Adjoint sensitivity of sea-level and inter-basin transports to surface forcing and circulation anomalies in present and future climates

海平面上升是未来气候变化中为数不多的几个无可争辩的因素之一，我们已经承诺，无论未来的排放情况如何。对下个世纪区域海平面变化的预测与对全球海平面上升的预测在幅度上相似。然而，在对其模式、幅度和根本原因的模型预测之间存在着巨大的差异。该项目的广泛目标是确定区域海平面变化及其相关海洋环流变化、地表热量、淡水和动量通量、远程环流异常以及不确定模式参数的敏感性。这些敏感性将在当前气候和各种未来气候情景下确定。我们将使用最先进的海洋模型及其所谓的“伴随”来有效地确定这些灵敏度。与传统的建模研究不同，在传统的建模研究中，必须进行大量的实验来确定模型输出对模型输入的灵敏度，而伴随模型仅从单个模型运行中提供这些灵敏度中的每一个。该项目是及时的，因为它解决了上个月发布的政府间气候变化专门委员会报告中确定的有关海平面变化和环流预测的不确定性的关键问题。它还借鉴了该小组在使用海洋模型及其附属模型方面积累的专门知识和成功经验，通过目前由国家海洋研究中心资助的一个项目，将在大西洋翻转环流中观察到的变化归因于当地和偏远的表面强迫。

Sea level rise is one of the few undisputed elements of future climate change to which we are already committed regardless of future emissions scenario. Projections for regional sea level change over the next century are similar in magnitude to those for global sea level rise. Yet there are wide discrepancies between model projections of its pattern, amplitude and the underlying causes. The broad aim of this project is to determine the sensitivities of regional sea level changes, and associated changes in ocean circulation, to surface fluxes of heat, freshwater and momentum, to remote circulation anomalies, and to uncertain model parameters. These sensitivities will be determined for both the present climate and various future climate scenarios. We will use a state of the art ocean model and its so-called 'adjoint' to efficiently determine these sensitivities. In contrast to traditional modelling studies, in which a large number of experiments must be performed to determine the sensitivity of a model output to model inputs, the adjoint model provides each of these sensitivities from just a single model run. The project is timely in that it addresses key issues identified in the Intergovernmental Panel for Climate Change report, released last month, concerning uncertainties in projections of sea level change and circulation. It also draws on the expertise and success that the team has built up in using the ocean model and its adjoint through a current NERC-funded project to attribute changes observed in the overturning circulation in the Atlantic to local and remote surface forcing.