Collaborative Research: Towards an Understanding of the Role of the Atlantic Theremohaline and Wind Driven Circuluation in Tropical Atlantic Variability (TAV)

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ABSTRACTOCE-0623345Recent coupled climate model simulations show that changes in thermohaline circulation in the Atlantic Ocean can lead to a substantial response in the tropical Atlantic coupled climate system, which in turn can have an impact on global climate. If this proves correct, these modeling results can have tremendous implications on our understanding of the role of the ocean in global climate change. For this reason, it is critically important for us to gain a comprehensive understanding of the dynamical processes that link the changes in high latitudes to those in the tropics. The focus of this project is on the oceanic linkage. In particular, the investigators will explore how changes in the Atlantic Meridional Overturning Cell (MOC) can affect the pathways of the Sub-Tropical Cells (STCs), and how these changes in the STCs can affect the Sea Surface Temperatures (SSTs), and finally how these SST changes can affect the coupled climate variability in the tropical Atlantic. The investigation will be conducted via a hierarchy of coupled climate models in conjunction with observational analysis. An atmospheric model coupled to a 2.5-layer reduced-gravity-ocean model, perhaps the simplest and yet most efficient coupled model suited to investigate MOC/STC interaction and its effect on coupled climate variability, will be used to conduct extensive process-oriented experiments by varying the strength of the imposed MOC to shed light on the effect of the MOC on the Tropical Atlantic Variability (TAV). Then , an atmospheric circulation model coupled to a regional high resolution ocean circulation model capable of resolving mesoscale features in the tropical Atlantic circulation will be forced through its northern and southern open boundaries to allow a more complete look at the effect of the MOC/STCs on coupled feedback. Finally, the output of a comprehensive global coupled climate model used for IPCC assessment will be analyzed and used in conjunction with the other two model experiments to gain further understanding of the impact of Atlantic MOC change on global climate.INTELLECTUAL MERIT: The anticipated outcome of this research will make an important contribution to the understanding of the fundamental ocean circulation physics in Atlantic climate variability and global climate change. A more refined theory of the connection between the different components of the Atlantic ocean circulation is expected to emerge from this study through hypothesis testing and systematic examination of the coupled model experiments. The modeling tools developed in this study will be valuable for future climate studies. BROADER IMPACT: The proposed research addresses the issues pertinent to debates and discussions in climate change sciences. The proposed research will enhance our understanding of long-term climate variability in the tropical Atlantic sector, which has important social and economic impacts on countries in the region. The findings from this study will help educate the general public about the importance of the oceans in global climate change. The project will also help train the next generation of physical oceanographers and climate scientists by directly involving graduate students and postdoctoral researchers in research endeavors with faculty. Some of research results from this project will be integrated into the graduate courses at TAMU.