Arctic Sea Ice

Third storm

Are we getting used to this? After the persistent cyclone in May and June, and the spiffy, but short-lived cyclone of two weeks ago, the Arctic is visited by yet another intense storm that goes below 980 hPa. In fact, according to Environment Canada it is currently at 976 hPa, which is lower than the lowest pressure of the previous storm (click for a larger version):

Do also note the high pressure over the Beaufort Sea, Canadian Archipelago and Greenland. Yesterday's DMI SLP map also shows the storm developing:

According to the ECMWF weather forecast the storm will stay intense today and tomorrow, and then wind down again, albeit more slowly than the last one, and accompanied by more high pressure on the American side of the Arctic (click for a larger version):

Second storm

There's another storm brewing in the Arctic, the second this year after PAC-2013, the persistent Arctic cyclone that stayed in place for weeks on end and caused the first half of the melting season to be very slow. And also the second storm after last year's Great Arctic Cyclone, the iconic image of which is shown to the right (source: UCAR's AtmosNews).

The ice pack will probably be able to withstand the storm better than last year because there's more ice and it looks less patchy. Besides, the storm is occurring two weeks earlier, and won't match GAC-2013 in duration or magnitude. Nevertheless, this as of yet unnamed storm (a tradition we're trying to start over here on the ASIB) will probably become intense enough to leave a mark on the ice, which is why I decided to dedicate a blog post to it. 

To see what we're talking about, here's the SLP map from the Danish Meteorological Institute, with the cyclone in question, getting ready for two big days:

I made this panel that shows the ECMWF weather forecast for the coming 4 days (click for a bigger version):

Peeking through the clouds 6

It's been very cloudy in the Arctic this year. Luckily commenter dabize kept on sending me his 'declouded' version of the False-Colour Composite images Environment Canada makes of the LANCE-MODIS satellite images. These give us a good indication of what's going on. Hopefully he'll have the time for a couple more now that the freezing season is starting. Thanks for the great work so far, dabize!

Here is the latest animation:

Peeking through the clouds 4

Commenter dabize has sent me the latest 'declouded' version of the False-Colour Composite images Environment Canada makes of the LANCE-MODIS satellite images. They give us an excellent view of week to week changes. Due to some resolution incompatibilities I had to exclude last week's image (it's in the 3rd instalment of this Peeking through the clouds series), which makes the changes caused by the Arctic summer storm even more pronounced:  

Peeking through the clouds 3

Clouds blocking our view of events below make the False-Colour Composite images Environment Canada makes of the LANCE-MODIS satellite images very welcome (for further explanation read the first and second blog posts with the same title), especially after they have been 'declouded' by commenter dabize.

The latest animation showing weekly changes from July 3rd to August 7th:

Here's another panel dabize made showing the latest declouded false-colour composite image on the right, and changes compared to a month ago (red) in the image on the left, and to a week ago in the image in the middle (click for a larger version):

Thank you, dabize!

It will be interesting to see the declouded images in two weeks from now. Why two weeks? The Arctic has been so incredibly cloudy because of that huge summer storm that I wonder if we're going to be able to see much next week. But who knows.

As mentioned in Peeking through the clouds 2 with regards to the NWP:

Arctic storm part 3: detachment

Yes, ladies and gentlemen, the Arctic summer storm is still there. After approximately 48 hours (which is long for an Arctic summer storm) it has weakened some compared to yesterday or the day before, but as far as I can see sea level pressure in the centre of the storm is still around 970 mb, which is low.

And so we're still seeing significant changes on the Uni Bremen sea ice concentration maps. Here's the animation from August 3rd to 7th:

That large patch of sea ice in the East Siberian Sea is almost entirely detached from the main ice pack. This is something I for one have never seen before, and I wouldn't be surprised if it's unprecedented in the satellite era. We have speculated a lot about this in previous melting seasons, but now the moment seems to have finally arrived. The fact that the ice pack can get divided like this, is yet another sign that the ice is exceptionally thin, as thin ice gets pushed around more easily and melts quicker, leaving open space between thicker, slower moving ice floes.

I've also updated the animation of DMI sea level pressure maps that shows the development and position of the storm:

Peeking through the clouds 2: animation

This a follow-up to last week's blog post with the same title, in which I discussed the MODIS Composites that are made every week by Environment Canada. Their False-Colour Composite image which can be downloaded here is particularly interesting because it allows us to see through the clouds. This is useful, because low-pressure systems have been dominating the Arctic in the past weeks, and that means that clouds hide the situation below.

Now right after I posted this blog post commenter dabize sent me alternative versions of these composite images, in which he had removed the clouds even more. This image that he sent me yesterday clearly shows the ice loss (red) since June 5th up till now:

But even more visually stunning are the blue images he sent me that I have turned into an animation (each frame represents a week of averaged LANCE-MODIS satellite images):

Peeking through the clouds

When low-pressure areas take over the Arctic, they do two things: make the ice pack diverge and increase cloudiness. The diverging of the pack is hidden by the clouds, but we can sometimes see the holes in the ice pack through holes in the cloud cover on the LANCE-MODIS satellite images. We saw some early examples of that this year, ever since lows started to invade the central Arctic (for instance here and here), but it was and remained difficult to get an idea of the extent of holes in the ice pack. Until commenter Dr Tskoul came up with this tip:
MODIS Composites by Environment Canada.

Every Wednesday EC releases a 7 day MODIS satellite composite image, compiled to create a mosaic image of the Arctic Basin. They make a True-Colour Composite image as well as a False-Colour Composite image. I find the latter particularly interesting because it shows the holes best, as it highlights colour differences between sea ice and cloud. As a result, sea ice and snow appear light blue and clouds appear white (and purple over water).

This is the latest composite image (found in this directory):