The Affect of Altered Ocean Heat Transports on Climate: Feedback Potential During Periods of Atmospheric Trace Gas Increase

Chandler, Mark A. Martinson, David Gornitz, Vivien M. Rind, David H.哥伦比亚大学题目：海洋热输送变化对气候的影响：大气微量气体增加时期的反馈势。本项目目的是研究气候变化数值模拟中海洋热输送的年代际到世纪尺度的影响。该项目使用戈达德空间研究所的大气环流模型，结合一个海洋模型（包括海洋经向热量输送），直接测试海洋热量输送的变化是否会增强或减轻由微量气体引起的全球变暖的影响。该项目设计为一个为期三年，分两个阶段的研究：第一阶段，将使用GCM实验的表面热通量诊断来计算与历史（20世纪）海面温度和海冰范围异常相关的潜在海洋热输送。海温和海冰异常将从最全面的数据集获得，包括：COADS， Navy/NOAA, Walsh， ESMR， SMMR和SMM/I，所有这些数据集目前都是内部的。此外，将根据小冰期（约公元1700年）和末次盛冰期（约18-2lky BP）的GCM模拟和代理数据计算海洋热输运，以便获得更接近系统潜在变率的更大的热通量变化。该项目的第二阶段侧重于模拟海洋热输送变化对瞬态微量气体增加情景的气候影响。计划进行10次100年模拟，其中第一阶段计算的海洋热值将用于干扰与大气微量气体增加有关的正常气候变化模式。根据对运行在IBM RS/6000-580工作站上的GISS 4ox50 GCM当前计算效率的估计，第二阶段的模拟将需要大约两年的时间才能完成。单个瞬态实验将以每三个月一次的速度完成和分析。该项目的主要目标是确定与空气/海洋/冰系统变率相关的气候变化模式，并估计可能伴随大气微量气体增加引起的气候变化的潜在海洋能反馈。对这种气候模式进行指纹识别将提高我们探测海洋引起的气候变化迹象的能力，并能提高我们区分自然变率和人为气候变化的能力。此外，它将为我们提供海洋能力的定量评估，通过能量输运反馈，改变气候敏感性和GCM对未来气候变化的预测。完全耦合的大气-海洋-冰模式在不久的将来不太可能达到可靠的预测能力，而这些实验为测量海洋改变GCM未来气候诊断的能力提供了现实的替代方案。本项目由美国国家科学基金气候建模、分析和预测项目资助。

Abstract ATM-9320372 Chandler, Mark A. Martinson, David Gornitz, Vivien M. Rind, David H. Columbia University Title: The Affect of Altered Ocean Heat Transports on Climate: Feedback Potential During Periods of Atmospheric Trace Gas Increase The objective of this project is to investigate the decadal to century-scale affects of ocean heat transports in numerical climate change simulations. The project uses the Goddard Institute for Space Studies atmospheric general circulation model, coupled to an ocean model that includes meridional transport of heat by the oceans, to test directly whether changes in ocean heat transport could enhance or ameliorate the effects of trace-gas-induced global warming. The project is designed as a three year, two phase study: In the first phase, surface heat flux diagnostics from GCM experiments will be used to calculate the potential ocean heat transport associated with historical (20th century) anomalies in sea surface temperatures and sea ice extent. The SST and sea ice anomalies will be acquired from the most comprehensive data sets available including: COADS, Navy/NOAA, Walsh, ESMR, SMMR, and SMM/I, all of which are currently in-house. In addition, ocean heat transports will be calculated from GCM simulations and proxy data from the Little Ice Age (ca. 1700 AD) and Last Glacial Maximum (ca. 18-2lky BP) in order to obtain larger variations of heat fluxes that may be closer to the potential variability of the system. The second phase of the project focuses on simulations of the climatic effects of altered ocean heat transports in conjunction with transient trace gas increase scenarios. Ten 100- year simulations are planned in which the ocean heat values, calculated in phase one, will be used to perturb the normal pattern of climate change associated with the atmospheric trace gas increase. The simulations in phase two will take approximately two years to complete, based on estimates of the current comput ational efficiency of the GISS 4ox5o GCM running on IBM RS/6000-580 workstation. Individual transient experiments will be completed and analyzed at the rate of one every three months. The primary objective of this project is to identify patterns of climate change that are associated with variability in the air/sea/ice system and to estimate the potential ocean energy feedbacks that may accompany climate changes induced by atmospheric trace gas increase. Fingerprinting of such climate patterns will improve our ability to detect the signs of ocean-induced climate change and can improve our ability to distinguish between natural variability and anthropogenic climate change. Furthermore, it will provide us with a quantitative assessment of the oceans ability, through energy transport feedbacks, to alter the climate sensitivity and GCM predictions of future climate change. In lieu of fully coupled atmosphere-ocean-ice models, which are unlikely to reach a reliable predictive capacity in the near future, these experiments provide the realistic alternative for gauging the ability of the oceans to alter GCM future climate diagnoses. This project is funded under the USGCRP NSF Climate Modeling, Analysis and Prediction program.