Python codes for "Regional Greening as a 'Positive' Tipping Phenomenon".

# Regional Greening as a 'Positive' Tipping Phenomenon

## Contents

- [Overview](#overview)
- [Repo Contents](#repo-contents)
- [System Requirements](#system-requirements)
- [Installation Guide](#installation-guide)
- [Demo](#demo)

# Overview

The Python codes for our paper "Regional Greening as a 'Positive' Tipping Phenomenon".

# Repo Contents
- [Code](./Code): main code for simulation and visualization
    - [Tibet](Code/Tibet) : site percolation simulation and related analysis for Qinghai-Tibetan Plateau (QTP) area.
        - [EVI_Percolation](Code/Tibet/EVI_Percolation):
            fragment-size distribution exponent and
            fractal dimensions for QTP
        - [EVI_Percolation_Shuffle](Code/Tibet/EVI_Percolation_Shuffle): null models for QTP
        - [EVI_Percolation_Snapshots](Code/Tibet/EVI_Percolation_Snapshots): correlation length and susceptibility for QTP
        - [EVI_Percolation_Protection](Code/Tibet/EVI_Percolation_Protection): Optimal enhancing resilience model for QTP
        - [EVI_Enhanced](Code/Tibet/EVI_Enhanced): Enhanced EVI Coverage for QTP
    - [Sahel](Code/Sahel) site percolation simulation and related analysis for Sahel area.
        - [EVI_Percolation](Code/Sahel/EVI_Percolation):
            fragment-size distribution exponent and
            fractal dimensions for Sahel
        - [EVI_Percolation_Shuffle](Code/Sahel/EVI_Percolation_Shuffle): null models for Sahel
        - [EVI_Percolation_Snapshots](Code/Sahel/EVI_Percolation_Snapshots): correlation length and susceptibility for Sahel
        - [EVI_Percolation_Protection](Code/Sahel/EVI_Percolation_Protection): Optimal enhancing resilience model for Sahel
        - [EVI_Enhanced](Code/Sahel/EVI_Enhanced): Enhanced EVI Coverage for Sahel
    - [Plot_Figs](Code/Plot_Figs) : Draw the pictures
- [GEE_Data_Download_Script](./GEE_Data_Download_Script): scripts to download data from Google Earth Engine (GEE)
- [Shapefile](./Shapefile): shapefiles used to select the Sahel and Tibet regions in the study.
- [SRCJl](./SRCJl) and [SRCPy](./SRCPy) : custom function libraries.

# System Requirements

## Software Requirements

### OS Requirements

The package development version is tested on *Linux* operating systems. The developmental version of the package has been tested on the following systems:

Linux: Ubuntu 22.04  

# Installation Guide

1. Users should build Python (3.9) and Julia (1.9) environment first.
For Python, visit [https://www.anaconda.com/download](https://www.anaconda.com/download) to download and install the Anaconda distribution.
For Julia, go to [https://julialang.org/downloads/](https://julialang.org/downloads/) and download the Julia installer for your platform. Follow the installation instructions provided on these websites.

2. Compile the libraries.
```
cd SRCJl\Flib\sitep
bash compile_site_percolation.sh
```

# Prepare Data
1. Download data from GEE by using the [GEE_Data_Download_Script](./GEE_Data_Download_Script) and [shapefile](./Shapefile).
2. Place the data in the corresponding path:
    - MODIS EVI V6 (QTP): [Code/Tibet/Data/Tibet_EVI_V6/Summer](Code/Tibet/Data/Tibet_EVI_V6/Summer/)
    - MODIS EVI V6 (Sahel) : [Code/Sahel/Data/Sahel_EVI_V6/Summer](Code/Sahel/Data/Sahel_EVI_V6/Summer/)
    - TerraClimate Summer precipitation (QTP) : [Code/Tibet/Data/Tibet_TerraClimate_pr_Summer](Code/Tibet/Data/Tibet_TerraClimate_pr_Summer)
    - TerraClimate Summer precipitation (Sahel) : [Code/Tibet/Data/Sahel_TerraClimate_pr_Summer](Code/Sahel/Data/Tibet_TerraClimate_pr_Summer)

# Demo
```
cd Code/Sahel/EVI_Percolation
bash run_all.sh
```
```
cd Code/Tibet/EVI_Percolation_Shuffle
bash run_all.sh
```
```
cd Code/Tibet/EVI_Percolation_Snapshots
bash run_all.sh
```
```
cd Code/Tibet/EVI_Percolation_Protection
bash run_all.sh
```
```
cd ode/Tibet/EVI_Enhanced
bash run_all.sh
```