NSM
This year has been remarkable, in fact currently not only is the sea at the front not free, but there is no polynya, neither at the SSM, nor at the center, nor at the NSM.
I tried to make a small statistic of the state at the end of October from 2000 to 2020 based on the images of Worldview and I find :
> that the sea was completely free in a majority of the years: 2001, 2002, from 2008 to 2016 and 2019
> that apart from the year 2017, in which a major calving had just occurred and there was a narrow band of open sea between the PIG and the iceberg and for which one cannot thus establish the presence of polynyas, in all the other years there was always a polynya in the SSM and often a polynya in the NSM and/or in the center.
I recall that these polynyas are generated by the warmer water currents coming out below the ice shelf.
So, if the absence of open sea in front of the PIG is generated by the weather conditions of this southern spring, the absence of polynyas seems to indicate that the outgoing currents are weaker than usual (beyond the weather conditions) and therefore also the CDW is weaker than usual.
Before this end of October there were from time to time polynyas at the NSM and SSM, but very small and larger polynyas formed either in correspondence of the Ice Rise Evan's Knoll on the NIS side, or in correspondence of the SM (shear margin) between the SWT and the SIS, thus caused by outflows not related to the PIG.
I find this important and noteworthy.
Coming to what happened at the NSM on 07 and today I present an animation based on the images of 01, 06, 07 and 09 November (the images of 06 and 09 being at low resolution).
It can be noted that what happened on the 07th is a violent event which, among other things, moved the iceberg that I noted "A" by 2km and by turning it by 180° and apparently exploded the iceberg that I circled with red. The present debris was swept away, which produced a "polynya" effect, pushing it to invade the polynya in front of Evan's Knoll Ice Rise. Needless to say, that day it was better not to be there. This calving did not correspond to the detachment of new pieces from the ice shelf, but interested the mix of icebergs that had formed at the NSM.
It seems that a new calving (still iceberg mixture) has just occurred (image of 09, to be confirmed with a better resolved image) which filled again the bay (no more open sea).