======= Atmospheric Reanalysis =======
"Climate reanalyses combine past observations with models to generate consistent time series of multiple climate variables. Reanalyses are among the most-used datasets in the geophysical sciences. They provide a comprehensive description of the observed climate as it has evolved during recent decades, on 3D grids at sub-daily intervals." ([[https://climate.copernicus.eu/climate-reanalysis|Copernicus]])

Global reanalyses are produced by major Numerical Weather Prediction centers and they are under continuous development. This wiki page focuses on some of the most commonly used current-generation reanalysis products: ERA5, MERRA2, JRA-3Q, and NCEP. 

^  Source  ^  Name and access link   ^   Temporal coverage   ^   Horizontal resolution    ^  Available format  ^  Documentation/further information ^
| European Centre for Medium-Range Weather Forecast  (ECMWF) | [[https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=dataset|ERA5]]    | hourly, daily and monthly \\ (1940/01 - present, some variables start later)  | 0.25° x 0.25°   | GRIB \\ NetCDF | [[https://confluence.ecmwf.int/pages/viewpage.action?pageId=82870405#ERA5:datadocumentation-Parameterlistings|ERA5 documentation]] |
| Japanese Meteorological Agency | [[https://data.diasjp.net/dl/storages/filelist/dataset:645|JRA-3Q]]  \\ | 6-hourly, monthly (also hourly or daily for some variables) \\ (1947/09 - present) | 40 km | GRIB  | [[https://jra.kishou.go.jp/JRA-3Q/document/JRA-3Q_TL479_format_en.pdf|JRA-3Q documentation]] |
| NASA Goddard Space Flight Center re-analysis | [[https://disc.gsfc.nasa.gov/datasets?page=1&keywords=MERRA-2|MERRA 2]] | hourly, 3-hourly, 6-hourly, daily and monthly values \\ (1980/01 - present) | 0.5° x 0.625° | NetCDF | [[https://gmao.gsfc.nasa.gov/reanalysis/MERRA/|MERRA documentation]]|
| National Center for Environmental Prediction (NCEP) | [[https://www.esrl.noaa.gov/psd/data/gridded/data.ncep.reanalysis.html|NCEP/NCAR Reanalysis 1]] | 6-hourly, daily and monthly values \\ (1948/01 - present) | 2.5° x 2.5° | NetCDF | [[https://journals.ametsoc.org/doi/abs/10.1175/1520-0477(1996)077%3C0437:TNYRP%3E2.0.CO;2/|Kalnay et al (1996)]] |

Note that there are more, including regional reanalysis products that may be more suitable for regional studies (e.g., [[https://reanalysis.meteo.uni-bonn.de/|COSMO]] and [[https://climate.copernicus.eu/copernicus-regional-reanalysis-europe-cerra|CERRA]] for Europe, [[https://www.ncei.noaa.gov/products/weather-climate-models/north-american-regional|NARR]] for North America, [[https://essd.copernicus.org/articles/15/2329/2023/|EARS]] for East Asia, [[https://www.copernicus.eu/en/access-data/copernicus-services-catalogue/reanalysis-carra-single-levels|CARRA]] for the Arctic).