Add Google Colab workflow for ATMOS-BUD

[RonaldRN]

Description

This pull request adds a new google-colab/ directory containing four Jupyter notebooks that provide a Google Colab workflow for preparing ERA5 data and running ATMOS-BUD.

The main workflow is:

Access_to_Reanalysis_ERA5.ipynb
              ↓
       ERA5 NetCDF file
              ↓
      track_file.ipynb
              ↓
 track_<cyclone_name>.txt
              ↓
ATMOSBUD_Google_Colab.ipynb
              ↓
        ATMOS-BUD -t
              ↓
   Atmospheric budget results

The workflow is designed for cyclone-following applications using the ATMOS-BUD -t option. The ERA5 NetCDF file and the cyclone track file must contain matching dates and time steps.

Added notebooks

• Access_to_Reanalysis_ERA5.ipynb
  Downloads and prepares the ERA5 meteorological fields required as input for ATMOS-BUD.

• track_file.ipynb
  Creates the track_<cyclone_name>.txt file containing the cyclone position and analysis-domain dimensions for each time step.

• ATMOSBUD_Google_Colab.ipynb
  Provides step-by-step instructions for installing and running ATMOS-BUD on Google Colab, including the use of the -t option for a moving domain that follows the cyclone.

• Synoptic_chart_Reanalysis_ERA5.ipynb
  Provides a complementary tool for generating synoptic charts from ERA5 reanalysis data, following the general visualization style of the synoptic maps developed by Alicia M. Bentley.

The synoptic-chart notebook is optional and is not required for the ATMOS-BUD calculations.

Documentation

A README.md file was also added to the google-colab/ directory describing the recommended workflow, input requirements, temporal consistency between ERA5 and track files, and the purpose of each notebook.

Motivation

The goal of this contribution is to provide an additional cloud-based workflow for ATMOS-BUD, making the software easier to use in teaching, training, and research environments where a local installation may not be available.

The notebooks do not modify the core ATMOS-BUD source code.