The Synergy Preprocessor is the first of three main modules within the MERIS/(A)ATSR Synergy toolbox. Its purpose is to create a colocated MERIS/(A)ATSR L1b product containing radiances/reflectances of all channels of both MERIS and AATSR. This colocated product shall be used as input for the cloud screening module.

There is no separate user interface for the Synergy Preprocessor, also, there are no processing parameters. The preprocessor is invoked automatically when a MERIS/AATSR colocated product is generated either as final product or as intermediate product required for cloud screening or aerosol retrieval. These options are provided through radio buttons on the Synergy Toolbox I/O Parameters Tab Pane (see below).

4.1.1. I/O Parameters Tab Pane

Figure 4.2. Synergy Toolbox: I/O Parameters Tab Pane

This tab pane consists of the following components:

• MERIS source product file: Select the source product file by either typing the product path into the text filed or by pressing the file selection button to invoke a standard file dialog. This source product must be a standard MERIS L1b product.
• AATSR source product file: Select the source product file by either typing the product path into the text filed or by pressing the file selection button to invoke a standard file dialog. This source product must be a standard AATSR L1b product.
• Target product file: Select the target product file by either typing the product path into the text filed or by pressing the file selection button to invoke a standard file dialog.
• Target product format and target directory:
  • 'Save as': If this checkbox is selected, the output product will be saved to disk.
  • Target product format: Select one of the available output product formats.
  • Select the target product directory by either typing the product path into the text filed or by pressing the file selection button to invoke a standard file dialog.
• 'Open in Visat': If this checkbox is selected, the output product is opened in Visat after successful processing.
• Target product specification: This user option is represented by radio buttons and specifies the computation type and results written to the target product:
  • 'Only create a colocated MERIS/AATSR product': If this radio button is selected, just a colocated MERIS/AATSR product will be generated. No cloud screening or aerosol retrieval is performed.
  • 'Create a cloud screening product': If this radio button is selected, a cloud screening product will be generated. A colocated MERIS/AATSR product is created as intermediate product. No aerosol retrieval is performed.
  • 'Create an aerosol and atmospheric correction product': If this radio button is selected, an aerosol and atmospheric correction product will be generated. Atmospheric correction over land can be added by aerosol retrieval user option (seeSection 4.3) The aerosol retrieval processor automatically creates a colocated MERIS/AATSR product and performs cloud screening as foregoing steps.

4.1.2. Control Buttons

From the 'I/O Parameters' tab pane, the following control buttons can be accessed:

• 'Run': If this button is clicked, the processor will start the computations.
• 'Close': If this button is clicked, the 'MERIS/(A)ATSR Synergy Toolbox' dialog is closed.
• 'Help': If this button is clicked, this manual is displayed as online help.

Figure 4.3. Synergy Toolbox: control buttons