| 1 | file README.io_esmf |
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| 2 | Tom Henderson 10/10/06 |
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| 3 | |
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| 4 | This version of WRF has been tested with ESMF 2.2.0rp1. Since ESMF interfaces |
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| 5 | are still changing with each new release, it is quite likely that this version |
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| 6 | of WRF will not work with other versions of ESMF. |
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| 7 | |
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| 8 | NOTE: ESMF 3.0.0 is available at the time of this writing. However, |
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| 9 | ESMF 3.0.0 fails to build with IBM's xlf 10.1 compiler. (The ESMF core |
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| 10 | team expects this problem to be resolved by a later release of xlf.) |
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| 11 | Therefore WRF was not tested with ESMF 3.0.0. |
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| 12 | |
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| 13 | New environment variables ESMFLIB and ESMFINC may be set to trigger |
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| 14 | build using a separately installed ESMF library instead of the default |
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| 15 | library embedded in external/esmf_time_f90/. These new environment variables |
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| 16 | must be set to point to library and module paths for the separately |
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| 17 | installed ESMF library before WRF "configure" is run. For example, an |
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| 18 | installation of ESMF on bluesky built with default ESMF settings in |
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| 19 | /home/bluesky/hender/esmf requires the following settings: |
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| 20 | ESMFLIB /home/bluesky/hender/esmf/lib/libO/AIX.default.32.default |
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| 21 | ESMFINC /home/bluesky/hender/esmf/mod/modO/AIX.default.32.default |
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| 22 | (Note that the portions of the pathnames following |
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| 23 | "/home/bluesky/hender/esmf/" are defined by ESMF and described in the ESMF |
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| 24 | documentation.) |
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| 25 | |
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| 26 | When ESMFLIB and ESMFINC are set, a new main program is built in |
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| 27 | main/wrf_SST_ESMF.exe. This program is a sample coupled application in |
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| 28 | which WRF is coupled to a very simple "data-ocean" component named SST via |
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| 29 | a very simple coupler. While this is a functional example of coupling WRF |
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| 30 | to another ESMF component, it should be considered *HIGHLY EXPERIMENTAL*. |
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| 31 | The implementation is quite primitive and has severe limitations. |
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| 32 | Most important, it is only possible to couple with another component that |
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| 33 | uses the exact same grid as WRF due to limitations of ESMF at the time this |
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| 34 | work was done. Also, the ESMF component only works with the DM-Parallel RSL |
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| 35 | build and has only been tested on AIX. These and a large number of other |
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| 36 | issues are described in external/io_esmf/TODO.list. |
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| 37 | |
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| 38 | Since external/io_esmf is an implementation of the WRF I/O and coupling |
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| 39 | API (WRF IOAPI), ESMF coupling can be controlled by the user in the same |
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| 40 | manner as other WRF I/O. Specifically, contents of ESMF import and export |
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| 41 | states are defined in the Registry (see Registry.EM_SST for example) and |
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| 42 | timing of coupling is defined in namelist.input. In the case of the WRF-SST |
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| 43 | coupling example, the SST component simply reads SST values stored in a file |
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| 44 | and sends it to WRF. Since the SST component also uses the WRF IOAPI and |
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| 45 | the format and metadata of SST data files is compatible with the WRF IOAPI, |
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| 46 | it is possible to switch from coupled operation to stand-alone operation (in |
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| 47 | which WRF reads the SST data directly via auxinput5), simply by changing |
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| 48 | the io_form in the namelist. |
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| 49 | |
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| 50 | This is a work-in-progress! |
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| 51 | |
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