MPH/CHL Processor - User Interface |

## Processor user interface

The MPH/CHL processor is invoked from the 'Optical --> Thematic Water Processing' menu by selecting the 'MPH/CHL Processor' command. On the command line the MPH/CHL processor is available by means of the Graph Processing Tool gpt which is located in the SNAP bin directory. Typing gpt MphChl -h displays further information.

Selecting the 'MPH/CHL Processor' command from the SNAP 'Optical --> Thematic Water Processing' menu pops up the following dialog:

### Source Product Group

Source Product: Here the user specifies the source product, which can be either an OLCI or MERIS L1b product, or a product containing bottom-of-Rayleigh corrected reflectances, which was generated with the Rayleigh correction processor available in 'Optical --> Preprocessing --> Rayleigh correction'. The combo box presents a list of all products open in SNAP. The user may select one of these or, by clicking on the button next to the combo box, choose a product from the file system.

### Target Product Group:

Name: Used to specify the name of the target product

Save as: Used to specify whether the target product should be saved to the file system. The combo box presents a list of available file formats. The text field or the button next to it allow to specify a target directory.

Open in SNAP: Used to specify whether the target product should be opened in SNAP. When the target product is not saved, it is opened in SNAP automatically.

### Processing Parameters Panel

Valid pixel expression: An expression which identifies valid input pixels according to flags that are available in the input image.

Cyano max value: Threshold to cap maximum chlorophyll concentration estimated for cyanobacteria-dominant waters.

Chl thresh for float flag: Value, above which cyanobacteria scum is expected, even if not indicated by a BRR maximum at 753 nm (see Algorithm specification, second figure).

Export mph: Write the internally calculated MPH value to a separate band for the evaluation of custom peak height to concentration conversions.

Apply low pass filter: If selected, a 3x3 low-pass filter is applied on the CHL result image.