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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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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).

↑ top ↑

Abstract base class for coordinate systems.

class iris.coord_systems.CoordSystem[source]#

Abstract base class for coordinate systems.

__eq__(other)[source]#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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#

↑ top ↑

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]#

Create a new GeogCS.

Parameters
• semi_major_axis (*) – Axes of ellipsoid, in metres. At least one must be given (see note below).

• 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). Default 0.0

• longitude_of_prime_meridian (*) – Specifies the prime meridian on the ellipsoid, in degrees. Default 0.0

Notes

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).

After object creation, altering any of these properties will not update the others. semi_major_axis and semi_minor_axis are used when creating Cartopy objects.

Examples:

cs = GeogCS(6371229)
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)

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

classmethod from_datum(datum, longitude_of_prime_meridian=None)[source]#
xml_element(doc)[source]#

Default behaviour for coord systems.

property datum#
grid_mapping_name = 'latitude_longitude'#
property inverse_flattening#
longitude_of_prime_meridian#

Describes ‘zero’ on the ellipsoid in degrees.

property semi_major_axis#
property semi_minor_axis#

↑ top ↑

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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’).

↑ top ↑

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

↑ top ↑

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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).

↑ top ↑

A coordinate system in the Mercator projection.

class iris.coord_systems.Mercator(longitude_of_projection_origin=None, ellipsoid=None, standard_parallel=None, scale_factor_at_projection_origin=None, false_easting=None, false_northing=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 .

• scale_factor_at_projection_origin:

Scale factor at natural origin. Defaults to unused.

• false_easting:

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

• false_northing:

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

• datum:

If given, specifies the datumof the coordinate system. Only respected if iris.Future.daum_support is set.

Note: Only one of standard_parallel and scale_factor_at_projection_origin should be included.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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 the planar origin in metres.

false_northing#

Y offset from the planar origin in metres.

grid_mapping_name = 'mercator'#
longitude_of_projection_origin#

True longitude of planar origin in degrees.

standard_parallel#

The latitude where the scale is 1.

↑ top ↑

A Specific transverse mercator projection on a specific ellipsoid.

class iris.coord_systems.OSGB[source]#

A Specific transverse mercator projection on a specific ellipsoid.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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 ↑

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

↑ top ↑

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))

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

↑ top ↑

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

↑ top ↑

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)

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.

__eq__(other)#

Override equality

The _globe and _crs attributes are not compared because they are cached properties and completely derived from other attributes. The nature of caching means that they can appear on one object and not on another despite the objects being identical, and them being completely derived from other attributes means they will only differ if other attributes that are being tested for equality differ.

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.