The NOAA NCEP Climate Forecast System Reanalysis (CFSR) and Climate Forecast System Version 2 (CFSv2)

Overview

This document provides an overview of the snow products from the Climate Forecast system reanalysis (CFSR) and its operational extension CFSv2. The CFSR is a third generation reanalysis product, developed by the National Oceanic and Atmospheric Administration's (NOAA) National Center for Environmental Prediction (NCEP), and it is using a global, high resolution, coupled atmosphere-ocean-land surface-sea ice system. The spatial resolution of the global atmospheric data is ~38 km (T382) and many atmospheric variables are provided at hourly temporal resolution.

Provider's contact information

CFSR is developed by the National Oceanic and Atmospheric Administration's (NOAA) National Center for Environmental Prediction (NCEP).

Contact name: DOC/NOAA/NESDIS/NCEI > National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce

Contact email: Contact: cfs@noaa.gov

Licensing and citation

CFSR data is freely available

Please reference the following article when using the CFS Reanalysis (CFSR) data:

Saha, S., S. Moorthi, H.-L. Pan, X. Wu, J. Wang, S. Nadiga, P. Tripp, R. Kistler, J. Woollen, D. Behringer, H. Liu, D. Stokes, R. Grumbine, G. Gayno, J. Wang, Y.-T. Hou, H. Chuang, H. H. Juang, J. Sela, M. Iredell, R. Treadon, D. Kleist, P. Van Delst, D. Keyser, J. Derber, M. Ek, J. Meng, H. Wei, R. Yang, S. Lord, H. van den Dool, A. Kumar, W. Wang, C. Long, M. Chelliah, Y. Xue, B. Huang, J. Schemm, W. Ebisuzaki, R. Lin, P. Xie, M. Chen, S. Zhou, W. Higgins, C. Zou, Q. Liu, Y. Chen, Y. Han, L. Cucurull, Ri. W. Reynolds, G. Rutledge, and M. Goldberg, 2010: The NCEP Climate Forecast System Reanalysis. Bulletin of the American Meteorological Society 91, 8, 1015-1058, https://doi.org/10.1175/2010BAMS3001.1.

For hourly data downloaded from UCAR RDA: Saha, S., et al. 2010. NCEP Climate Forecast System Reanalysis (CFSR) Selected Hourly Time-Series Products, January 1979 to December 2010. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D6513W89. Accessed dd mmm yyyy.

For monthly data downloaded from UCAR RDA: Saha, S., et al. 2010. NCEP Climate Forecast System Reanalysis (CFSR) Monthly Products, January 1979 to December 2010. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D6DN438J. Accessed dd mmm yyyy.

Please reference the following article when using the CFS Reforecast model or data:

Saha, S., S. Moorthi, X. Wu, J. Wang, S. Nadiga, P. Tripp, D. Behringer, Y. Hou, H. Chuang, M. Iredell, M.Ek, J. Meng, R. Yang, M.P. Mendez, H. van den Dool, Q. Zhang, W. Wang, M. Chen, and E. Becker, 2014: The NCEP Climate Forecast System Version 2, Journal of Climate, 27(6), 2185-2208, doi:10.1175/JCLI-D-12-00823.1.

For hourly data downloaded from UCAR RDA: Saha, S., et al. 2011, updated monthly. NCEP Climate Forecast System Version 2 (CFSv2) Selected Hourly Time-Series Products. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D6N877VB. Accessed dd mmm yyyy.

For monthly data downloaded from UCAR RDA: Saha, S., et al. 2012. NCEP Climate Forecast System Version 2 (CFSv2) Monthly Products. Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://doi.org/10.5065/D69021ZF. Accessed dd mmm yyyy.

Variable name and units:

The following table summarizes the name of the variables available at NCAR RDA as time series.

Notation (name)	Time step	Units
SNO D (Snow depth)	6 h and monthly	m
WEASD (Water equivalent of accumulated snow depth)	Hourly and monthly	kg m-2
SWE (Snow Water Equivalent; instantaneous) in Flux set of data at NCEI	Hourly and monthly	kg m-2
SNOWC (Snow cover)	6 h and monthly	%

Note: The forecast at the first time step (f00) of 3 minutes constitutes a spin up of the model physics, and IT IS NOT THE ANALYSIS.

Spatial coverage and resolution:

CFSR data, is a global dataset. Snow-related variables are provided on the same horizontal regular latitude-longitude grid with a spatial resolution of ~38 km (T382).

Temporal coverage and resolution:

CFSR is covering 01Jan1979 - 31Mar2011 period. The product was extended beyond 2011 as an operational real-time product, using a new version: NCEP's Climate Forecast System Version 2 (CFSv2). CFSR snow products are available at an hourly or 6 hour time resolution (see below table).

The data is available also as monthly means.

Information about observations (number, homogeneity)

All available conventional and satellite observations were included in the CFSR. Satellite observations were used in radiance form and were bias corrected with “spin up” runs at full resolution, taking into account variable CO2 concentrations. This procedure enabled smooth transitions of the climate record due to evolutionary changes in the satellite observing system.

It is extremely difficult to assimilate 2 m temperature over land in systems like the CFSR. Therefore, surface temperature from stations is not assimilated in CFSR.

The CFSR uses the NCEP operational observation quality control procedures.

Methodology

The CFSR is a third generation reanalysis product, and it is using global, high resolution, coupled atmosphere-ocean-land surface-sea ice system. It includes (1) coupling of atmosphere and ocean during the generation of the 6 hour guess field, (2) an interactive sea-ice model, and (3) assimilation of satellite radiances. The CFSR global atmosphere resolution is ~38 km (T382) with 64 levels. The global ocean is 0.25° at the equator, extending to a global 0.5° beyond the tropics, with 40 levels. The global land surface model has 4 soil levels and the global sea ice model has 3 levels. The CFSR atmospheric model contains observed variations in carbon dioxide (CO2), together with changes in aerosols and other trace gases and solar variations.

Snow Analysis used in the CFSR (George.Gayno@noaa.gov): Snow liquid equivalent depth was updated using analysis data from the Air Force Weather Agency’s SNODEP model (Kopp et al. 1996) and the NESDIS Interactive Multisensor Snow and Ice Mapping System (IMS) (Helfrich et al. 2007). SNODEP uses in situ observations, an SSM/I-based detection algorithm, and its own climatology to produce a global analysis of physical snow depth once per day at 47 km resolution. Analysts may further adjust the analysis. SNODEP has been operational since 1975 and its data were available for the entire reanalysis period. The IMS data is a manually generated northern hemisphere snow cover analysis produced once per day. Analysts use surface data, geostationary and polar orbiting imagery, and microwave-based detection algorithms to determine whether an area is either snow covered or snow free. IMS data were available at 23 km resolution starting February 1997 and at 4 km resolution starting February 2004.

Information about the technical and scientific quality

The CSFR products are superior to previous NCEP reanalyses with respect to: improved model, finer resolution, advanced assimilation schemes, atmosphere-land-ocean-sea ice coupling, assimilates satellite radiances rather than retrievals, and accounts for changing CO2 and other trace gasses, aerosols, and solar variations.

Known CFSRR data issues are explained in the August 2011 CFSRR Known Issues Technical Document.

Problems with snow depth were noted during the following dates:

Dec 26, 1980
Dec 25,27-28 1999
All days between Jan 1, 2009, and Jan 1, 2011
Jan 25, 2011

Limitations and strengths for application in North Canada

GENERAL KEY STRENGTHS:

Approaches the horizontal resolution of regional reanalyses like the NARR and Arctic System Reanalysis

GENERAL KEY LIMITATIONS:

Ocean-atmosphere interactions are not used directly. Rather the information is used for background information. The actual reanalysis is uncoupled.

References to documents describing the methodology or/and the dataset

Saha, S., S. Moorthi, X. Wu, J. Wang, S. Nadiga, P. Tripp, D. Behringer, Y. Hou, H. Chuang, M. Iredell, M.Ek, J. Meng, R. Yang, M.P. Mendez, H. van den Dool, Q. Zhang, W. Wang, M. Chen, and E. Becker, 2014: The NCEP Climate Forecast System Version 2, Journal of Climate, 27(6), 2185-2208, doi:10.1175/JCLI-D-12-00823.1.

Link to download the data and format of data:

The CFSR data (1979 to 2011) are available in GRIB-2 format and can be accessed in multiple ways.

NCEI NOMADS THREDDS Data Server: URL: https://nomads.ncdc.noaa.gov/thredds/cfsr.html

NOAA NOMADS FTP access: URL: ftp://nomads.ncdc.noaa.gov/CFSR/

At UCAR RDA data is grouped as follows:

NCEP Climate Forecast System Version 2 (CFSv2) Monthly Products (ds094.2)

NCEP Climate Forecast System Version 2 (CFSv2) 6-hourly Products (ds094.0)

NCEP Climate Forecast System Version 2 (CFSv2) Selected Hourly Time-Series Products (ds094.1)

NCEP Climate Forecast System Reanalysis (CFSR) Monthly Products, January 1979 to December 2010 (ds093.2)

NCEP Climate Forecast System Reanalysis (CFSR) 6-hourly Products, January 1979 to December 2010 (ds093.0)

NCEP Climate Forecast System Reanalysis (CFSR) Selected Hourly Time-Series Products, January 1979 to December 2010 (ds093.1)

Publications including dataset evaluation or comparison with other data in Canada