Weather Data Fetcher

A simple R-based CLI tool to download Copernicus ERA5 weather data for specified months, years, and bounding box, and optionally create a hybrid weather dataset.

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Table of Contents

• Requirements
• Installation
• Input JSON Structure
• Usage
• Example
• Output

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Requirements

• R (>= 4.0.0)
• ncdf4 R package
• Internet connection (for Copernicus API)

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Installation

1. Clone this repository:

   git clone https://github.com/yourusername/weather-fetcher.git
   cd weather-fetcher

2. Install required R packages (if not already installed):

   install.packages("ncdf4")

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Input JSON Structure

Your configuration JSON file should include the following fields:

{
  "uid": "YOUR_COPERNICUS_UID",
  "key": "YOUR_COPERNICUS_KEY",
  "start_month": 1,
  "end_month": 12,
  "start_year": 2025,
  "end_year": 2025,
  "bounding_box": {
    "north": 40.613687151061505,
    "south": 35.99538225441254,
    "east": -89.09913230512305,
    "west": -95.76804054400543
  },
  "make_hybrid_weather": true
}

Field	Type	Description
uid	string	Your Copernicus ERA5 API user ID.
key	string	Your Copernicus ERA5 API key.
start_month	integer	Numeric month to start (1 = January, …, 12 = December).
end_month	integer	Numeric month to end (inclusive).
start_year	integer	Year (e.g., 2025) to start downloading data.
end_year	integer	Year to end downloading data.
bounding_box	object	Geographic bounding box for data request.
└─ north	numeric	Maximum latitude (degrees north).
└─ south	numeric	Minimum latitude (degrees north).
└─ east	numeric	Maximum longitude (degrees east).
└─ west	numeric	Minimum longitude (degrees east).
make_hybrid_weather	boolean	If true, create a combined/hybrid weather dataset from downloaded variables.

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Usage

From the repository root, run:

Rscript main.R path/to/input.json

• main.R: Main script that parses the JSON configuration, fetches data via the Copernicus API, and (optionally) generates a hybrid weather file.
• path/to/input.json: Path to your JSON configuration file.

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Example

1. Create a file named config.json:

   {
     "uid": "abc123def456",
     "key": "789ghi012jkl",
     "start_month": 1,
     "end_month": 12,
     "start_year": 2025,
     "end_year": 2025,
     "bounding_box": {
       "north": 40.613687151061505,
       "south": 35.99538225441254,
       "east": -89.09913230512305,
       "west": -95.76804054400543
     },
     "make_hybrid_weather": true
   }

2. Run the script:

   Rscript main.R config.json

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Output

• One NetCDF file per requested variable and year/month, saved in ./data/.
• If make_hybrid_weather = true, a combined NetCDF named hybrid_weather_{start_year}_{end_year}.nc will be created in the project directory.