satpy.readers.fci_l1c_nc module
Interface to MTG-FCI L1c NetCDF files.
This module defines the FCIL1cNCFileHandler
file handler, to
be used for reading Meteosat Third Generation (MTG) Flexible Combined
Imager (FCI) Level-1c data. FCI will fly
on the MTG Imager (MTG-I) series of satellites, scheduled to be launched
in 2022 by the earliest. For more information about FCI, see EUMETSAT.
For simulated test data to be used with this reader, see test data release. For the Product User Guide (PUG) of the FCI L1c data, see PUG.
Note
This reader currently supports Full Disk High Spectral Resolution Imagery (FDHSI) files. Support for High Spatial Resolution Fast Imagery (HRFI) files will be implemented when corresponding test datasets will be available.
Geolocation is based on information from the data files. It uses:
From the shape of the data variable
data/<channel>/measured/effective_radiance
, start and end line columns of current swath.From the data variable
data/<channel>/measured/x
, the x-coordinates for the grid, in radians (azimuth angle positive towards West).From the data variable
data/<channel>/measured/y
, the y-coordinates for the grid, in radians (elevation angle positive towards North).From the attribute
semi_major_axis
on the data variabledata/mtg_geos_projection
, the Earth equatorial radiusFrom the attribute
inverse_flattening
on the same data variable, the (inverse) flattening of the ellipsoidFrom the attribute
perspective_point_height
on the same data variable, the geostationary altitude in the normalised geostationary projectionFrom the attribute
longitude_of_projection_origin
on the same data variable, the longitude of the projection originFrom the attribute
sweep_angle_axis
on the same, the sweep angle axis, see https://proj.org/operations/projections/geos.html
From the pixel centre angles in radians and the geostationary altitude, the
extremities of the lower left and upper right corners are calculated in units
of arc length in m. This extent along with the number of columns and rows, the
sweep angle axis, and a dictionary with equatorial radius, polar radius,
geostationary altitude, and longitude of projection origin, are passed on to
pyresample.geometry.AreaDefinition
, which then uses proj4 for the actual
geolocation calculations.
The reading routine supports channel data in counts, radiances, and (depending on channel) brightness temperatures or reflectances. The brightness temperature and reflectance calculation is based on the formulas indicated in PUG. Radiance datasets are returned in units of radiance per unit wavenumber (mW m-2 sr-1 (cm-1)-1). Radiances can be converted to units of radiance per unit wavelength (W m-2 um-1 sr-1) by multiplying with the radiance_unit_conversion_coefficient dataset attribute.
For each channel, it also supports a number of auxiliary datasets, such as the pixel quality, the index map and the related geometric and acquisition parameters: time, subsatellite latitude, subsatellite longitude, platform altitude, subsolar latitude, subsolar longitude, earth-sun distance, sun-satellite distance, swath number, and swath direction.
All auxiliary data can be obtained by prepending the channel name such as
"vis_04_pixel_quality"
.
Warning
The API for the direct reading of pixel quality is temporary and likely to
change. Currently, for each channel, the pixel quality is available by
<chan>_pixel_quality
. In the future, they will likely all be called
pixel_quality
and disambiguated by a to-be-decided property in the
DataID.
Note
For reading compressed data, a decompression library is
needed. Either install the FCIDECOMP library (see PUG), or the
hdf5plugin
package with:
pip install hdf5plugin
or:
conda install hdf5plugin -c conda-forge
If you use hdf5plugin
, make sure to add the line import hdf5plugin
at the top of your script.
- class satpy.readers.fci_l1c_nc.FCIL1cNCFileHandler(filename, filename_info, filetype_info)[source]
Bases:
satpy.readers.netcdf_utils.NetCDF4FileHandler
Class implementing the MTG FCI L1c Filehandler.
This class implements the Meteosat Third Generation (MTG) Flexible Combined Imager (FCI) Level-1c NetCDF reader. It is designed to be used through the
Scene
class using theload
method with the reader"fci_l1c_nc"
.Initialize file handler.
- calibrate_counts_to_physical_quantity(data, key)[source]
Calibrate counts to radiances, brightness temperatures, or reflectances.
- property end_time
Get end time.
- property start_time
Get start time.