Improve the SAR-C reading and Ice composite

satpy/__init__.py

@@ -40,6 +40,9 @@
     'reflectance',
     'radiance',
     'counts',
+    'gamma',
+    'sigma_nought',
+    'beta_nought',
 ]
 CALIBRATION_ORDER = os.getenv('PYTROLL_CALIBRATION_ORDER', None)
 if CALIBRATION_ORDER is None:

satpy/composites/sar.py

@@ -24,23 +24,23 @@
 
 import logging
 
-import xarray.ufuncs as xu
+import numpy as np
 from satpy.composites import GenericCompositor
 from satpy.dataset import combine_metadata
 
 LOG = logging.getLogger(__name__)
 
 
-def overlay(top, bottom):
+def overlay(top, bottom, maxval=None):
     """Blending two layers.
 
     from: https://docs.gimp.org/en/gimp-concepts-layer-modes.html
     """
-    maxval = xu.maximum(top.max(), bottom.max())
+    if maxval is None:
+        maxval = np.maximum(top.max(), bottom.max())
 
     res = ((2 * top / maxval - 1) * bottom + 2 * top) * bottom / maxval
-
-    return res
+    return res.clip(min=0)
 
 
 class SARIce(GenericCompositor):
@@ -49,12 +49,31 @@ class SARIce(GenericCompositor):
     def __call__(self, projectables, *args, **kwargs):
         """Create the SAR Ice composite."""
         (mhh, mhv) = projectables
-        green = overlay(mhh, mhv)
+        ch1attrs = mhh.attrs
+        ch2attrs = mhv.attrs
+        mhh = np.sqrt(mhh ** 2 + 0.002) - 0.04
+        mhv = np.sqrt(mhv ** 2 + 0.002) - 0.04
+        mhh.attrs = ch1attrs
+        mhv.attrs = ch2attrs
+        green = overlay(mhh, mhv, 30) * 1000
         green.attrs = combine_metadata(mhh, mhv)
 
         return super(SARIce, self).__call__((mhv, green, mhh), *args, **kwargs)
 
 
+class SARIceLegacy(GenericCompositor):
+    """The SAR Ice composite, legacy version with dynamic stretching."""
+
+    def __call__(self, projectables, *args, **kwargs):
+        """Create the SAR RGB composite."""
+
+        (mhh, mhv) = projectables
+        green = overlay(mhh, mhv)
+        green.attrs = combine_metadata(mhh, mhv)
+
+        return super(SARIceLegacy, self).__call__((mhv, green, mhh), *args, **kwargs)
+
+
 class SARRGB(GenericCompositor):
     """The SAR RGB composite."""
 

satpy/etc/composites/sar.yaml

@@ -6,17 +6,21 @@ composites:
     prerequisites:
     - name: measurement
       polarization: hh
+      calibration: gamma
     - name: measurement
       polarization: hv
+      calibraion: gamma
     standard_name: sar-ice
 
   sar-ice-iw:
     compositor: !!python/name:satpy.composites.sar.SARIce
     prerequisites:
     - name: measurement
       polarization: vv
+      calibration: gamma
     - name: measurement
       polarization: vh
+      calibration: gamma
     standard_name: sar-ice
 
   sar-rgb:
@@ -36,3 +40,21 @@ composites:
     - name: measurement
       polarization: hv
     standard_name: sar-quick
+
+  sar-ice-legacy:
+    compositor: !!python/name:satpy.composites.sar.SARIceLegacy
+    prerequisites:
+    - name: measurement
+      polarization: hh
+    - name: measurement
+      polarization: hv
+    standard_name: sar-ice-legacy
+
+  sar-land:
+    compositor: !!python/name:satpy.composites.sar.SARIce
+    prerequisites:
+    - name: measurement
+      polarization: hh
+    - name: measurement
+      polarization: hv
+    standard_name: sar-land

satpy/etc/enhancements/generic.yaml

@@ -222,6 +222,21 @@ enhancements:
   sar-ice:
     standard_name: sar-ice
     operations:
+    - name: stretch
+      method: *stretchfun
+      kwargs:
+        stretch: crude
+        min_stretch: [0, 0, 0]
+        max_stretch: [0.10, 1.37, 0.32 ]
+
+    - name: gamma
+      method: *gammafun
+      kwargs:
+        gamma: [2, 3, 2]
+
+  sar-ice-legacy:
+    standard_name: sar-ice-legacy
+    operations:
     - name: stretch
       method: *stretchfun
       kwargs:
@@ -232,6 +247,20 @@ enhancements:
       kwargs:
         gamma: [1, 1.2, 1]
 
+  sar-land:
+    standard_name: sar-land
+    operations:
+    - name: stretch
+      method: *stretchfun
+      kwargs:
+        stretch: crude
+        min_stretch: [0.01, 1. , 0.15 ]
+        max_stretch: [0.765, 50., 1.4]
+    - name: gamma
+      method: *gammafun
+      kwargs:
+        gamma: [1.5, 2.25, 1.5]
+
   sar-rgb:
     standard_name: sar-rgb
     operations:

satpy/etc/readers/sar-c_safe.yaml

@@ -47,14 +47,16 @@ datasets:
     wavelength: [5.400, 5.405, 5.410]
     resolution: 80
     polarization: [hh, hv, vv, vh]
-    # navigation: esa_geo
-    # calibration:
-    #   radiance:
-    #     standard_name: toa_outgoing_radiance_per_unit_wavelength
-    #     units: W m-2 um-1 sr-1
-    #   reflectance:
-    #     standard_name: toa_bidirectional_reflectance
-    #     units: "%"
+    calibration:
+      gamma:
+        standard_name: backscatter
+        units: 1
+      sigma_nought:
+        standard_name: backscatter
+        units: 1
+      beta_nought:
+        standard_name: backscatter
+        units: 1
     coordinates: [longitude, latitude]
     file_type: safe_measurement
 

satpy/readers/goes_imager_nc.py

@@ -66,91 +66,123 @@
 maximum calibration coefficients and computing the difference. The maximum
 differences are:
 
+======= ===== ====
 GOES-8
-======
-00_7 0.0   %  # Counts are normalized
-03_9 0.187 K
-06_8 0.0   K  # only one detector
-10_7 0.106 K
-12_0 0.036 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    0.0   %  # Counts are normalized
+03_9    0.187 K
+06_8    0.0   K  # only one detector
+10_7    0.106 K
+12_0    0.036 K
+======= ===== ====
+
+======= ===== ====
 GOES-9
-========
-00_7 0.0   %  # Counts are normalized
-03_9 0.0   K  # coefs identical
-06_8 0.0   K  # only one detector
-10_7 0.021 K
-12_0 0.006 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    0.0   %  # Counts are normalized
+03_9    0.0   K  # coefs identical
+06_8    0.0   K  # only one detector
+10_7    0.021 K
+12_0    0.006 K
+======= ===== ====
+
+======= ===== ====
 GOES-10
-========
-00_7 1.05  %
-03_9 0.0   K  # coefs identical
-06_8 0.0   K  # only one detector
-10_7 0.013 K
-12_0 0.004 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    1.05  %
+03_9    0.0   K  # coefs identical
+06_8    0.0   K  # only one detector
+10_7    0.013 K
+12_0    0.004 K
+======= ===== ====
+
+======= ===== ====
 GOES-11
-========
-00_7 1.25  %
-03_9 0.0   K  # coefs identical
-06_8 0.0   K  # only one detector
-10_7 0.0   K  # coefs identical
-12_0 0.065 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    1.25  %
+03_9    0.0   K  # coefs identical
+06_8    0.0   K  # only one detector
+10_7    0.0   K  # coefs identical
+12_0    0.065 K
+======= ===== ====
+
+======= ===== ====
 GOES-12
-========
-00_7 0.8   %
-03_9 0.0   K  # coefs identical
-06_5 0.044 K
-10_7 0.0   K  # coefs identical
-13_3 0.0   K  # only one detector
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    0.8   %
+03_9    0.0   K  # coefs identical
+06_5    0.044 K
+10_7    0.0   K  # coefs identical
+13_3    0.0   K  # only one detector
+======= ===== ====
+
+======= ===== ====
 GOES-13
-========
-00_7 1.31  %
-03_9 0.0   K  # coefs identical
-06_5 0.085 K
-10_7 0.008 K
-13_3 0.0   K  # only one detector
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    1.31  %
+03_9    0.0   K  # coefs identical
+06_5    0.085 K
+10_7    0.008 K
+13_3    0.0   K  # only one detector
+======= ===== ====
+
+======= ===== ====
 GOES-14
-========
-00_7 0.66  %
-03_9 0.0   K  # coefs identical
-06_5 0.043 K
-10_7 0.006 K
-13_3 0.003 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    0.66  %
+03_9    0.0   K  # coefs identical
+06_5    0.043 K
+10_7    0.006 K
+13_3    0.003 K
+======= ===== ====
+
+======= ===== ====
 GOES-15
-========
-00_7 0.86  %
-03_9 0.0   K  # coefs identical
-06_5 0.02  K
-10_7 0.009 K
-13_3 0.008 K
-
+------------------
+Channel Diff  Unit
+======= ===== ====
+00_7    0.86  %
+03_9    0.0   K  # coefs identical
+06_5    0.02  K
+10_7    0.009 K
+13_3    0.008 K
+======= ===== ====
 
 References:
 
-[GVAR] https://goes.gsfc.nasa.gov/text/GVARRDL98.pdf
-[BOOK-N] https://goes.gsfc.nasa.gov/text/GOES-N_Databook/databook.pdf
-[BOOK-I] https://goes.gsfc.nasa.gov/text/databook/databook.pdf
-[IR] https://www.ospo.noaa.gov/Operations/GOES/calibration/gvar-conversion.html
-[VIS] https://www.ospo.noaa.gov/Operations/GOES/calibration/goes-vis-ch-calibration.html
-[FAQ] https://www.ncdc.noaa.gov/sites/default/files/attachments/Satellite-Frequently-Asked-Questions_2.pdf
-[SCHED-W] http://www.ospo.noaa.gov/Operations/GOES/west/imager-routine.html
-[SCHED-E] http://www.ospo.noaa.gov/Operations/GOES/east/imager-routine.html
+- [GVAR] https://goes.gsfc.nasa.gov/text/GVARRDL98.pdf
+- [BOOK-N] https://goes.gsfc.nasa.gov/text/GOES-N_Databook/databook.pdf
+- [BOOK-I] https://goes.gsfc.nasa.gov/text/databook/databook.pdf
+- [IR] https://www.ospo.noaa.gov/Operations/GOES/calibration/gvar-conversion.html
+- [VIS] https://www.ospo.noaa.gov/Operations/GOES/calibration/goes-vis-ch-calibration.html
+- [FAQ] https://www.ncdc.noaa.gov/sites/default/files/attachments/Satellite-Frequently-Asked-Questions_2.pdf
+- [SCHED-W] http://www.ospo.noaa.gov/Operations/GOES/west/imager-routine.html
+- [SCHED-E] http://www.ospo.noaa.gov/Operations/GOES/east/imager-routine.html
 
 Eumetsat formated netCDF data:
 
 The main differences are:
-1: The geolocation is in a separate file, used for all bands
-2: VIS data is calibrated to Albedo (or reflectance)
-3: IR data is calibrated to radiance.
-4: VIS data is downsampled to IR resolution (4km)
-5: File name differs also slightly
-6: Data is received via EumetCast
+
+1. The geolocation is in a separate file, used for all bands
+2. VIS data is calibrated to Albedo (or reflectance)
+3. IR data is calibrated to radiance.
+4. VIS data is downsampled to IR resolution (4km)
+5. File name differs also slightly
+6. Data is received via EumetCast
 
 """