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MerraSource

Classes:

  • MerraSource –

    The MerraSource object manages weather data (as netCDF4 files) coming from the

MerraSource 

MerraSource(source, bounds=None, index_pad=5, **kwargs)

Bases: NCSource

The MerraSource object manages weather data (as netCDF4 files) coming from the MERRA2 climate data products<https://gmao.gsfc.nasa.gov/reanalysis/MERRA-2/>

If furthermore allows access a number of common functionalities and constants which are often encountered when simulating renewable energy technologies

Note:

Various constants can have been set for this weather source which can impact later simulation workflows.

These constants include: MAX_LON_DIFFERENCE = 0.625 The maximum longitude difference to accept between a grid cell's center and the coordinates to extract data for

MAX_LAT_DIFFERENCE = 0.5
    The maximum latitude difference to accept between a grid cell's center and the coordinates
        to extract data for

WIND_SPEED_HEIGHT_FOR_WIND_ENERGY = 50
    The suggested altitude of wind speed data to use for wind-energy simulations

WIND_SPEED_HEIGHT_FOR_SOLAR_ENERGY = 2
    The suggested altitude of wind speed data to use for wind-energy simulations

LONG_RUN_AVERAGE_WINDSPEED :
    <RESKit path>/weather/MerraSource/data/merra_average_windspeed_50m-shifted.tif

    A path to a raster file with the long-time average wind speed in each grid cell
    * Can be used in wind energy simulations
    * Calculated at the height specified in `WIND_SPEED_HEIGHT_FOR_WIND_ENERGY`
    * Time range includes 1980 until the end of 2017 (the time of first calculation)
    * Only a few regions have been precomputed, therefore applications which require this
        data will not work outside of these regions. They include:
        - Europe
        - Australia
        - Iceland
        - Parts of south america
        - Parts of north america


LONG_RUN_AVERAGE_GHI :
    <RESKit path>/weather/MerraSource/data/merra_average_SWGDN_1994-2015_globe.tif

    A path to a raster file with the long-time average global horizontal irradiance in
        each grid cell
    * Can be used in solar energy simulations
    * Calculated at the surface
    * Time range includes 1994 until the end of 2015 (to match the global solar atlas)
    * Only a few regions have been precomputed, therefore applications which require this
        data will not work outside of these regions. They include:
        - Europe
        - Australia
        - Iceland
        - Parts of south america
        - Parts of north america
See Also

reskit.weather.MerraSource reskit.weather.SarahSource reskit.weather.Era5Source

Initialize a MERRA2 style netCDF4 file source

Compared to the generic NCSource object, the following parameters are automatically set: * tz = "GMT" * time_name = "time" * lat_name = "lat" * lon_name = "lon" * flip_lat = False * flip_lon = False * time_offset_minutes = 0

Parameters:

  • path

    (str or list of str) –

    The path to the main data file(s) to load

    If multiple files are given, or if a directory of netCDF4 files is given, then it is assumed that all files ending with the extension '.nc' or '.nc4' should be managed by this object. * Be sure that all the netCDF4 files given share the same time and spatial dimensions!

  • bounds

    (Anything acceptable to geokit.Extent.load(), default: None ) –

    The boundaries of the data which is needed * Usage of this will help with memory management * If None, the full dataset is loaded in memory * The actual extent of the loaded data depends on the source's available data

  • index_pad

    (int, default: 5 ) –

    The padding to apply to the boundaries * Useful in case of interpolation * Units are in longitudinal degrees

  • verbose

    (bool) –

    If True, then status outputs are printed when searching for and reading weather data

  • forward_fill

    (bool) –

    If True, then missing data in the weather file is forward-filled * Generally, there should be no missing data at all. This option is only intended to catch the rare scenarios where one or two timesteps are missing

See Also

MerraSource SarahSource Era5Source

Methods:

Source code in reskit/weather/MerraSource/MerraSource.py 
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def __init__(self, source, bounds=None, index_pad=5, **kwargs):
    """Initialize a MERRA2 style netCDF4 file source

    Compared to the generic NCSource object, the following parameters are automatically set:
        * tz = "GMT"
        * time_name = "time"
        * lat_name = "lat"
        * lon_name = "lon"
        * flip_lat = False
        * flip_lon = False
        * time_offset_minutes = 0


    Parameters
    ----------
    path : str or list of str
        The path to the main data file(s) to load

        If multiple files are given, or if a directory of netCDF4 files is given, then it is assumed
        that all files ending with the extension '.nc' or '.nc4' should be managed by this object.
        * Be sure that all the netCDF4 files given share the same time and spatial dimensions!

    bounds : Anything acceptable to geokit.Extent.load(), optional
        The boundaries of the data which is needed
          * Usage of this will help with memory management
          * If None, the full dataset is loaded in memory
          * The actual extent of the loaded data depends on the source's
            available data

    index_pad : int, optional
        The padding to apply to the boundaries
          * Useful in case of interpolation
          * Units are in longitudinal degrees

    verbose : bool, optional
        If True, then status outputs are printed when searching for and reading weather data

    forward_fill : bool, optional
        If True, then missing data in the weather file is forward-filled
        * Generally, there should be no missing data at all. This option is only intended to
            catch the rare scenarios where one or two timesteps are missing

    See Also
    --------
    MerraSource
    SarahSource
    Era5Source
    """
    super().__init__(
        source=source,
        bounds=bounds,
        time_name="time",
        lat_name="lat",
        lon_name="lon",
        index_pad=index_pad,
        _max_lon_diff=self.MAX_LON_DIFFERENCE,
        _max_lat_diff=self.MAX_LAT_DIFFERENCE,
        tz="GMT",
        **kwargs,
    )

context_area_at_index 

context_area_at_index(latI, lonI)

Compute the context area surrounding the specified index of the original source

Source code in reskit/weather/MerraSource/MerraSource.py 
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def context_area_at_index(self, latI, lonI):
    """Compute the context area surrounding the specified index of the original source"""
    # Make and return a box
    lowLat = self.lats[latI] - 0.25
    highLat = self.lats[latI] + 0.25
    lowLon = self.lons[lonI] - 0.3125
    highLon = self.lons[lonI] + 0.3125

    return gk.geom.box(lowLon, lowLat, highLon, highLat, srs=gk.srs.EPSG4326)

sload_elevated_wind_direction 

sload_elevated_wind_direction()

Standard loader function for the variable 'elevated_wind_direction'

Automatically reads the variables "UM" and "VM" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'elevated_wind_direction' in the data library

Where '' is the height specified by MerraSource.ELEVATED_WIND_SPEED_HEIGHT

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_elevated_wind_direction(self):
    """Standard loader function for the variable 'elevated_wind_direction'

    Automatically reads the variables "U<X>M" and "V<X>M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'elevated_wind_direction' in
    the data library

    Where '<X>' is the height specified by `MerraSource.ELEVATED_WIND_SPEED_HEIGHT`
    """
    self.data["elevated_wind_direction"] = self._load_wind_speed(height=self.ELEVATED_WIND_SPEED_HEIGHT)

sload_elevated_wind_speed 

sload_elevated_wind_speed()

Standard loader function for the variable 'elevated_wind_speed'

Automatically reads the variables "UM" and "VM" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'elevated_wind_speed' in the data library

Where '' is the height specified by MerraSource.ELEVATED_WIND_SPEED_HEIGHT

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_elevated_wind_speed(self):
    """Standard loader function for the variable 'elevated_wind_speed'

    Automatically reads the variables "U<X>M" and "V<X>M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'elevated_wind_speed' in
    the data library

    Where '<X>' is the height specified by `MerraSource.ELEVATED_WIND_SPEED_HEIGHT`
    """
    self.data["elevated_wind_speed"] = self._load_wind_speed(height=self.ELEVATED_WIND_SPEED_HEIGHT)

sload_global_horizontal_irradiance 

sload_global_horizontal_irradiance()

Standard loader function for the variable 'global_horizontal_irradiance'

Automatically reads the variable "SWGDN" from the given MERRA2 source and saves it as the variable 'global_horizontal_irradiance' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_global_horizontal_irradiance(self):
    """Standard loader function for the variable 'global_horizontal_irradiance'

    Automatically reads the variable "SWGDN" from the given MERRA2 source and saves it as the
    variable 'global_horizontal_irradiance' in the data library
    """
    return self.load("SWGDN", name="global_horizontal_irradiance")

sload_surface_air_temperature 

sload_surface_air_temperature()

Standard loader function for the variable 'surface_air_temperature'

Automatically reads the variable "T2M" from the given MERRA2 source and saves it as the variable 'surface_air_temperature' in the data library

Temperature values are also converted from kelvin to degrees celsius

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_surface_air_temperature(self):
    """Standard loader function for the variable 'surface_air_temperature'

    Automatically reads the variable "T2M" from the given MERRA2 source and saves it as the
    variable 'surface_air_temperature' in the data library

    Temperature values are also converted from kelvin to degrees celsius
    """
    return self.load("T2M", name="surface_air_temperature", processor=lambda x: x - 273.15)

sload_surface_dew_temperature 

sload_surface_dew_temperature()

Standard loader function for the variable 'surface_dew_temperature'

Automatically reads the variable "T2MDEW" from the given MERRA2 source and saves it as the variable 'surface_dew_temperature' in the data library

Temperature values are also converted from kelvin to degrees celsius

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_surface_dew_temperature(self):
    """Standard loader function for the variable 'surface_dew_temperature'

    Automatically reads the variable "T2MDEW" from the given MERRA2 source and saves it as the
    variable 'surface_dew_temperature' in the data library

    Temperature values are also converted from kelvin to degrees celsius
    """
    return self.load("T2MDEW", name="surface_dew_temperature", processor=lambda x: x - 273.15)

sload_surface_pressure 

sload_surface_pressure()

Standard loader function for the variable 'surface_pressure'

Automatically reads the variable "PS" from the given MERRA2 source and saves it as the variable 'surface_pressure' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_surface_pressure(self):
    """Standard loader function for the variable 'surface_pressure'

    Automatically reads the variable "PS" from the given MERRA2 source and saves it as the
    variable 'surface_pressure' in the data library
    """
    return self.load("PS", name="surface_pressure")

sload_surface_wind_direction 

sload_surface_wind_direction()

Standard loader function for the variable 'surface_wind_direction'

Automatically reads the variables "UM" and "VM" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'surface_wind_direction' in the data library

Where '' is the height specified by MerraSource.SURFACE_WIND_SPEED_HEIGHT

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_surface_wind_direction(self):
    """Standard loader function for the variable 'surface_wind_direction'

    Automatically reads the variables "U<X>M" and "V<X>M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'surface_wind_direction' in
    the data library

    Where '<X>' is the height specified by `MerraSource.SURFACE_WIND_SPEED_HEIGHT`
    """
    self.data["surface_wind_direction"] = self._load_wind_speed(height=self.SURFACE_WIND_SPEED_HEIGHT)

sload_surface_wind_speed 

sload_surface_wind_speed()

Standard loader function for the variable 'surface_wind_speed'

Automatically reads the variables "UM" and "VM" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'surface_wind_speed' in the data library

Where '' is the height specified by MerraSource.SURFACE_WIND_SPEED_HEIGHT

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_surface_wind_speed(self):
    """Standard loader function for the variable 'surface_wind_speed'

    Automatically reads the variables "U<X>M" and "V<X>M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'surface_wind_speed' in
    the data library

    Where '<X>' is the height specified by `MerraSource.SURFACE_WIND_SPEED_HEIGHT`
    """
    self.data["surface_wind_speed"] = self._load_wind_speed(height=self.SURFACE_WIND_SPEED_HEIGHT)

sload_wind_direction_at_10m 

sload_wind_direction_at_10m()

Standard loader function for the variable 'wind_direction_at_10m'

Automatically reads the variables "U10M" and "V10M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_direction_at_10m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_direction_at_10m(self):
    """Standard loader function for the variable 'wind_direction_at_10m'

    Automatically reads the variables "U10M" and "V10M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_direction_at_10m' in
    the data library
    """
    self.data["wind_direction_at_10m"] = self._load_wind_speed(10)

sload_wind_direction_at_2m 

sload_wind_direction_at_2m()

Standard loader function for the variable 'wind_direction_at_2m'

Automatically reads the variables "U2M" and "V2M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_direction_at_2m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_direction_at_2m(self):
    """Standard loader function for the variable 'wind_direction_at_2m'

    Automatically reads the variables "U2M" and "V2M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_direction_at_2m' in
    the data library
    """
    self.data["wind_direction_at_2m"] = self._load_wind_speed(2)

sload_wind_direction_at_50m 

sload_wind_direction_at_50m()

Standard loader function for the variable 'wind_direction_at_50m'

Automatically reads the variables "U50M" and "V50M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_direction_at_50m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_direction_at_50m(self):
    """Standard loader function for the variable 'wind_direction_at_50m'

    Automatically reads the variables "U50M" and "V50M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_direction_at_50m' in
    the data library
    """
    self.data["wind_direction_at_50m"] = self._load_wind_speed(50)

sload_wind_speed_at_10m 

sload_wind_speed_at_10m()

Standard loader function for the variable 'wind_speed_at_10m'

Automatically reads the variables "U10M" and "V10M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_speed_at_10m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_speed_at_10m(self):
    """Standard loader function for the variable 'wind_speed_at_10m'

    Automatically reads the variables "U10M" and "V10M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_speed_at_10m' in
    the data library
    """
    self.data["wind_speed_at_10m"] = self._load_wind_speed(10)

sload_wind_speed_at_2m 

sload_wind_speed_at_2m()

Standard loader function for the variable 'wind_speed_at_2m'

Automatically reads the variables "U2M" and "V2M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_speed_at_2m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_speed_at_2m(self):
    """Standard loader function for the variable 'wind_speed_at_2m'

    Automatically reads the variables "U2M" and "V2M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_speed_at_2m' in
    the data library
    """
    self.data["wind_speed_at_2m"] = self._load_wind_speed(2)

sload_wind_speed_at_50m 

sload_wind_speed_at_50m()

Standard loader function for the variable 'wind_speed_at_50m'

Automatically reads the variables "U50M" and "V50M" from the given MERRA2 source, computes the total windspeed, and saves it as the variable 'wind_speed_at_50m' in the data library

Source code in reskit/weather/MerraSource/MerraSource.py 
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def sload_wind_speed_at_50m(self):
    """Standard loader function for the variable 'wind_speed_at_50m'

    Automatically reads the variables "U50M" and "V50M" from the given MERRA2 source,
    computes the total windspeed, and saves it as the variable 'wind_speed_at_50m' in
    the data library
    """
    self.data["wind_speed_at_50m"] = self._load_wind_speed(50)