.. _gen_NLDAS2:

National Land Data Assimilation Product V2
^^^^^^^^^^^^^^^^^^

The NLDAS grid is a 1/8th degree grid that covers the entire contiguous US.  This dataset contains the NLDAS2 forcing data at 1/8th degree resolution and a 1 hour time step.  This dataset was used to force the `conus1_baseline_mod <https://hf-hydrodata.readthedocs.io/en/latest/gen_conus1_baseline_mod.html>`_ simulation.  This dataset is adjusted and bias corrected per the description in `O'Neill et al GMD 2021 <https://gmd.copernicus.org/articles/14/7223/2021/>`_.

**Dataset Name**: NLDAS2

**Data Source**: nasa

**Data Collection or Processing Notes:**

    Heavily bias corrected per `O'Neill et al GMD 2021 <https://gmd.copernicus.org/articles/14/7223/2021/>`_.  The bias correction is applied to the NLDAS2 data before it is bilinearly interpolated to the ParFlow CONUS1 grid.

**Citations:**

Please refer to the following citations for more information on this dataset and cite them if you use the data

* https://doi.org/10.5194/gmd-14-7223-2021;

* https://doi.org/10.1002/2016GL069964

* https://ldas.gsfc.nasa.gov/nldas/v2/forcing

**Extent and Resolution**:

* Available Date Range: 2002-10-01 to 2006-09-30

* Grid: conus1

  - Spacial Resolution:  1000 meters

  - XY Grid Spacial Extent:  3342 x 1888

  - LatLon Spacial Exent:  -121.47939483437318, 31.651836025255015,  -76.09875469594509, 50.49802132270979

  - Origin (meters): -1885055.4995, -604957.0654

  - Projection: +proj=lcc +lat_1=33 +lat_2=45 +lon_0=-96.0 +lat_0=39 +a=6378137.0 +b=6356752.31

Variables
^^^^^^^^^^^^^^^^^^

This describes the available variables of the dataset.
Use the dataset, variables and temporal_resolution in python access functions as described in the Working with Gridded Data, and Working with Point Observations.

.. list-table:: Atmospheric Variables
    :widths: 25 60 30 20 20 20 20
    :header-rows: 1

    * - variable
      - description
      - temporal_resolution
      - units
      - aggregation
      - grid
      - 3D
    * - north_windspeed
      - Meridional windspeed
      - daily, hourly
      - m/s
      - mean
      - conus1
      - no
    * - air_temp
      - Air temperature
      - daily, hourly, monthly, annual_clim, monthly_clim
      - K
      - min, mean, max
      - conus1
      - no
    * - downward_shortwave
      - Downward shortwave radiation
      - hourly, daily
      - w/m2
      - mean
      - conus1
      - no
    * - downward_longwave
      - Downward longwave radiation
      - hourly, daily
      - w/m2
      - mean
      - conus1
      - no
    * - specific_humidity
      - Specific humidity
      - hourly, daily
      - kg/kg
      - mean
      - conus1
      - no
    * - east_windspeed
      - Zonal windspeed
      - hourly, daily
      - m/s
      - mean
      - conus1
      - no
    * - precipitation
      - Precipitation
      - monthly, daily, annual_clim, monthly_clim, hourly
      - mm
      - sum
      - conus1
      - no
    * - atmospheric_pressure
      - Atmospheric pressure
      - hourly, daily
      - pa
      - mean
      - conus1
      - no