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Topics - JimboOmega

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Greenland and Arctic Circle / Where Does The Water Go?
« on: August 10, 2019, 12:05:25 AM »
On the DMI Greenland site, losses are often expressed in terms of Gigatons, which they explain as being equivalent to a cubic kilometer of water.  In a typical year, it seems like ~200 GT might melt, whereas in the worst years like this one, 300 or 400 GT might melt.

This is a tremendous amount , and it's very fresh water, assuming it melts and winds up in the surrounding waters. 300 Gt could cover the entire arctic ocean 2cm deep; or it could cover a million square kilometers 30 cm deep.

Does such a large impulse of fresh water actually impact the surrounding currents and oceans? In years where it's way more than climatology, what weird effects occur? Does the water go somewhere else (for instance, evaporating into the atmosphere)?  On some days, like recently, 10GT are removed in a day, do those pulses have impacts on other things in the cryosphere? Or are they mostly of concern only to the greenland ice sheet itself?

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Arctic sea ice / When is Radiation Breakeven?
« on: March 26, 2018, 07:55:10 PM »
Assume an area of open ocean, under a clear sky, at the freezing point of the water, with no interaction from the atmosphere, currents, etc.

At what amount of insolation does it breakeven - in the sense of losses to space are the same as inbound solar radiation?

Ideally I'd like some sort of general way to figure out what day of the solar year this occurs at a given latitude.

The motivation for the question is - in the winter, water opening up as Polynya causes the system to (overall) lose more heat to space and leads to more ice forming.  In the summer, the opposite is true, as expanses of open water absorb more sunlight than they lose heat to space. In the spring, like right now, I don't really have any idea.


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Arctic sea ice / What happened (or didn't) in May?
« on: June 02, 2017, 11:42:32 PM »
So May came, and with volume so much below normal, some people were calling for a cliff.

Instead (as extent goes) we had a pretty unimpressive month, especially compared to last year.

So... what happened - or didn't - in May?  Anybody want to take a shot at explaining it before NSIDC does?

4
Arctic sea ice / When is heat flux breakeven?
« on: April 05, 2017, 06:06:47 PM »
So a relatively simple question motivated by seeing some new ice form...

Do we know what day is breakeven for heat flux, counting only radiation, at various latitudes? Assume clear skies (though I'd be curious for cloudy too), and open water at 0C for albedo/blackbody purposes.

That is - if we only look at heat gained from the sun and heat lost via longwave to space (ignore atmospheric interaction, upwelling, currents, etc), what day of the solar year does this breakeven occur at various latitudes?

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The rest / Any Local Discussions?
« on: November 23, 2016, 02:52:47 AM »
Given the unprecedented scale of "the current weirdness", I find myself craving real-time conversation a little more than usual.

So I'm curious, are there any local discussion groups people are aware of? Any forumites in the SF Bay Area?

6
Antarctica / Ice Sheet Balance Graph?
« on: November 21, 2016, 10:48:03 PM »
We have the ice sheet mass balance graphs for Greenland from DMI, that is continuously updated...

Do we have anything like that for Antarctica?

7
Arctic sea ice / Freezing Season Basics?
« on: September 09, 2016, 10:43:02 PM »
So I'm new to watching the ice during the freezing season...

Can anyone explain the basics? Like what areas freeze first, how the weather influences freezing? What sort of set up from the melting season has impact on the freezing season? What should we expect this year different from previous years?  Is there "freezing momentum"? 

All of those kind of things, for a newbie like me!

8
Arctic sea ice / Total Arctic Ocean Heat?
« on: August 29, 2016, 08:12:32 PM »
Do we have any sort of measurement that quantifies how much heat there is in the oceans at arctic latitudes?

I've heard all season that there's a lot of "extra heat" in the oceans (that is not reaching the ice necessarily), and I'm curious if we've quantified that, especially in a way that can be compared to previous years.

I'm thinking of something that includes heat in the form of extra ice and warmer water both. For simplicity there's not really a need to go into things like snowpack, greenland ice, etc.  Also, probably, only some small (top) portion of the water column matters.

9
Greenland and Arctic Circle / Stupid Questions about DMI Data
« on: July 26, 2016, 01:08:50 AM »
So I like to watch the DMI data, showing what areas are melting and how much today.

But I have a few stupid questions.

One, the graph at the bottom that shows accumulated ice over the whole season - I notice the "average" ends well above 0.  I assume the extra snow gets lost in calving events. Is that right? Is there a way to view that same graph "corrected" for calving, so as to see the actual mass balance over a whole season?

Second, I see that the southeast is very dark blue, where snow has accumulated, while other areas are more red. Is this anomalous? Or does the southeast usually end the year positive? If it is anomalous... does it matter in the broader picture of things?

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Arctic sea ice / HYCOM vs ASMR2 Imagery
« on: July 11, 2016, 09:16:57 PM »
So looking at HYCOM (which I know some have questioned) and the DMI's ASMR2 imagery... there's a big difference.

HYCOM's nowcast shows a large area of  green-to-yellow concentration (40-60%) stretching from the ESS almost to the north pole, with it being thinnest closer to the pole.  ASMR2 shows nothing of the sort - purples (and thus 90%+) almost the whole way.

Why would the "nowcast" of HYCOM show that? I get why the model could have errors in forecasting - but "now"?  Is it simply crazy? Or is there a weakness in the ASMR2 imagery?


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Arctic sea ice / Ice Crashing Into Ice
« on: June 22, 2016, 10:03:46 PM »
So there's been a fair amount of discussion - me asking in stupid questions, and people speculating about the current low pressure - about floes colliding.

What do people think happens?

I assume floes tend to  move in the same relative direction - and thus not crash into each other so much.

But what if they get pushed back into landface ice, the pack, etc?  What if underlying wave action causes them to grind on each other where they are already pressed into each other? 

Do they fracture ever smaller? Do they form into a slush? Do they somehow "weld"?

I have no idea, but am opening this thread to speculation, science, and any facts or thoughts people might have.

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Arctic sea ice / Gambling on The Ice
« on: June 08, 2016, 12:03:04 AM »
Let's say that you expect this year will set an extent record (some of us do, some of us don't).

Let's say you're also a rather speculative investor...  What would you put money on? Shipping companies? Agriculture futures? Alternative energy? Arctic property?

I imagine that when(if) we set the all time low sea ice extent , it'll bubble up through the media consciousness from "completely out of mind" to "might merit a brief mention in a presidential debate". 

Any investments you think would be favored by a lower-than-expected extent?

13
Arctic sea ice / Decaying Tropical Cyclones?
« on: June 06, 2016, 06:16:19 PM »
So being the weather geek I am I was watching Tropical Storm Colin.  I noticed the last point the NHC has for the (by then extratropical) cyclone is at 55N, heading Northeast, and still reasonably strong (45kt winds)

Do these storms affect the ice in a way that a "native" arctic cyclone wouldn't?  Is it unlikely to ever get to that high a latitude to matter? Do the waves kicked up smash the ice at the margins?

14
Arctic sea ice / Triple Point Of Water
« on: May 12, 2016, 11:14:15 PM »
I've been pondering arctic phase changes and etc for a while and kept getting confused by one thing...

If you have an ice floe or similar condition of both ice and liquid existing close to the freezing point, you also have water vapor existing, right?  But as I understand the usual phase diagram, in normal conditions (e.g., ~100kpA/1ATM pressure) you should only have liquid and solid states, the triple point being much lower.

What am I missing?

What I ultimately want to know is the equation for the water vapor capacity of air vs temperature even well below 0C.

Another thing I've  been pondering, and quite related, is where the extra heat goes as one approaches a state where the arctic is increasingly ice free (since it doesn't go into melting the ice any more). The sun shines on the water and it absorbs heat (in the summer).  Presumably it loses heat to the atmosphere via evaporation, albeit at a much lower rate than would be the case in the tropics, but is this a meaningful number? And even if it is, where else can that heat go?  I assume the extra longwave radiation is not that significant. 

In other words, how much heat could be retained in the cryosphere season-to-season? 

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