Modifiers
Modifiers are filters applied to datasets prior to computing composites. They take at least one input (a dataset) and have exactly one output (the same dataset, modified). They can take additional input datasets or parameters.
Modifiers are defined in composites files in etc/composites
within
$SATPY_CONFIG_PATH
.
The instruction to use a certain modifier can be contained in a composite definition or in a reader definition. If it is defined in a composite definition, it is applied upon constructing the composite.
When using built-in composites, Satpy users do not need to understand the mechanics of modifiers, as they are applied automatically. The Composites documentation contains information on how to apply modifiers when creating new composites.
Some readers read data where certain modifiers are already applied. Here, the reader definition will refer to the Satpy modifier. This marking adds the modifier to the metadata to prevent it from being applied again upon composite calculation.
Commonly used modifiers are listed in the table below. Further details on those modifiers can be found in the linked API documentation.
Label |
Class |
Description |
---|---|---|
|
Modifies solar channels for the solar zenith angle to provide smoother images. |
|
|
Modifies solar channels for atmospheric path length of solar radiation. |
|
|
Calculates reflective part of channels at the edge of solar and terrestrial radiation (3.7 µm or 3.9 µm). |
|
|
Calculates emissive part of channels at the edge of solar and terrestrial radiation (3.7 µm or 3.9 µm) |
|
|
Modifies solar channels to filter out the visual impact of rayleigh scattering. |
A complete list can be found in the etc/composites
source code and in the modifiers
module documentation.