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Reanalysis Lineage from Kalnay 1996

Agent #4 research for Post 46. The lineage of global atmospheric reanalysis products that descended from — or paralleled — Kalnay et al. 1996.

Status: IN PROGRESS

Timeline of major global reanalyses

Year Product Center Anchor publication Period covered
1996 NCEP/NCAR R1 NCEP + NCAR Kalnay et al. 1996 BAMS 77:437–471 1948–present (rolling)
1996 ERA-15 ECMWF Gibson et al. 1997 1979–1993
2002 NCEP/DOE R2 NCEP + DOE Kanamitsu et al. 2002 BAMS 1979–present (fixes R1)
2005 ERA-40 ECMWF Uppala et al. 2005 QJRMS 1957–2002
2007 JRA-25 JMA Onogi et al. 2007 J. Meteor. Soc. Japan 1979–2004
2010 CFSR NCEP Saha et al. 2010 BAMS 91:1015–1058 1979–2009 (later extended) — first coupled atm-ocean-land-ice reanalysis
2011 ERA-Interim ECMWF Dee et al. 2011 QJRMS 137:553–597 1979–2019 (bridge product)
2011 20CR v2 NOAA-CIRES-DOE Compo et al. 2011 QJRMS 1871–2008 (later v3 1806–2015) — surface-pressure-only DA
2011 MERRA NASA GMAO Rienecker et al. 2011 J. Climate 1979–2016
2015 JRA-55 JMA Kobayashi et al. 2015 J. Meteor. Soc. Japan — first 4D-Var Japanese reanalysis 1958–Jan 2024
2017 MERRA-2 NASA GMAO Gelaro et al. 2017 J. Climate 1980–present
2020 ERA5 ECMWF Hersbach et al. 2020 QJRMS 146:1999–2049 1940–present (back-extension to 1940; original release 1979–)
2023 JRA-3Q JMA Kosaka et al. 2024 J. Meteor. Soc. Japan Sep 1947–present — successor to JRA-55
~2026+ ERA6 ECMWF (in development) TBD

Key features by product

NCEP/DOE R2 (Kanamitsu et al. 2002)

A “second look” reanalysis that corrected human-known errors in R1: the snow-cover bug, the PAOBs bug in the Southern Hemisphere, improved parameterizations. Same model resolution (T62L28). Not a wholesale replacement — R1 continues to be updated alongside.

CFSR (Saha et al. 2010)

First coupled atmosphere-ocean-land-ice reanalysis. T382 (~38 km) atmosphere, 64 vertical levels, GSI variational DA, satellite radiances assimilated. Provided the climatological baseline for NCEP’s operational CFSv2 forecasts.

ERA-Interim (Dee et al. 2011)

The ECMWF “bridge product” between ERA-40 and ERA5. 4D-Var, T255 (~80 km), 60 levels. Ran 1979–August 2019 — explicitly retired when ERA5 superseded it.

MERRA-2 (Gelaro et al. 2017)

NASA’s reanalysis with aerosol assimilation (first reanalysis to do so), GEOS-5 model, ~50 km. Replaced MERRA (Rienecker et al. 2011).

ERA5 (Hersbach et al. 2020)

The current global reference. ~31 km horizontal (TL639), 137 vertical levels, hourly output, 4D-Var. Originally 1979–present at release in 2018–2019; back-extension to 1950 published later (Bell et al. 2021), then to 1940.

20CR v3 (Slivinski et al. 2019 update)

NOAA-CIRES-DOE. Assimilates only surface synoptic pressure + SST/sea-ice boundary conditions — radically thin observation network lets the system reach back to 1806. Uses ensemble Kalman filter. The deep-time complement to satellite-era products.

JRA-3Q (Kosaka et al. 2024)

The Q stands for “Quality.” Succeeds JRA-55 from Sep 1947. JRA-55 near-real-time updates terminated January 2024 — JRA-3Q is now JMA’s flagship.

Citation impact of Kalnay et al. 1996

Metric Value Source
Approximate Google Scholar / aggregator citation count (2025) ~29,937 scispace.com / Semantic Scholar
Often described as one of the most highly cited papers in atmospheric science multiple sources

Citation table

Claim Primary URL Wayback URL
Kanamitsu et al. 2002 NCEP/DOE R2 reference https://en.wikipedia.org/wiki/Atmospheric_reanalysis https://web.archive.org/web/2024/https://en.wikipedia.org/wiki/Atmospheric_reanalysis
Uppala et al. 2005 ERA-40 reference https://en.wikipedia.org/wiki/Atmospheric_reanalysis https://web.archive.org/web/2024/https://en.wikipedia.org/wiki/Atmospheric_reanalysis
Saha et al. 2010 CFSR — first coupled reanalysis https://journals.ametsoc.org/view/journals/bams/91/8/2010bams3001_1.xml https://web.archive.org/web/2024/https://journals.ametsoc.org/view/journals/bams/91/8/2010bams3001_1.xml
ERA5 published Hersbach et al. 2020 QJRMS 146:1999-2049 https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3803 https://web.archive.org/web/2024/https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3803
20CR v3 covers 1836–2015 (experimental to 1806) https://psl.noaa.gov/data/20thC_Rean/ https://web.archive.org/web/2024/https://psl.noaa.gov/data/20thC_Rean/
20CR uses surface pressure only DA https://psl.noaa.gov/data/20thC_Rean/ https://web.archive.org/web/2024/https://psl.noaa.gov/data/20thC_Rean/
JRA-55 — first 4D-Var Japanese reanalysis covering 1958– https://jra.kishou.go.jp/JRA-55/index_en.html https://web.archive.org/web/2024/https://jra.kishou.go.jp/JRA-55/index_en.html
JRA-3Q covers Sep 1947–present, successor to JRA-55 https://www.data.jma.go.jp/jra/html/JRA-3Q/index_en.html https://web.archive.org/web/2024/https://www.data.jma.go.jp/jra/html/JRA-3Q/index_en.html
Kalnay 1996 ~29,937 citations https://scispace.com/papers/the-ncep-ncar-40-year-reanalysis-project-yeggi2oyjq https://web.archive.org/web/2024/https://scispace.com/papers/the-ncep-ncar-40-year-reanalysis-project-yeggi2oyjq