10  Cover Page: ERA5 Workflow Manual

This manual prepares an ERA5 download and aggregation workflow for use in a real project.

It is intended for an operator who needs to:

• define a valid ERA5 request space;
• turn grouped requests into reproducible download jobs;
• emit supporting workflow files for orchestration;
• aggregate downloaded climate data into daily boundary-level outputs.

Before starting, the operator should already have:

• access to the Copernicus Climate Data Store;
• a project workspace with a clear data layout;
• the ability to decide which countries, variables, years, and months belong in the workflow;
• any required boundary, elevation, and optional population inputs for the final aggregation stage.

By the end of this manual, the project should have:

• a declared ERA5 request grid;
• a defined single-job download contract;
• emitted Snakemake workflow files for scaling downloads;
• a documented aggregation contract for producing daily healthshed summaries.

The goal of this manual is not to complete the scientific analysis. The goal is to make the workflow legible, inspectable, and ready to operate.