source: NEMO/branches/2020/dev_r13648_ASINTER-04_laurent_bulk_ice/tests/STATION_ASF/README.rst @ 13781

*Station Air-Sea Fluxes* demonstration case
===========================================

Last successful test done with NEMOGCM trunk: ``r13263``

Author: Laurent Brodeau, 2020

NOTE: if working with the trunk of NEMO, you are strongly advised to use
the same test-case but on the ``NEMO-examples`` GitHub depo:
`https://github.com/NEMO-ocean/NEMO-examples/tree/master/STATION_ASF <https://github.com/NEMO-ocean/NEMO-examples/tree/master/STATION_ASF>`__

Objectives
----------

``STATION_ASF`` is a demonstration test-case that mimics a (static)
in-situ station (buoy, platform) dedicated to the estimation of surface
air-sea fluxes by means of *widely-measured* (bulk) meteorological
surface parameters.

``STATION_ASF`` has been constructed by merging the *single column* and
the *standalone surface module* configurations of NEMO. In short, it can
be defined as "SAS meets C1D". As such, the spatial domain of
``STATION_ASF`` is punctual (1D, well actually 3 x 3 as in C1D).

``STATION_ASF`` is therefore a versatile tool, and extremely lightweight
in terms of computing requirements, to test the different bulk
algorithms and cool-skin/warm-layer parameterization options included in
NEMO.

As input ``STATION_ASF`` will require the traditional *bulk* sea surface
parameters:

-  Bulk sea surface temperature (SST) at *zSST* meters below the surface
-  Surface current vector
-  Sea surface salinity

as well as the usual surface atmospheric state:

-  air temperature at *zt* meters above the surface
-  air humidity at *zt* meters above the surface (specific humidity or
   relative humidity or dew-point temperature)
-  wind speed vector at *zu* meters above the surface
-  Sea level atmospheric pressure (SLP)
-  Downwelling solar radiation
-  Downwelling longwave radiation

Example of diagnostics from ``STATION_ASF``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

(Generated with script ``./EXPREF/plot_station_asf_simple.py``)

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Physical description
--------------------

Important namelist parameters specific to STATION_ASF
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

-  ``rn_dept1@namusr_def:`` depth (m) at which the prescribed SST is
   taken (*i.e.* depth of first T-point); important due to impact on
   warm-layer estimate, the deeper, the more pronounced!

-  ``rn_lat1d,rn_lon1d@namc1d:`` fixed coordinates of the location of
   the station (buoy, platform, etc).

-  ``namsbc_blk:`` to be filled carefully, just as for "C1D", the
   prescribed surface ATMOSPHERIC state (files) are time series of shape
   3x3 in space

-  ``namsbc_sas:`` to be filled carefully, just as for "C1D", the
   prescribed surface OCEAN state (files) are time series of shape 3x3
   in space

Input files to test STATION ASF
-------------------------------

One full year (2018) of processed hourly data from the PAPA station
(buoy) is found into the ``input_data`` directory. These three files are
everything you need to play with the set of *namelists* provided for
this test-case.

-  ``Station_PAPA_50N-145W_atm_hourly_y2018.nc`` → contains hourly
   surface atmospheric state
-  ``Station_PAPA_50N-145W_precip_daily_y2018.nc`` → contains daily
   precipitation
-  ``Station_PAPA_50N-145W_oce_hourly_y2018.nc`` → contains hourly sea
   surface state

For station PAPA (50.1 N, 144.9 W), air temperature and humidity are
measured at 2.5 m, the wind speed at 4 m, and the SST at 1 m below the
surface, hence the following namelist parameters are given:

-  ``&namusr_def``

   -  ``rn_dept1 =    1.``

-  ``&namc1d``

   -  ``rn_lat1d =  50.1``
   -  ``rn_lon1d = 215.1``

-  ``&namsbc_blk``

   -  ``rn_zqt   =   2.5``
   -  ``rn_zu    =    4.``

Testing the sanity of the SBCBLK (bulk atmospheric forcing) interface of NEMO
-----------------------------------------------------------------------------

``STATION_ASF`` can be used to perform a sanity test of the SBCBLK
interface of NEMO. It will test all the bulk-parameterization algorithms
using an idealized forcing that includes a wide range of *SSX / surface
atmospheric state* conditions to detect potential error /
inconsitencies. Both a short report and boolean output: *passed* or
*failed* is provided as an output.

First compile the ``STATION_ASF`` test-case as follows (compile with
xios-2.5 support → check your ARCH file):

``./makenemo -a STATION_ASF -m <your_arch> -n STATION_ASF2 -j 4``

(successfull compilation generates
``tests/STATION_ASF2/BLD/bin/nemo.exe``

Move to: ``tests/STATION_ASF/EXPREF/``

There, in script ``sanity_check_SBCBLK.sh``, double check that the
variables given a value in the first lines are consistent with your
setup (it should).

Launch the script:

::

   $ ./sanity_check_SBCBLK.sh

The report is both interactively shown in the standard output and
spwaned in the report file:

-  ``SBCBLK.success`` the test passed :)
-  ``SBCBLK.fail`` the test failed :(

In case of failure, read the rapport to know which algorithm/computed
variables did not pass the test... You should also re-run the script
``sanity_check_SBCBLK.sh`` with the "more" argument:

::

   $ ./sanity_check_SBCBLK.sh more

This will generate more output such as figure of time series for the
tested variables.

Dependencies
~~~~~~~~~~~~

In order for the python script ``analyze_output.py`` to work, you need
``Python 3`` with the following modules:

-  numpy
-  netCDF4
-  (matplotlib)

Playing with STATION_ASF
------------------------

First compile the test-case as follows (compile with xios-2.5 support →
check your ARCH file):

``./makenemo -a STATION_ASF -m <your_arch> -n STATION_ASF2 -j 4``

Move to: ``tests/STATION_ASF/EXPREF/``

to launch 3 simulations (one for each bulk parameterization available).
You need to adapt the following variable to your environment in the
script:

-  ``NEMO_ROOT_DIR`` : NEMO root directory where to fetch compiled
   STATION_ASF ``nemo.exe`` + setup (such as
   ``${NEMO_ROOT_DIR}/tests/STATION_ASF``)

-  ``PROD_DIR`` : Directory where to run the simulation

-  ``DATA_IN_DIR`` : Directory containing sea-surface + atmospheric
   forcings (found here in ``input_data/``)

If everything goes according to plan, ``launch_sasf.sh`` should have
generated the 3 following sets of output files into
``${PROD_DIR}/output``:

::

   STATION_ASF-COARE3p6_1h_20180101_20181231_gridT.nc
   STATION_ASF-COARE3p6_1h_20180101_20181231_gridU.nc 
   STATION_ASF-COARE3p6_1h_20180101_20181231_gridV.nc 
   STATION_ASF-ECMWF_1h_20180101_20181231_gridT.nc 
   STATION_ASF-ECMWF_1h_20180101_20181231_gridU.nc 
   STATION_ASF-ECMWF_1h_20180101_20181231_gridV.nc 
   STATION_ASF-NCAR_1h_20180101_20181231_gridT.nc 
   STATION_ASF-NCAR_1h_20180101_20181231_gridU.nc 
   STATION_ASF-NCAR_1h_20180101_20181231_gridV.nc

--------------

*/Laurent, July 2020.*

.. |plot| image:: https://github.com/NEMO-ocean/NEMO-examples/blob/master/STATION_ASF/figs/01_temperatures_ECMWF.svg
.. |plot| image:: https://github.com/NEMO-ocean/NEMO-examples/blob/master/STATION_ASF/figs/Cd.svg
.. |plot| image:: https://github.com/NEMO-ocean/NEMO-examples/blob/master/STATION_ASF/figs/dT_skin.svg
.. |plot| image:: https://github.com/NEMO-ocean/NEMO-examples/blob/master/STATION_ASF/figs/Qlat.svg