Happy New Year 2024 (and sorry for the forum being offline some hours) /DM
Quote from: Glen Koehler on November 19, 2023, 12:06:00 AM Thanks Uniquorn! Even when it gets all white there still appears to be flow out the south end throughout most of 2012-2018.Hello Glen. This was mentioned before, last spring. The ice below the arch is new ice forming in the polynya and drifting away in a SW direction. See https://forum.arctic-sea-ice.net/index.php/topic,176.msg364648.html#msg364648
Thanks Uniquorn! Even when it gets all white there still appears to be flow out the south end throughout most of 2012-2018.
Updated Nares Arch formation list (seeing as the arch this year has persisted for well over 1 week now and may well last into the summer).2023 - March 30th2022 - No arch https://forum.arctic-sea-ice.net/index.php/topic,176.msg364064.html#msg3640642021 - December 5th (2020).2020 - December 17 (2019)2019 - No arch2018 - March 1st2017 - No arch (in the strait proper)2016 - December 6th (2015)2015 - February 13th2014 - January 5th (northern arch started - southern just after)2013 - November 8th (2012)2012 - December 6th (2011)2011 - January 29th2010 - No arch2009 - Visible sat image shows arch at extreme north end of channel on March 10. Start date was sometime before this.2008 - April 1st2007 - No arch
Sea ice concentration satellite retrievals influenced by surface changes due to warm air intrusions: A case study from the MOSAiC expeditionJanna E. Rückert,Philip Rostosky,Marcus Huntemann,David Clemens-Sewall,Kerstin Ebell,Lars Kaleschke,Juha Lemmetyinen,Amy R. Macfarlane,Reza Naderpour,Julienne Stroeve,Andreas Walbröl,Gunnar Spreenhttps://doi.org/10.1525/elementa.2023.00039extract:QuoteOf particular interest here is the large-scale surface glazing, observed at the MOSAiC CO, which can affect the microwave emissions as described above. Before, during, and after the warm air intrusions, the actual SIC in the vicinity of MOSAiC was high (>95%). Single leads opened during the events but nothing major in comparison to the periods before and after as confirmed by optical (MODIS) and radar (Sentinel-1) satellite data, by observations from the expedition participants, and by helicopter-borne thermal infrared imagery (Thielke et al., 2022). The latter gives a value for lead fraction, that is, fraction of open water and thin (<30 cm) young ice, which was on the order of 1.5% over the CO on April 23, about three days after the intrusions. Still the warm air intrusion events affected satellite products of SIC based on microwave radiometry. In conjunction with the warming events, and lasting for several days after them, most satellite products showed a (wrong) decrease in SIC and inter-product variability increased.
Of particular interest here is the large-scale surface glazing, observed at the MOSAiC CO, which can affect the microwave emissions as described above. Before, during, and after the warm air intrusions, the actual SIC in the vicinity of MOSAiC was high (>95%). Single leads opened during the events but nothing major in comparison to the periods before and after as confirmed by optical (MODIS) and radar (Sentinel-1) satellite data, by observations from the expedition participants, and by helicopter-borne thermal infrared imagery (Thielke et al., 2022). The latter gives a value for lead fraction, that is, fraction of open water and thin (<30 cm) young ice, which was on the order of 1.5% over the CO on April 23, about three days after the intrusions. Still the warm air intrusion events affected satellite products of SIC based on microwave radiometry. In conjunction with the warming events, and lasting for several days after them, most satellite products showed a (wrong) decrease in SIC and inter-product variability increased.
Abstract The Odden sea ice feature of the Greenland Sea is identified in a rotated principal component analysis of Hadley Center winter sea ice concentration data extending from 1951–2005. Time series of the Odden ice extent are evaluated in the context of sea level pressure, surface wind, air temperature, cloud, and energy flux variations using NCEP-NCAR reanalyses. Odden was a recurring feature in winters 1966–1972, during the Great Salinity Anomaly (GSA), and appeared occasionally in the 1980s and 1990s but has occurred rarely since 2000. Odden formation is associated with northernmost Atlantic high pressure, a negative North Atlantic Oscillation, and anomalous westerly winds. Its formation is most highly correlated, however, to air temperature and fluxes of sensible/latent heat, and downward longwave radiation. Air temperature and downward longwave flux anomalies in the preceding autumn are also unusually low in advance of a winter Odden ice cover while heat fluxes are weakly positive. All parameters, including the ice cover anomaly, exhibit significant winter to winter persistence over time.
Conclusions Two basic types of Odden features have been identified. The first, which we term a thermodynamic Odden, is definitely a winter feature, occurring between November and late April or early May. It is composed primarily of locally formed frazil and pancake ice, although a few older floes may occur within this matrix (as was seen by one of the authors in March 1997 aboard the Jan Mayen. The ice grows during cold air outbreaks, may suffer a number of partial meltbacks, and changes shape (tongue, island, bulge) due to wind stress. Locally, high salt fluxes may occur due to ice formation, with consequences for the destabilization of the surface water and the initiation of convection. The second, rarer, type of feature is an advective Odden, which shows itself in a pure form in spring or summer when thermodynamic conditions do not permit new ice growth. It is composed of older ice (first- and/or multi-year) derived from the East Greenland Current, in the form of floes of moderate diameters (5-20 m) and thicknesses of 1-2 m with occasional ridge remnants achieving 7 m. Local melt, the consequences of which were detected in September 1996, would act to freshen and stabilize the surface water. During the years 1979-1997 no Odden developed in 1984, 1994, and 1995. In all other years a thermodynamic Odden developed, while in 1987 and 1996 a late-season advective Odden was observed after the thermodynamic Odden had disappeared. Other time periods when the advective Odden may have occurred to a minor degree, as suggested by satellite images, were in spring of 1982, 1988, 1989, 1991, and 1992. A thermodynamic Odden provides a mechanism for preconditioning surface water toward convection through a salt flux due to local net growth of frazil-pancake ice, whereas an advective Odden causes the introduction of meltwater that stabilizes the water column. The Greenland Sea is one of only a few areas in the world ocean where ventilation occurs through open ocean convection [Killworth, 1983], and there is strong evidence through tracers and hydrographic data that convection has weakened and become more shallow in recent years [Rhein, 1991 ]. In estimating the role of Odden in these oceanographic changes, it is therefore necessary to be able to discriminate between these two modes of appearance of the ice regime in the region.
Looks like the Odden ice tongue is being clipped by the mask.Edit: false alarm, it's not clipped
Odden was a recurring feature in winters 1966–1972, during the Great Salinity Anomaly (GSA)
Drift in the Parry Channel east of Resolute has barely stopped this freezing season.@seaice.de Is that judder tidal movement or an artefact of different orbits or swaths?oct2023-feb2024
Quote from: uniquorn on February 12, 2024, 01:18:34 PMDrift in the Parry Channel east of Resolute has barely stopped this freezing season.@seaice.de Is that judder tidal movement or an artefact of different orbits or swaths?oct2023-feb2024I don't know but it looks like a real movement and could well be inertial or tidal. And maybe also some aliasing due to half-daily sampling with the AMSR2 product. But this is just my speculation without any analysis.https://link.springer.com/article/10.1007/s10236-022-01516-w
Pease et al. (1995) in their harmonic analysis of the Argos buoys in the Barents Sea continental shelf region observed that the M2 tidal constituent in the subdaily sea ice motion was a magnitude larger than the inertial oscillation. Also, Kowalik and Proshutinsky (1994) using their model for the Arctic Central Basin noted that the subdaily sea ice motion is dominated by tides but not inertial forces. This was in contrast to Hibler et al. (2006) who, using a sea ice model proposed by Heil and Hibler (2002), showed that in the subdaily sea ice oscillations of the Arctic Central basin, the inertial effects dominate and are enhanced by tidal forcing. This contradiction could be attributed to the different sea ice models used by Kowalik and Proshutinsky (1994) and Hibler et al. (2006). While Pease et al. (1995) and Kowalik and Proshutinsky (1994) had similar conclusions of tides being a dominant aspect of subdaily sea ice motion, the relative magnitude of inertial oscillations in both the studies was different. The difference here, might be a result of different magnitudes of internal stresses in the drifting ice field in the central Arctic and the Barents Sea region. This adds to the complexity as drifting sea ice field with and without significant internal stresses and based on the region of the Arctic could have different dissipation on the tides.
Because the McLure/Parry passage follows a parallel +/- it's hard to think of where water comes from that would have more eastbound inertia to drive the flow. My best guess would be that low pressure at the southern end of Baffin combined with tidal forcings draws more water from the north than can be accomodated by Nares, it also suggests a slight but persistent overpressure on the Arctic side of the archipelago and extensive lows in the N.Atlantic are in play. If there is an established flow then it will connect with incoming through Bering and as the N.Pacific warms an open alternative to Fram for southbound waters displaced by Atlantic inflow. Some of the coastlines through there are very smooth suggesting permafrost or very soft rock 'foundations'.
Always wondered about that hard to freeze area in the central Okhotsk. Deepest part is around 1750m, ice heading south tends to hug the shelf. One section over the northern shelf break, which rises to 130m, keeps flashing in and out, seems to be on the edge of freezing point at night, melting during the day. Possibly some tidal influence, rammb not providing enough consecutive frames to tell.High contrast bathy from https://www.gmrt.org/GMRTMapTool/np/
