Overview of current atmospheric reanalyses

Bureau's Atmospheric high-resolution Regional Reanalysis for Australia (BARRA)

BARRA

The Bureau of Meteorology Atmospheric high-resolution Regional Reanalysis for Australia (BARRA) is a high-resolution multi-decadal atmospheric reanalysis. The reanalysis provides information about surface conditions (such as temperature, precipitation, wind speed and direction, humidity, evaporation and soil moisture), information at pressure and model levels, and information on solar radiation and cloud cover. The reanalysis suite is based on the Australian Community Climate Earth-System Simulator (ACCESS) and extends 70 levels (up to 80 km) into the atmosphere. It is nested within the required boundary and/or initial conditions provided by ERA-Interim reanalysis, Operational SST and Sea Ice Analysis, and the Bureau offline soil moisture reanalysis. The region covered by the reanalysis is the Australian continent, and the surrounding region including parts of southeast Asia, New Zealand, and south to the ice edge of the Antarctic continent. About 100 parameters are available at hourly time steps at approximately 12-km resolution, in this dataset. For a small number of subdomains (South-West W.A., S.A., Eastern N.S.W., and Tasmania), ), dynamically downscaled analyses at a 1.5-km resolution are available separately.

BARRA2

BARRA2 is the new version of the regional atmospheric reanalysis over Australia and surrounding regions, spanning 1979-present day time period. When completed, it replaces the first version of BARRA (Su et al., 2019), completed in June 2019, which provided a shorter 1990-2019 February reanalysis.

Bureau's Atmospheric high-resolution Regional Reanalysis for Australia Version 2 (BARRA2)

COSMO Regional Reanalyses: 1995-present

Several reanalysis systems are developed to generate high-resolution regional reanalysis data sets for Europe based on the NWP model COSMO. The first available data set at a horizontal resolution of 6km covers the entire European continent for the years 1995-2015 with output of model variables being available for every hour. A subsequent second data set covers large parts of Central Europe in a convection-permitting setup with 2km horizontal resolution and is available for the period 2007-2013.

Reanalysis consortium: Hans-Ertel-Centre - Climate Monitoring and Diagnostics, German Meteorological Service (DWD) - Climate and Environment, Meteorological Institute of the University of Bonn, Institute for Geophysics and Meteorology of the University of Cologne

Time Range: 1995-2015

Assimilation: Continuous nudging, separate DA modules for soil moisture, snow, SST and sea ice, latent heat nudging scheme

Dataset Output Times: 15 minutes for surface, hourly for upper air fields

COSMO-REA6 – 6.2 km
Model Resolution: 6.2 km, 40 eta levels
Period available: 1995-2018
Domain: Europe (CORDEX-11 domain)
Production of a second (updated) version of COSMO-REA6 is expected to start late 2020

COSMO-REA2 – 2 km
Model Resolution: 2 km, 50 eta levels
Period available: 2007-2013, production for 2014-2015 is currently under way, will be updated regularly
Domain: Central Europe

COSMO-ENS-REA12 – 12 km

Period available: 2006-2010

Data Access: COSMO reanalysis website

References

ECMWF CERA-20C: 1901-2010

CERA-20C is a global 20th-century reanalysis which aims to reconstruct the past weather and climate of the Earth system including the atmosphere, ocean, land, waves and sea ice. CERA-20C is part of the EU-funded ERA-CLIM2 project and extends the reanalysis capability developed in ERA-20C to the ocean and sea-ice components.

A new assimilation system (CERA) has been developed to simultaneously ingest atmospheric and ocean observations in the coupled Earth system model used for ECMWF’s ensemble forecasts. It is based on a variational method with a common 24-hour assimilation window. Air-sea interactions are taken into account when observation misfits are computed and when the increments are applied to the initial condition. In this context, ocean observations can have a direct impact on the atmospheric analysis and, conversely, atmospheric observations can have an immediate impact on the analysed state of the ocean.

CERA-20C assimilates only surface pressure and marine wind observations (ISPDv3.2.6 and ICOADSv2.5.1) as well as ocean temperature and salinity profiles (EN4). The air-sea interface is relaxed towards the sea-surface temperature from the HadISST2 monthly product to avoid model drift while enabling the simulation of coupled processes. No data assimilation is performed in the land, wave and sea-ice components, but the use of the coupled model ensures some dynamical consistency.

The evolution of the global weather for the period 1901–2010 is represented by a ten-member ensemble of 3-hourly estimates for ocean, surface and upper-air parameters. The resolution of the atmospheric model is set to TL159L91 (IFS version 41r2), which corresponds to a 1.125° horizontal grid (125 km) with 91 vertical levels going up to 0.1hPa. The ocean model (NEMO version 3.4) uses the ORCA1 grid, which has approximately 1° horizontal resolution with meridional refinement at the equator. There are 42 vertical ocean levels with a first-layer thickness of 10m.

Data Access: ECMWF

References | Data documentation | ClimateDataGuide

ECMWF ERA-20C: 1900 - 2010

ERA-20C is ECMWF's first atmospheric reanalysis of the 20th century, from 1900-2010. It is an outcome of the ERA-CLIM project.

ERA-20C was produced with the same surface and atmospheric forcings as the final version of the atmospheric model integration ERA-20CM. A coupled Atmosphere/Land-surface/Ocean-waves model is used to reanalyse the weather, by assimilating surface observations. The ERA-20C products describe the spatio-temporal evolution of the atmosphere (on 91 vertical levels, between the surface and 0.01 hPa), the land-surface (on 4 soil layers), and the ocean waves (on 25 frequencies and 12 directions). The horizontal resolution is approximately 125 km (spectral truncation T159). Note, atmospheric data are not only available on the native 91 model levels, but also on 37 pressure levels (as in ERA-Interim), 16 potential temperature levels, and the 2 PVU potential vorticity level. Monthly means, daily, and invariant data are available. The temporal resolution of the daily products is usually 3-hourly.

The assimilation methodology is 24-hour 4D-Var analysis, with variational bias correction of surface pressure observations. Analysis increments are at T95 horizontal resolution (aprox. 210 km). The analyses provide the initial conditions for subsequent forecasts that serve as backgrounds to the next analyses. A 10-member ensemble was produced initially, to estimate the spatio-temporal evolution of the background errors.

The observations assimilated in ERA-20C include surface pressures and mean sea level pressures from ISPDv3.2.6 and ICOADSv2.5.1, and surface marine winds from ICOADSv2.5.1. The observation feedback from ERA-20C is available. It includes the observations but also departures before and after assimilation and usage flags.

Data Access: ECMWF and NCAR

ECMWF ERA-20CM Model integration (no data assimilation): 1900 - 2010

The ERA-20CM atmospheric model integrations were produced in the framework of the ERA-CLIM project.

There are two versions, ERA-20CM and ERA-20CMv0, each comprising of a 10-member ensemble. The first version is 'final', the second is 'experimental'. The 'experimental' version was an early production and should not be used to initiate new research.

The model integration is forced by radiative forcing from CMIP5 and also by sea-surface temperature (SST) and sea ice cover from HadISST2.

Access: ECMWF

References | ClimateDataGuide

ECMWF ERA5: 1940-present

ERA5 is the latest climate reanalysis produced by ECMWF, providing hourly data on many atmospheric, land-surface and sea-state parameters together with estimates of uncertainty. ERA5 data are available on regular latitude-longitude grids at 0.25o x 0.25o resolution, with atmospheric parameters on 37 pressure levels. Recently, 1940-1978 has been added.

Data Access: Copernicus | NCAR | ECMWF

References

ECMWF Interim Reanalysis (ERA-Interim): 1979-present

Ends Aug 2019

ERA-Interim was originally planned as an 'interim' reanalysis in preparation for the next-generation extended reanalysis to replace ERA-40. It uses a December 2006 version of the ECMWF Integrated Forecast Model (IFS Cy31r2). It originally covered dates from 1 Jan 1989 but an additional decade, from 1 January 1979, was added later. ERA-Interim is being continued in real time. The spectral resolution is T255 (about 80 km) and there are 60 vertical levels, with the model top at 0.1 hPa (about 64 km). The data assimilation is based on a 12-hourly four-dimensional variational analysis (4D-Var) with adaptive estimation of biases in satellite radiance data (VarBC). With some exceptions, ERA-Interim uses input observations prepared for ERA-40 until 2002, and data from ECMWF's operational archive thereafter. See Dee et al. (2011) in the references below for a full description of the ERA-Interim system.

Data Access: ECMWF | NCAR

ECMWF 40 Year Reanalysis (ERA-40): Sep 1957-Aug 2002

Completed in 2003, ERA-40 is a global atmospheric reanalysis of the 45-year period 1 September 1957 - 31 August 2002. It was produced using a June 2001 version of the ECMWF Integrated Forecast Model (IFS Cy28r3). The spectral resolution is T159 (about 125 km) and there are 60 vertical levels, with the model top at 0.1 hPa (about 64 km). Observations were assimilated using a 6-hourly 3D variational analysis (3D-Var). Satellite data used include Vertical Temperature Profile Radiometer radiances starting in 1972, followed by TOVS, SSM/I, ERS and ATOVS data. Cloud Motion Winds are used from 1979 onwards. Various data from past field experiments were used, such as the 1974 Atlantic Tropical Experiment of the Global Atmospheric Research Program, GATE, 1979 FGGE, 1982 Alpine Experiment, ALPEX and 1992-1993 TOGA-COARE.

Data Access: ECMWF | NCAR

ECMWF 15 Year Reanalysis (ERA-15): Jan 1979-Dec 1993

Completed in 1996, ERA-15 is a global atmospheric reanalysis of the 15-year period 1 January 1979 - 31 December 1993. It was produced using an April 1995 version of the ECMWF Integrated Forecast Model (IFS Cy13r4). The spectral resolution is T106 (about 190 km) and there are 31 vertical levels, with the model top at 10 hPa (about 31 km altitude). Observations were assimilated using a 6-hourly Optimum Interpolation analysis (OI). Satellite data used were limited to cloud-cleared TOVS radiances and Cloud Motion Winds from GOES, GMS, and METEOSAT. Pseudo-observations of surface pressure (PAOBS) were also used, as well various data from past field experiments: 1979 FGGE, 1982 Alpine Experiment (ALPEX), TOGA, SUBDUCTION, and those found in the COADS dataset.

Data Access: ECMWF | NCAR

Japanese 25-year Reanalysis (JRA-25): 1979-2004, JCDAS: 2005-Jan.2014

The Japanese 25-year Reanalysis (JRA-25) represents the first long-term global atmospheric reanalysis undertaken in Asia. Covering the period 1979-2004, it was completed using the Japan Meteorological Agency (JMA) numerical assimilation and forecast system and specially collected and prepared observational and satellite data from many sources including the European Center for Medium-Range Weather Forecasts (ECMWF), the National Climatic Data Center (NCDC), and the Meteorological Research Institute (MRI) of JMA. A primary goal of JRA-25 is to provide a consistent and high-quality reanalysis dataset for climate research, monitoring, and operational forecasts, especially by improving the coverage and quality of analysis in the Asian region. JRA-25 was conducted by JMA and CRIEPI (Central Research Institute of Electric Power Industry). It had been continued as JCDAS (JMA Climate Data Assimilation System) operated by JMA in near real time basis. The data assimilation systems of JRA-25 and JCDAS are the same. Users can use JRA-25 and JCDAS as one continuous reanalysis dataset. JCDAS data provision was terminated in early Feburay 2014 because it was replaced with JRA-55 in operational. The available data period of JRA-25/JCDAS is for 35 years and 1 month (January 1979 to January 2014).

Data Access: NCAR

Homepage | Atlas | References | ClimateDataGuide

Japanese 55-year Reanalysis (JRA-55): 1958-2012, and extended to present
[JRA-55C(1972-2012) and JRA-55AMIP(1958-2012)] <-- not extended to present

JMA has carried out the second reanalysis project named the Japanese 55-year Reanalysis (JRA-55) (nicknamed JRA Go! Go!) using a more sophisticated NWP system, which is based on the operational system as of December 2009, and newly prepared past observations. The analysis period is extended to 55 years starting from 1958, when the regular radiosonde observations became operational on the global basis. Many of deficiencies in JRA-25 have been diminished or reduced in JRA-55 because many improvements achieved after JRA-25 have been introduced. JRA-55 provides a consistent climate dataset over the last half century. JRA-55 has been continued in near real time basis after 2013. If you need real time basis (2 days behind) data, please access to JMA. The real time basis data are also provided to other cooperating organizations (Note: half year behind). Note that the products for extended period after 2013 are also called JRA-55. As "JRA-55 family", there are two subproducts JRA-55C and JRA-55AMIP produced by MRI/JMA. JRA-55C assimilated conventional observations only. JRA-55C covers from 1972 to 2012. Before 1971, use JRA-55 instead because no satellite data was assimilated in JRA-55 before 1971. JRA-55AMIP (AMIP type run of JRA-55, with no observations) covers 1958 to 2012. JRA-55C and JRA-55AMIP data are available from DIAS and NCAR. Note that JRA-55C and JRA-55AMIP are not extended to present. JRA-55 Atlas (climate charts) is now available.

Data Access: JMA | DIAS (JRA-55) (JRA-55C) (JRA-55AMIP) | NCAR (JRA-55: Daily 3-Hourly and 6-Hourly Data, Monthly Means and Variances) (JRA-55C: Daily(3-hourly,6-hourly), Monthly) (JRA-55AMIP: Daily(3-hourly,6-hourly), Monthly) | ESGF/NASA/WCRP | ECMWF |

Homepage | References | JRA-55 Atlas |

Japanese Reanalysis for Three Quarters of a Century (JRA-3Q): Sep.1947 to present

JMA is currently conducting the Japanese Reanalysis for Three Quarters of a Century (JRA-3Q), which covers the period from September 1947 onward to extend the current period of data coverage and improve the quality of long-term reanalysis. The project involves a sophisticated data assimilation system (based on the operational set-up as of December 2018) incorporating development results from the operational NWP system and sea surface temperature analysis achieved since JRA-55 (based on the operational set-up as of :2009). New datasets of past observations are also assimilated, including rescued historical observations and reprocessed satellite data supplied by meteorological and satellite centers worldwide. Many of the deficiencies of JRA-55 are alleviated in JRA-3Q, providing a high-quality homogeneous reanalysis dataset that covers the previous 75 years.

Data Access: DIAS | NCAR |

Homepage | References |

Sub-product JRA-3Q-COBE

In JRA-3Q, the sea surface temperature (SST) specified as the lower boundary condition is the Centennial In Situ Observation-based Estimates of the Variability of SSTs and Marine Meteorological Variables Version 2 (COBE-SST2) with a resolution of 1° based on in situ observations until May 1985 and the Merged Satellite and In-Situ Data Global Daily Sea Surface Temperature (MGDSST) with a resolution of 0.25° based on satellite observations since June 1985. To enable evaluation of changes in product characteristics following the switch from COBE-SST2 to MGDSST, a sub-product using COBE-SST2 (JRA-3Q-COBE) is also provided for the period from June 1985 to December 1990.

Data Access: DIAS |

NASA Modern Era Reanalysis for Research and Applications (MERRA): 1979-2016(Feb)

MERRA is a NASA reanalysis for the satellite era using a major new version (circa 2008) of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5) produced by the NASA GSFC Global Modeling and Assimilation Office (GMAO). The Project focused on historical analyses of the hydrological cycle on a broad range of weather and climate time scales and placed the NASA EOS suite of observations in a climate context.

Data Access: GES MDISC | ESGF

NASA Modern Era Reanalysis for Research and Applications Version-2 (MERRA-2): 1980-present

MERRA-2 is a NASA reanalysis for the satellite era using a major new version of the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5) produced by the NASA GSFC Global Modeling and Assimilation Office (GMAO). MERRA-2 assimilates observations not available to MERRA during the 2010s, and therefore, will continue processing in real time longer than MERRA. There are numerous improvements and updates to the data assimilaiton, model and observing system. One notable change is the assimilation of aerosol observations, including black and organic carbon, sulfate and dust. Production began in the spring of 2014 and is presently available for access.

Data Access: GES MDISC | FTP Subsetter

Home Page | File Specification | Documentation | AMS Special Collection

References

NCEP Climate Forecast System Reanalysis (CFSR): 1979-present

The National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) spans 1979 to present. The CFSR was designed and executed as a global, high resolution, coupled atmosphere-ocean-land surface-sea ice system to provide the best estimate of the state of these coupled domains over this period. The T382 resolution atmospheric data spans 1979 to 2010. The current T574 analysis is an extension of the CFSR as an operational, real time CFSv2 product from 2011 into the future.

Data Access: NCEP | NCDC NOMADS | NCAR (includes real time CFSv2) | ESGF

Notes/questions/comments

NCEP Climate Forecast System Reanalysis version 2 (CFSv2): 2011-present

The Climate Forecast System Version 2 (CFSv2) produced by the NOAA National Centers for Environmental Prediction (NCEP) is a fully coupled model representing the interaction between the Earth's oceans, land and atmosphere. The four-times-daily, 9-month control runs, consist of all 6-hourly forecasts, and the monthly means and variable time-series (all variables). The CFSv2 outputs include: 2-D Energetics (EGY); 2-D Surface and Radiative Fluxes (FLX); 3-D Pressure Level Data (PGB); 3-D Isentropic Level Data (IPV); 3-D Ocean Data (OCN); Low-resolution output (GRBLOW); Dumps (DMP); and High- and Low-resolution Initial Conditions (HIC and LIC). The monthly CDAS variable timeseries includes all variables. The CFSv2 period of record begins on April 1, 2011 and continues onward. CFS output is in GRIB-2 file format.

Data Access: https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ncdc:C00877

NCEP/DOE Reanalysis II: 1979-near present

NCEP produced a second version of their first reanalysis starting from the beginning of the major satellite era. More observations were added, assimilation errors were corrected and a better version of the model was used.

Data Access: NCEP NOMADS | NCAR | ESRL | KNMI | IRI

NCEP/NCAR Reanalysis I: 1948-present

This reanalysis was the first of its kind for NOAA. NCEP used the same climate model that were initialized with a wide variety of weather observations: ships, planes, RAOBS, station data, satellite observations and many more. By using the same model, scientists can examine climate/weather statistics and dynamic processes without the complication that model changes can cause. The dataset is kept current using near real-time observations.

Data access: NCEP NOMADS| NCAR | NOAA PSL | IRI | KNMI

References | FAQ | FGDC | ClimateDataGuide

NCEP North American Regional Reanalysis (NARR): 1979-near present

The NARR reanalysis was done to produce very high resolution output over the North American region. Observational inputs were similar to NCEP I with the addition of assimilated precipitation. The NARR model region was nested in a global, lower resolution model. Outputs are similar to the NCEP I and II models but with more snow, ice and precipitation related variables.

Data Access: NCDC and NCEP NOMADS | NCAR | NOAA PSL

References | FAQ | ClimateDataGuide

NOAA-CIRES 20th Century Reanalysis version 2 (20CRv2): 1871-2012

The 20th Century Reanalysis version 2 (20CRv2) dataset contains global weather conditions and their uncertainty in six hour intervals from the year 1871 to 2012. Surface and sea level pressure observations are combined with a short-term forecast from an ensemble of 56 integrations of an NCEP numerical weather prediction model using the Ensemble Kalman Filter technique to produce an estimate of the complete state of the atmosphere, and the uncertainty in that estimate. The uncertainty is approximately inversely proportional to the density of observations. Additional observations and a newer version of the NCEP model that includes time-varying CO2 concentrations, solar variability, and volcanic aerosols are used in version 2. The long time range of this dataset allows scientists to examine better long time scale climate processes such as the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation as well as looking at the dynamics of historical climate and weather events. Verification tests have shown that using only pressure creates reasonable atmospheric fields up to the tropopause. Additional tests suggest some correspondence with observed variations in the lower stratosphere.

Homepage | References | Related Publications | ClimateDataGuide

NOAA-CIRES 20th Century Reanalysis version 2c (20CRv2c): 1851-2012 [2013-2014]

The 20th Century Reanalysis version 2 (20CRv2c) dataset contains global weather conditions and their uncertainty in six hour intervals from the year 1851 to 2012. Surface and sea level pressure observations are combined with a short-term forecast from an ensemble of 56 integrations of an NCEP numerical weather prediction model using the Ensemble Kalman Filter technique to produce an estimate of the complete state of the atmosphere, and the uncertainty in that estimate. The uncertainty is approximately inversely proportional to the density of observations. Additional observations from ISPDv3.2.9 and new boundary conditions from the Simple Ocean Data Assimilation with sparse observational input (SODAsi.2) pentad sea surface temperature and COBE-SST2 monthly sea ice concentration are used. For the 2013 and 2014 extension, SSTs are from the NOAA daily 1/4 degree Optimal Interpolation version 2. 2014 does not include tropical cyclone pressure observations after April.

Data Access: NOAA PSL | NCAR | ESGF | NERSC (every member)

Homepage | References | Related Publications | ClimateDataGuide

NOAA-CIRES-DOE 20th Century Reanalysis version 3 (20CRv3): 1806-2015

The 20th Century Reanalysis version 3 (20CRv3) is now available. It provides 8-times daily estimates of global tropospheric variability across ~75 km grids, spanning 1836 to 2015 and experimentally back to 1806 at NERSC.

Data Access: NOAA PSL | NCAR | NERSC (every member back to 1806)

Homepage | References | Related Publications