ERA5 — Reanalysis

What This Dataset Is

ERA5 is a global atmospheric reanalysis produced by ECMWF. It combines a numerical weather prediction model with data assimilation of observations (including scatterometers, buoys, aircraft, and satellites) to reconstruct a physically consistent atmospheric state.

It is not a forecast product, but it is model-based.

How It Works

1. A global atmospheric model simulates the atmosphere.
2. Observations from many platforms are assimilated.
3. The model state is continuously adjusted to match observations.
4. The result is a dynamically consistent hourly dataset.

Strengths

• Complete global coverage
• Physically consistent atmospheric fields
• Long time series (1979–present)
• Strong validation against observations
• Suitable for climate analysis

Limitations

• Model-dependent
• Small-scale gradients may be smoothed
• Extreme winds may be underestimated
• Coastal representation limited by grid resolution
• Not purely observational

Appropriate Uses

• Climate studies
• Large-scale wind analysis
• Model forcing datasets
• Machine learning training

Not Recommended For

• Safety-critical navigation
• Real-time operational planning
• Local harbor-scale decisions