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iris.coord_systems

Definitions of coordinate systems.

In this module:

A coordinate system in the Albers Conical Equal Area projection.

class iris.coord_systems.AlbersEqualArea(latitude_of_projection_origin=None, longitude_of_central_meridian=None, false_easting=None, false_northing=None, standard_parallels=None, ellipsoid=None)[source]

Constructs a Albers Conical Equal Area coord system.

Kwargs:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees. Defaults to 0.0 .

  • longitude_of_central_meridian:

    True longitude of planar central meridian in degrees. Defaults to 0.0 .

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • standard_parallels (number or iterable of 1 or 2 numbers):

    The one or two latitudes of correct scale. Defaults to (20.0, 50.0).

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'albers_conical_equal_area'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_central_meridian

True longitude of planar central meridian in degrees.

standard_parallels

The one or two latitudes of correct scale (tuple of 1 or 2 floats).

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Abstract base class for coordinate systems.

class iris.coord_systems.CoordSystem[source]

Abstract base class for coordinate systems.

abstract as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

abstract as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)[source]

Default behaviour for coord systems.

grid_mapping_name = None

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A geographic (ellipsoidal) coordinate system, defined by the shape of the Earth and a prime meridian.

class iris.coord_systems.GeogCS(semi_major_axis=None, semi_minor_axis=None, inverse_flattening=None, longitude_of_prime_meridian=None)[source]

Creates a new GeogCS.

Kwargs:

  • semi_major_axis, semi_minor_axis:

    Axes of ellipsoid, in metres. At least one must be given (see note below).

  • inverse_flattening:

    Can be omitted if both axes given (see note below). Defaults to 0.0 .

  • longitude_of_prime_meridian:

    Specifies the prime meridian on the ellipsoid, in degrees. Defaults to 0.0 .

If just semi_major_axis is set, with no semi_minor_axis or inverse_flattening, then a perfect sphere is created from the given radius.

If just two of semi_major_axis, semi_minor_axis, and inverse_flattening are given the missing element is calculated from the formula: \(flattening = (major - minor) / major\)

Currently, Iris will not allow over-specification (all three ellipsoid parameters).

Examples:

cs = GeogCS(6371229)
pp_cs = GeogCS(iris.fileformats.pp.EARTH_RADIUS)
airy1830 = GeogCS(semi_major_axis=6377563.396,
                  semi_minor_axis=6356256.909)
airy1830 = GeogCS(semi_major_axis=6377563.396,
                  inverse_flattening=299.3249646)
custom_cs = GeogCS(6400000, 6300000)
as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_globe()[source]
as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc)[source]

Default behaviour for coord systems.

grid_mapping_name = 'latitude_longitude'
inverse_flattening

\(1/f\) where \(f = (a-b)/a\).

longitude_of_prime_meridian

Describes ‘zero’ on the ellipsoid in degrees.

semi_major_axis

Major radius of the ellipsoid in metres.

semi_minor_axis

Minor radius of the ellipsoid in metres.

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A geostationary satellite image map projection.

class iris.coord_systems.Geostationary(latitude_of_projection_origin, longitude_of_projection_origin, perspective_point_height, sweep_angle_axis, false_easting=None, false_northing=None, ellipsoid=None)[source]

Constructs a Geostationary coord system.

Args:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees.

  • longitude_of_projection_origin:

    True longitude of planar origin in degrees.

  • perspective_point_height:

    Altitude of satellite in metres above the surface of the ellipsoid.

  • sweep_angle_axis (string):

    The axis along which the satellite instrument sweeps - ‘x’ or ‘y’.

Kwargs:

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'geostationary'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_projection_origin

True longitude of planar origin in degrees.

perspective_point_height

Altitude of satellite in metres.

sweep_angle_axis

The sweep angle axis (string ‘x’ or ‘y’).

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A coordinate system in the Lambert Azimuthal Equal Area projection.

class iris.coord_systems.LambertAzimuthalEqualArea(latitude_of_projection_origin=None, longitude_of_projection_origin=None, false_easting=None, false_northing=None, ellipsoid=None)[source]

Constructs a Lambert Azimuthal Equal Area coord system.

Kwargs:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees. Defaults to 0.0 .

  • longitude_of_projection_origin:

    True longitude of planar origin in degrees. Defaults to 0.0 .

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'lambert_azimuthal_equal_area'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_projection_origin

True longitude of planar origin in degrees.

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A coordinate system in the Lambert Conformal conic projection.

class iris.coord_systems.LambertConformal(central_lat=None, central_lon=None, false_easting=None, false_northing=None, secant_latitudes=None, ellipsoid=None)[source]

Constructs a LambertConformal coord system.

Kwargs:

  • central_lat:

    The latitude of “unitary scale”. Defaults to 39.0 .

  • central_lon:

    The central longitude. Defaults to -96.0 .

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • secant_latitudes (number or iterable of 1 or 2 numbers):

    Latitudes of secant intersection. One or two. Defaults to (33.0, 45.0).

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

central_lat

True latitude of planar origin in degrees.

central_lon

True longitude of planar origin in degrees.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'lambert_conformal_conic'
secant_latitudes

The standard parallels of the cone (tuple of 1 or 2 floats).

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A coordinate system in the Mercator projection.

class iris.coord_systems.Mercator(longitude_of_projection_origin=None, ellipsoid=None, standard_parallel=None)[source]

Constructs a Mercator coord system.

Kwargs:

  • longitude_of_projection_origin:

    True longitude of planar origin in degrees. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

  • standard_parallel:

    The latitude where the scale is 1. Defaults to 0.0 .

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

grid_mapping_name = 'mercator'
longitude_of_projection_origin

True longitude of planar origin in degrees.

standard_parallel

The latitude where the scale is 1.

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A Specific transverse mercator projection on a specific ellipsoid.

class iris.coord_systems.OSGB[source]

A Specific transverse mercator projection on a specific ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'transverse_mercator'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_central_meridian

True longitude of planar origin in degrees.

scale_factor_at_central_meridian

Scale factor at the centre longitude.

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An orthographic map projection.

class iris.coord_systems.Orthographic(latitude_of_projection_origin, longitude_of_projection_origin, false_easting=None, false_northing=None, ellipsoid=None)[source]

Constructs an Orthographic coord system.

Args:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees.

  • longitude_of_projection_origin:

    True longitude of planar origin in degrees.

Kwargs:

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'orthographic'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_projection_origin

True longitude of planar origin in degrees.

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A coordinate system with rotated pole, on an optional GeogCS.

class iris.coord_systems.RotatedGeogCS(grid_north_pole_latitude, grid_north_pole_longitude, north_pole_grid_longitude=None, ellipsoid=None)[source]

Constructs a coordinate system with rotated pole, on an optional GeogCS.

Args:

  • grid_north_pole_latitude:

    The true latitude of the rotated pole in degrees.

  • grid_north_pole_longitude:

    The true longitude of the rotated pole in degrees.

Kwargs:

  • north_pole_grid_longitude:

    Longitude of true north pole in rotated grid, in degrees. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

Examples:

rotated_cs = RotatedGeogCS(30, 30)
another_cs = RotatedGeogCS(30, 30,
                           ellipsoid=GeogCS(6400000, 6300000))
as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc)[source]

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

grid_mapping_name = 'rotated_latitude_longitude'
grid_north_pole_latitude

The true latitude of the rotated pole in degrees.

grid_north_pole_longitude

The true longitude of the rotated pole in degrees.

north_pole_grid_longitude

Longitude of true north pole in rotated grid in degrees.

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A stereographic map projection.

class iris.coord_systems.Stereographic(central_lat, central_lon, false_easting=None, false_northing=None, true_scale_lat=None, ellipsoid=None)[source]

Constructs a Stereographic coord system.

Args:

  • central_lat:

    The latitude of the pole.

  • central_lon:

    The central longitude, which aligns with the y axis.

Kwargs:

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • true_scale_lat:

    Latitude of true scale.

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

central_lat

True latitude of planar origin in degrees.

central_lon

True longitude of planar origin in degrees.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'stereographic'
true_scale_lat

Latitude of true scale.

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A cylindrical map projection, with XY coordinates measured in metres.

class iris.coord_systems.TransverseMercator(latitude_of_projection_origin, longitude_of_central_meridian, false_easting=None, false_northing=None, scale_factor_at_central_meridian=None, ellipsoid=None)[source]

Constructs a TransverseMercator object.

Args:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees.

  • longitude_of_central_meridian:

    True longitude of planar origin in degrees.

Kwargs:

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • scale_factor_at_central_meridian:

    Reduces the cylinder to slice through the ellipsoid (secant form). Used to provide TWO longitudes of zero distortion in the area of interest. Defaults to 1.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

Example:

airy1830 = GeogCS(6377563.396, 6356256.909)
osgb = TransverseMercator(49, -2, 400000, -100000, 0.9996012717,
                          ellipsoid=airy1830)
as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'transverse_mercator'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_central_meridian

True longitude of planar origin in degrees.

scale_factor_at_central_meridian

Scale factor at the centre longitude.

↑ top ↑

A vertical/near-side perspective satellite image map projection.

class iris.coord_systems.VerticalPerspective(latitude_of_projection_origin, longitude_of_projection_origin, perspective_point_height, false_easting=None, false_northing=None, ellipsoid=None)[source]

Constructs a Vertical Perspective coord system.

Args:

  • latitude_of_projection_origin:

    True latitude of planar origin in degrees.

  • longitude_of_projection_origin:

    True longitude of planar origin in degrees.

  • perspective_point_height:

    Altitude of satellite in metres above the surface of the ellipsoid.

Kwargs:

  • false_easting:

    X offset from planar origin in metres. Defaults to 0.0 .

  • false_northing:

    Y offset from planar origin in metres. Defaults to 0.0 .

  • ellipsoid (GeogCS):

    If given, defines the ellipsoid.

as_cartopy_crs()[source]

Return a cartopy CRS representing our native coordinate system.

as_cartopy_projection()[source]

Return a cartopy projection representing our native map.

This will be the same as the as_cartopy_crs() for map projections but for spherical coord systems (which are not map projections) we use a map projection, such as PlateCarree.

xml_element(doc, attrs=None)

Default behaviour for coord systems.

ellipsoid

Ellipsoid definition (GeogCS or None).

false_easting

X offset from planar origin in metres.

false_northing

Y offset from planar origin in metres.

grid_mapping_name = 'vertical_perspective'
latitude_of_projection_origin

True latitude of planar origin in degrees.

longitude_of_projection_origin

True longitude of planar origin in degrees.

perspective_point_height

Altitude of satellite in metres.