Operational processors are required to generate data which are as precise as possible, either in near-real-time (NRT) or in offline mode. Sometimes the algorithmic core for both types of processors is almost identical, but there are also cases in which especially customized algorithms must be used in order to meet the stringent time demands of NRT operation. In addition to the specifications for operational processors, a prototype is created at every processing level for testing and development purposes, which permits interactive control and, as necessary, detailed investigation of individual processing steps. Which algorithms are used in the processors is described in detail in the Algorithm and Technical Baseline Document (ATBD). For the mission operator, these ATBDs, along with other specifications, are the foundation for industrial implementation of the processor software which is finally to be installed in the ground segment. This outcome requires close cooperation among the team’s algorithm experts, mission operators and industry and includes processor testing, for which test scenarios and data need to be created in the course of the development work. The final step is industrial implementation which ends with a Factory Acceptance Test (FAT) before the products generated by the newly installed processors are verified and validated with actual measurement data.
Processors and the algorithms which form their basis are improved further in the course of a mission. Calibration of the instrument improves with the length of the mission, as does the capability to extract already defined or even new geophysical parameters from the measurement data. For this reason, ideally all measurement data are routinely subjected to reprocessing which each time employs the state-of-the-art algorithms being implemented in the operational software at that time. This means that the responsibility for the algorithms and processors given to the Atmospheric Processors department and its Processor Development team is a long-term commitment which accompanies a mission from Phase C/D (design and development) to operation in orbit and beyond.