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.