satpy.readers.seviri_l1b_hrit module

SEVIRI Level 1.5 HRIT format reader.

Introduction

The seviri_l1b_hrit reader reads and calibrates MSG-SEVIRI L1.5 image data in HRIT format. The format is explained in the MSG Level 1.5 Image Data Format Description. The files are usually named as follows:

H-000-MSG4__-MSG4________-_________-PRO______-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000001___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000002___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000003___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000004___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000005___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000006___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000007___-201903011200-__
H-000-MSG4__-MSG4________-IR_108___-000008___-201903011200-__
H-000-MSG4__-MSG4________-_________-EPI______-201903011200-__

Each image is decomposed into 24 segments (files) for the high-resolution-visible (HRV) channel and 8 segments for other visible (VIS) and infrared (IR) channels. Additionally, there is one prologue and one epilogue file for the entire scan which contain global metadata valid for all channels.

Reader Arguments

Some arguments can be provided to the reader to change its behaviour. These are provided through the Scene instantiation, eg:

scn = Scene(filenames=filenames, reader="seviri_l1b_hrit", reader_kwargs={'fill_hrv': False})

To see the full list of arguments that can be provided, look into the documentation of HRITMSGFileHandler.

Compression

This reader accepts compressed HRIT files, ending in C_ as other HRIT readers, see satpy.readers.hrit_base.HRITFileHandler.

This reader also accepts bzipped file with the extension .bz2 for the prologue, epilogue, and segment files.

Nominal start/end time

Warning

attribute access change

nominal_start_time and nominal_end_time should be accessed using the time_parameters attribute.

nominal_start_time and nominal_end_time are also available directly via start_time and end_time respectively.

Here is an exmaple of the content of the start/end time and time_parameters attibutes

Start time: 2019-08-29 12:00:00
End time:   2019-08-29 12:15:00
time_parameters:
                {'nominal_start_time': datetime.datetime(2019, 8, 29, 12, 0),
                 'nominal_end_time': datetime.datetime(2019, 8, 29, 12, 15),
                 'observation_start_time': datetime.datetime(2019, 8, 29, 12, 0, 9, 338000),
                 'observation_end_time': datetime.datetime(2019, 8, 29, 12, 15, 9, 203000)
                 }

Example:

Here is an example how to read the data in satpy:

from satpy import Scene
import glob

filenames = glob.glob('data/H-000-MSG4__-MSG4________-*201903011200*')
scn = Scene(filenames=filenames, reader='seviri_l1b_hrit')
scn.load(['VIS006', 'IR_108'])
print(scn['IR_108'])

Output:

<xarray.DataArray (y: 3712, x: 3712)>
dask.array<shape=(3712, 3712), dtype=float32, chunksize=(464, 3712)>
Coordinates:
    acq_time  (y) datetime64[ns] NaT NaT NaT NaT NaT NaT ... NaT NaT NaT NaT NaT
  * x         (x) float64 5.566e+06 5.563e+06 5.56e+06 ... -5.566e+06 -5.569e+06
  * y         (y) float64 -5.566e+06 -5.563e+06 ... 5.566e+06 5.569e+06
Attributes:
    orbital_parameters:       {'projection_longitude': 0.0, 'projection_latit...
    platform_name:            Meteosat-11
    georef_offset_corrected:  True
    standard_name:            brightness_temperature
    raw_metadata:             {'file_type': 0, 'total_header_length': 6198, '...
    wavelength:               (9.8, 10.8, 11.8)
    units:                    K
    sensor:                   seviri
    platform_name:            Meteosat-11
    start_time:               2019-03-01 12:00:09.716000
    end_time:                 2019-03-01 12:12:42.946000
    area:                     Area ID: some_area_name\\nDescription: On-the-fl...
    name:                     IR_108
    resolution:               3000.403165817
    calibration:              brightness_temperature
    polarization:             None
    level:                    None
    modifiers:                ()
    ancillary_variables:      []

The filenames argument can either be a list of strings, see the example above, or a list of satpy.readers.FSFile objects. FSFiles can be used in conjunction with fsspec, e.g. to handle in-memory data:

import glob

from fsspec.implementations.memory import MemoryFile, MemoryFileSystem
from satpy import Scene
from satpy.readers import FSFile

# In this example, we will make use of `MemoryFile`s in a `MemoryFileSystem`.
memory_fs = MemoryFileSystem()

# Usually, the data already resides in memory.
# For explanatory reasons, we will load the files found with glob in memory,
#  and load the scene with FSFiles.
filenames = glob.glob('data/H-000-MSG4__-MSG4________-*201903011200*')
fs_files = []
for fn in filenames:
    with open(fn, 'rb') as fh:
        fs_files.append(MemoryFile(
            fs=memory_fs,
            path="{}{}".format(memory_fs.root_marker, fn),
            data=fh.read()
        ))
        fs_files[-1].commit()  # commit the file to the filesystem
fs_files = [FSFile(open_file) for open_file in filenames]  # wrap MemoryFiles as FSFiles
# similar to the example above, we pass a list of FSFiles to the `Scene`
scn = Scene(filenames=fs_files, reader='seviri_l1b_hrit')
scn.load(['VIS006', 'IR_108'])
print(scn['IR_108'])

Output:

<xarray.DataArray (y: 3712, x: 3712)>
dask.array<shape=(3712, 3712), dtype=float32, chunksize=(464, 3712)>
Coordinates:
    acq_time  (y) datetime64[ns] NaT NaT NaT NaT NaT NaT ... NaT NaT NaT NaT NaT
  * x         (x) float64 5.566e+06 5.563e+06 5.56e+06 ... -5.566e+06 -5.569e+06
  * y         (y) float64 -5.566e+06 -5.563e+06 ... 5.566e+06 5.569e+06
Attributes:
    orbital_parameters:       {'projection_longitude': 0.0, 'projection_latit...
    platform_name:            Meteosat-11
    georef_offset_corrected:  True
    standard_name:            brightness_temperature
    raw_metadata:             {'file_type': 0, 'total_header_length': 6198, '...
    wavelength:               (9.8, 10.8, 11.8)
    units:                    K
    sensor:                   seviri
    platform_name:            Meteosat-11
    start_time:               2019-03-01 12:00:09.716000
    end_time:                 2019-03-01 12:12:42.946000
    area:                     Area ID: some_area_name\\nDescription: On-the-fl...
    name:                     IR_108
    resolution:               3000.403165817
    calibration:              brightness_temperature
    polarization:             None
    level:                    None
    modifiers:                ()
    ancillary_variables:      []

References

class satpy.readers.seviri_l1b_hrit.HRITMSGEpilogueFileHandler(filename, filename_info, filetype_info, calib_mode='nominal', ext_calib_coefs=None, include_raw_metadata=False, mda_max_array_size=None, fill_hrv=None, mask_bad_quality_scan_lines=None)[source]

Bases: HRITMSGPrologueEpilogueBase

SEVIRI HRIT epilogue reader.

Initialize the reader.

read_epilogue()[source]: Read the epilogue metadata.

reduce(max_size)[source]: Reduce the epilogue metadata.

class satpy.readers.seviri_l1b_hrit.HRITMSGFileHandler(filename, filename_info, filetype_info, prologue, epilogue, calib_mode='nominal', ext_calib_coefs=None, include_raw_metadata=False, mda_max_array_size=100, fill_hrv=True, mask_bad_quality_scan_lines=True)[source]

Bases: HRITFileHandler

SEVIRI HRIT format reader.

Calibration

See satpy.readers.seviri_base.

Padding of the HRV channel

By default, the HRV channel is loaded padded with no-data, returning a full-disk dataset. If you want the original, unpadded data, just provide the fill_hrv as False in the reader_kwargs:

scene = satpy.Scene(filenames,
                    reader='seviri_l1b_hrit',
                    reader_kwargs={'fill_hrv': False})

Metadata

See satpy.readers.seviri_base.

Initialize the reader.

_add_scanline_acq_time(dataset)[source]: Add scanline acquisition time to the given dataset.

_get_area_extent(pdict)[source]

Get the area extent of the file.

Until December 2017, the data is shifted by 1.5km SSP North and West against the nominal GEOS projection. Since December 2017 this offset has been corrected. A flag in the data indicates if the correction has been applied. If no correction was applied, adjust the area extent to match the shifted data.

For more information see Section 3.1.4.2 in the MSG Level 1.5 Image Data Format Description. The correction of the area extent is documented in a developer’s memo.

_get_calib_coefs(channel_name)[source]: Get coefficients for calibration from counts to radiance.

_get_header()[source]: Read the header info, and fill the metadata dictionary.

_get_raw_mda()[source]: Compile raw metadata to be included in the dataset attributes.

_mask_bad_quality(data)[source]: Mask scanlines with bad quality.

property _repeat_cycle_duration: Get repeat cycle duration from epilogue.

_update_attrs(res, info)[source]: Update dataset attributes.

calibrate(data, calibration)[source]: Calibrate the data.

property end_time: Get the general end time for this file.

get_area_def(dsid)[source]: Get the area definition of the band.

get_dataset(key, info)[source]: Get the dataset.

property nominal_end_time: Get the end time and round it according to scan law.

property nominal_start_time: Get the start time and round it according to scan law.

property observation_end_time: Get the observation end time.

property observation_start_time: Get the observation start time.

pad_hrv_data(res)[source]: Add empty pixels around the HRV.

property start_time: Get general start time for this file.

class satpy.readers.seviri_l1b_hrit.HRITMSGPrologueEpilogueBase(filename, filename_info, filetype_info, hdr_info)[source]

Bases: HRITFileHandler

Base reader for prologue and epilogue files.

Initialize the file handler for prologue and epilogue files.

_reduce(mda, max_size)[source]: Reduce the metadata.

reduce(max_size)[source]: Reduce the metadata (placeholder).

class satpy.readers.seviri_l1b_hrit.HRITMSGPrologueFileHandler(filename, filename_info, filetype_info, calib_mode='nominal', ext_calib_coefs=None, include_raw_metadata=False, mda_max_array_size=None, fill_hrv=None, mask_bad_quality_scan_lines=None)[source]

Bases: HRITMSGPrologueEpilogueBase

SEVIRI HRIT prologue reader.

Initialize the reader.

get_earth_radii()[source]

Get earth radii from prologue.

Returns:: Equatorial radius, polar radius [m]

read_prologue()[source]: Read the prologue metadata.

reduce(max_size)[source]: Reduce the prologue metadata.

property satpos

Get actual satellite position in geodetic coordinates (WGS-84).

Evaluate orbit polynomials at the start time of the scan.

Returns: Longitude [deg east], Latitude [deg north] and Altitude [m]

satpy.readers.seviri_l1b_hrit.pad_data(data, final_size, east_bound, west_bound)[source]: Pad the data given east and west bounds and the desired size.