Gandul, I haven't read the paper itself yet but I get the feeling you are misreading this paragraph. While the positive feedback (reduced sea ice => higher mixing rates => reduced sea ice) is a (very reasonable) hypothesis, the increased coupling of AW heat and the sea ice is not, if I read this correctly.
You read as I read. But the hypothesis here in particular is that there are mechanisms the enhanced turbulence due to shear and not diminished due to lack of ice will be able to breach the stratification and bring heat from the Atlantic Water.
Is it reasonable? I don’t know, I thought the top of this layer was 50 to 150m and a big storm like the GAC 2012 apparently was unable to pull energy from more than 50m (and that was a feat). But if these guys see it possible, I accept it, but as a hypothesis, not a fact. This forum is an echo chamber and pretty soon everyone will be accepting the Atlantification of Laptev sea as a fact.
Hello,
This is an extract of one of the researchs in the Arctic about haloclin
excuse me, I don't see any assumptions here, but conclusions supported by measurements made on several points during 15 years, it is not the same thing. Some points are not well understood in arctic, but the weakening of the halocline is well noted
"Time series measurements from a 15-yr mooring record in the eastern EB of the Arctic Ocean demonstrate that the previously identified weakening of stratification over the halocline, which isolates intermediate depth AW from the sea surface, over the period 2003–15 (e.g., Polyakov et al. 2017, 2018), has continued at an increasing rate in more recent years (2015–18). In consequence, oceanic heat fluxes for the winters of 2016–18 are estimated to be greater than 10 W m−2. These fluxes are substantially larger than the previously reported winter estimates for the region for 2007/08 of 3–4 W m−2 (Lenn et al. 2009; Polyakov et al. 2019) and comparable to the estimates for the winters of 2013–15 (Polyakov et al. 2017), implying a significant enhancement of the role of oceanic heat in this region in recent years.
Moreover, the increased vertical heat fluxes have been accompanied by increased upper-ocean current speeds |U| and the magnitude of vertical shear in the horizontal velocities |Uz| over the period 2015–18 (Polyakov et al. 2020b, manuscript submitted to Geophys. Res. Lett.). Using mooring observations from 2003 to 2018, these authors showed that time-averaged values of |U| and |Uz| in the upper 60 m of the water column increased by about 20% and 40%, respectively. In the lower halocline (110–140 m), |U| was generally larger after 2008, increasing on average from 2.5–3.5 cm s−1 in 2003–08 to about 4–5 cm s−1 in 2009–18 (Figs. 3c,d) although the change was not as strong in very recent years, 2016 and 2018, when compared to 2009–15. There is also a clear transition in |Uz|, with significantly larger shears evident post-2010, and in particular in the summer of 2018 (Figs. 3c,d). However, Pnyushkov et al. (2018a) found no significant change in the mean along-slope water transport over the same period.
The combination of reduced stratification and increased shear implies a decrease of the gradient Richardson number (Ri) defined in section 3 (Figs. 3e,f), consistent with an increased turbulent heat flux, associated with vertical mixing by shear instabilities. Although the Ri estimates are based on 20 m vertical resolution measurements, they show a clear trend toward reduced dynamic stability, which may be interpreted as a tendency toward increased turbulent mixing in recent years, coincident with the increase in maximum halocline heat content (Fig. 4). This tendency is particularly strong in 2018 with amplified velocity shear in the relatively weakly stratified upper ocean (Fig. 3)."
https://journals.ametsoc.org/jcli/article/33/18/8107/353233/Weakening-of-Cold-Halocline-Layer-Exposes-Sea-IceAnd. we spoked about effets if wind a few post before
This is an other action, winds increase thé CO2 from the athmosphere from the oceans
"The combination of open leads (i.e. lower ice concentration) and strong winds likely enabled large fluxes of heat, moisture, and gases between the ocean and atmosphere at these times56,57. For example, Fransson et al.57 estimated that the CO2 flux from the atmosphere into the ocean was approximately 20 times higher during storm periods, compared with average wind speed conditions and fewer open leads57."
https://www.nature.com/articles/s41598-019-45574-5And about thé effet if wind cause deep mix or only surface mix in the océan, how deep are this effets?
"I don’t know, I thought the top of this layer was 50 to 150m and a big storm like the GAC 2012 apparently was unable to pull energy from more than 50m (and that was a feat). But if these guys see it possible, I accept it, but as a hypothesis, not a fact. "
An other fact hère
Légend is:
"Time series of atmospheric, sea-ice, and oceanographic observations during the first two N-ICE2015 ice drifts in January–March 2015"
note that this does not concern an ice free area but an area with good concentration, in march with halocline thick
Légend for the ultimate diagram
"Ocean mixing given by dissipation rate60 (colour bar, warm colours correspond to stronger mixing), mixed layer depth62 (black line), and presence of Atlantic Water (red bar). Bold red bar indicates Atlantic Water (>2 °C) shallower than 250 m62. The two drift periods are highlighted by black bars in top of panel (a). Storm periods (M1-M6) are shaded as in Fig"
Please note the deep of mixed water, despite of the good ice concentration
Image here (i can't importe it, cause HTML sorry)
https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs41598-019-45574-5/MediaObjects/41598_2019_45574_Fig5_HTML.png?as=webp
