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Author Topic: [SUPPORT] Snow and Sea Ice  (Read 2970 times)

Plutonium

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[SUPPORT] Snow and Sea Ice
« on: September 07, 2014, 11:32:33 PM »
Hi everyone,
I am not sure if this is a bug or not, that is why I need some help to understand.

1. The first picture shows considerable amount of snow after a collision and surface temperature about 2500C.

2. The Second picture shows Earth with "Advanced Sea Ice" turned on: the Black and Caspean seas are frozen but the land seems ice-free.

C7

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Re: [SUPPORT] Snow and Sea Ice
« Reply #1 on: September 08, 2014, 07:27:20 AM »
Thank you for reporting this, we ran into this issue while doing demoing at PAX. We're still working on a permanent fix for it.

Basically the climate updates once per day, and the impacts happen on a very small time scale, so the planet will heat up before the ice has melted. We just need to improve the behavior between the two systems.

Plutonium

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Re: [SUPPORT] Snow and Sea Ice
« Reply #2 on: September 08, 2014, 10:08:08 PM »
Thanks for explaining, hope the fix will be found)

What about the second picture? It is pretty unrealistic to have the seas covered by ice while the land is "green". This happenes in "summer", in "winter" everything is ok.

One more issue but with Snowball Earth:
I lower the CO2 level to 0 to get Snowball Earth effect with surface temperature -46C, but after that it is impossible to warm it even when I set CO2 to its max 1 000 000 ppm. The warmest surface temperature I get is -35C (all other params on default values).

C7

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Re: [SUPPORT] Snow and Sea Ice
« Reply #3 on: September 09, 2014, 08:39:44 AM »
I'll forward this over to Naomi. She's got a better understanding of the Climate model and will know if this is a bug, or just a counter intuitive result.


Naomi

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Re: [SUPPORT] Snow and Sea Ice
« Reply #4 on: September 10, 2014, 11:15:19 AM »
Thank you for bringing up these issues. We very much appreciate our dedicated alpha users.

1. This was a bug with the timing of our updates of graphics which has been fixed. You'll see it in the next alpha update.
2. The "Advanced Sea Ice", as you'll see if you hover over it in the property window, is experimental. That means I was experimenting with it and it's currently broken. It was proving to be slow relative to the benefit derived from including it, and will probably be disabled in the next update because it's not a priority to fix.
3. re: Snowball Earth: this is a problem that I'm working on. The way that outgoing energy currently scales with CO2 concentration is a good approximation for concentrations and temperatures in the ranges that usually interest us studying modern climate and climate change (we often look at the doubling of CO2 as a metric). This approximation is less appropriate for the conditions of a snowball Earth when it's much colder and when more sophisticated radiation models indicate it would have required something like 350 times as much CO2 as present to get out of a globally frozen state. So, long story short, I'm going to extend this to handle these extreme cases better.

Plutonium

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Re: [SUPPORT] Snow and Sea Ice
« Reply #5 on: September 11, 2014, 12:55:03 AM »
Naomi,
Thanks for the explanation))
Does the software calculate the sea level change with regard to the amount of ice accumulated??
Are Milankhovich cycles planned feature or I'm expecting too much??)))

Also, it is currently a pain to shift between Earth and Sun property windows to change parameters. Please consider adding a possibility to have multiple property windows opened at the same time. Or even splitting the view to have close ups of multiple objects (would have been a great feature!!).

Naomi

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Re: [SUPPORT] Snow and Sea Ice
« Reply #6 on: September 11, 2014, 09:37:44 AM »
Great questions. There are no immediate plans to calculate changes in sea level from melting. We don't model glaciers, and it's the big ice sheets on Greenland and Antarctica the melting of which would have a big impact. In our model they're covered in snow, much like the seasonal snow that appears on land elsewhere. The sea ice is a thin skin of ice over the ocean - just a couple of meters thick typically. Because itís floating on the ocean, melting it doesnít change sea level anyway. Additionally, our elevation model doesnít have quite the vertical resolution to handle the expected sea level rise of just one or two meters, even though such a change would put a number of important coasts underwater.

Milankhovich cycles would be hard to get right with the gravity calculations, and you'd be waiting a long time anyway because the climate calculations have a fixed time step of one day, and your computer won't be able to handle too terribly many simulated days per real second. But any changes you make to the tilt and the orbit will affect the planet. So you can jump to some other orientation from a different time in Earth history. Maybe at some point we'll create preset combos of parameters to make that easier.

I'll pass along your comment about the property windows. I agree that would be nice. It wouldn't be impossible, but I doubt we'll do it soon. Thanks again for the questions and suggestions.

Plutonium

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Re: [SUPPORT] Snow and Sea Ice
« Reply #7 on: September 21, 2014, 10:49:09 PM »
When I increase the obliquity to ~90 deg and set the rotational period to 0 the winter/summer pattern stays almost the same- snow in winter in Antarctica and never any snow in Australia. Same with N and S Americas- N America is covered by snow while S America shows up green.

Is this how it should be and I'm missing something or something is not right?

Naomi

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Re: [SUPPORT] Snow and Sea Ice
« Reply #8 on: September 24, 2014, 04:42:50 PM »
Another good question. For now changing the rotation period doesn't actually do anything except for visually change how fast the Earth (or any planet) is spinning. The climate sim is always assuming the Earth rotates on its axis once every day (86,400 seconds). The one exception to that is if you've tried the 'Tidally Lock' button, you've seen what happens when the rotation period is equal to a year. We check only for that one special case of slow rotation, and not all possible rotation rates.

So for the purposes of the 90 degree obliquity you were trying, even though you set rotation period to zero, it was still acting like the rotation period is 1 day, so it makes sense that the "top" and "bottom" of the planet don't get cold like the usual poles do, like you might have been expecting to happen. The poles remain the poles and completely melt when they are facing the Sun, and freeze again when they're not.

This is surprisingly difficult to fix given the way that we do the calculations, but it's on the long-term list.

Plutonium

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Re: [SUPPORT] Snow and Sea Ice
« Reply #9 on: September 24, 2014, 11:10:48 PM »
Oh, that explains a lot.
Does "Tidally Lock" button work for obliquities greater than 0 deg (not as high as 90 but say 10-30)??

Also the current version climate seems to be "colder", after ~6 years of sim time everything higher than ~65 deg North appears covered by snow in summers. Using the preset Climate Simulation scenario without any changes.


P.S. I'm really glad that GA plans to implement more advanced climate simulation options. This is one of a kind consumer grade software. Pretty soon It can even be used to make some low budget amateur SiFi movies)))

im4space

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Re: [SUPPORT] Snow and Sea Ice
« Reply #10 on: September 25, 2014, 06:13:42 AM »
P.S. I'm really glad that GA plans to implement more advanced climate simulation options. This is one of a kind consumer grade software. Pretty soon It can even be used to make some low budget amateur SiFi movies)))

The original Universe Sandbox was used in a Documentary called "Cosmic Collisions" that was shown on the Discovery Channel in the United States on 28 January 2009. Here is a link to it on IMDB
http://www.imdb.com/title/tt1376486/?ref_=fn_al_tt_1

Plutonium

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Re: [SUPPORT] Snow and Sea Ice
« Reply #11 on: November 02, 2014, 04:06:21 AM »
I tried to play with climate, as usual, I tried to get the Snowball Earth effect by lowering the main parameters to see at which point it will happen. I ended up having as low as 1 ppm CO2 with no luck, also played with the other parameters like EtP difference.

Only 1 thing forced the effect- 0 ppm CO2! Appears to be some sort of a bug.