SWOT Level-3: version 3.0 reprocessing & shorter latency

A new SWOT Level-3 release (v3.0) is now available on AVISO : L3 basic & expert 2-km products have been upgraded. There is also a new “technical L3” product (as per requests from ST members). The main changes are described in this short presentation. The reprocessing of the L3 unsmoothed 250-m, and the L3 wind & waves, is ongoing with ETA 2026Q1 and Q2. The L3 is also synchronized with the new improved latency of the L2 upstream (our L3 target latency is 48h). 

1/ One step-closer to near real time 

Following various requests from operational users, the SWOT Project (NASA/CNES) has made a large effort to reduce the latency of Level-2 LR products. 

Thanks to this L2 change, we are now able to synchronize the L3 processor for a much shorter L3 latency of 48h in nominal conditions. This timeliness meets the requirements from operational oceanography centers or the latency of IGDR / STC products in nadir altimetry. Note that beyond their timeliness, the SWOT L3 products are also consistent with their operational Copernicus counterparts (e.g. KaRIn can be mixed with the nadir constellation in ocean model assimilation). The new L2 & L3 short latency systems are deployed already. We expect that a couple of hiccups might happen in the next week or two before smoother sailing.

2/ The third release of the Level-3 products is available 

Since the release of the L3 version 2.0.1, we have received your feedback and suggestions, and we have been working on new or improved algorithms/corrections/models. The new release, or v3.0, is now available on AVISO. At the moment, only the 2km variants are online, and the 250-m is expected to arrive early next year. 

In addition to the upgrades on the basic & expert product variants, a new 'technical L3' variant is being added (ETA: one week or two). Following multiple requests from community experts, the purpose of the technical L3 is to provide additional and optional content such as alternative geophysical models, or algorithms, for specific expert studies or if you want to customize the L3 baseline. We have a lot of flexibility on this new product: if anything is missing, your feedback would be most welcome. 

We have put together this short presentation with a comprehensive outline of the main changes and impacts. You can also find more details and examples in the handbook (issue 3.1) with the changes and some known limitations. 

3/ Data Access 

For AVISO Account Holders 
If you already have an AVISO account, you can access the data via the following service: 

• FTP/SFTP (with personal credentials)
  • FTP Access: ftp://ftp-access.aviso.altimetry.fr:21
  • SFTP Access: sftp://ftp-access.aviso.altimetry.fr:2221
  • Path: /swot_products/l3_karin_nadir/l3_lr_ssh/v3_0
• THREDDS Data Server (TDS), No account required
  • L3_LR_SSH v3.0 TDS Access: THREDDS Catalog for L3_LR_SSH