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Global Warming II: Create Your Own Models in Python

32 classificações

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The University of Chicago

Global Warming II: Create Your Own Models in Python

32 classificações

This class provides a series of Python programming exercises intended to explore the use of numerical modeling in the Earth system and climate sciences. The scientific background for these models is presented in a companion class, Global Warming I: The Science and Modeling of Climate Change. This class assumes that you are new to Python programming (and this is indeed a great way to learn Python!), but that you will be able to pick up an elementary knowledge of Python syntax from another class or from on-line tutorials.

Na lição

Time-Dependent Energy Balance Model

This class is intended to complement a Coursera class called Global Warming I: The Science and Modeling of Climate Change, which presents much of the background to the material here. In this class you'll be using spreadsheets (maybe) and Python (definitely) to do some simple numerical calculations on topics in Earth System Science. The model you'll be working on this week is based on material from Unit 3 of that class, called First Climate Model.

Conheça os instrutores

David Archer
Professor
Geophysical Sciences

Hello, and welcome to part two of my global warming Coursera class.

Part two is considered to be an optional add-on to part one,

which is where all the sort of climate science content is.

Part two is designed to give you a chance to learn

how to do some simple climate modeling in a language called Python.

So, the Python background you'll

need to get in some sort of a Python class or tutorial.

And the climate background you can get in this other class.

But we will be showing how to use both Python scripting and

also spreadsheets to create simple models of things that go on in the earth system

science, such as the first problem we'll be solving is an energy balance

problem where you have the solar energy coming into a planet and the infrared

light leaving, and the temperature is determined by the energy balance.

So in the other class we calculate the equilibrium temperature,

the temperature that it would reach after a long amount of time, but

in this class we'll be developing a model to take time steps so

that we can resolve a transient change in temperature such as this.

We have to be careful when doing time steps not to take a time step that's too

far that would extrapolate us into numerical error kind of land.

So this is what a spreadsheet version of that first

problem might look like, with some parameter values

up at the top that you can change interactively, and

some time steps down below, sort of down through here.

And this is a plot of planetary temperature as a function of time,

and the different symbols there are the time steps.

If we look at that as a Python script,

you can see it's just a short little thing there.

We can run that Python script, and

it does the same thing as the Excel spreadsheet does.

Other Python tricks that we will do in this class include an ice sheet.

So, here, we're taking time steps and

plotting the elevation of an ice sheet as a function of lateral distance.

So there's snow falling everywhere throughout the domain,

and the values at the edges are held at 0 as a boundary condition.

And eventually it reaches a steady state, where the inflow and

the outflow of ice at any grid cell reaches balance.

And that's when the elevation

of the thing stops changing.

The red dot in the middle here,

box was sort of a tower of water at the initial condition.

And so the water started flowing out and

it made waves that went all over the place.

But now, after a few rotational periods, the flow has found this equilibrium where

it's going around and around the tower of water instead of just flowing out from it.

You can see these sorts of rings, so

these are the basic equations of motion that govern fluid flow.

Anyway, welcome to the class, and I hope you find it of use.

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