Effects of Freshwater Flux Forcing on Interannual Climate Variability and Predictability in the Tropical Pacific

淡水通量强迫对热带太平洋年际气候变化和可预测性的影响

• 批准号: 1061998
• 负责人: Rong-Hua Zhang
• 金额: $ 60万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-12-01 至 2014-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1061998&HistoricalAwards=false
• 关键词: Effects; Freshwater; Flux; Forcing; Interannual

Freshwater flux (FWF) is an important atmospheric forcing to the ocean, involving interactions among the Earth's water cycle, ocean circulation, and climate. Recent modeling studies have shown that the FWF-related ocean salinity in the tropical Pacific is important to the tropical dynamics and El Niño-Southern Oscillation (ENSO), and also has important implications for the use and interpretation of sea level, and for ocean data assimilation. However, FWF forcing and its related salinity effects in the tropical Pacific have not been realistically represented in many state-of-the-art coupled climate models; the FWF forcing has not been even included in most simplified coupled models used for ENSO forecasts. This project will investigate the roles of FWF forcing in modulating interannual variability and predictability for the tropical Pacific climate system using observational data and a hybrid coupled model (HCM). The investigators will test a hypothesis that FWF forcing in the tropical Pacific induces a positive climate feedback, which presents a new mechanism for the modulation of ENSO and significant tropical bias sources for ENSO simulation and prediction. They will develop an empirical model for interannual FWF variability from historical precipitation and evaporation data. This Sea Surface Temperature (SST)-dependent, prognostic representation of anomalous FWF forcing allows for an interactive feedback between FWF and SST during ENSO cycles. Then, this FWF model will be incorporated into an HCM of the tropical Pacific to take into account FWF forcing and to represent FWF-induced climate feedback. The realistic inclusion of FWF forcing in a coupled ocean-atmosphere model is expected to lead to better ENSO simulations and predictions. Various numerical experiments will be conducted to quantify the extent to which FWF forcing can contribute to seasonal-to-interannual climate variability and predictability in the region. In particular, the effect of FWF forcing on the ENSO modulation will be a focus. The broader impacts of this project include (1) the potential for direct improvements in ENSO simulations and predictions in coupled ocean-atmosphere models by taking into account the FWF-induced climate feedback; (2) important implication for understanding global water cycle in a changing climate due to global warming; (3) interdisciplinary learning and training experience for undergraduate and graduate students, and postdoctoral researchers; (4) wide dissemination of the results through publications and meeting/workshop presentations.

淡水通量（FWF）是一个重要的大气强迫海洋，涉及到地球水循环，海洋环流和气候之间的相互作用。最近的模拟研究表明，热带太平洋与FWF相关的海洋盐度对热带动力学和厄尔尼诺-南方涛动（ENSO）非常重要，对海平面的使用和解释以及海洋数据同化也具有重要意义。然而，FWF强迫及其相关的热带太平洋盐度的影响，并没有现实地表现在许多国家的最先进的耦合气候模式，FWF强迫甚至没有被包括在最简化的耦合模式用于ENSO预测。本项目将利用观测资料和一个混合耦合模式（HCM）研究FWF强迫在调节热带太平洋气候系统年际变率和可预报性方面的作用。研究人员将检验一个假设，即热带太平洋的FWF强迫引起正的气候反馈，这为ENSO的调制提供了一种新的机制，并为ENSO模拟和预测提供了重要的热带偏差来源。他们将根据历史降水和蒸发数据建立一个FWF年际变化的经验模型。这种依赖于海表温度（SST）的异常FWF强迫的预报表示允许在ENSO循环期间FWF和SST之间的交互反馈。然后，这个FWF模式将被纳入热带太平洋的HCM考虑FWF强迫和FWF引起的气候反馈。在一个耦合的海洋-大气模式中现实地包括FWF强迫，预计将导致更好的ENSO模拟和预测。将进行各种数值试验，以量化FWF强迫对该地区季节到年际气候变率和可预测性的贡献程度。特别是FWF强迫对ENSO调制的影响将是一个焦点。 该项目更广泛的影响包括：（1）通过考虑FWF引起的气候反馈，有可能直接改进耦合海洋-大气模式中的ENSO模拟和预测;（2）对理解全球变暖引起的气候变化中的全球水循环具有重要意义;（3）为本科生、研究生和博士后研究人员提供跨学科学习和培训经验;（4）通过出版物和会议/研讨会演讲广泛传播结果。