Source code for satpy.readers.iasi_l2

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2017-2020 Satpy developers
# This file is part of satpy.
# satpy 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.
# satpy 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
# satpy.  If not, see <>.
"""IASI L2 HDF5 files."""

import datetime as dt
import logging

import dask.array as da
import h5py
import numpy as np
import xarray as xr

from satpy import CHUNK_SIZE
from satpy.readers.file_handlers import BaseFileHandler

# Scan timing values taken from
# Time between each scan in one scanline [ms]
SCAN_STEP_TIME = 8. / 37.
# Duration of one measurement [ms]
# Time correction used between each 4-footprint measurements


# Epoch for the dates
EPOCH = dt.datetime(2000, 1, 1)

SHORT_NAMES = {'M01': 'Metop-B',
               'M02': 'Metop-A',
               'M03': 'Metop-C'}

DSET_NAMES = {'ozone_mixing_ratio': 'O',
              'ozone_mixing_ratio_quality': 'QO',
              'pressure': 'P',
              'pressure_quality': 'QP',
              'temperature': 'T',
              'temperature_quality': 'QT',
              'water_mixing_ratio': 'W',
              'water_mixing_ratio_quality': 'QW',
              'water_total_column': 'WC',
              'ozone_total_column': 'OC',
              'surface_skin_temperature': 'Ts',
              'surface_skin_temperature_quality': 'QTs',
              'emissivity': 'E',
              'emissivity_quality': 'QE'}

GEO_NAMES = {'latitude': 'Latitude',
             'longitude': 'Longitude',
             'satellite_azimuth_angle': 'SatAzimuth',
             'satellite_zenith_angle': 'SatZenith',
             'sensing_time': {'day': 'SensingTime_day',
                              'msec': 'SensingTime_msec'},
             'solar_azimuth_angle': 'SunAzimuth',
             'solar_zenith_angle': 'SunZenith'}

LOGGER = logging.getLogger(__name__)

[docs]class IASIL2HDF5(BaseFileHandler): """File handler for IASI L2 HDF5 files.""" def __init__(self, filename, filename_info, filetype_info): """Init the file handler.""" super(IASIL2HDF5, self).__init__(filename, filename_info, filetype_info) self.finfo = filename_info self.lons = None self.lats = None self.sensor = 'iasi' self.mda = {} short_name = filename_info['platform_id'] self.mda['platform_name'] = SHORT_NAMES.get(short_name, short_name) self.mda['sensor'] = 'iasi' @property def start_time(self): """Get the start time.""" return self.finfo['start_time'] @property def end_time(self): """Get the end time.""" end_time = dt.datetime.combine(, self.finfo['end_time'].time()) if end_time < self.start_time: end_time += dt.timedelta(days=1) return end_time
[docs] def get_dataset(self, key, info): """Load a dataset.""" with h5py.File(self.filename, 'r') as fid: LOGGER.debug('Reading %s.', key['name']) if key['name'] in DSET_NAMES: m_data = read_dataset(fid, key) else: m_data = read_geo(fid, key) m_data.attrs.update(info) m_data.attrs['sensor'] = self.sensor return m_data
[docs]def read_dataset(fid, key): """Read dataset.""" dsid = DSET_NAMES[key['name']] dset = fid["/PWLR/" + dsid] if dset.ndim == 3: dims = ['y', 'x', 'level'] else: dims = ['y', 'x'] data = xr.DataArray(da.from_array(dset[()], chunks=CHUNK_SIZE), name=key['name'], dims=dims).astype(np.float32) data = xr.where(data > 1e30, np.nan, data) dset_attrs = dict(dset.attrs) data.attrs.update(dset_attrs) return data
[docs]def read_geo(fid, key): """Read geolocation and related datasets.""" dsid = GEO_NAMES[key['name']] add_epoch = False if "time" in key['name']: days = fid["/L1C/" + dsid["day"]][()] msecs = fid["/L1C/" + dsid["msec"]][()] data = _form_datetimes(days, msecs) add_epoch = True dtype = np.float64 else: data = fid["/L1C/" + dsid][()] dtype = np.float32 data = xr.DataArray(da.from_array(data, chunks=CHUNK_SIZE), name=key['name'], dims=['y', 'x']).astype(dtype) if add_epoch: data.attrs['sensing_time_epoch'] = EPOCH return data
def _form_datetimes(days, msecs): """Calculate seconds since EPOCH from days and milliseconds for each of IASI scan.""" all_datetimes = [] for i in range(days.size): day = int(days[i]) msec = msecs[i] scanline_datetimes = [] for j in range(int(VALUES_PER_SCAN_LINE / 4)): usec = 1000 * (j * VIEW_TIME_ADJUSTMENT + msec) delta = (dt.timedelta(days=day, microseconds=usec)) for _k in range(4): scanline_datetimes.append(delta.total_seconds()) all_datetimes.append(scanline_datetimes) return np.array(all_datetimes, dtype=np.float64)