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Author Topic: The 2023/2024 Antarctic melting season  (Read 21115 times)

Stephan

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Re: The 2023/2024 Antarctic melting season
« Reply #100 on: December 04, 2023, 05:07:57 PM »
Yes, there have been really impressive sea ice extent losses. Is there a specific region where this event has concentrated on or are all seas more or less affected?
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oren

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Re: The 2023/2024 Antarctic melting season
« Reply #101 on: December 04, 2023, 06:24:20 PM »
I'd say Indian and Weddell are the main culprits and are both lowest for the date (in the AMSR2 dataset), but it's all of them to a degree.

oren

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Re: The 2023/2024 Antarctic melting season
« Reply #102 on: December 04, 2023, 06:31:04 PM »
An AMSR2 animation of sea ice concentration and movement around Antarctica, courtesy of the Alfred Wegener institute (AWI), based on the SIC-LEADS algorithm. Many thanks to seaice.de for making this available.
Source is mirrored on https://seaice.de/AMSR2_Antarctic_SIC-LEADS.gif

Some ice candy from the relentless Steven (https://sites.google.com/view/arctic-sea-ice/home/surface-melt):
Weighted SMOS pixel count, roughly indicating surface wetness (inverse).
7-day SMOS animation.
925mb temperatures.

kassy

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Re: The 2023/2024 Antarctic melting season
« Reply #103 on: December 04, 2023, 11:40:02 PM »
While the extent losses are impressive the area losses are much less. This is also because they are two different metrics and extent is counting per grid boxes hitting a treshold.

It would be cool if we could have the actual grid used for extent projected over the ASMR2 animation (and if we had that you can colour the boxes that qualify vs those that dropped of vs those that were water).

Anyway i assume all the extent boxes JAXA uses are similar in size? If so what size?
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oren

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Re: The 2023/2024 Antarctic melting season
« Reply #104 on: December 05, 2023, 12:39:03 AM »
At least the AMSR2 grid is quite small, each cell is around 4km x 4km, maybe less.

gerontocrat

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Re: The 2023/2024 Antarctic melting season
« Reply #105 on: December 05, 2023, 12:43:19 PM »
Pixel sizes

NSIDC                   25km x 25 km = 625 km2
ADS Vishop (JAXA) 10km x 10 km = 100 km2 (I think)
AMSR2                   3.125 km x 3.125 km = 9.77 km2



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uniquorn

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Re: The 2023/2024 Antarctic melting season
« Reply #106 on: December 09, 2023, 12:15:09 AM »
An interesting video presentation

Slowdown of Antarctic Bottom Water export driven by climatic wind & sea-ice changes


Phil.

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Re: The 2023/2024 Antarctic melting season
« Reply #107 on: December 09, 2023, 06:15:26 PM »
It'll be interesting to see what the effect of the storm will be on the Weddell Sea.

https://www.youtube.com/shorts/lvkriEyaSs8

uniquorn

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Re: The 2023/2024 Antarctic melting season
« Reply #108 on: December 15, 2023, 11:02:58 PM »
Another climate coffee presentation posted yesterday. These are good if you want to hear the authors take you through their papers, roughly 30min.

Recent reduced abyssal overturning and ventilation in the Australian Antarctic Basin.
Gunn, K.L., Rintoul, S.R., England, M.H. et al.
Nat. Clim. Chang. 13, 537–544 (2023). https://www.nature.com/articles/s41558-023-01667-8
Quote
Dense water formed near Antarctica, known as Antarctic bottom water (AABW), drives deep ocean circulation and supplies oxygen to the abyssal ocean. Observations show that AABW has freshened and contracted since the 1960s, yet the drivers of these changes and their impact remain uncertain. Here, using observations from the Australian Antarctic Basin, we show that AABW transport reduced by 4.0 Sv between 1994 and 2009, during a period of strong freshening on the continental shelf. An increase in shelf water salinity between 2009 and 2018, previously linked to transient climate variability, drove a partial recovery (2.2 Sv) of AABW transport. Over the full period (1994 to 2017), the net slowdown of −0.8 ± 0.5 Sv decade−1 thinned well-oxygenated layers, driving deoxygenation of −3 ± 2 μmol kg−1 decade−1. These findings demonstrate that freshening of Antarctic shelf waters weakens the lower limb of the abyssal overturning circulation and reduces deep ocean oxygen content.


Steven

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Re: The 2023/2024 Antarctic melting season
« Reply #109 on: December 17, 2023, 09:09:35 PM »
Since Wipneus' website went offline a few years ago, it has been a bit frustrating for me that no numeric data are available anymore for the daily (1-day) NSIDC sea ice area. 

So I downloaded the NSIDC gridded data files this weekend, and used it to calculate the daily Antarctic sea ice area (and also regional area and extent).  I made the results available here:

https://sites.google.com/view/arctic-sea-ice/home/nsidc

This webpage has csv-files with the numeric data in case it's of use to anyone, and also some graphics for the total and regional Antarctic NSIDC area and extent.

oren

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Re: The 2023/2024 Antarctic melting season
« Reply #110 on: December 18, 2023, 12:23:04 AM »
As usual, thanks a lot Steven. I used to prowl that website and dig at the data, also producing various charts (back when I had more time). Ever since the site died a lot of the data became non-existent, at least for my skill level/time investment.
Your website is now much better, containing more data and more resources, and is very much appreciated.

oren

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Re: The 2023/2024 Antarctic melting season
« Reply #111 on: December 19, 2023, 02:44:42 PM »
An AMSR2 animation of sea ice concentration and movement around Antarctica, courtesy of the Alfred Wegener institute (AWI), based on the SIC-LEADS algorithm. Many thanks to seaice.de for making this available.
Source is mirrored on https://seaice.de/AMSR2_Antarctic_SIC-LEADS.gif

More from Steven (https://sites.google.com/view/arctic-sea-ice/home/surface-melt):
Weighted SMOS pixel count, roughly indicating surface wetness (inverse).
7-day SMOS animation.
925mb temperatures.

Steven

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Re: The 2023/2024 Antarctic melting season
« Reply #112 on: December 20, 2023, 06:39:47 PM »
The sea ice in Weddell Sea still looks strong and is lagging quite a bit behind the strongest melt years.  On the other hand, the Indian Ocean sector is record low for the date, and it looks like most of Bellingshausen, Amundsen and Ross Sea are on track to melt out soon. 

I'm wondering if the high-concentration sea ice region at the northwest boundary of the Ross Sea (near 65-70°S and 150-180°E) has a chance of surviving the melt season.

kassy

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Re: The 2023/2024 Antarctic melting season
« Reply #113 on: December 29, 2023, 05:42:39 PM »
So 22/23 is the Antarctic variant of 2012 assuming this melt season does nothing really spectacular?

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nadir

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Re: The 2023/2024 Antarctic melting season
« Reply #114 on: December 29, 2023, 06:13:49 PM »
That has meant hundreds of thousands of km2 of ice reflecting sunlight back to space at insolation peak wrt previous seasons.

Where’s Kiwichick when we need them for the good news?

Happy new year!

grixm

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Re: The 2023/2024 Antarctic melting season
« Reply #115 on: December 29, 2023, 10:13:36 PM »
That has meant hundreds of thousands of km2 of ice reflecting sunlight back to space at insolation peak wrt previous seasons.

Where’s Kiwichick when we need them for the good news?

Happy new year!

Unfortunately cumulative net insolation anomalies are still record high for the season.

Steven

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Re: The 2023/2024 Antarctic melting season
« Reply #116 on: December 30, 2023, 05:01:59 PM »
Unfortunately cumulative net insolation anomalies are still record high for the season.

Yes, but there's a bug in those graphs due to a misalignment of the data, as discussed before.  Those graphs overestimate the AWP for 2023 relative to the other years.

interstitial

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Re: The 2023/2024 Antarctic melting season
« Reply #117 on: December 31, 2023, 05:44:54 AM »
Due to the always ice free surrounding ocean the albedo anomaly is less significant in the Antarctic than the Arctic.

uniquorn

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Re: The 2023/2024 Antarctic melting season
« Reply #118 on: January 02, 2024, 11:00:47 PM »
Antarctic sic-leads with meltdays (sum of surface melt), dec16-jan1

https://seaice.de/AMSR2_Antarctic_SIC-LEADS.gif
https://spore.social/@icesheetmike/111613481317993147
« Last Edit: January 03, 2024, 12:24:12 AM by uniquorn »

Steven

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Re: The 2023/2024 Antarctic melting season
« Reply #119 on: January 06, 2024, 01:41:07 PM »
NSIDC sea ice area in the Bellingshausen-Amundsen sea has been dropping fast recently.  Weddell is still holding up well.

https://sites.google.com/view/arctic-sea-ice/home/nsidc

gerontocrat

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Re: The 2023/2024 Antarctic melting season
« Reply #120 on: January 09, 2024, 03:01:55 PM »
Antarctic Albedo Warming Potential (AWP) is showing the impact of the slow melting season.

In addition Antarctic surface air temperatures, especially over the Southern Ocean regional seas are also cool.

At the moment there is no reason to believe the melting season will switch to above average sea ice loss.
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kiwichick16

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Re: The 2023/2024 Antarctic melting season
« Reply #121 on: January 13, 2024, 06:07:34 AM »
sea temps increasing again   .....thankfully generally cool around Antartica

https://climatereanalyzer.org/clim/sst_daily/

kiwichick16

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Re: The 2023/2024 Antarctic melting season
« Reply #122 on: January 13, 2024, 11:25:13 PM »
Apologies  Gero   :'(    will have to wait for the ocean temps to warm up more

https://www.nature.com/articles/d41586-024-00081-0

Espen

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Re: The 2023/2024 Antarctic melting season
« Reply #123 on: January 21, 2024, 11:27:40 AM »
Does anyone know this tongue of ice in Wilkes Land?
Have a ice day!

uniquorn

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Re: The 2023/2024 Antarctic melting season
« Reply #124 on: February 05, 2024, 09:55:57 PM »
seaice.de has a poll on the Antarctic minimum at https://det.social/@seaice/111850892259449212

I don't think foundation SST supports a new minimum at this point, additionally, ocean temperatures at depth in the Weddell and Ross seas tend to be cooler than surface from 50m down to 250m so any mixing due to storms may cool the surface.

sadmird

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Re: The 2023/2024 Antarctic melting season
« Reply #125 on: February 06, 2024, 09:11:48 AM »
While it may not be likely to end up as a new low on record, a new drop of extent to just 2.37M km2 on February 5th shows that Antarctica's sea ice extent is likely going to be a strong contender or tied for 2nd lowest. It is already ranked 6th out of last 19 years, after all.

Given that I expect it to be no different than the last couple of years in terms of a date the refreeze finally overpowers the melting of ice, it means there should be at least 2 weeks of melting season left, maybe even 3. We'll see how it turns out soon.

oren

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Re: The 2023/2024 Antarctic melting season
« Reply #126 on: February 06, 2024, 01:34:20 PM »
Area is high compared to extent, relatively speaking, so I also doubt the possibility of a new record. But a 2nd place finish is certainly possible. When starting with poor ice, even a season with mediocre melting weather can do wonders.

FredBear

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Re: The 2023/2024 Antarctic melting season
« Reply #127 on: February 15, 2024, 11:35:06 PM »
Usually there is quite a gap at the southern edge of the Weddell Sea between the ice shelf and the floating pack ice as the freezing season begins. Worldview shows new ice tending to drift northwards and drape itself over the retreating pack ice to the north around the end of January most years but this year, because of clouds and the small gap it is much less apparent - it may be around 12th February before it became clearly visible.

Even at this stage of the season other patches of fast ice are still breaking up round Antarctica after many patches of "mushy (finer?)" pack ice have melted away.

The icebergs to the north of South Georgia are breaking up in the warmer latitudes, with D28 splitting in 2 on today's image.

FredBear

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Re: The 2023/2024 Antarctic melting season
« Reply #128 on: February 15, 2024, 11:59:24 PM »
Does anyone know this tongue of ice in Wilkes Land?

It appears to be a lasting feature for more than 20 years but the edge (towards Amery) that was breaking away is moving more rapidly in the last few days, with the ice in the gap being flushed away. Worldview has a clear image of it breaking away on 2024 10 February but later images have more cloud.

(I imagine that the tongue is marked as outside the fast ice/ice shelf as there is a fissure breaking through the base.)

The tongue is situated towards the western end of the West Ice Shelf and one map has three research stations (Australian, Russian, Chinese) between it and the Amery Ice Shelf - does this indicate that it is an interesting area?
« Last Edit: February 16, 2024, 11:39:54 AM by FredBear »

Often Distant

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Re: The 2023/2024 Antarctic melting season
« Reply #129 on: February 19, 2024, 01:08:10 PM »
The tongue is of longtime grounded iceberg D-15 which calved in 1992. At a rough guess it could consist of potentially 100 years worth of ice if 100km extended at 1km per year. The giant iceberg split in two against shallow bathymetry in 2016. With sea ice at low levels, D-15B is moving west along with D-34, which calved recent as October 2023. Further break up of the segments and groundings of fragments in collision with bathymetry are possible within close proximity. The remaining D-15A tongue appears due dislodgement and disintegration, which is likely to collapse Barrier Bay cold polynyas that have long been large drivers of regional sea ice formation, somewhat shielding the Amery Ice Shelf. Local ocean currents, weather patterns and ecosystem will change with seascape changes. Remaining fasted sea ice area is of importance to doomed emperor penguins. The area will remain interesting into the freeze season, prone to further break up in rough weather. Tributary glaciers are speeding up in anticipation of the ocean opening out wide in front of them. Do they have names?

From the abstract of a publication dating December 2021: "based on current trajectories, the entire ice tongue will disintegrate in 1-3 years".
https://ui.adsabs.harvard.edu/abs/2021AGUFM.C45F1063W/abstract
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Iceburn

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Re: The 2023/2024 Antarctic melting season
« Reply #130 on: February 20, 2024, 12:57:46 PM »
One more dip in JAXA or are we done?
Some parts of Antarctic still showing milder than average but it looks like the climb is imminent.

sadmird

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Re: The 2023/2024 Antarctic melting season
« Reply #131 on: February 23, 2024, 11:05:36 AM »
One more dip in JAXA or are we done?
Some parts of Antarctic still showing milder than average but it looks like the climb is imminent.

I think that we are past this year's minimum extent by JAXA (notice that last increase to 2.16M km2, I'd argue that there's a very low chance for extent to drop under 2.09M km2 for this melting season). Sea ice area might drop a bit further, but not much, if at all.

gerontocrat

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Re: The 2023/2024 Antarctic melting season
« Reply #132 on: February 28, 2024, 08:18:55 PM »
Now the Antarctic melting season is over, a last look at Albedo Warming Potential (AWP).

The season started with Antarctic sea ice area at a record low maximum , but sea ice area melt was about 1.2 million below the 10 year average. The result was a high, but not a record high, Accumulated AWP.

The only region where accumululated AWP was very high was in the Indian Ocean Region.

Images from Nico Sun @ https://cryospherecomputing.com/NRTawp-south.html
click images to enlarge

ps: time to open the 2024 Antarctic Freezing Season thread?
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uniquorn

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Re: The 2023/2024 Antarctic melting season
« Reply #133 on: March 10, 2024, 04:45:39 PM »
https://det.social/@icesheetmike@spore.social/112071864660331394
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This late-fall Antarctic Peninsula heat wave has definitely turned into *A THING*

gerontocrat

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Re: The 2023/2024 Antarctic melting season
« Reply #134 on: March 10, 2024, 05:54:15 PM »
In a few months we might be able to see from GFZ data the change to Antarctic Ice Sheet Mass for the Peninsula Basins during the whole of the melting season.

(last update was to Oct '23 but more frequent updates were promised this year (sigh))
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oren

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Re: The 2023/2024 Antarctic melting season
« Reply #135 on: March 11, 2024, 01:18:27 AM »
Quote
ps: time to open the 2024 Antarctic Freezing Season thread?
Yes. Volunteer needed.