#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2020, 2021, 2022 Pytroll developers
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""Reader for the AAPP AMSU-B/MHS level-1c data.
https://nwp-saf.eumetsat.int/site/download/documentation/aapp/NWPSAF-MF-UD-003_Formats_v8.0.pdf
"""
import logging
import dask.array as da
import numpy as np
from satpy.readers.aapp_l1b import AAPPL1BaseFileHandler, create_xarray
from satpy.utils import get_legacy_chunk_size
logger = logging.getLogger(__name__)
CHUNK_SIZE = get_legacy_chunk_size()
LINE_CHUNK = CHUNK_SIZE ** 2 // 90
MHS_AMSUB_CHANNEL_NAMES = ['1', '2', '3', '4', '5']
MHS_AMSUB_ANGLE_NAMES = ['sensor_zenith_angle', 'sensor_azimuth_angle',
'solar_zenith_angle', 'solar_azimuth_difference_angle']
MHS_AMSUB_PLATFORM_IDS2NAMES = {15: 'NOAA-15',
16: 'NOAA-16',
17: 'NOAA-17',
18: 'NOAA-18',
19: 'NOAA-19',
1: 'Metop-B',
2: 'Metop-A',
3: 'Metop-C',
4: 'Metop simulator'}
MHS_AMSUB_PLATFORMS = ['Metop-A', 'Metop-B', 'Metop-C', 'NOAA-18', 'NOAA-19']
[docs]
class MHS_AMSUB_AAPPL1CFile(AAPPL1BaseFileHandler):
"""Reader for AMSU-B/MHS L1C files created from the AAPP software."""
def __init__(self, filename, filename_info, filetype_info):
"""Initialize object information by reading the input file."""
super().__init__(filename, filename_info, filetype_info)
self.channels = {i: None for i in MHS_AMSUB_CHANNEL_NAMES}
self.units = {i: 'brightness_temperature' for i in MHS_AMSUB_CHANNEL_NAMES}
self._channel_names = MHS_AMSUB_CHANNEL_NAMES
self._angle_names = MHS_AMSUB_ANGLE_NAMES
self._set_filedata_layout()
self.read()
self._get_platform_name(MHS_AMSUB_PLATFORM_IDS2NAMES)
self._get_sensorname()
[docs]
def _set_filedata_layout(self):
"""Set the file data type/layout."""
self._header_offset = HEADER_LENGTH
self._scan_type = _SCANTYPE
self._header_type = _HEADERTYPE
[docs]
def _get_sensorname(self):
"""Get the sensor name from the header."""
if self._header['instrument'][0] == 11:
self.sensor = 'amsub'
elif self._header['instrument'][0] == 12:
self.sensor = 'mhs'
else:
raise IOError("Sensor neither MHS nor AMSU-B!")
[docs]
def get_angles(self, angle_id):
"""Get sun-satellite viewing angles."""
satz = self._data["angles"][:, :, 0] * 1e-2
sata = self._data["angles"][:, :, 1] * 1e-2
sunz = self._data["angles"][:, :, 2] * 1e-2
suna = self._data["angles"][:, :, 3] * 1e-2
name_to_variable = dict(zip(MHS_AMSUB_ANGLE_NAMES, (satz, sata, sunz, suna)))
return create_xarray(name_to_variable[angle_id])
[docs]
def navigate(self, coordinate_id):
"""Get the longitudes and latitudes of the scene."""
lons, lats = self._get_coordinates_in_degrees()
if coordinate_id == 'longitude':
return create_xarray(lons)
if coordinate_id == 'latitude':
return create_xarray(lats)
raise KeyError("Coordinate {} unknown.".format(coordinate_id))
[docs]
def _get_coordinates_in_degrees(self):
lons = self._data["latlon"][:, :, 1] * 1e-4
lats = self._data["latlon"][:, :, 0] * 1e-4
return lons, lats
[docs]
def _calibrate_active_channel_data(self, key):
"""Calibrate active channel data only."""
return self.calibrate(key)
[docs]
def calibrate(self, dataset_id):
"""Calibrate the data."""
units = {'brightness_temperature': 'K'}
mask = True
idx = ['1', '2', '3', '4', '5'].index(dataset_id['name'])
ds = create_xarray(
_calibrate(self._data, idx,
dataset_id['calibration'],
mask=mask))
ds.attrs['units'] = units[dataset_id['calibration']]
ds.attrs.update(dataset_id._asdict())
return ds
[docs]
def _calibrate(data,
chn,
calib_type,
mask=True):
"""Calibrate channel data.
*calib_type* in brightness_temperature.
"""
if calib_type not in ['brightness_temperature']:
raise ValueError('Calibration ' + calib_type + ' unknown!')
channel = da.from_array(data["btemps"][:, :, chn] / 100., chunks=(LINE_CHUNK, 90))
mask &= channel != 0
if calib_type == 'counts':
return channel
channel = channel.astype(np.float_)
return da.where(mask, channel, np.nan)
HEADER_LENGTH = 1152*4
_HEADERTYPE = np.dtype([("siteid", "S3"),
("cfill_1", "S1"),
("l1bsite", "S3"),
("cfill_2", "S1"),
("versnb", "<i4"),
("versyr", "<i4"),
("versdy", "<i4"),
("hdrcnt", "<i4"),
("satid", "<i4"),
("instrument", "<i4"),
("satht", "<i4"),
("period", "<i4"),
("startorbit", "<i4"),
("startdatayr", "<i4"),
("startdatady", "<i4"),
("startdatatime", "<i4"),
("endorbit", "<i4"),
("enddatayr", "<i4"),
("enddatady", "<i4"),
("enddatatime", "<i4"),
("scnlin", "<i4"),
("misscnlin", "<i4"),
("vnantennacorr", "<i4"),
("spare", "<i4"),
("tempradcnv", "<i4", (3, 5)),
("wmosatid", "<i4"),
("filler", "<i4", (1114,)),
])
_SCANTYPE = np.dtype([("scnlin", "<i4"),
("scnlinyr", "<i4"),
("scnlindy", "<i4"),
("scnlintime", "<i4"),
("qualind", "<i4"),
("scnlinqual", "<i4"),
("chanqual", "<i4", (5, )),
("instrtemp", "<i4"),
("spare1", "<i4", (2, )),
# Navigation
("latlon", "<i4", (90, 2)), # lat/lon in degrees for Bnfovs:
# first : 10^4 x (latitude)
# second : 10^4 x (longitude)
("angles", "<i4", (90, 4)), # scan angles for Bnfovs:
# first: 10^2 x (local zenith angle)
# second: 10^2 x (local azimuth angle)
# third: 10^2 x (solar zenith angle)
# fourth: 10^2 x (solar azimuth angle)
("scalti", "<i4"), # sat altitude above reference ellipsoid, km*10
("spare2", "<i4", (2, )),
# Calibration
("btemps", "<i4", (90, 5)), # BT data for Bnfovs 10^2 x scene Tb (K), channels 1-5
("dataqual", "<i4", (90, )),
("filler", "<i4", (55, ))
])