上观测的缺乏。气候模式还发现高纬度地区特别具有挑战性，那里的海洋过程的长度尺度比低纬度地区小得多。海洋与冰冻圈相互作用的模拟是一个活跃的研究领域。该项目将南大洋和南极洲周围的新观测结果与英国气象局ipcc级气候模型hagem的最新发展结合在一起。它将讨论IPCC模型与海洋测量数据的对比效果如何，并评估正在hagem实施的新冰架模型对气候的影响。相对温暖的海洋与漂浮的冰架的相互作用可能会加速南极冰盖的融化，从而导致海平面上升。海冰融化和冰架融化都会引起大陆架的新鲜。随后的海冰形成导致盐度和密度的增加。这些水团的转变过程产生了密集、寒冷的流出物，成为南极底水。即使在漩涡解析的海冰模型中，这些过程也没有得到很好的体现；在气候模式中，这些过程是亚网格尺度的，必须参数化。该项目有两个方面。首先，学生将研究现有的IPCC气候模式对南大洋和南极大陆架的模拟，这是一个验证不足的地区。学生将量化水质量特性的表现程度，并评估在模型和观测领域中密集水的形成位置和方式。观测数据将包括SASSI的经向水文剖面和一年的系泊，SASSI是一个国际极地年项目，在南极大陆架和斜坡上有一个密集的实地阶段（2008-2010）。这将有助于评估环极和季节性水团特征。再往北，我们将利用Argo浮标覆盖南大洋2000米以上的区域。第二个方面将涉及学生对哈格姆新发展的评价。一个冰架模型被包括在HadGEM中，作为一个更广泛的模型开发的一部分，将相互作用的冰盖与海洋和大气结合起来。这取决于经过充分验证的参数化，以将温暖的中深水输送到冰架底部，因此模型水团的验证将直接影响到这方面。学生将评估海洋与冰架相互作用的过程，包括温暖的中深水上涌到大陆架和冰架融化水对海洋的影响。这是一个难得的机会，让学生参与评估一个主要气候模式的重大升级，以及随之而来的海洋和大气成分是否得到了“改善”。学生将接受处理大型数据集的训练；计算机编程;数值模拟和海洋/气候动力学。他们将参加南大洋研究巡航，学习观测海洋学技术和数据质量控制。他们将受益于参与国际SASSI项目的综合阶段，包括参加讲习班和会议。所有东英吉利大学的博士生都参加可转换技能培训。这个项目通过用新的观测资料验证气候模式的发展，使气象局受益。该学生通过与开发和运行下一代IPCC气候模型的人员密切合作而获益。

The polar regions are most sensitive in responding to climate change, and host key processes driving that change. Yet they are the regions where least is known, in part because of the historical paucity of observations. Climate models also find the high latitudes particularly challenging, where length-scales of ocean processes are much smaller than at low latitudes. Modelling the interaction of ocean and cryosphere is an active area of research. This project brings together new observations in the Southern Ocean and around Antarctica with the latest developments in the UK Met Office's IPCC-class climate model HadGEM. It will address how well the IPCC models perform against ocean measurements, and assess the climate impacts of the new ice shelf model being implemented in HadGEM. Melting of the Antarctic ice sheet may be accelerated by interaction of the relatively warm ocean with floating ice shelves, contributing to sea level rise. Both sea ice melt and ice shelf melt cause a freshening on the continental shelf. Subsequent sea ice formation causes an increase in salinity and hence density. These water mass transformation processes create the dense, cold outflow that becomes Antarctic Bottom Water. These processes are poorly represented even in eddy-resolving ocean-ice models; in climate models these processes are sub-gridscale and must be parameterised. The project has two aspects. First, the student will study simulations from the available IPCC climate models of the Southern Ocean and Antarctic shelf, a poorly validated region. The student will quantify how well the water mass properties are represented, and assess where and how dense water forms in the models and observational fields. Observational data will include the meridional hydrographic sections and year-long moorings of SASSI, an International Polar Year project with an intensive field phase (2008-2010) on the Antarctic continental shelf and slope. This will enable assessing circumpolar and seasonal water mass characteristics. Further north, we will exploit the coverage of the upper 2000 m of the Southern Ocean from Argo floats. The second aspect will involve the student in appraisal of a new development of HadGEM. An ice shelf model is being included in HadGEM, as part of a broader model development to couple interactive ice sheets to the oceans and atmosphere. This depends on well validated parameterisations to transport warm mid-depth waters to the base of the ice shelves, so the validation of model water masses will feed directly into this aspect. The student will assess the processes of interaction of ocean with ice shelves, both the upwelling of warm mid-depth waters onto the continental shelf and impact of ice shelf melt water on the ocean. This is a rare opportunity for a student to be involved in assessing a substantial upgrade to one of the major climate models, and whether the consequent ocean and atmosphere components are 'improved'. The student will be trained in handling large datasets; computer programming; numerical modelling and ocean/climate dynamics. They will participate in a Southern Ocean research cruise to learn observational oceanographic techniques and data quality control. They will benefit from embedding in the synthesis phase of the international SASSI project, including attending workshops and conference sessions. All UEA PhD students attend transferable skills training. This project benefits the Met Office through the verification of climate model developments with new observations. The student gains by working closely with those who are developing and running the next generation of IPCC climate models.