``Daymet``
==========

In this file, the details of the dataset is explained.

.. warning::
   The dataset files are divided between three different
   spatial domains: 1) North America (na), 2) Peurto Rico (pr), and 3)
   Hawaii (hi). For the moment, only the ``na`` domain is considered in
   ``datatool``.

Location of Dataset Files
-------------------------

The global ``Daymet`` dataset is located under the following directory
accessible from multiple clusters:

.. code::

   # DRAC Graham HPC locations
   /project/rpp-kshook/Model_Output/Daymet_Daily_V4R1/data/ # rpp-kshook allocation

   # DRAC Fir HPC locations
   /project/rrg-alpie/data/meteorological-data/daymet-v4r1-ornl # rrg-alpie allocation

   # UCalgary ARC HPC locations
   /work/comphyd_lab/data/meteorological-data/daymet-v4r1-ornl # comphyd_lab allocation

   # Perdue University Anvil HPC locations
   /anvil/datasets/meteorological/ORNL_Daymet # community data storage

and the structure of the dataset hourly files is as following:

.. code:: console

   /path/to/dataset/files/
   ├── daymet_v4_daily_hi_dayl_1980.nc
   ├── daymet_v4_daily_hi_dayl_1981.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_hi_dayl_2022.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_hi_vp_1980.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_hi_vp_2022.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_{%domain}_{%variable}_{%year}.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_na_dayl_1980.nc
   ├── .
   ├── .
   ├── .
   ├── daymet_v4_daily_na_vp_2022.nc
   ├── daymet_v4_daily_pr_dayl_1950.nc
   ├── .
   ├── .
   ├── .
   └── daymet_v4_daily_pr_vp_2022.n

Coordinate Variables and Time-stamps
------------------------------------

Coordinate Variables
~~~~~~~~~~~~~~~~~~~~

The coordinate variables of the ``Daymet`` simulations are ``lon`` and
``lat`` representing the longitude and latitude points, respectively.
The coordinate system is 2-dimensional and follows a Lambert Conformal
Conic projection system. ### Time-stamps The time-stamps are included in
the original files.

Dataset Variables
-----------------

The NetCDF files of the dataset contain 7 variables. You may see a list
of variables by browsing the dataset directory and listing the files.

Spatial Extent
--------------

The spatial resolutaion of ``Daymet`` gridded data is 1 :math:`km`. The
model files are divided between three different domains: 1) North
American (na), 2) Peurto Rico (pr), and 3) Hawaii (hi). Each domains
spatial extents are printed in the following table:

.. list-table:: Domain Extents
   :header-rows: 1

   * - Number
     - Domain
     - Latitude extents
     - Longitude extents
   * - 1
     - ``na``
     - ``+6.08°`` to ``+83.79°``
     - ``-180°`` to ``+180°``
   * - 2
     - ``pr``
     - ``+16.85°`` to ``+19.93°``
     - ``-67.97°`` to ``-64.13°``
   * - 3
     - ``hi``
     - ``+17.96°`` to ``+23.51°``
     - ``-160.30°`` to ``-154.78°``


.. warning::
  As mentioned previously, only the ``na`` domain is
  considered in the subsetting process of ``datatool``.

Temporal Extent
---------------

The time-steps are daily and the temporal extent for each domain is
listed in the following table:

.. list-table::
   :header-rows: 1

   * - Number
     - Domain
     - Time-step interval
     - Start date
     - End date
   * - 1
     - ``na``
     - daily
     - ``1980-01-01``
     - ``2022-12-31``
   * - 2
     - ``pr``
     - daily
     - ``1950-01-01``
     - ``2022-12-31``
   * - 3
     - ``hi``
     - daily
     - ``1980-01-01``
     - ``2022-12-31``

Also, “[t]he Daymet calendar is based on a standard calendar year. All
Daymet years have 1 - 365 days, including leap years. For leap years,
the Daymet database includes leap day. Values for December 31 are
discarded from leap years to maintain a 365-day year.”

.. warning::
   As mentioned previously, only the ``na`` domain is
   considered in the subsetting process of ``datatool``.

Short Description on ``Daymet`` Variables
-----------------------------------------

The variables currently available through the ``Daymet`` dataset and
their details are described in the table below, taken from the
`source <https://daymet.ornl.gov/overview>`__:

.. list-table:: Daymet Variables
   :header-rows: 1

   * - Variable Name
     - `Daymet` Variable
     - Unit
     - Comments
   * - day length
     - ``dayl``
     - ``s/day``
     - Duration of the daylight period in seconds per day. This calculation is based on the period of the day during which the sun is above a hypothetical flat horizon.
   * - precipitation
     - ``prcp``
     - ``mm/day``
     - Daily total precipitation in millimeters per day, sum of all forms converted to water-equivalent. Precipitation occurrence on any given day may be ascertained.
   * - shortwave radiation
     - ``srad``
     - ``W/m2``
     - Incident shortwave radiation flux density in watts per square meter, taken as an average over the daylight period of the day. NOTE: Daily total radiation (``MJ/m2/day``) can be calculated as follows: ``((srad (W/m2) * dayl (s/day)) / 1,000,000)``.
   * - snow water equivalent
     - ``swe``
     - ``kg/m2``
     - Snow water equivalent in kilograms per square meter. The amount of water contained within the snowpack.
   * - maximum air temperature
     - ``tmax``
     - ``deg C``
     - Daily maximum 2-meter air temperature in degrees Celsius.
   * - minimum air temperature
     - ``tmin``
     - ``deg C``
     - Daily minimum 2-meter air temperature in degrees Celsius.
   * - water vapor pressure
     - ``vp``
     - ``Pa``
     - Water vapor pressure in pascals. Daily average partial pressure of water vapor.


For a complete catalog of the dataset, see
`here <https://daymet.ornl.gov/overview>`__.