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Image

Data Source

These weather maps are generated from the NCEP Climate Forecast System version 2 (CFSV2) and CFS Reanalysis (CFSR) model frameworks. CFSV2 is the core of NCEP's operational Global Forecast System (GFS) model, available for April 2011 onward. CFSR is based on version 1 of CFS, and constitutes a state-of-the-art 3rd generation reanalysis. CFSR is available for January 1st, 1979 to 31 March, 2011 on a T382 gaussian grid (~38 km) with 64 vertical levels. CFSR/CFSV2 output fields shown here are from 0.5°x0.5° rectilinear grids downloaded from NCAR CISL Research Data Archive. Daily averages are computed from 3-hourly forecast fields beginning at 0000 UTC. The graphics here are generally updated at the end of each month (e.g., January output images are made at the beginning of February, and so on).

Miscellaneous

  • Temperature refers to air temperature at 2 meters above the surface.

  • Sea surface temperaure (SST) is obtained from the skin temperature model output with land values removed.

  • SST (skin temperature over ocean) and sea ice are analysis fields in CFSR/CFSV2. Ingests for these parameters are made from bouy (SST) and satellite measurements (SST and sea ice) from the previous day.

  • Anomaly fields for both SST and 2-meter air temperature are made in reference to a 1979-2000 climatology derived for the current day of the year from CFSR.

    • Why does Climate Reanalyzer not use the WMO 1981-2010 climate normal?

      The Arctic and much of the Northern Hemisphere have warmed beyond historically-observed values since about the year 2000 (see this example from the original NCEP Reanalysis; and also this summary from NCAR). A 1979-2000 period average is used here in order to avoid warm bias inherent in 1981-2010 climate normal. CFSR begins January 1, 1979, which precludes deriving earlier climatologies within the CFSR/CFSV2 framework. Click here to see how the different averagering periods compare against the NASA GISS 1880-2014 global land-ocean temperature index.