NCAR Climate Data Guide Content with Tag: Atmospheric Reanalysis

Arctic System Reanalysis (ASR)
Years of Record: 2000/01 to 2012/12
"The Arctic System Reanalysis (ASR) is produced using a high-resolution version of the Polar Weather Forecast Model (PWRF) and the WRF-VAR and High Resolution Land Data Assimilation (HRLDAS) data assimilation systems that have been optimized for the Arctic. ASR-Interim is a 30km data set...
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Formats: netCDF Timestep: Sub-daily,Monthly Domain: Arctic
Atmospheric Reanalysis: Overview & Comparison Tables
Reanalysis a systematic approach to produce data sets for climate monitoring and research. Reanalyses are created via an unchanging ("frozen") data assimilation scheme and model(s) which ingest all available observations every 6-12 hours over the period being analyzed. This unchanging framework...
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Tropical Instability Waves (contributed by E. de Boisseson)
CERA-20C: ECMWF's Coupled Ocean-Atmosphere Reanalysis of the 20th Century
Years of Record: 1901/01 to 2010/12
The CERA-20C is a global, coupled reanalysis spanning 1901-2010 with a focus on low-frequency climate variability.  Similar to ERA-20C, the surface observations assimilated include surface pressures from the International Surface Pressure Databank v3.2.6 and ICOADS v 2.5.1, and surface winds...
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
See Expert Guidance by Laloyaux, Patrick
Climate Forecast System Reanalysis (CFSR)
Years of Record: 1979/01 to 2011/01
The CFSR is a third generation reanalysis product. It is a global, high resolution, coupled atmosphere-ocean-land surface-sea ice system designed to provide the best estimate of the state of these coupled domains over this period. The CFSR includes (1) coupling of atmosphere and ocean during the...
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Formats: GRIB Timestep: Sub-daily,Monthly Domain: Global
ERA-15
Years of Record: 1979/01 to 1993/12
The ERA-15 production system generated re-analyses for 15 years (1979-1993)  using a special version of their 1995 operational data assimilation system and model. The resulting analyses include full model resolution analyses or  reduced resolution analyses and climate and statistics data...
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Formats: GRIB Timestep: Sub-daily,Monthly Domain: Global
SLP anomaly in DJF 1925-26 in ERA-20C
ERA-20C: ECMWF's atmospheric reanalysis of the 20th century (and comparisons with NOAA's 20CR)
Years of Record: 1900/01 to 2011/01
The ECMWF's first atmospheric reanalysis of the 20th Century, ERA-20C, provides a long, gridded dataset of many climate variables, spanning 1900-2010.  Observations assimilated include surface pressures from the International Surface Pressure Databank v3.2.6 and ICOADS v 2.5.1, and surface...
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
Climate Data Guide Image: ERA-Interim
ERA-Interim
Years of Record: 1979/01 to 2017/07
Using a much improved atmospheric model and assimilation system from those used in ERA-40, ERA-Interim represents a third generation reanalysis. Several of the inaccuracies exhibited by ERA-40 such as too-strong precipitation over oceans from the early 1990's onwards and a too-strong Brewer-Dobson...
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
ERA-Interim: derived components
Years of Record: 1979/01 to 2015/12
Era-Interim data are used to derive monthly mass, moisture and energy budget products. Each term is available. Atmospheric energy, mass, and moisture budgets can be computed by vertically integrating reanalysis fields and employing suitable corrections (e.g. mass). The budgets are uniquely...
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Formats: netCDF Timestep: Monthly Domain: Global
ERA40
Years of Record: 1957/09 to 2002/08
ERA 40 is a second generation reanalysis. It is the first reanalysis to directly assimilate satellite radiance data (TOVS, SSM/I, ERS and ATOVS). Cloud Motion Winds are also used. The result is better circulation over the tropics and southern hemisphere. However, unless comparing  to previous...
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Formats: netCDF | GRIB Timestep: Sub-daily,Monthly Domain: Global
JRA-25
Years of Record: 1979/01 to 2004/12
JRA-25 is a second generation reanalysis product. The model and data assimilation are from the operational system in April 2004. It was the first reanalysis to assimilate wind profiles around tropical cyclones deduced from best-track data, resulting in improved tropical cyclone analysis in a global...
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Formats: GRIB Timestep: Sub-daily,Monthly Domain: Global
JRA-55
Years of Record: 1957/12 to 2017/07
Spanning 1958-present, JRA-55 is the longest third-generation reanalysis that uses the full observing system (in contrast, products like ERA-20C and NOAA 20CR assimilate a very limited set of observations while NCEP R1 uses an antiquated model and assimilation scheme).  Compared to the...
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Formats: GRIB Timestep: Sub-daily,Monthly Domain: Global
See Expert Guidance by Kobayashi, Shinya
NASA MERRA
Years of Record: 1979/01 to 2016/11
The Modern Era Retrospective-Analysis for Research and Applications (MERRA) was undertaken by NASA’s Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA’s Earth Observing System satellites into a climate context and to improve upon the hydrologic...
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Formats: netCDF | HDF Timestep: Sub-daily,Monthly Domain: Global
NCEP NARR
Years of Record: 1979/01 to 2017/09
A high resolution (32km x 29 pressure levels) data set focused upon the North American Region. Relative to the NCEP-DOE (R2) it has a much improved land-hydrology, diurnal cycle and land-atmosphere interaction. As such, it can be considered a second generation reanalysis. A unique feature is the...
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Formats: GRIB Timestep: Climatology,Sub-daily,Monthly Domain: North America
NCEP Reanalysis (R2)
Years of Record: 1979/01 to 2017/09
NCEP-DOE Reanalysis II (R2) is an improved version of the NCEP-NCAR Reanalysis I (R1). The improvements include an updated model with better physical parameterizations, assorted data assimilation errors were fixed and additional data were included. Still, it is still a 'first generation' product.
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
NCEP-NCAR (R1): An Overview
Years of Record: 1948/01 to 2017/09
NCEP-NCAR (R1) is the original reanalysis effort. It uses a frozen global state-of-the-art global data assimilation system (as of 11 January 1995). The original database was enhanced (additional, quality checked datasets) by NCAR's Data Support Section. Originally planned to span 1957-96 ("40-Year...
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
Climate Data Guide image
NOAA 20th-Century Reanalysis, Version 2 and 2c
Years of Record: 1850/12 to 2014/12
The Twentieth Century Reanalysis (20CR) provides a comprehensive global atmospheric circulation data set spanning 1850-2014. Its chief motivation is to provide an observational validation data set, with quantified uncertainties, for assessing climate model simulations of the 20th century, with...
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Formats: netCDF | GRIB Timestep: Sub-daily,Daily,Monthly Domain: Global
Simplistic Overview of Reanalysis Data Assimilation Methods
Data assimilation is the process of combining observations from a wide variety of sources and forecast output from a weather prediction model. The resulting analysis is considered to be the 'best' estimate of the state of the atmosphere at a particular instant in time. The process of combining the...
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