New reader for Himawari L2 NOAA enterprise cloud products.

satpy/etc/readers/ahi_l2_nc.yaml

@@ -0,0 +1,175 @@
+reader:
+  name: ahi_l2_nc
+  short_name: AHI L2 NetCDF4
+  long_name: Himawari-8/9 AHI Level 2 products in netCDF4 format from NOAA enterprise
+  status: Beta
+  supports_fsspec: true
+  sensors: ['ahi']
+  reader: !!python/name:satpy.readers.yaml_reader.FileYAMLReader
+
+
+file_types:
+    ahi_l2_mask:
+        file_reader: !!python/name:satpy.readers.ahi_l2_nc.HIML2NCFileHandler
+        file_patterns:
+         - '{sensor:3s}-CMSK_{version:4s}_{platform:3s}_s{start_time:%Y%m%d%H%M%S%f}_e{end_time:%Y%m%d%H%M%S%f}_c{creation_time:%Y%m%d%H%M%S%f}.nc'
+
+    ahi_l2_type:
+        file_reader: !!python/name:satpy.readers.ahi_l2_nc.HIML2NCFileHandler
+        file_patterns:
+         - '{sensor:3s}-CPHS_{version:4s}_{platform:3s}_s{start_time:%Y%m%d%H%M%S%f}_e{end_time:%Y%m%d%H%M%S%f}_c{creation_time:%Y%m%d%H%M%S%f}.nc'
+
+    ahi_l2_height:
+        file_reader: !!python/name:satpy.readers.ahi_l2_nc.HIML2NCFileHandler
+        file_patterns:
+         - '{sensor:3s}-CHGT_{version:4s}_{platform:3s}_s{start_time:%Y%m%d%H%M%S%f}_e{end_time:%Y%m%d%H%M%S%f}_c{creation_time:%Y%m%d%H%M%S%f}.nc'
+
+datasets:
+  # Products from the cloud mask files
+  cloud_mask:
+    name: cloud_mask
+    file_key: CloudMask
+    file_type: [ ahi_l2_mask ]
+
+  cloud_mask_binary:
+    name: cloud_mask_binary
+    file_key: CloudMaskBinary
+    file_type: [ ahi_l2_mask ]
+
+  cloud_probability:
+    name: cloud_probability
+    file_key: CloudProbability
+    file_type: [ ahi_l2_mask ]
+
+  ice_cloud_probability:
+    name: ice_cloud_probability
+    file_key: IceCloudProbability
+    file_type: [ ahi_l2_mask ]
+
+  phase_uncertainty:
+    name: phase_uncertainty
+    file_key: PhaseUncertainty
+    file_type: [ ahi_l2_mask ]
+
+  dust_mask:
+    name: dust_mask
+    file_key: Dust_Mask
+    file_type: [ ahi_l2_mask ]
+
+  fire_mask:
+    name: fire_mask
+    file_key: Fire_Mask
+    file_type: [ ahi_l2_mask ]
+
+  smoke_mask:
+    name: smoke_mask
+    file_key: Smoke_Mask
+    file_type: [ ahi_l2_mask ]
+
+  # Products from the cloud phase / type files
+  cloud_phase:
+    name: cloud_phase
+    file_key: CloudPhase
+    file_type: [ ahi_l2_type ]
+
+  cloud_phase_flag:
+    name: cloud_phase_flag
+    file_key: CloudPhaseFlag
+    file_type: [ ahi_l2_type ]
+
+  cloud_type:
+    name: cloud_type
+    file_key: CloudType
+    file_type: [ ahi_l2_type ]
+
+  # Products from the cloud height files
+  cloud_optical_depth:
+      name: cloud_optical_depth
+      file_key: CldOptDpth
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_emissivity:
+      name: cloud_top_emissivity
+      file_key: CldTopEmss
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_pressure:
+      name: cloud_top_pressure
+      file_key: CldTopPres
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_pressure_low:
+      name: cloud_top_pressure_low
+      file_key: CldTopPresLow
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_temperature:
+      name: cloud_top_temperature
+      file_key: CldTopTemp
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_temperature_low:
+      name: cloud_top_temperature_low
+      file_key: CldTopTempLow
+      file_type: [ ahi_l2_height ]
+
+  cloud_height_quality:
+      name: cloud_height_quality
+      file_key: CloudHgtQF
+      file_type: [ ahi_l2_height ]
+
+  retrieval_cost:
+      name: retrieval_cost
+      file_key: Cost
+      file_type: [ ahi_l2_height ]
+
+  inversion_flag:
+      name: inversion_flag
+      file_key: InverFlag
+      file_type: [ ahi_l2_height ]
+
+  latitude_parallax_corrected:
+      name: latitude_parallax_corrected
+      file_key: Latitude_Pc
+      file_type: [ ahi_l2_height ]
+
+  longitude_parallax_corrected:
+      name: longitude_parallax_corrected
+      file_key: Longitude_Pc
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_pressure_error:
+      name: cloud_top_pressure_error
+      file_key: PcError
+      file_type: [ ahi_l2_height ]
+
+  processing_order:
+      name: processing_order
+      file_key: ProcOrder
+      file_type: [ ahi_l2_height ]
+
+  shadow_mask:
+      name: shadow_mask
+      file_key: Shadow_Mask
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_temperature_error:
+      name: cloud_top_temperature_error
+      file_key: TcError
+      file_type: [ ahi_l2_height ]
+
+  cloud_top_height_error:
+      name: cloud_top_height_error
+      file_key: ZcError
+      file_type: [ ahi_l2_height ]
+
+  # Datasets in all three file types
+  latitude:
+      name: latitude
+      file_key: Latitude
+      file_type: [ ahi_l2_height, ahi_l2_type, ahi_l2_mask ]
+
+  longitude:
+      name: longitude
+      file_key: Longitude
+      file_type: [ ahi_l2_height, ahi_l2_type, ahi_l2_mask ]

satpy/readers/ahi_l2_nc.py

@@ -0,0 +1,136 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# Copyright (c) 2023 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/>.
+"""Reader for Himawari L2 cloud products from NOAA's big data programme.
+
+For more information about the data, see: <https://registry.opendata.aws/noaa-himawari/>.
+
+These products are generated by the NOAA enterprise cloud suite and have filenames like:
+AHI-CMSK_v1r1_h09_s202308240540213_e202308240549407_c202308240557548.nc
+
+The second letter grouping (CMSK above) indicates the product type:
+    CMSK - Cloud mask
+
+    CHGT - Cloud height
+
+    CPHS - Cloud type and phase
+
+These products are generated from the AHI sensor on Himawari-8 and Himawari-9, and are
+produced at the native instrument resolution for the IR channels (2km at nadir).
+
+NOTE: This reader is currently only compatible with full disk scenes. Unlike level 1 himawari
+data, the netCDF files do not contain the required metadata to produce an appropriate area
+definition for the data contents, and hence the area definition is hardcoded into the reader.
+
+A warning is displayed to the user highlighting this. The assumed area definition is a full
+disk image at the nominal subsatellite longitude of 140.7 degrees East.
+
+All the simple data products are supported here, but multidimensional products are not yet
+supported. These include the CldHgtFlag and the CloudMaskPacked variables.
+"""
+
+import logging
+from datetime import datetime
+
+import xarray as xr
+
+from satpy._compat import cached_property
+from satpy.readers._geos_area import get_area_definition, get_area_extent
+from satpy.readers.file_handlers import BaseFileHandler
+
+logger = logging.getLogger(__name__)
+
+EXPECTED_DATA_AREA = 'Full Disk'
+
+
+class HIML2NCFileHandler(BaseFileHandler):
+    """File handler for Himawari L2 NOAA enterprise data in netCDF format."""
+
+    def __init__(self, filename, filename_info, filetype_info):
+        """Initialize the reader."""
+        super().__init__(filename, filename_info, filetype_info)
+        self.nc = xr.open_dataset(self.filename,
+                                  decode_cf=True,
+                                  mask_and_scale=False,
+                                  chunks={"xc": "auto", "yc": "auto"})
+
+        # Check that file is a full disk scene, we don't know the area for anything else
+        if self.nc.attrs['cdm_data_type'] != EXPECTED_DATA_AREA:
+            raise ValueError('File is not a full disk scene')
+
+        self.sensor = self.nc.attrs['instrument_name'].lower()
+        self.nlines = self.nc.dims['Columns']
+        self.ncols = self.nc.dims['Rows']
+        self.platform_name = self.nc.attrs['satellite_name']
+        self.platform_shortname = filename_info['platform']
+        self._meta = None
+
+    @property
+    def start_time(self):
+        """Start timestamp of the dataset."""
+        dt = self.nc.attrs['time_coverage_start']
+        return datetime.strptime(dt, '%Y-%m-%dT%H:%M:%SZ')
+
+    @property
+    def end_time(self):
+        """End timestamp of the dataset."""
+        dt = self.nc.attrs['time_coverage_end']
+        return datetime.strptime(dt, '%Y-%m-%dT%H:%M:%SZ')
+
+    def get_dataset(self, key, info):
+        """Load a dataset."""
+        var = info['file_key']
+        logger.debug('Reading in get_dataset %s.', var)
+        variable = self.nc[var]
+
+        # Data has 'Latitude' and 'Longitude' coords, these must be replaced.
+        variable = variable.rename({'Rows': 'y', 'Columns': 'x'})
+
+        variable = variable.drop('Latitude')
+        variable = variable.drop('Longitude')
+
+        variable.attrs.update(key.to_dict())
+        return variable
+
+    @cached_property
+    def area(self):
+        """Get AreaDefinition representing this file's data."""
+        return self._get_area_def()
+
+    def get_area_def(self, dsid):
+        """Get the area definition."""
+        del dsid
+        return self.area
+
+    def _get_area_def(self):
+        logger.info('The AHI L2 cloud products do not have the metadata required to produce an area definition.'
+                    ' Assuming standard Himawari-8/9 full disk projection.')
+
+        # Basic check to ensure we're processing a full disk (2km) scene.n
+        if self.nlines != 5500 or self.ncols != 5500:
+            raise ValueError("Input L2 file is not a full disk Himawari scene. Only full disk data is supported.")
+
+        pdict = {'cfac': 20466275, 'lfac': 20466275, 'coff': 2750.5, 'loff': 2750.5, 'a': 6378137.0, 'h': 35785863.0,
+                 'b': 6356752.3, 'ssp_lon': 140.7, 'nlines': self.nlines, 'ncols': self.ncols, 'scandir': 'N2S'}
+
+        aex = get_area_extent(pdict)
+
+        pdict['a_name'] = 'Himawari_Area'
+        pdict['a_desc'] = "AHI Full Disk area"
+        pdict['p_id'] = f'geos{self.platform_shortname}'
+
+        return get_area_definition(pdict, aex)