Tag Archives: frazil ice

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As daylight has returned to Antarctica it is straightforward to pick out polynya forming on the edge of the Antarctic continent.

This one by the Stange Ice Shelf and Rydberg Peninsula caught my eye. It is a latent heat polynya formed as the winds push the sea ice away from the land to reveal the ocean that appears black beneath.

The wispy trails of grey which appear in the black are new sea ice forming as frazil ice.

A wind formed latent heat polynya forming in front of the Rydberg Peninsula and Stange ice Shelf, 22-26 October 2017.
A latent heat polynya forming in front of the Rydberg Peninsula and Stange ice Shelf, 22-26 October 2017.

This is the location of the peninsula.

The location of the Rydberg Peninsula.
The location of the Rydberg Peninsula.

I visited that area in 2007 and took this picture. You can a thin skim of young nilas ice in front of the ice shelf, and sea smoke too.

The Stange Ice Shelf with a thin skim of sea ice in front.
The Stange Ice Shelf with a thin skim of sea ice in front.

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I noticed yesterday that a polynya had formed in front of the Ronne Ice Shelf over the last 2 weeks.

Screengrab from NASA Worldview 17 February 2017
Screengrab from NASA Worldview 17 February 2017

In that image it is about 27,000 kmin area.

I mapped the opening of the polynya from MODIS imagery over the last two weeks. There is cloud in the images but the opening of the polynya is fairly clear.

Formation of the Ronne Polynya 30 January to 14 February 2017.
Formation of the Ronne Polynya 30 January to 14 February 2017.

On 31 January 2017 there is no open water, but then over the 16 day period it opens to the ~27,000 kmin area. If you're eagle eyed you can see that there is thin frazil ice forming in the open water in front of the ice shelf at the end of the sequence.

So what caused it?

...continue reading

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My previous posts on Amundsen Sea Polynya and their development showed ~37,600 km2 of open water in front of the ice shelves. It is very early spring in Antarctica at this time of the year and it’s still cold.

That means sea ice can still grow.

This is the Dotson Getz polynya on 9 October 2016. It has a perimeter of ~800 km and an area of ~25,500 km2.

The Dotson Getz polynya on 9 October 2016. Open water is black and streaks of sea ice growth are clear. The location of the Bear Peninsula Automatic Weather Station is marked.
The Dotson Getz polynya on 9 October 2016. Open water is black and streaks of sea ice growth are clear. The location of the Bear Peninsula Automatic Weather Station is marked.

I put together the satellite data from 9-12 October 2016 and it shows extremely rapid sea ice growth.

...continue reading