Arctic System Reanalysis (ASR): 2000-2011

The Arctic System Reanalysis (ASR), which can be viewed as a blend of modeling and observations, will provide a high resolution description in space (10-30 km) and time (3 hourly) of the atmosphere-sea ice-land surface system of the Arctic.  There are two versions of ASR:

Arctic System Reanalysis-Interim (ASR-int)
Source: The Ohio State University, Byrd Polar Research Center, Polar Meteorology Group
Time Range: 2000-2010
Assimilation: WRFDA-3DVAR
Model Resolution: 30 km, 71 sigma levels
Model Output Resolution: 30 km
Publicly Available Dataset Resolution: 30 km
Dataset Output Times and Time Averaging: 3-hourly for surface and upper air fields
Monthly means of selected variables
Here is the dataset location: http://rda.ucar.edu/datasets/ds631.4/
A new version is expected late 2012.

Arctic System Reanalysis-Final (ASR-fnl)
Source: The Ohio State University, Byrd Polar Research Center, Polar Meteorology Group
Time Range: 2000-2011
Assimilation: WRFDA-3DVAR
Model Resolution: 10 km, 71 sigma levels
Model Output Resolution: 10 km
Publicly Available Dataset Resolution: 10 km
Dataset Output Times and Time Averaging: 3-hourly for surface and upper air fields
Monthly means of selected variables
Dataset location will also be: http://rda.ucar.edu/datasets/ds631.4/
Expected available by end of 2012.

Data Access: Polar Meteorology Group

References | ClimateDataGuide

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

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

References | ClimateDataGuide

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

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

References | ClimateDataGuide

Japanese 25-year Reanalysis (JRA-25): 1979-2004, JCDAS: 2005-present

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 has been continued as JCDAS (JMA Climate Data Assimilation System) operated by JMA on 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.  The second Japanese reanalysis JRA-55 (1958-2012) is ongoing.

Data Access: JMA | NCAR

References | ClimateDataGuide

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

MERRA 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). The Project focuses on historical analyses of the hydrological cycle on a broad range of weather and climate time scales and places the NASA EOS suite of observations in a climate context.

Data Access: GES MDISC

Home Page | References | FAQ | Atlas | Blog | ClimateDataGuide

NCEP Climate Forecast System Reanalysis (CFSR): 1979-2011

The National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR) was completed over the 31-year period of 1979 to 2009 in January 2010. 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 current CFSR will be extended as an operational, real time product into the future.

Data Access: NCDC NOMADS | NCAR

References | ClimateDataGuide/

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

References | ClimateDataGuide

NCEP/NCAR Reanalysis I: 1948-present

This reanalysis was the first of it's 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 | ESRL | 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 | ESRL

References | FAQ | ClimateDataGuide

NOAA-CIRES 20th Century Reanalysis V2 (20CR): 1871-2010

The 20th Century Reanalysis version 2 (20CRv2) dataset contains global weather conditions and their uncertainty in six hour intervals from the year 1871 to 2010. Surface and sea level pressure observations are combined with a short-term forecast from an ensemble of 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.

Data Access: ESRL | KNMI | IRI | NCAR | NERSC | BADC

References | Related Publications | ClimateDataGuide