Collection 1 Change Summary
As a result of major improvements to the cloud detection algorithm, a reprocessing campaign was planned. Together with these improvements, several other modifications to the PROBA-V data and metadata were included. Data files will be identified as .v1xx in the filenames, while the current available data collection (referred to as ‘Collection 0’) is identified as .v0xx.
All data from 16 October 2013 onwards is reprocessed, starting from the raw data. Further, all data is stored on disk in HDF5 and GeoTiff format for fast access. Further, for the first time the intermediate Level 2A data products are made available to the users at all resolutions. The changes that were implemented during the reprocessing are described below.
1. Improved cloud detection algorithm
A new cloud detection algorithm was developed to improve on major detection issues in the operational algorithm. This change gives the most significant differences between the Collection 1 and Collection 0 data products. More information on the new cloud detection methodology can be found in Appendix B of the PROBA-V Product User Manual, while an extensive evaluation of the new cloud detection algorithm is given by Stelzer et al. (2016).
2. Updates to the radiometric ICP files
With changes to the radiometric ICP files, users benefit from improved reflectance values due to updated absolute calibration coefficients, a better inter-camera consistency, and an overall improvement of the radiometric pixel quality.
The changes that were made to the radiometric ICP files include:
- Inter-camera adjustments to the VNIR absolute calibration coefficients;
- The application of a degradation model to the SWIR absolute calibration coefficients;
- Improvement of the low frequency multi-angular coefficients (i.e., equalization) for the SWIR strips of the CENTER camera;
- Changes to the dark current values;
- Minor changes to the status of bad pixels.
Users that are interested in more details on the above mentioned changes are referred to Appendix C of the PROBA-V Products User Manual.
3. Update product metadata for Climate Forecast (CF) compliancy
Metadata from 16 October 2013 to present will be made compliant to the Climate and Forecast metadata conventions (CF v1.6). In Collection 0, metadata was already compliant to these conventions for data from 6 January 2016 onwards. More details on the CF conventions can be found in Section 4.5 of the PROBA-V Products User Manual.
The most important bug fixes that were applied were:
- Bugfix to limit the impact of on-board compression errors for all data before July 2015.
- Bugfix in the processing facility component to update the module that checks the satellite attitude data. Some data before 10 February 2016 might be incorrectly marked as ‘No data’.