Hindcast Output

You can extract output from the seasonal forecasting hindcasts by running these codes:

  1. To avoid conflict with others, copy the code(s) you need to use into your own subdirectory. Then copy the appropriate data file to your subdirectory. E.g.,

    > cp Extract_Thind WJG/
    > cp 03_01/stmp WJG/

    (The output files are big files, so copying can take a minute or two. Please try to remember to delete these files when you are done with your project, since they are so big.)

    Alternatively, instead of copying, simply make a link to the desired file. This is actually a better way of doing it, because then you take up less disk space and can "switch" input files simply be creating a new link. Thus, enter (following the same example)

    > cd WJG
    > ln -s ../03_01/stmp stmp

    An apparent file called stmp will appear in your directory, but in reality, the "file" is a pointer to where the real file is located (a link to it). Please remember to include the " -s " in the command line.

    You should think carefully about which directory you copy files from and which files to use. Here are the possible choices of fields to use:

    1. stmp - surface temperature [K]
    2. prcp - precipitation [mm/sec]
    3. z200 - 200 hPa geopotential height [m]

    The directory tells you what year and month the hind/forecast output was produced. Thus, 03_01 was produced in January (month 1) of 2003. The first month of output is for the next month. Thus, the 03_01 directory has a forecast for February (one month lead time). Overall, there are six months "forecast" in the hindcast runs, so 03_01 has forecasts for February, March, April, May, June, and July.

    There are 21 years of "forecasts" in the hindcast files. Year 1 = 1979, Year 2 = 1980, ... Year 21 = 1999.
    (Note: The definition of Year 1 could change. You should verify that the identification of Year 1 with 1979, etc., is still true.)

  2. Next, swich to the code's subdirectory, and run the code

    > cd WJG
    > ./Extract_Thind

    Do not forget to put the "./" in front of the code's name.

    Execution of the code is the same as for the forecast codes you ran earlier. Output will appear in similar "stat" and "out" files, only for the hindcasts, ensembles have only 10 members. Output in these files is given for each year separately.

  3. If you want to make changes to the Extract codes and compile your own versions, you need to make sure the compiled code will "byteswap" the input data (if running on a Linux machine). This requires some care to do correctly. If you don't know what byte swapping entails, please ask for help!

    One way to do this is to compile the code using the Portland Group compiler (pgf77) and its "-byteswapio" switch. This requires compiling the code on a Linux machine where we have the PGF lisence activated. Another way is to use the Intel compiler with an environment parameter set so that code will byteswap the input data. Note that the standard compiler on the metl machines, the GNU compiler, can not do the job.

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