Source code for satpy.readers.seviri_l2_bufr

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (c) 2019 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 <http://www.gnu.org/licenses/>.

"""SEVIRI L2 BUFR format reader.

References:
    EUMETSAT Product Navigator
    https://navigator.eumetsat.int/

"""
import logging
from datetime import datetime, timedelta

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

from satpy import CHUNK_SIZE
from satpy.readers._geos_area import get_geos_area_naming
from satpy.readers.eum_base import get_service_mode, recarray2dict
from satpy.readers.file_handlers import BaseFileHandler
from satpy.readers.seviri_base import mpef_product_header
from satpy.resample import get_area_def

try:
    import eccodes as ec
except ImportError:
    raise ImportError(
        "Missing eccodes-python and/or eccodes C-library installation. Use conda to install eccodes")

logger = logging.getLogger('SeviriL2Bufr')

data_center_dict = {55: {'ssp': 'E0415', 'name': '08'}, 56:  {'ssp': 'E0000', 'name': '09'},
                    57: {'ssp': 'E0095', 'name': '10'}, 70: {'ssp': 'E0000', 'name': '11'}}

seg_size_dict = {'seviri_l2_bufr_asr': 16, 'seviri_l2_bufr_cla': 16,
                 'seviri_l2_bufr_csr': 16, 'seviri_l2_bufr_gii': 3,
                 'seviri_l2_bufr_thu': 16, 'seviri_l2_bufr_toz': 3}


[docs]class SeviriL2BufrFileHandler(BaseFileHandler): """File handler for SEVIRI L2 BUFR products. **Loading data with AreaDefinition** By providing the `with_area_definition` as True in the `reader_kwargs`, the dataset is loaded with an AreaDefinition using a standardized AreaDefinition in areas.yaml. By default, the dataset will be loaded with a SwathDefinition, i.e. similar to how the data are stored in the BUFR file: scene = satpy.Scene(filenames, reader='seviri_l2_bufr', reader_kwargs={'with_area_definition': False}) """ def __init__(self, filename, filename_info, filetype_info, with_area_definition=False, **kwargs): """Initialise the file handler for SEVIRI L2 BUFR data.""" super(SeviriL2BufrFileHandler, self).__init__(filename, filename_info, filetype_info) if ('server' in filename_info): # EUMETSAT Offline Bufr product self.mpef_header = self._read_mpef_header() else: # Product was retrieved from the EUMETSAT Data Center timeStr = self.get_attribute('typicalDate')+self.get_attribute('typicalTime') buf_start_time = datetime.strptime(timeStr, "%Y%m%d%H%M%S") sc_id = self.get_attribute('satelliteIdentifier') self.mpef_header = {} self.mpef_header['NominalTime'] = buf_start_time self.mpef_header['SpacecraftName'] = data_center_dict[sc_id]['name'] self.mpef_header['RectificationLongitude'] = data_center_dict[sc_id]['ssp'] self.with_adef = with_area_definition self.seg_size = seg_size_dict[filetype_info['file_type']] @property def start_time(self): """Return the repeat cycle start time.""" return self.mpef_header['NominalTime'] @property def end_time(self): """Return the repeat cycle end time.""" return self.start_time + timedelta(minutes=15) @property def platform_name(self): """Return spacecraft name.""" return 'MET{}'.format(self.mpef_header['SpacecraftName']) @property def ssp_lon(self): """Return subsatellite point longitude.""" # e.g. E0415 ssp_lon = self.mpef_header['RectificationLongitude'] return float(ssp_lon[1:])/10.
[docs] def get_area_def(self, key): """Return the area definition.""" try: return self._area_def except AttributeError: raise NotImplementedError
def _read_mpef_header(self): """Read MPEF header.""" hdr = np.fromfile(self.filename, mpef_product_header, 1) return recarray2dict(hdr)
[docs] def get_attribute(self, key): """Get BUFR attributes.""" # This function is inefficient as it is looping through the entire # file to get 1 attribute. It causes a problem though if you break # from the file early - dont know why but investigating - fix later fh = open(self.filename, "rb") while True: # get handle for message bufr = ec.codes_bufr_new_from_file(fh) if bufr is None: break ec.codes_set(bufr, 'unpack', 1) attr = ec.codes_get(bufr, key) ec.codes_release(bufr) fh.close() return attr
[docs] def get_array(self, key): """Get all data from file for the given BUFR key.""" with open(self.filename, "rb") as fh: msgCount = 0 while True: bufr = ec.codes_bufr_new_from_file(fh) if bufr is None: break ec.codes_set(bufr, 'unpack', 1) # if is the first message initialise our final array if (msgCount == 0): arr = da.from_array(ec.codes_get_array( bufr, key, float), chunks=CHUNK_SIZE) else: tmpArr = da.from_array(ec.codes_get_array( bufr, key, float), chunks=CHUNK_SIZE) arr = da.concatenate((arr, tmpArr)) msgCount = msgCount+1 ec.codes_release(bufr) if arr.size == 1: arr = arr[0] return arr
[docs] def get_dataset(self, dataset_id, dataset_info): """Create dataset. Load data from BUFR file using the BUFR key in dataset_info and create the dataset with or without an AreaDefinition. """ arr = self.get_array(dataset_info['key']) if self.with_adef: xarr = self.get_dataset_with_area_def(arr, dataset_id) # coordinates are not relevant when returning data with an AreaDefinition if 'coordinates' in dataset_info.keys(): del dataset_info['coordinates'] else: xarr = xr.DataArray(arr, dims=["y"]) if 'fill_value' in dataset_info: xarr = xarr.where(xarr != dataset_info['fill_value']) self._add_attributes(xarr, dataset_info) return xarr
[docs] def get_dataset_with_area_def(self, arr, dataset_id): """Get dataset with an AreaDefinition.""" if dataset_id['name'] in ['latitude', 'longitude']: self.__setattr__(dataset_id['name'], arr) xarr = xr.DataArray(arr, dims=["y"]) else: lons_1d, lats_1d, data_1d = da.compute(self.longitude, self.latitude, arr) self._area_def = self._construct_area_def(dataset_id) icol, irow = self._area_def.get_array_indices_from_lonlat(lons_1d, lats_1d) data_2d = np.empty(self._area_def.shape) data_2d[:] = np.nan data_2d[irow.compressed(), icol.compressed()] = data_1d[~irow.mask] xarr = xr.DataArray(da.from_array(data_2d, CHUNK_SIZE), dims=('y', 'x')) ntotal = len(icol) nvalid = len(icol.compressed()) if nvalid < ntotal: logging.warning(f'{ntotal-nvalid} out of {ntotal} data points could not be put on ' f'the grid {self._area_def.area_id}.') return xarr
def _construct_area_def(self, dataset_id): """Construct a standardized AreaDefinition based on satellite, instrument, resolution and sub-satellite point. Returns: AreaDefinition: A pyresample AreaDefinition object containing the area definition. """ res = dataset_id['resolution'] area_naming_input_dict = {'platform_name': 'msg', 'instrument_name': 'seviri', 'resolution': res, } area_naming = get_geos_area_naming({**area_naming_input_dict, **get_service_mode('seviri', self.ssp_lon)}) # Datasets with a segment size of 3 pixels extend outside the original SEVIRI 3km grid (with 1238 x 1238 # segments a 3 pixels). Hence, we need to use corresponding area defintions in areas.yaml if self.seg_size == 3: area_naming['area_id'] += '_ext' area_naming['description'] += ' (extended outside original 3km grid)' # Construct AreaDefinition from standardized area definition in areas.yaml. stand_area_def = get_area_def(area_naming['area_id']) return stand_area_def def _add_attributes(self, xarr, dataset_info): """Add dataset attributes to xarray.""" xarr.attrs['sensor'] = 'SEVIRI' xarr.attrs['platform_name'] = self.platform_name xarr.attrs['ssp_lon'] = self.ssp_lon xarr.attrs['seg_size'] = self.seg_size xarr.attrs.update(dataset_info)