Direct Answer
Reanalysis data combines historical observations with weather and climate models to produce consistent, gridded records of past atmospheric, land, ocean, and climate conditions. It is neither a pure observation nor a standalone model. Reanalysis blends both to support historical hazard baselines, past-event comparisons, model evaluation and calibration, and forward-looking climate-risk interpretation (Copernicus ERA5; ECMWF).
How It Works
The three baselines are:
- Historical hazard baselines.
- Past-event replay and comparison.
- Model evaluation and calibration in the context of forward-looking projections.
Reanalysis can help analysts understand how heat, wind, rainfall, humidity, drought, and other variables behaved historically in a region. It can also help assess whether forward-looking projections are plausible given known conditions. Before estimating future heat risk for an asset, for example, analysts can use reanalysis to understand historical heat behavior, threshold exceedance, and event timing. ClimaTwin’s Climate Business Intelligence™ uses reanalysis, observations, model evaluation, and local context to make climate data more traceable and useful for decision-making.
Limitations
Reanalysis quality can vary by variable, region, altitude, time period, and observing-system density. It may not fully resolve local microclimates, small watersheds, urban conditions, or site-level hazards without additional local data and interpretation.
Frequently Asked Questions (FAQs)
- What are the three baselines? Historical hazard baselines, past-event replay and comparison, and model-evaluation context.
- Is reanalysis the same as observed weather data? No. Reanalysis blends observations with model physics to create consistent gridded estimates.
- Why is reanalysis useful? It supports historical baselines, model evaluation, past-event analysis, and calibration.
- Can reanalysis validate the future? It can benchmark historical behavior, but it cannot prove that future projections will be exact.
- How does ClimaTwin use reanalysis? ClimaTwin uses reanalysis with observations, model outputs, local context, and uncertainty to strengthen risk baselines.
Sources
- Copernicus Climate Change Service. (n.d.). Climate reanalysis.
- Copernicus Climate Change Service. (n.d.). ERA5 hourly data on single levels from 1940 to present.
- European Centre for Medium-Range Weather Forecasts. (n.d.). ERA5 science and dataset documentation.
- Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horanyi, A., Munoz-Sabater, J., Nicolas, J., Peubey, C., Radu, R., Schepers, D., Simmons, A., Soci, C., Abdalla, S., Abellan, X., Balsamo, G., Bechtold, P., Biavati, G., Bidlot, J., Bonavita, M., … Thepaut, J.-N. (2020). The ERA5 global reanalysis. Quarterly Journal of the Royal Meteorological Society, 146(730), 1999-2049. https://doi.org/10.1002/qj.3803.
Ready to get started? To learn how ClimaTwin can help you assess the physical and financial impacts of future weather and climate extremes on your infrastructure assets, capital programs, and investment portfolios, please visit www.climatwin.com today.
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