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.
- 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.
- _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.
- property _repeat_cycle_duration
Get repeat cycle duration from epilogue.
- property end_time
Get the general end time for this file.
- 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.
- 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.
- 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]
- 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]