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Greenland fjords provide a pathway for the inflow of warm shelf waters to glacier termini and outflow of glacially modified waters to the coastal ocean. Characterizing the dominant modes of variability in fjord circulation, and how they vary over subannual and seasonal time scales, is critical for predicting ocean heat transport to the ice. Here we present a 2‐year hydrographic record from a suite of moorings in Davis Strait and two neighboring west Greenland fjords that exhibit contrasting fjord and glacier geometry (Kangerdlugssuaq Sermerssua and Rink Isbræ). Hydrographic variability above the sill exhibits clear seasonality, with a progressive cooling of near‐surface waters and shoaling of deep isotherms above the sill during winter to spring. Renewal of below‐sill waters coincides with the arrival of dense waters at the fjord mouth; warm, salty Atlantic‐origin water cascades into fjord basins from winter to midsummer. We then use Seaglider observations at Davis Strait, along with reanalysis of sea ice and wind stress in Baffin Bay, to explore the role of the West Greenland Current and local air‐sea forcing in driving fjord renewal. These results demonstrate the importance of both remote and local processes in driving renewal of near‐terminus waters, highlighting the need for sustained observations and improved ocean models that resolve the complete slope‐trough‐fjord‐ice system. Submarine melting of ice due to warm ocean waters has been implicated as a mechanism for the retreat and destabilization of marine‐terminating glaciers worldwide. In Greenland, fjords provide an important connection between marine‐terminating glaciers and warm subsurface waters located offshore. However, due to sparse ocean‐glacier observations in these ice‐choked systems, especially during winter months, we lack an understanding of how the large‐scale circulation along Greenland's periphery influences near‐glacier ocean temperatures. To address this, we present a 2‐year mooring record from Davis Strait and two neighboring west Greenland fjords. Above the sill, fjord temperatures exhibit a clear seasonal cycle that is inherited from the continental shelf and slope. Below the sill, warming of fjord waters occurs more intermittently and is initiated when salty Atlantic‐origin waters arrive at the fjord mouth. In summary, these novel observations allow for a better understanding of ocean‐glacier interactions in Greenland. We analyze a 2‐year hydrographic record from a suite of moorings in Davis Strait and two adjacent west Greenland fjordsHydrography above the sill exhibits clear seasonality; subannual warming of basin waters coincides with the arrival of dense Atlantic‐origin waters at the mouthWe use Seaglider observations and reanalysis of sea ice and winds to explore the role of local and remote forcing in driving fjord renewal more...

In the Main Development Region (MDR) for Atlantic hurricanes, the volume of water warmer than 26.5°C quantifies the potential source of energy for major storms. Taking a Lagrangian perspective, this warm water is backtracked on seasonal timescales in an eddy‐resolving ocean model hindcast spanning 1988–2010. Being confined near the surface and assuming a mixed layer depth of 50 m, net heat fluxes into or out of water parcels advected toward the MDR are inferred from along‐trajectory temperature tendencies. To first order, these heat fluxes match surface net heat fluxes during the months over which water advects into the region. Contributions to this warm water in the preceding 6 months include water resident in the MDR (20%–40%), arriving via the North Brazil Current (NBC, 5%–15%), or via Ekman drift across 10°S. In relative terms, decreased contributions from the NBC and Ekman drift and more in situ warming within the MDR lead to warmer, more active hurricane seasons. More and stronger hurricanes can be maintained by a larger quantity of warm ocean water in the North Atlantic. This water can be tracked backwards through time in high resolution model data to see where it originated. While some of the warm water is already in the tropical Atlantic 6 months before the hurricane season, some moves into the area via ocean currents or is pushed northwards by local winds. More and stronger hurricanes are more likely to occur in years where there is less movement of water into the tropical North Atlantic, along with more local heating of the region in the months leading into the hurricane season. 20%–40% of the warm water available in the Main Development Region (MDR) for Atlantic hurricanes in June is resident there 6 months previouslyOf the remaining warm water, which arrives from outside the MDR, 5%–15% arrives via the North Brazil CurrentYears of anomalous warmth in the MDR are associated with reduced arrival from outside the MDR and more local air‐sea heat exchange 20%–40% of the warm water available in the Main Development Region (MDR) for Atlantic hurricanes in June is resident there 6 months previously Of the remaining warm water, which arrives from outside the MDR, 5%–15% arrives via the North Brazil Current Years of anomalous warmth in the MDR are associated with reduced arrival from outside the MDR and more local air‐sea heat exchange more...

The Gulf Stream (GS) is central to the global redistribution of heat due to the transport of large volumes of warm water from the tropics to high latitudes and the extreme ocean heat loss to the atmosphere. This study assesses the extent to which winter surface heat fluxes and wind stress curl can drive interannual variations of the full‐depth GS transport. Intensification of the GS has been observed (e.g., April 1977) immediately after a winter of frequent cold air outbreaks that led to a deepening of the mixed layer and subsequent steepening of meridional temperature gradients to the south of the GS. This forcing process is further investigated here using the ORCA12 hindcast (1978–2010) from the global, eddy‐resolving, ocean‐only Nucleus for European Modeling of the Ocean model in order to understand GS forcing mechanisms. Lagrangian analysis is also undertaken to examine the impact on the southern recirculation gyre. Results show that surface heat fluxes and wind stress curl can act in concert to effect year‐to‐year changes of up to 38% of the spring GS transport at 70°W. However, anomalous heat losses (∼200 Wm‐2) over the western Subtropical Gyre are found to be the dominant cause of peaks in GS transport via two mechanisms: (1) a strengthening of cross‐stream density gradients on the northern flank of the GS from an intense cooling (up to 4°C) in the Slope Water and (2) a westward intensification of the southern recirculation, which can also limit the formation of deeper mixed layers to the south of the GS near 70°W. The amount of water transported by the Gulf Stream (GS) is found to vary from year‐to‐year by up to 38%. Severe winters in Northeast North America can cause this cold air to blow over the GS region, which leads to large heat losses from the ocean to the overlying atmosphere. This study uses a state‐of‐the‐art ocean model to show that these large heat losses can cause the GS to speed up by the end of winter via two mechanisms: (1) intense cooling to the north of the GS leads to large temperature gradients across the current and (2) greater westward flow of the southern recirculation to the south of the GS. Buoyancy forcing dominates wind forcing in driving interannual variations in Gulf Stream (GS) transportIntense winter air‐sea heat exchange can lead to an increase in GS transport of up to 38%Stronger meridional temperature gradients to the north and an intensified southern recirculation are associated with increased transport Buoyancy forcing dominates wind forcing in driving interannual variations in Gulf Stream (GS) transport Intense winter air‐sea heat exchange can lead to an increase in GS transport of up to 38% Stronger meridional temperature gradients to the north and an intensified southern recirculation are associated with increased transport more...