PPE Filtering - Algorithm Specification |

### Introduction

This algorithm is used for filtering noise produced by PPE (Prompt Particle Events). By default filtering is applied only over water. The filter is applied to every single pixel separately, checking the difference between a pixel and its nearest four vertical neighbors. If the difference is higher than a threshold, the value of the pixel is replaced by the median of the pixel and its neighboring pixels.
The processor supports the Sentinel-3 OLCI Level1 RR and FR data.

The algorithm is described in the following article:
Juan I. Gossn. Effect of Prompt Particle Events on OLCI Ocean Color Imagery in the South Atlantic Anomaly: Detection and Removal