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Technical milestone reached: global earth system simulations with 1.2 km resoln

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Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#51

Post by diroussel »

adamius wrote: post #40

How does such a simulation work? Eg how do hou predict the temperature at x,y? Is it ground type, water, sand?Altitude? Neighboring values thereof? What are the inputs? Do you give it a starting point and apply it to a bunch of elements like some giant automata like game of life? Some kind of finite element analysis thing? So many questions.

Here is a very brief and basic introduction to numerical simulation:

Simulation of dynamic systems is a big deep area. In general you use what is called numerical simulation where you have a model describing your system, in the form of a partial differential equal equations.

You start with the chosen initial conditions, choose a delta-t as your time increment, and solve the equation for those inputs. That result is the input to the next iteration.

The most basic algorithm to solve such an equation is “Newton’s method” but no one actually uses that, they use many more advanced methods. But if you are learning that is where you start.

This approach has advanced greatly over the last 70 years. Doing numerical simulation is why early computing work got funding, to simulated nuclear reaction inside bombs.

Now numerical simulation is the occupation of all the worlds top super computers. It’s used for climate simulation, bridge strength, how sky scrapers flex in the wind, testing car crashes or even simulating the strength of ceramics. Oh and it used a lot in financial simulations to model risk and calculate the price of assets.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#53

Post by adamius »

Certhas wrote: post #45
adamius wrote: post #40

How does such a simulation work? Eg how do hou predict the temperature at x,y? Is it ground type, water, sand?Altitude? Neighboring values thereof? What are the inputs? Do you give it a starting point and apply it to a bunch of elements like some giant automata like game of life? Some kind of finite element analysis thing? So many questions.

If only there was a way to find out...

I know, right? But together we can still dream.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#54

Post by hackandthink »

Being curious about the implementation language. Viewing the code is not easy.

If you guess Fortran, you might be right:

(different ICON Project) "The infrastructure, ICON-Land, for this ICON-A land component has been newly designed in a Fortran2008 object-oriented, modular, and flexible way."

https://mpimet.mpg.de/fileadmin/publikationen/Reports/WEB_Bz...

Fortran alive and kicking:

https://developer.nvidia.com/cuda-fortran

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#55

Post by kzrdude »

robertlagrant wrote: post #52

Why did they target 1.2km instead of 1? Or any other number?

I guess best ask the authors.

> Our ICON-ESM configuration is already used in production mode for scientific purpose with horizontal resolutions of 10 km, 5 km and 2.5 km. With the 1.2 km configuration we have now opened the door for a new class of numerical models which will allow us to investigate local impacts of climate change, such as extremes of precipitation, storms and droughts.

Some evidence of them using 10 km cells and then subdividing into halves, gets you down to 1.25 km.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#56

Post by adamius »

diroussel wrote: post #51
adamius wrote: post #40

How does such a simulation work? Eg how do hou predict the temperature at x,y? Is it ground type, water, sand?Altitude? Neighboring values thereof? What are the inputs? Do you give it a starting point and apply it to a bunch of elements like some giant automata like game of life? Some kind of finite element analysis thing? So many questions.

Here is a very brief and basic introduction to numerical simulation: Simulation of dynamic systems is a big deep area. In general you use what is called numerical simulation where you have a model describing your system, in the form of a partial differential equal equations. You start with the chosen initial conditions, choose a delta-t as your time increment, and solve the equation for those inputs. That result is t…

Right now I'm playing with simulated weather systems using an automata for each grid location at an effective resolution of a square km. I'm getting predictive real-world accuracy within around 10 degrees C with a range of 2 days. Very rough. Takes a long time to simulate a globe which I've found is really important to do. A limited region is usually not as useful.

Its an interesting field. But its seems not so easy to get the real methods used by the bigger models.

(I'm not using a supercomputer...)

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#57

Post by argiope »

qbit wrote: post #18
superkuh wrote: post #6

"I don't know, Timmy, being God is a big responsibility" https://qntm.org/responsibility , Topic relevant short scifi on Earth simulation.

Also relevant and mind-expanding essay: Simulation, Consciousness, Existence Hans Moravec, 1998. https://frc.ri.cmu.edu/~hpm/project.archive/general.articles...

Thank you for sharing that essay. I found it fascinating.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#58

Post by Maursault »

adgjlsfhk1 wrote: post #48
Maursault wrote: post #22

Earlier quoted context omitted.

If we're ever going to get to the femtometer resolution required for very precise 100 day weather forecasting, we have to start somewhere, so let them waste their time. It's not as though this is part of a growing trend to abandon conventional weather and climate modeling.

there's a very good physical argument that this is impossible. if you want to store 1 bit per femptometer simulated, at current computer sizes, we are taking about a computer billions the size of the earth. even if you use 1 atom per bit, your computer will be almost as big as the earth. such a computer will collapse under it's own gravity.

> at current computer sizes

This. No, not at all at current computer sizes, but at future computer sizes. This is the same mistake someone in the 1970's might make about billions having a smartphone today (supercomputer by their standards). Consider how everything at current computer sizes is effectively two dimensional, even stacked processors are still fundamentally 2D designs. There is still a lot of computing advancement ahead. 40 years from now they'll look back and think the same things we think when we look back 40 years, that the machines were so primitive, hardly anything could be done with them, and some will be nostalgic for them, talk about their strengths, while others will shake their heads and think even messing with the fastest workstation today is a waste of time. Just because we can't conceive of how, doesn't mean it's not possible, some day.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#59

Post by Maursault »

Certhas wrote: post #50
doctor_eval wrote: post #32

Earlier quoted context omitted.

Are we thinking about the same femtometer? 10^-15 of a meter? https://en.wikipedia.org/wiki/Femtometre I mean you can’t even fit a thermometer into a cubic femtometer..?

I think Maursault has thoroughly demonstrated their lack of serious thought or reading on the subject. But just for giggles and for the casual reader, the lattice spacing of silicon is 200,000 femtometer. So if you encode only one bit per cube of this fm cubic lattice, and you manage to encode this into single atoms of silicon, you need a volume of silicon 8,000,000,000,000,000 times larger than the system you model.

> I think Maursault has thoroughly demonstrated their lack of serious thought

When you can't beat the argument, pull out the ad hominem fallacy and attack the man. Fallacy, of course, is faulty reasoning.

> So if you encode only one bit per cube of this fm cubic lattice, and you manage to encode this into single atoms of silicon, you need a volume of silicon 8,000,000,000,000,000 times larger than the system you model.

This explanation is indicative of linear thinking. Apparently Google Earth is not possible, as it would require a computer the size of the planet. Digitizing the Library of Congress apparently requires a memory stick the size of Congress. Seriously? You just can not comprehend how things could ever get better than your current understanding of how things are right now? Consider that if you lived in 1500BC, were an expert at the time in farming, and a plough was described to you, you would mock the person describing it, and insist that tilling soil was impossible.

Re: Technical milestone reached: global earth system simulations with 1.2 km resoln

#60

Post by Maursault »

adrianN wrote: post #49
Maursault wrote: post #41

Earlier quoted context omitted.

Unless you know it to be physically or logically impossible, you could not really know how likely it is or isn't. Ask anyone in the mid-1970's how likely it is that billions of people would be walking around with a supercomputer in their pockets, and they'd come up with all sorts of reasons why it was extremely unlikely, such as no individual would ever need so much computing power. The practicality of the precision…

A femtometer is a few orders of magnitude smaller than an atom. There are about 2*140 atoms in the atmosphere. You can't even count to that number, let alone do any fluid dynamics to that. I'm confident that we won't have femtometer scale simulations of the atmosphere before the sun becomes a red giant and swallows the earth.

> A femtometer is a few orders of magnitude smaller than an atom.

Thank you for telling me what a femtometer is, as though my using the word wasn't a pretty good indicator I knew what it was. You mean a femtometer is a real thing? And I just made that up out of thin air to mean a meter stick to give to women. What are the odds?

> There are about 2*140 atoms in the atmosphere. You can't even count to that number, let alone do any fluid dynamics to that.

Would you like me to explain how your argument is a straw man, or can I trust you to figure it out?

> I'm confident that we won't have femtometer scale simulations of the atmosphere before the sun becomes a red giant and swallows the earth.

Very colorful, but all you're really saying is that you are pessimistic about technology and about any staggeringly large advancements in computer design or weather sensor tech, while I, otoh, optimistically say I just don't know, but I bet computers will get faster, smaller and cheaper, and that within only a hundred years there will be weather tech that we are incapable of conceiving of today.

Sure, a femtometer is mind-bogglingly small, but it's only 15 orders of magnitude smaller than a meter. It's way bigger than a zeptometer. How is it even possible femtometers can be described so simply? But of course, there could never be any more advancements in mathematics, physics, computer engineering or our current understanding of weather and climate. We basically know all there is to know right now. Huh.

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