Different events can lead to a reduction of data availability. Among these, the most common events are the following:
- A change in the altimeter constellation: either the loss or the introduction of an additional altimeter in the constellation directly impacts the number of altimeter measurements available.
- For a specific platform, a reduction in the number of altimeter measurements available as inputs of the DUACS system processing. This can be linked to an anomaly onboard the platform or on the ground segment, preventing the data reception and impacting the L0 to L2 processing. It can also be induced by an degraded aquisition of the DUACS system that can be induced by missing upstream products and/or auxiliaries (e.g : various geophysical correction specificaly updated at L3)
- An increase of invalid measurements used as inputs of the DUACS system processing. This is usually linked to specific platform events (e.g., manoeuvres), but can also be induced by L0-L2 processing anomalies or specificities. In some rare cases, degraded acquisition by the DUACS system can also lead to an bad data selection.
- An anomaly of the L3/L4 processing
We list in the folowing table the main events impacting the quality and availability of the NRT L3/L4 products.
| Date | Platform | Event |
| 2020/01/31-2020/02/13 | J3 | The mission entered in safe hold mode.
The Sentinel-3A mission is used as temporary anchor mission for cross-calibration processing from 2020/02/06 to 2020/03/03 |
| 2020/06/15-2020/06/23 | J3 | The mission entered in safe hold mode |
| 2020/07/07 | HY-2B | HY-2B is introduced in DUACS NRT processing |
| 2020/11/30-2020/12/04 | HY-2B | No upstream measurement available |
| 2021/08/16-2021/08/17 | HY-2B | No upstream measurement available |
| 2020/07/15-2020/10/29 | C2 | The processing of the C2 mission was inhibited, time to manage an orbit change for this mission |
| 2022/04/06 | S6A | Sentinel6A (HR measurement) is introduced in DUACS NRT processing |
| 2022/04/06 – 2022/05/24 | J3 | The processing of the mission was inhibited, time to manage an orbit change for this mission |
| 2022/10/09-2022/10/11 | HY-2B | No upstream measurement available |
| 2022/10/11 | AL | No L3 measurement available |
| 2022/11/17-2022/12/02 | S6A | Various sections of tracks are missing in upstream products. |
| 2022/12/30- 2023/01/08 | AL | |
| 2023/04/30-2023/05/05 | S3A & S3B | Data available with few days delay due to missing L0 inputs from the Marine PDGS (Payload Data Ground Segment) |
| 2023/0731-2023/08/05 | H2B | Data unavailability due to satellite manoeuvre |
| 2023/11/30 | SWON | SWOT-nadir is introduced in DUACS NRT processing |
| 2024/05/11-2024/05/17 | H2B | Data unavailability |
| 2024/12/18-2025/01/25 | H2B | Data invalidity : no valid data available for L3 processing |
| 2024/01/07-2025/05/xx | J3 | Jason-3 moved on a tandem orbit with Sentinel-6A. During this period, Jason-3 measurements are not processed in L3 |
| 2025/05/xx | J3 | Jason-3 moved on a interleaved long repeat orbit. L3 products are delivered in the new “j3g” dataset |