def calibrate_rad_to_bt(self, radiance, key):
"""IR channel calibration."""
# using the method from PUG section Converting from Effective Radiance to Brightness Temperature for IR Channels
measured = self.get_channel_measured_group_path(key['name'])
vc = self[measured +
"/radiance_to_bt_conversion_coefficient_wavenumber"]
a = self[measured + "/radiance_to_bt_conversion_coefficient_a"]
b = self[measured + "/radiance_to_bt_conversion_coefficient_b"]
c1 = self[measured + "/radiance_to_bt_conversion_constant_c1"]
c2 = self[measured + "/radiance_to_bt_conversion_constant_c2"]
for v in (vc, a, b, c1, c2):
if v == v.attrs.get("FillValue",
default_fillvals.get(v.dtype.str[1:])):
logger.error("{:s} set to fill value, cannot produce "
"brightness temperatures for {:s}.".format(
v.attrs.get(
"long_name",
"at least one necessary coefficient"),
measured))
return radiance * np.nan
nom = c2 * vc
denom = a * np.log(1 + (c1 * vc**3) / radiance)
res = nom / denom - b / a
return res
def _ir_calibrate(self, radiance, measured, root):
"""IR channel calibration."""
coef = self[measured + "/radiance_unit_conversion_coefficient"]
wl_c = self[root + "/central_wavelength_actual"]
a = self[measured + "/radiance_to_bt_conversion_coefficient_a"]
b = self[measured + "/radiance_to_bt_conversion_coefficient_b"]
c1 = self[measured + "/radiance_to_bt_conversion_constant_c1"]
c2 = self[measured + "/radiance_to_bt_conversion_constant_c2"]
for v in (coef, wl_c, a, b, c1, c2):
if v == v.attrs.get("FillValue",
default_fillvals.get(v.dtype.str[1:])):
logger.error("{:s} set to fill value, cannot produce "
"brightness temperatures for {:s}.".format(
v.attrs.get(
"long_name",
"at least one necessary coefficient"),
root))
return xr.DataArray(da.full(shape=radiance.shape,
chunks=radiance.chunks,
fill_value=np.nan),
dims=radiance.dims,
coords=radiance.coords,
attrs=radiance.attrs)
Lv = radiance * coef
vc = 1e6 / wl_c # from wl in um to wn in m^-1
nom = c2 * vc
denom = a * np.log(1 + (c1 * vc**3) / Lv)
res = nom / denom - b / a
res.attrs["units"] = "K"
return res
def calibrate_rad_to_refl(self, radiance, key):
"""VIS channel calibration."""
measured = self.get_channel_measured_group_path(key['name'])
cesi = self[measured + "/channel_effective_solar_irradiance"]
if cesi == cesi.attrs.get("FillValue",
default_fillvals.get(cesi.dtype.str[1:])):
logger.error(
"channel effective solar irradiance set to fill value, "
"cannot produce reflectance for {:s}.".format(measured))
return radiance * np.nan
sun_earth_distance = np.mean(
self["state/celestial/earth_sun_distance"]) / 149597870.7 # [AU]
# TODO remove this check when old versions of IDPF test data (<v5) are deprecated.
if sun_earth_distance < 0.9 or sun_earth_distance > 1.1:
logger.info(
'The variable state/celestial/earth_sun_distance contains unexpected values'
'(mean value is {} AU). Defaulting to 1 AU for reflectance calculation.'
''.format(sun_earth_distance))
sun_earth_distance = 1
res = 100 * radiance * np.pi * sun_earth_distance**2 / cesi
return res
def _get_aux_data_lut_vector(self, aux_data_name):
"""Load the lut vector of an auxiliary variable."""
lut = self[AUX_DATA[aux_data_name]]
fv = default_fillvals.get(lut.dtype.str[1:], np.nan)
lut = lut.where(lut != fv)
return lut
def get_dataset(self, key, info=None):
"""Load a dataset."""
logger.debug('Reading {} from {}'.format(key.name, self.filename))
# Get the dataset
# Get metadata for given dataset
measured, root = self.get_channel_dataset(key.name)
radlab = measured + "/effective_radiance"
data = self[radlab]
attrs = data.attrs.copy()
info = info.copy()
fv = attrs.pop("FillValue",
default_fillvals.get(data.dtype.str[1:], np.nan))
vr = attrs.pop("valid_range", [-np.inf, np.inf])
if key.calibration == "counts":
attrs["_FillValue"] = fv
nfv = fv
else:
nfv = np.nan
data = data.where(data >= vr[0], nfv)
data = data.where(data <= vr[1], nfv)
if key.calibration == "counts":
# from package description, this just means not applying add_offset
# and scale_factor
attrs.pop("scale_factor")
attrs.pop("add_offset")
data.attrs["units"] = "1"
res = data
else:
data = (data * attrs.pop("scale_factor", 1) +
attrs.pop("add_offset", 0))
if key.calibration in ("brightness_temperature", "reflectance"):
res = self.calibrate(data, key, measured, root)
else:
res = data
data.attrs["units"] = attrs["units"]
# pre-calibration units no longer apply
info.pop("units")
attrs.pop("units")
self.nlines, self.ncols = res.shape
res.attrs.update(key.to_dict())
res.attrs.update(info)
res.attrs.update(attrs)
return res
def get_dataset(self, key, info=None):
"""Load a dataset."""
logger.debug('Reading {} from {}'.format(key.name, self.filename))
# Get the dataset
# Get metadata for given dataset
measured = self.get_channel_measured_group_path(key.name)
data = self[measured + "/effective_radiance"]
attrs = data.attrs.copy()
info = info.copy()
fv = attrs.pop("FillValue",
default_fillvals.get(data.dtype.str[1:], np.nan))
vr = attrs.get("valid_range", [-np.inf, np.inf])
if key.calibration == "counts":
attrs["_FillValue"] = fv
nfv = fv
else:
nfv = np.nan
data = data.where(data >= vr[0], nfv)
data = data.where(data <= vr[1], nfv)
res = self.calibrate(data, key)
# pre-calibration units no longer apply
info.pop("units")
attrs.pop("units")
res.attrs.update(key.to_dict())
res.attrs.update(info)
res.attrs.update(attrs)
res.attrs["platform_name"] = self._platform_name_translate.get(
self["/attr/platform"], self["/attr/platform"])
# remove unpacking parameters for calibrated data
if key.calibration in ['brightness_temperature', 'reflectance']:
res.attrs.pop("add_offset")
res.attrs.pop("warm_add_offset")
res.attrs.pop("scale_factor")
res.attrs.pop("warm_scale_factor")
# remove attributes from original file which don't apply anymore
res.attrs.pop('long_name')
return res
def calibrate_rad_to_refl(self, radiance, key):
"""VIS channel calibration."""
measured = self.get_channel_measured_group_path(key['name'])
cesi = self[measured + "/channel_effective_solar_irradiance"]
if cesi == cesi.attrs.get("FillValue",
default_fillvals.get(cesi.dtype.str[1:])):
logger.error(
"channel effective solar irradiance set to fill value, "
"cannot produce reflectance for {:s}.".format(measured))
return radiance * np.nan
sun_earth_distance = np.mean(
self["state/celestial/earth_sun_distance"]) / 149597870.7 # [AU]
res = 100 * radiance * np.pi * sun_earth_distance**2 / cesi
return res
def _vis_calibrate(self, radiance, measured):
"""VIS channel calibration."""
# radiance to reflectance taken as in mipp/xrit/MSG.py
# again FCI User Guide is not clear on how to do this
cesilab = measured + "/channel_effective_solar_irradiance"
cesi = self[cesilab]
if cesi == cesi.attrs.get("FillValue",
default_fillvals.get(cesi.dtype.str[1:])):
logger.error(
"channel effective solar irradiance set to fill value, "
"cannot produce reflectance for {:s}.".format(measured))
return xr.DataArray(da.full(shape=radiance.shape,
chunks=radiance.chunks,
fill_value=np.nan),
dims=radiance.dims,
coords=radiance.coords,
attrs=radiance.attrs)
sirr = float(cesi)
res = radiance / sirr * 100
res.attrs["units"] = "%"
return res
def _get_dataset_measurand(self, key, info=None):
"""Load dataset corresponding to channel measurement.
Load a dataset when the key refers to a measurand, whether uncalibrated
(counts) or calibrated in terms of brightness temperature, radiance, or
reflectance.
"""
# Get the dataset
# Get metadata for given dataset
measured = self.get_channel_measured_group_path(key['name'])
data = self[measured + "/effective_radiance"]
attrs = data.attrs.copy()
info = info.copy()
fv = attrs.pop("FillValue",
default_fillvals.get(data.dtype.str[1:], np.nan))
vr = attrs.get("valid_range", [-np.inf, np.inf])
if key['calibration'] == "counts":
attrs["_FillValue"] = fv
nfv = fv
else:
nfv = np.nan
data = data.where(data >= vr[0], nfv)
data = data.where(data <= vr[1], nfv)
res = self.calibrate(data, key)
# pre-calibration units no longer apply
attrs.pop("units")
# For each channel, the effective_radiance contains in the
# "ancillary_variables" attribute the value "pixel_quality". In
# FileYAMLReader._load_ancillary_variables, satpy will try to load
# "pixel_quality" but is lacking the context from what group to load
# it: in the FCI format, each channel group (data/<channel>/measured) has
# its own data variable 'pixel_quality'.
# Until we can have multiple pixel_quality variables defined (for
# example, with https://github.com/pytroll/satpy/pull/1088), rewrite
# the ancillary variable to include the channel. See also
# https://github.com/pytroll/satpy/issues/1171.
if "pixel_quality" in attrs["ancillary_variables"]:
attrs["ancillary_variables"] = attrs[
"ancillary_variables"].replace("pixel_quality",
key['name'] + "_pixel_quality")
else:
raise ValueError(
"Unexpected value for attribute ancillary_variables, "
"which the FCI file handler intends to rewrite (see "
"https://github.com/pytroll/satpy/issues/1171 for why). "
f"Expected 'pixel_quality', got {attrs['ancillary_variables']:s}"
)
res.attrs.update(key.to_dict())
res.attrs.update(info)
res.attrs.update(attrs)
res.attrs["platform_name"] = self._platform_name_translate.get(
self["/attr/platform"], self["/attr/platform"])
# remove unpacking parameters for calibrated data
if key['calibration'] in ['brightness_temperature', 'reflectance']:
res.attrs.pop("add_offset")
res.attrs.pop("warm_add_offset")
res.attrs.pop("scale_factor")
res.attrs.pop("warm_scale_factor")
# remove attributes from original file which don't apply anymore
res.attrs.pop('long_name')
return res
