In this study, we investigate eddy dynamics in the northern Greenland Sea and the Fram Strait using AVISO altimetry, spaceborne synthetic aperture radar (SAR), and Finite Element Sea ice‐Ocean Model (FESOM) high‐resolution numerical model data. In the region, eddies are thought to play an important role in the redistribution of the warmer and saltier Atlantic Water between the Arctic Ocean and the areas of deep convection in the central Greenland Sea. We found that eddies detected in AVISO and in SAR form two complementary data sets of large mesoscale eddies (with typical radii of 30–50 km) and of small mesoscale/submesoscale eddies (with typical radii of 1–5 km and not exceeding 30 km), respectively. For large mesoscale eddies, the number of cyclones and anticyclones is approximately the same, while for submesoscale eddies, cyclones are strongly dominating. The limitations and possible biases in each of the data sets are discussed and cross‐validated against FESOM results. It is noted that the most energetic eddies are concentrated along the major currents and in the northern part of the region. Eddy translations follow the mean currents in their overall cyclonic circulation around the northern Greenland Sea. A convergence of the eddies toward the Nordbukta area is detected. On seasonal time scale, a higher number of more intense mesoscale eddies is observed during winter, associated with a quasi‐simultaneous intensification of the mean currents. Model results also show an increase in the number of small eddies in spring‐early summer attributed to the decay of large eddies, while in late autumn, the opposite tendency suggests eddy merger.

An increase of surface air temperature (SAT) in the marine Arctic (a part of the Arctic covered with sea ice in winter) shows a good relationship with reduction of sea ice extent (SIE) in summer. For instance, a strong correlation (a coefficient equal to −0.93) was found between the summer SAT in the marine Arctic and satellite-derived 1980-2014 September sea ice index (the average of SIE in the Arctic since 1978, in millions of km 2 ). Based on this finding, anomalies of Arctic September SIE were reconstructed from the beginning of 20th century using a linear regression relationship. This reconstructed SIE shows a substantial decrease in the 1930-1940s with a minimum occurring in 1936, which, however, is only a half of the decline in 2012. The strong relationship between the summer SAT and September SIE was used to assess the onset of summer sea ice disappearance in the Arctic Ocean. According to the estimates made with a simple regression model, we can expect a seasonally ice-free Arctic Ocean as early as in the mid-2030s. An impact of the inflow of warm and salty Atlantic water (AW) on winter SIE was evaluated as an example for the Barents Sea. This evaluation reveals a coherent spatial pattern of the AW spreading, presented by surface salinity distribution, and the position of sea ice edge, and significant correlation between the inflow of the AW and maximal SIE. This publication presents a revised version of an 'Arctic sea ice extent in changing climate' report (Alekseev et al., 2015).

Atmospheric heat and moisture transfers from the North Atlantic make the main contribution to the Arctic warming in winter. The increase in transfer is associated with changes in atmospheric circulation in the Northern Hemisphere under the influence of the sea surface temperature (SST) in low latitudes, where the bulk of the heat influx from the Sun accumulated. The mechanism of influence includes the interaction between the circulation of the ocean and atmosphere, which enhances the oceanic heat influx into the Norwegian and Barents seas, and atmospheric transport to the Arctic. SST rises with participation of orbital-forced increase of the solar insolation. Changes in insolation are small, but their effect is enhanced by feedbacks between temperature, water vapour content and downward long-wave radiation in low latitudes. An increase in water inflow, heat and moisture transfers to the Atlantic Arctic lead to increase in air temperature, water vapour content, downward long-wave radiation, and a reduction of ice thickness growth and its extent in the Barents and Greenland Seas in winter.

Global climate models, focused on projecting anthropogenic warming, have not detected an increase in sea surface temperature (SST) at low latitudes comparable to the observed one. This appears to be one reason for the discrepancy between the model estimates of warming and reduction of the sea ice extent in the Arctic and the observed changes in the climate system. In previous studies, it was shown that short-term manifestations of the impact of low latitudes on the Arctic climate were identified in 2–3 weeks as a result of strengthening of atmospheric circulation patterns. In this paper, for the first time, a climatic relationship was established among an increase in SST, air temperature, and water vapor content at low latitudes, and a decrease in sea ice extent in the Arctic. ECMWF Re-Analysis data (ERA-Interim, ERA5), Hadley Centre Sea Ice and Sea Surface Temperature data set (HadISST), sea ice archives of the World Centers NSIDC (USA), and Arctic and Antarctic Research Institute (Russia), observations of water temperature in the Kola section (33°30′ E), calculated sea ice parameters using the Arctic and Antarctic Research Institute coupled ice-ocean circulation model (AARI–IOCM). Methods of multivariate correlation analysis, calculating spectra and coherence, and creating correlation graphs were used to obtain the results. For the first time, estimates of the effect of heat transport from low to high latitudes on climate change and sea ice extent in the Arctic over the past 40 years have been obtained, explaining a significant part of their variability. The increase in heat transport is affected by an increase in SST at low latitudes, where a significant part of the solar heat is accumulated. Due to the increase in SST, the amount of heat transported by the ocean and the atmosphere from low latitudes to the Arctic increases, leading to an increase in the air temperature, water vapor content, downward longwave radiation at high latitudes, and a decrease in the thickness and extent of winter sea ice. Potential topics include, but are not limited to: the role of heat and moisture transport in the Arctic warming, effect of SST at low latitudes on transports, linkage of warming in low latitudes and in shrinking of the Arctic sea ice.

SummaryInfluence of anomalies of the sea surface temperature (SST) in low latitudes of the North Atlantic on the sea ice cover and the near-surface air temperature in the marine Arctic is discussed in the article. Data on the SST in the Atlantic Ocean from the HadISST dataset, climatic series of the water temperature at the section along the Kola meridian together with mean monthly data on the sea ice extent and the air surface temperature in the Maritime Arctic and the Northern hemisphere were analyzed. Multivariate cross-correlation analysis was applied to determine the maximum correlation coefficients between the SST anomalies, climate characteristics and their corresponding delays within time limits of 33 to 38 months. Existence of intimate link had been found between changes of the Atlantic SST in low latitudes and the sea ice extent in the Arctic with correlation coefficients up to 0.90 and delays up to 3 years. A mechanism of formation of the remote influence of low-latitude SST anomalies on the sea ice anomalies in the Arctic Ocean is proposed. The interpretation of this mechanism includes into consideration the interaction between atmospheric and oceanic circulation modes.Citation: Alekseev G.V., Kuzmina S.I., Glok N.I., Vyazilova A.E., Ivanov N.E., Smirnov A.V. Influence of Atlantic on the warming and reduction of sea ice in the Arctic.