Forcing of oceanic heat anomalies by air-sea interactions in the Nordic Seas area

Abstract

[1] Hydrographic data and atmospheric reanalysis from 1982 to 2005 are used to show a strong link of the Atlantic water temperature (AWT) anomalies observed in the transition zone between the Norwegian Atlantic current and the West Spitsbergen current in summer to the surface heat flux (SHF) anomalies observed over the Barents Sea open water in the preceding late winter. A mechanism proposed for this link is formation of ocean temperature anomalies in a deep mixed layer and their subsequent westward export by a branch of Atlantic water recirculating in the western Barents Sea. The SHF anomalies over the Barents Sea are due to advection of temperature and humidity by anomalous winds across the Arctic ice edge and do not strongly depend on the North Atlantic oscillation (NAO). Correlations of up to about 0.9 between the AWT anomalies and indices of atmospheric variability over the Barents Sea open prospects for seasonal AWT predictability. It is also shown that the wind-forcing responsible for positive AWT anomalies is involved in a cyclonic perturbation of the atmospheric circulation over the Nordic Seas. This perturbation generates, through influence on the sea ice distribution, a lobe of SHF anomalies in the marginal ice zone (MIZ) on the eastern (Barents Sea) and western (Greenland Sea) sides of the Nordic Seas which has the opposite sign to the open water lobe. In contrast to the Barents Sea MIZ, the diabatic heating of the atmosphere by upward SHF anomalies in the Greenland Sea MIZ competes with cold advection.Citation: Schlichtholz, P., and M.-N. Houssais (2011), Forcing of oceanic heat anomalies by air-sea interactions in the Nordic Seas area,

The Arctic Winter Sea Ice Quadrupole Revisited

“…This lends support to the idea that it is the gradient at the interface of the Siberian high that is key in determining the sea ice evolution (discussed further below) and that this regional variability is not necessarily well represented by large-scale metrics such as the Arctic Oscillation. This result is consistent with previous studies that have suggested that local SLP gradients control interannual Barents Sea ice variability (Sorteberg and Kvingedal 2006;Schlichtholz and Houssais 2011;Inoue et al 2012;Herbaut et al 2015) and with studies that have suggested a combined role of both the Aleutian low and Siberian high in driving ice-ocean conditions in the Sea of Okhotsk (e.g., Parkinson 1990;Tachibana et al 1996;Nakanowatari et al 2015, among others).…”

Seasonal Cycle of Mesoscale Instability of the West Spitsbergen Current

“…This especially explains the increased flow in the offshore branch that is more closely related to the gyre circulation than the flow near the West Spitsbergen shelf break and causes an increase in recirculation in central Fram Strait in winter (de Steur et al 2014). Similarly, the airsea heat fluxes over the Nordic Seas are much stronger in winter than in summer (Simonsen and Haugan 1996;Schlichtholz and Houssais 2011), and this is the reason for the hydrographic structure of the Atlantic Water (AW) in the WSC in the different seasons. The weak stratification in winter is a result of the intense winter cooling that the water has been subjected to in the Nordic Seas.…”

Empirical relationships between summertime oceanic heat anomalies in the Nordic seas and large-scale atmospheric circulation in the following winter

“…The NAO not only controls large-scale atmospheric conditions, but it also influences oceanic variability. In particular, our summer AWT index is significantly linked to the NAO index of previous winters (Schlichtholz and Houssais 2011). However, it is not correlated with the NAO index of the following winter (r = −0.06).…”

“…Oceanic heat variability is represented by the summer (JJAS) time series of AWT constructed by Schlichtholz and Houssais (2011) (Boyer et al 2006). The temperature data were averaged over the Atlantic water core (100-300 m) in the BSO area (13-17 • E, 70-76 • N; magenta box in Fig.…”

“…The wintertime variability of sea ice cover in the Barents Sea is not only influenced by changes in the Atlantic water transport, but also by anomalies of Atlantic water temperature (AWT). The latter are either advected from the North Atlantic (Nakanowatari et al 2014) or driven by local airsea interactions occurring in the Nordic seas region during the preceding winter-to-spring season (Schlichtholz and Houssais 2011). Whatever their origin, the subsurface ocean temperature anomalies, which in summer are insulated from interactions with the atmosphere by a shallow seasonal pycnocline, are entrained into the deepening ocean surface mixed layer during the cooling season and subsequently affect sea ice formation.…”