Reconciling US Southwest Hydroclimate Model Projections and Geologic Data: Constraints from the Miocene Climate Optimum

协调美国西南水文气候模型预测和地质数据：中新世气候最佳值的限制

• 批准号: 2202916
• 负责人: Maria Rugenstein
• 金额: $ 56.8万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2202916&HistoricalAwards=false
• 关键词: Reconciling; US; Southwest; Hydroclimate; Model

As atmospheric CO2 rises and the world warms, water availability in the US Southwest remains a pressing concern. Ongoing population growth combined with one of the worst droughts in more than a millennia has placed tremendous pressure on water resources in the region. Models that simulate global climate generally find that the US Southwest will become more arid as atmospheric CO2 rises, because higher temperatures will increase evaporation of water from the surface. In contrast to model projections, the Southwest US appears to be wetter during periods in the geologic past when atmospheric CO2 was higher. This disagreement between model projections and geologic data challenges our ability to understand how water availability in the US Southwest will change as atmospheric CO2 rises. This research focuses on understanding this disagreement by investigating how different climate model simulations project changes in the water cycle and comparing these simulations with new data from a globally warmer period 15 million years ago during the middle Miocene. This work will improve society’s ability to understand how the water cycle in the US Southwest will change in the future.This project will collect new sedimentary carbonate stable isotope data from Santa Fe Group of northern New Mexico that span the Miocene Climate Optimum (MCO). The sedimentary stable isotope values are sensitive to moisture source, precipitation seasonality, temperature, and primary productivity. In turns, numerous ash deposits in the targeted basin provide the potential for a high-resolution, absolute chronology to link to the oceanic record of the MCO. The researchers will analyze existing millennial-long coupled (ocean-atmosphere-land-sea ice) climate model simulations and large initial condition ensembles to differentiate between internal variability, the transient, and the equilibrium hydroclimate response to CO2 forcing and various SST patterns. Further simulations will apply a newly developed method of simulating a hydroclimate Green’s function to rapidly compute local P responses to a large range of SST pattern changes, which are hypothesized to force US Southwest rainfall. The combination of these tasks will permit the researchers to identify drivers of US Southwest hydroclimate change and reconcile model simulations and paleo archives to warming or pinpoint the discrepancies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

随着大气中二氧化碳含量的上升和全球变暖，美国西南部的水资源供应仍然是一个紧迫的问题。持续的人口增长加上千年以来最严重的干旱之一，给该地区模拟全球的水资源带来了巨大压力。气候普遍发现，随着大气中二氧化碳含量的上升，美国西南部将变得更加干旱，因为较高的温度会增加地表水的蒸发，与模型预测相反，在过去的地质时期，美国西南部的大气似乎更加湿润。模型预测和地质数据之间的这种差异挑战了我们了解美国西南部的可用水量如何随着大气中二氧化碳含量的上升而变化的能力。本研究的重点是通过调查不同的气候模型模拟如何预测水的变化来理解这种差异。循环并将这些模拟与 1500 万年前中新世中期全球变暖时期的新数据进行比较。这项工作将提高社会了解美国西南部水循环未来将如何变化的能力。该项目将收集新的沉积物。碳酸盐稳定来自新墨西哥州北部圣达菲群跨越中新世气候最佳期 (MCO) 的同位素数据，沉积物稳定同位素值对水分来源、降水季节性、温度和初级生产力敏感。目标盆地提供了与 MCO 海洋记录联系起来的高分辨率、绝对年代学的潜力，研究人员将分析现有的千年耦合（海洋-大气-陆地-海冰）气候模型模拟。和大型初始条件集合，以区分内部变异性、瞬态和平衡水文气候对二氧化碳强迫和各种海表温度模式的响应，进一步的模拟将应用新开发的模拟水文气候格林函数的方法来快速计算对大的局部 P 响应。这些任务的结合将使研究人员能够确定美国西南部水文气候变化的驱动因素，并协调模型模拟和古档案以变暖或查明气候变化。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。