# satpy.enhancements.atmosphere module

Enhancements related to visualising atmospheric phenomena.

satpy.enhancements.atmosphere._calc_essl_blue(ratio)[source]

Calculate values for blue based on scaled and clipped ratio.

satpy.enhancements.atmosphere._calc_essl_green(ratio)[source]

Calculate values for green based on scaled and clipped ratio.

satpy.enhancements.atmosphere._calc_essl_red(ratio)[source]

Calculate values for red based on scaled and clipped ratio.

satpy.enhancements.atmosphere._is_fci_test_data(data)[source]

Check if we are working with FCI test data.

satpy.enhancements.atmosphere._scale_and_clip(ratio, low, high)[source]

Scale ratio values to [0, 1] and clip values outside this range.

satpy.enhancements.atmosphere.essl_moisture(img, low=1.1, high=1.6) None[source]

Low level moisture by European Severe Storms Laboratory (ESSL).

Expects a mode L image with data corresponding to the ratio of the calibrated reflectances for the 0.86 µm and 0.906 µm channel.

This composite and its colorisation were developed by ESSL.

Ratio values are scaled from the range [low, high], which is by default between 1.1 and 1.6, but might be tuned based on region or sensor, to [0, 1]. Values outside this range are clipped. Color values for red, green, and blue are calculated as follows, where x is the ratio between the 0.86 µm and 0.905 µm channels:

$\begin{split}R = \max(1.375 - 2.67 x, -0.75 + x) \\ G = 1 - \frac{8x}{7} \\ B = \max(0.75 - 1.5 x, 0.25 - (x - 0.75)^2) \\\end{split}$

The value of img.data is modified in-place.

A color interpretation guide is pending further adjustments to the parameters for current and future sensors.

Parameters:
• img – XRImage containing the relevant composite

• low – optional, low end for scaling, defaults to 1.1

• high – optional, high end for scaling, defaults to 1.6