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README.md

CCPP Framwork

Common Community Physics Package (CCPP) Framework.

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Notes to Users

This repository contains the Common Community Physics Packages (CCPP) Framework.

The repository for the CCPP and the CCPP driver contains sufficient code for standalone testing of the CCPP. The CCPP repository may also be used in conjunction with the GMTB Single Column Model (SCM). Please see the GMTB SCM+CCPP page for more information on combining the GMTB SCM and the CCPP.

This is the release v0.1.0 of the CCPP. As this is the initial release, the CCPP only has infrastructure to support the neccesary functioning of the anticipated package, without having actual (i.e. physically valid) physical parameterization schemes included. The included physical parameterization schemes inside of the CCPP are "stub" only. While the schemes do have arguments similar to what traditional schemes require (wind, surface temperature, physical constants), the schemes immediately return after a message "I am in this scheme" has been output.

This repository for the CCPP and the CCPP driver contains tests to verify proper running of the CCPP and driver. Detailed information on how to include fully functioning physical parameterizations schemes will be provided once examples of fully functioning schemes are part of the CCPP.

Requirements

Compilers

The CCPP uses both the C and Fortran compilers. Note, the Fortran compiler must be 2008 compliant. There are a number of Fortran 2003 pieces, and a single convenience right now with Fortran 2008.

  1. GNU Compiler Collection
  2. Intel 16.0.2 and beyond work.
  3. PGI compilers do not easily support C functions calling Fortran routines. The PGI compilers attach the Fortran module name as a prefix to the Fortran symbol. This breaks the method that the CCPP uses to identify which schemes to call.

Cmake

The CCPP build system uses cmake.

LibXML2

The suite definition is currently written in XML, LibXML2 is currently used to parse these files.

Building

It is recommend to do an out of source build. This is "cmake" terminology for creating a separate directory where all of the built code (objects, libraries, executables) exist.

  1. Clone the repository.
git clone https://github.com/NCAR/ccpp-framework ccpp
  1. Change into the repository clone
cd ccpp
  1. Specify the compiler to use. For example the GNU compilers, when it is available as a module called gcc.
  • For sh or bash
ml gcc
export CC=gcc
export FC=gfortran
export CXX=g++
  • For csh or tcsh
ml gcc
setenv CC gcc
setenv FC gfortran
setenv CXX g++
  1. Make a build directory and change into it.
mkdir build
cd build
  1. Create the makefiles.
cmake ..
  1. Build the CCPP library and test programs.
make

Running Tests

There are a few test programs within the ccpp/src/tests directory. These should be built when the CCPP library is compiled.

To run the tests you have to add the CCPP check scheme library (libcheck.so) to your LD_LIBRARY_PATH (DYLD_LIBRARY_PATH for OS X).

For sh or bash:

export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:${PWD}/schemes/check/src/check-build/

For csh or tcsh:

setenv LD_LIBRARY_PATH ${LD_LIBRARY_PATH}:${cwd}/schemes/check/src/check-build/

Note that if CCPP was built as part of a build system, you might have to load the compiler and set environment variables that were used by the build system.

Then issue the following within the build directory.

  • make test

All tests should pass, if not, please open an issue. The output should be similar to:

Running tests...
Test project /home/tbrown/Sources/ccpp-framework/build
    Start 1: XML_1
1/8 Test #1: XML_1 ............................   Passed    0.02 sec
    Start 2: XML_2
2/8 Test #2: XML_2 ............................   Passed    0.01 sec
    Start 3: XML_3
3/8 Test #3: XML_3 ............................   Passed    0.01 sec
    Start 4: XML_4
4/8 Test #4: XML_4 ............................   Passed    0.01 sec
    Start 5: XML_5
5/8 Test #5: XML_5 ............................   Passed    0.00 sec
    Start 6: XML_6
6/8 Test #6: XML_6 ............................   Passed    0.00 sec
    Start 7: FIELDS
7/8 Test #7: FIELDS ...........................   Passed    0.00 sec
    Start 8: CHECK
8/8 Test #8: CHECK ............................   Passed    0.01 sec

100% tests passed, 0 tests failed out of 8


Total Test time (real) =   0.08 sec

Validating XML

A suite is defined in XML. There are several test suites defined within the ccpp/src/tests directory (which are able to test the build and installation of the standalone CCPP). There is also the XML Schema Definition in that directory too. To validate a new test suite, you can use xmllint. For example to validate suite_EXAMPLE.xml:

cd src/tests
xmllint --schema suite.xsd --noout suite_EXAMPLE.xml
suite_EXAMLE.xml validates

Within the src/tests directory there is a Fortran file test_init_finalize.f90 which will get built into an executable program when the CCPP library is built. This program only calls:

  • ccpp_init()
  • ccpp_finalize()

It is a program to check the suite XML validation within the CCPP library. The following is an example of using it from within the build directory.

src/tests/test_init_finalize my_suite.xml

For this to work, the library that is referenced in the xml file must be added to the LD_LIBRARY_PATH (see above). To test the correct functionality of CCPP itself, the suite suite_EXAMPLE.xml in src/tests can be used.

There are two general types of XML files for the CCPP. The first is the definition file for a suite. These reside in the host model repositories. Here is a fairly short example:

<?xml version="1.0" encoding="UTF-8"?>

<suite name="RAP">
  <ipd part="1">
    <subcycle loop="1">
      <scheme>RRTMGLW</scheme>
      <scheme>RRTMGSW</scheme>
      <scheme>MYNNSFC</scheme>
      <scheme>RUCLSM</scheme>
      <scheme>MYNNPBL</scheme>
      <scheme>GF</scheme>
    </subcycle>
  </ipd>
  <ipd part="2">
    <subcycle loop="1">
      <scheme>THOMPSONAERO</scheme>
    </subcycle>
  </ipd>
</suite>
  • suite
  • This text string "name" attribute is compared to the user-selected physics suite option at run-time.
  • ipd part
  • To allow for the design of the interface between the dynamics and physical parameterization schemes, this attribute clearly associates particular packages with the dynamical sections. In this XML example, there are two "part" sections, with the second part only containing the "THOMPSONAERO" microphysics scheme.
  • Users should carefully construct the XML file to map the schemes into the existing sections of the code that calls the physical parameterization schemes.
  • subcycle
  • This functionality is not fully enabled. It is expected to be utilized for early testing, and is included in the initial release.
  • scheme
  • The scheme elements fully describe the calling sequence of the physical parameterization schemes within the model.
  • For each scheme, an XML file (the scheme definition file) needs to exist. For the initial release, this XML file has not yet been designed.

Physics Schemes

All physics schemes are kept in the GitHub repository ccpp-physics.

To add a new scheme one needs to

  1. Add/Create the scheme within schemes. You should create a sub-directory under the schemes directory. You will need to add a ExternalProject_Add(). call to the schemes/CMakeLists.txt file.

  2. Create a cap subroutine. The CCPP will call your cap routine.

  3. The cap routine must be labelled "schemename_cap".

    For example, the dummy scheme has a cap called "dummy_cap". The requirements are that it is 1. The scheme name is lowercase (the symbol is called from a C function). 2. "_cap" is appended.

  4. Map all the inputs for the cap from the cdata encapsulating type (this is of the ccpp_t type). The cap will extract the fields from the fields array with the ccpp_field_get() subroutine.

An example of a scheme is schemes/check/test.f90. It has the cap routine and the run routine. The run routine prints out that the scheme has been entered.

Usage

The CCPP must first be initialized, this is done by calling ccpp_init(). Once initialized, all variables that will be required in a physics scheme have to be added to the ccpp data object (of type ccpp_t). These variables can later be retrieved in a physics schemes cap.

Example usage, in an atmosphere component:

type(ccpp_t), target :: cdata
character(len=128)   :: scheme_xml_filename
integer              :: ierr

ierr = 0

! Initialize the CCPP and load the physics scheme.
call ccpp_init(scheme_xml_filename, cdata, ierr)
if (ierr /= 0) then
    call exit(1)
end if

! Add surface temperature (variable surf_t).
call ccpp_field_add(cdata, 'surface_temperature', surf_t, ierr, 'K')
if (ierr /= 0) then
    call exit(1)
end if

! Call the first physics scheme
call ccpp_ipd_run(cdata%suite%ipds(1)%subcycles(1)%schemes(1), cdata, ierr)
if (ierr /= 0) then
    call exit(1)
end if

Example usage, in a physics cap:

type(ccpp_t), pointer      :: cdata
real, pointer              :: surf_t(:)
integer                    :: ierr

call c_f_pointer(ptr, cdata)
call ccpp_field_get(cdata, 'surface_temperature', surf_t, ierr)
if (ierr /= 0) then
    call exit(1)
end if

Note, the cap routine must

  • Accept only one argument of type type(c_ptr).
  • Be marked as bind(c).

Documentation

The code is documented with doxygen. To generate the documentation you must have doxygen and graphviz installed. Then execute:

make doc

Code Coverage

The code can be built and run to indicate code coverage. In order to do this, you must have GNU gcov and lcov installed. To generate the coverage:

  1. Make sure you are using the GNU compilers.
  2. Configure the build for coverage.
  • cmake -DCMAKE_BUILD_TYPE=Coverage ..
  1. Build the CCPP.
  • make
  1. Build the coverage report
  • make coverage The coverage report will be in the coverage directory within the build.
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