The Cloud Screening Processor is the second of three main modules within the MERIS/(A)ATSR Synergy toolbox. Its purpose is to add various bands (i.e cloud flags) to the colocated MERIS/(A)ATSR L1b product obtained from the preprocessor. The output product from the cloud screening shall be used as input for the third module (aerosol retrieval and atmospheric correction).
The user interface for the Cloud Screening Processor can be accessed by clicking the 'Cloud Screening' tab in the 'MERIS/(A)ATSR Synergy Toolbox' dialog. (Figure 4.4):
The Cloud Screening tab pane consists of the following components:
- 'Use the AATSR forward view when classifying': If his checkbox is selected, the AATSR forward view is considered in the cloud classification algorithm (otherwise nadir view only).
- 'Compute cloud index': If this checkbox is selected, a cloud index is computed and written as single band 'cloud_index_synergy' to the target product.
- 'Compute snow risk flag': If this checkbox is selected, a snow risk flag is computed and added to a flag band 'cloud_flags_synergy', which is written to the target product.
- 'Compute cloud shadow risk flag': If this checkbox is selected, a cloud shadow risk flag is computed and added to a flag band 'cloud_flags_synergy', which is written to the target product.
See [4] for more details on the computation and physical meaning of the quantities listed above.