P2C2: Constraining Mechanisms of Tropical Climate Change Using Simulations and Proxies of the Last Glacial Maximum (LGM)

最后一次冰川盛期(LGM)是21,000年前的一段时间，当时地球是冰川的，比今天要冷得多，它为测试气候一般环流模型提供了一套独特的边界条件。这项提议旨在利用对末次冰盖的模拟来确定当时的沃克环流是更强还是更弱。沃克环流是热带太平洋的一个大气-海洋耦合系统。该项目将试图解决几个重要问题，包括：1)水循环、海表面温度梯度、以及Sunda陆架暴露对过去Walker环流强度的影响？2)在这些机制之间的相互作用中，模式偏差的影响是什么？3)热带太平洋过去气候的不同重建能否被协调并用于约束每一种机制？4)最新的气候模式对LGM期间由于海平面降低而导致的Sunda陆架暴露的响应的模拟情况如何。将在研究中使用的模型也被用于产生关键的古气候模拟，将在IPCC AR5报告中讨论。因此，对不同模型的性能进行评估将对气候研究界非常有价值。

The Last Glacial Maximum (LGM), that period of time 21,000 years ago when the earth was glaciated and significantly colder than today, provides a unique set of boundary conditions to test climate general circulation models. This proposal aims to use simulations of the LGM to determine if the Walker Circulation, a coupled atmosphere-ocean system in the tropical Pacific, was stronger or weaker at that time. The project will attempt to address several important questions including: 1) How important are changes in the hydrological cycle, sea surface temperature gradients, and exposure of the Sunda shelf in affecting past intensity of the Walker Circulation? 2) What is the impact of model bias in the interaction among these mechanisms? 3) Can the different reconstructions of past climate in the tropical Pacific be reconciled and used to constrain each of these mechanisms? 4) How well do state-of-the-art climate models simulate the response of the Walker circulation to the exposure of the Sunda shelf due to lower sea level during the LGM.The models to be used in the study were also used to produce key paleoclimate simulations that will be discussed in the IPCC AR5 reports. Thus the evaluation of the performance of the different models will be very valuable to the climate research community.