Use of HadISST and production of SST and sea ice forcing data sets using the Karl Taylor procedure

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1. HadISST is an observationally based, globally complete, monthly SST and sea ice concentration data set. At the moment, it runs from January 1870 to December 1999. SST is provided in ^oC and sea ice is provided as a grid box area fraction. The missing data indicator is -1.0e30 for both data sets.

 
2. Research use of HadISST requires a license from the Met Office (Hadley Centre). License applications for C20C participants should be addressed to the Centre for Ocean-Land-Atmosphere Studies.

 
3. The data is supplied in the pp format. This consists of a series of header and data pairs (one per month). The headers contain the metadata and grid information for the following data. An example fortran 90 program (in free form format) shows how to read these files.

 
4. To prepare the data sets for use in forcing a model requires several steps:
 
• Combining the files into a temporally continuous file if necessary.

 
• Interpolation of the data set to the grid used for surface forcing in the model.

 
• Application of a fortran program to compute SST and sea ice forcing values using the Karl Taylor variance correction method. First edit the seven parameters at the top of the program. These are: nlon: the number of longitude points in the grid, nlat: the number of latitude points in the grid, mlat: the number of latitudes to do at one time (it is possible large nlon x nlat grids will give memory problems; start with mlat=nlat and reduce by factors),  abbr: a character string used in file naming (set to nlonxnlat), outpath: the path of the directory where output will be placed, insst: the full path name of the input sst file, insic: the full path name of the input sea ice file. Users should not edit the program below line 29 and should expect failure if they do so. An effort has been made to make the program entirely standard code, so it should compile using any f77 or f90 compiler and will run on a unix platform.  The program takes SST input in ^oC and sea ice input as fractions and gives SST output in Kelvin and sea ice output as fractions. Only input data for the 1870-1999 period is supported, and output is for 1871-1998 (as the method needs 12 months' buffer at either end of the data set).