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This study investigates the complex interactions between the North Atlantic Current (NAC) and the New England Seamount chain, focusing on the Atlantis II seamount. Employing a high‐resolution submesoscale permitting regional ocean circulation model nested within a basin‐wide simulation, it explores three distinct periods, each 2 weeks long, showcasing varied deep mesoscale and submesoscale circulations around the seamount. The analysis includes Eulerian statistics and Lagrangian particle tracing experiments to explore the transport and mixing impacts of the highly dynamic flow around the seamount. The results reveal significant density variations across the water column, attributed to the seamount's influence on local ocean currents. Specifically, mesoscale and submesoscale vortices, a seamount wake, and lee waves form during periods of increased near‐bottom current flow. These findings highlight the critical role of topographic features in modulating oceanic flows and ocean mixing, which have implications, among others, for nutrient distribution, acoustic propagation, and climate modeling. The variety and variability of the mesoscale and submesoscale circulations that arise in response to the variability in the NAC strength and position in relation to the New England Seamount Chain demonstrate the difficulty in extrapolating general behaviors from isolated observational campaigns. Plain Language Summary: In this study, we ask the question: What happens when a highly variable, strong ocean current interacts with the complex bathymetry of an undersea mountain? We focus on the North Atlantic Current, a major ocean current that originates from the Gulf Stream, and its interactions with the Atlantis II seamount, located several hundred miles off the coast of New England. We used a high‐resolution regional ocean model to simulate ocean currents and their movements around this seamount during different times and conditions. This study shows that the interaction between the North Atlantic Current and the seamount can lead to complex, highly variable dynamics, including, at times, swirling water masses, waves within the ocean, and a large wake that forms behind the mountain. These circulations are important for understanding how water mixes in deep ocean environments, and they affect how heat, salt, and nutrients crucial for marine life are distributed in the water column. Our findings illustrate the significant impact of underwater mountains on the overall ocean circulation and highlight the variability of circulations and mixing regimes that may take place and the inherent difficulties in generalizing behaviors from observational campaigns or idealized modeling studies. Key Points: The interaction of the North Atlantic Current with isolated seamounts is highly variable, generating diverse ocean circulation patternsThe North Atlantic Current's position relative to Atlantis II seamount can form mesoscale/submesoscale vortices, wakes, and lee wavesMesoscale/submesoscale variability around the Atlantis II seamount affects transport and mixing; rates are highly variable as well [ABSTRACT FROM AUTHOR]

Observational and modeling studies have elucidated the influential role played by the southern and northern extratropical Pacific (SEP and NEP) forcing in shaping dynamics of tropical Pacific climate variability. However, the relative importance of the NEP and SEP and the timescale on which they impact the tropics remain unclear. Using a linear inverse model (LIM) that selectively incorporates or excludes tropical‐extratropical coupling, we find a reduction in tropical interannual variability (∼40%) and low‐frequency (sub‐decadal to decadal) variability in the southeastern tropical Pacific region (∼70%) in the absence of SEP. Conversely, the absence of NEP yields no significant impact on tropical interannual variability but markedly diminishes low‐frequency variability in the central tropical Pacific region (∼70%). LIM and statistic diagnostics on CMIP6 models show the low‐frequency to total variability ratio in the tropical Pacific depending on their NEP and SEP representation. Models with more (less) low‐frequency power tend to show stronger NEP (SEP) dynamics. Plain Language Summary: The tropical Pacific climate variability exerts a strong impact on global climate, regional weather, and marine ecosystems. The tropical and extratropical Pacific are closely coupled with each other through oceanic and atmospheric processes. Previous studies have shown that the southern and northern extratropical Pacific (SEP and NEP) forcing greatly impact the tropical Pacific climate variability. To understand and predict tropical Pacific variability, it is necessary to study the relative importance and the timescale on which the SEP and NEP exert their influence. In this study, we use an empirical dynamical model to exclude the impacts of SEP or NEP on the tropical Pacific based on the observational data. We find that the absence of SEP leads to a significant reduction of interannual variance (∼40%) and the low‐frequency (sub‐decadal to decadal) variance in the southeastern tropical Pacific region (∼70%), while the absence of the NEP does not change the interannual variance but significantly reduces the low‐frequency variance in the central tropical Pacific region (∼70%). In observations, the ratio of low‐frequency to total tropical variability is 0.36, while CMIP6 models exhibit a wider range, with enhanced low (high) frequency power associated with stronger NEP (SEP) dynamics. Key Points: The SEP dynamics contribute ∼40% of the tropical interannual variance and ∼70% of the southeastern tropical low‐frequency varianceThe NEP dynamics do not impact the tropical interannual variance but lead to ∼70% of the central tropical low‐frequency variabilityCMIP6 models show stronger NEP (SEP) dynamics tend to manifest ENSO with more (less) low‐frequency (>6 years) power [ABSTRACT FROM AUTHOR]

The meridional heat transport (MHT) in the climate system is investigated using a state-of-the-art coupled climate model (CESM1.0). This work decomposes the MHT and studies their physics in detail. The meridional ocean heat transport (OHT) can be decomposed into the contributions from the Euler mean circulation, bolus circulation, sub-mesoscale circulation and dissipation. The Euler mean heat transport dominates the total OHT in most latitudes, except that in the Southern Ocean (40-50°S) where the OHT is determined by the eddy-induced circulation and dissipation. In the Indo-Pacific the OHT is fulfilled by the wind-driven circulation, which dominates the total global OHT in the tropics. In the Atlantic the OHT is carried by both the wind-driven circulation and the thermohaline circulation, and the latter dominates the total OHT in the mid-high latitudes. The meridional atmosphere heat transport consists of the dry static energy (DSE) and latent energy (LE) transport. In the tropics the LE transport is equatorward and compensates partially the poleward DSE transport. In the extratropics, the LE and DSE are poleward and reinforce one another, both of which are dominated by the eddy components. The LE transport can be considered as the 'joint air-sea mode' since the ocean controls the moisture supply. It can be also precisely obtained from the evaporation minus precipitation over the ocean and thus this work quantifies the individual ocean basin contributions to the LE transport. [ABSTRACT FROM AUTHOR]