Collaborative Research: Investigation of Ningaloo Nino: The role of Madden-Julian Oscillation and Leeuwin current variability

在2010-2011年的强烈拉尼娜事件期间，观测到了极端的海洋变暖和澳大利亚西海岸的海洋热浪。这一极端变暖事件被称为“宁格洛尼诺现象”，类似于太平洋的厄尔尼诺现象和大西洋的本格拉尼诺现象等其他东部大陆边界变暖现象。在最近的宁格洛尼诺事件期间，澳大利亚西海岸外的海温比长期季节性平均值高出5摄氏度以上，这足以影响大范围的大气环流，并对海洋生态系统和资源造成破坏性影响。在该区域，东南印度洋的局部和远程强迫海洋环流，如Leeuwin洋流系统，可能在宁格洛尼诺事件的发展中发挥关键作用。这一拟议项目的主要目标是了解控制宁格洛尼诺/尼娜现象发展的物理过程。拟议项目将有助于规划和设计重大国际实地活动，改进印度洋的观测网络，通过支持学生和博士后来加强教育，并促进气候预测。私人投资机构的其中一个机构被美国教育部认可为拉美裔服务机构，因此该项目将有助于为代表不足的少数族裔提供培训机会。此外，拟议的研究将确定必须在气候模型中很好地表示的关键过程，这将有助于改进气候模型模拟，并通过提供更可靠的气候预测而造福社会。在拟议的研究中，将探讨影响“宁格鲁尼诺”的各种海洋过程，包括：1)来自太平洋的远距离强迫和印度洋上的强迫对Leeuwin洋流系统和宁格洛尼诺/尼娜的影响；2)地形对向西辐射的Rossby波及其与宁格罗尼诺/尼娜事件相关的下涌/上升流的影响；3)MJO通过海洋过程对Leeuwin流和宁阿洛尼诺/尼娜的影响；4)澳大利亚夏季风在影响宁格鲁尼诺/尼娜事件中的作用。将采用一个高分辨率的印度-太平洋盆地海洋环流模式(OGCM)，该模式能够充分反映印度尼西亚海复杂的水深和地形。将对来自强化现场观测的数据和卫星数据进行彻底分析，并最大限度地利用这些数据来验证该模型。将进行一系列面向过程的OGCM实验，以量化远程和局地强迫对Leeuwin洋流系统和宁加洛/尼诺的影响，并确定涉及的关键过程，包括沿海Kelvin波的作用和Rossby波的辐射。结果将确定决定与宁格洛尼诺相关的海面温度和上层海洋变异性的物理过程，这可能会改变大气环流。特别是，马登-朱利安振荡和来自太平洋的远程强迫对Leeuwin洋流系统和宁加洛尼诺的影响将通过一系列OGCM实验来量化，这些影响不能仅通过观测来分离。因此，拟议项目的完成将大大促进我们对勒温洋流系统和宁格洛尼诺现象的动态的了解，宁格洛尼诺现象是东南印度洋的主要气候变化。

During the strong La Niña event in 2010-2011, extreme ocean warming and a marine heat wave off the west coast of Australia were observed. This extreme warming event is termed as "Ningaloo Niño", an analogy to other eastern continental boundary warming phenomena such as El Niño in the Pacific and the Benguela Niño in the Atlantic. During the recent Ningaloo Niño event, SSTs off the west coast of Australia were more than 5 degree centigrade above long-term seasonal means, which is sufficient to impact large-scale atmospheric circulation and has devastating impacts on marine ecosystems and resources. In this region, locally and remotely forced ocean circulations in the southeast Indian Ocean, such as Leeuwin current system, may play a crucial role in the development of the Ningaloo Niño event. The primary goal of this proposed project is to understand physical processes that control the development of Ningaloo Niño/Niña. The proposed project will contribute to the plan and design of major international field campaigns and improving observational network in the Indian Ocean, enhancing education through supporting students and a post-doc, and advancing climate prediction. One of the PIs' institutions is recognized as a Hispanic Serving Institution by the U.S. Department of Education, and thus the project will contribute to providing training opportunities for underrepresented minorities. In addition, the proposed research will identify key processes that must be represented well in climate models, which will help improve climate model simulation and benefit society by providing more reliable climate prediction. A variety of oceanic processes that affect the 'Ningaloo Niño' will be explored in the proposed study including: 1) The impact of the remote forcing from the Pacific Ocean versus forcing over the Indian Ocean on the Leeuwin current system and Ningaloo Niño/Niña; 2) Effects of topographic trapping of westward radiating Rossby waves and their associated downwelling/upwelling associated with Ningaloo Niño/Niña events; 3) The influence of the MJO on Leeuwin current and Ningaloo Niño/Niña via oceanic processes; 4) The role of Australian summer monsoon in affecting the Ningaloo Niño/Niña events. A high-resolution Indo-Pacific basin ocean general circulation model (OGCM) will be employed, which can adequately represent complex bathymetry and topography in the Indonesian Seas. The data from enhanced in-situ observations and satellite data will be thoroughly analyzed and maximally utilized to validate the model. A series of process-oriented OGCM experiments will be performed, to quantify the impacts of remote & local forcing on the Leeuwin current system and Ningaloo/Niño, and identify key processes involved, including the role of coastal Kelvin waves and radiation of Rossby waves. The results will identify the physical processes that determine the sea surface temperature and upper-ocean variability associated with Ningaloo Niño, which can alter atmospheric circulations. In particular, the impacts of Madden-Julian oscillation and the remote forcing from the Pacific on the Leeuwin current system and Ningaloo Niño, which cannot be isolated by observations alone, will be quantified by a series of OGCM experiments. Consequently, completion of the proposed project will substantially advance our understanding of the dynamics of Leeuwin current system and Ningaloo Niño that is major climate variability in the southeast Indian Ocean.