Envisat GDR 2014 validation activities

After the interruption of ENVISAT mission in 2012, the database of 10 years of altimetric data over ocean is still maintained, studied and used. Taken as a reference for the expected behavior of the very young or future missions such as AltiKa or Sentinel 3, historical database still evolves.

Next reprocessing is getting prepared with a tenth of algorithm improvements planned for the future products. In 2014, some of them have been developed and analysed in terms of expected effects notably on errors reduction. The table below presents an overview of the anticipated updates and the expected impacts at different scales. To complete the anticipation of the next Envisat whole dataset reprocessing, efforts were made this year to refine the analysis of misunderstood behaviours of Envisat data, notably for global MSL computation. Potential correlations have been established between observations and instrumental effects or configuration used.

Continuing such focused analysis is important to prepare future reprocessings too. A great effort was made in 2014 to prepare the next Envisat whole dataset reprocessing, this effort will continue in 2015 through the validation of new standards and refined analysis of Envisat altimetric data behavior.

See complete report of 2014 Envisat validation activities (February 2015, pdf, 8 Mb)

 Upgraded Fields Expected impact
Orbit GDR-E standards Climate scales geographical variations. Short scales error reduction (crossovers)
MWR wet tropospheric correction Coastal areas. Short scales error reduction (crossover). Reduction of difference with model
MWR derived fields (ice flags, atmospheric attentuation, ...) Mesoscale
SSB computed with all upgraded corrections Mesoscale
PTR internal path delay drift Climate scale
Look up tables for small waves correction Reduction of altimetry/ERA-Interim model dependency for Envisat small waves
L1b reprocessing: ICU, USO, IF mask Climate scale +punctual effects expected?
Ocean Tide: GOT 4V10 and FES2014 Mesoscale
Non eq. long period ocean tide Mesoscale
Updated MSS (CNES/CLS 12) Regional scale
New iono. filtering method Number of SLA valid data increase. Short scales error reduction (crossovers). Independant from editing step