# Preprocessing routines¶

Some elaborated variables need to be preprocessed, such as the moisture index. Thus, different preprocessing routines are available in AtmoSwing.

The main preprocessing routines implemented are:

Addition (

`Addition`

): add (point-wise) all the provided predictors.Average (

`Average`

): average (point-wise) all the provided predictors.Difference (

`Difference`

): process the difference (point-wise) between 2 predictor grids.Multiplication (

`Multiplication`

or`Multiply`

): multiply (point-wise) all the provided predictors.Humidity (or moisture) index (

`HumidityIndex`

): multiply the relative humidity and the precipitable waterHumidity (or moisture) flux (

`HumidityFlux`

): process the multiplication of the wind and the humidity index. Requires four predictors in the following order: 1) U wind, 2) V wind, 3) relative humidity and 4) precipitable waterWind speed (

`WindSpeed`

): process the wind speed with the provided U wind and V wind components.

The following preprocessing routines are usually not used directly (or are automatically handled by AtmoSwing):

Simple gradients (

`SimpleGradients`

): processing of differences between adjacent grid points by ignoring the horizontal distance.Real gradients (

`RealGradients`

): processing of real gradients between adjacent grid points (using the horizontal distance). This preprocessing method is automatically used when the analogy criterion is`S1`

.Simple gradients with Gaussian weights (

`SimpleGradientsWithGaussianWeights`

): same as before, but with a weighting of the spatial field by a gaussian ‘hat’-shaped pattern.Real gradients with Gaussian weights (

`RealGradientsWithGaussianWeights`

): same as before, but with a weighting of the spatial field by a gaussian ‘hat’-shaped pattern.Simple curvature (

`SimpleCurvature`

): processing of the ‘curvature’ between adjacent grid points by ignoring the horizontal distance.Real curvature (

`RealCurvature`

): processing of real ‘curvature’ between adjacent grid points (using the horizontal distance). This preprocessing method is automatically used when the analogy criterion is`S2`

.Simple curvature with Gaussian weights (

`SimpleCurvatureWithGaussianWeights`

): same as before, but with a weighting of the spatial field by a gaussian ‘hat’-shaped pattern.Real curvature with Gaussian weights (

`RealCurvatureWithGaussianWeights`

): same as before, but with a weighting of the spatial field by a gaussian ‘hat’-shaped pattern.