Obtaining Excel files of Lat-Lon-SLA L3 data as presented

[Sylvain Herlédan]

Hi Claude,

1) Computation of the mean SLA
I downloaded pass #444 for the 28 cycles currently available in the SWOT L3 250m product.
Out of these, two of them had no valid value at all for the sla_filtered variable, so I left them aside:

• 2024-02-09
  
• 2024-06-14
  

The file for 2023-12-30 has not been included in the computations for the mean SLA.

For the remaining 25 files, the values have been interpolated on the same grid as the 2023-12-30 pass, here is the result:

https://ftp.odl.bzh/odl/sherleda/for_cla...231230.png

The corresponding CSV file is available here: https://ftp.odl.bzh/odl/sherleda/for_cla...231230.csv

The mean SLA takes into account the fact that satellite passes had missing values in different locations. Here is a plot of the number of samples included in the mean computation for each pixel: https://ftp.odl.bzh/odl/sherleda/for_cla...231230.png

2) Original SLA on 2023-12-30

The content of the sla_filtered variable found in the SWOT L3 250m file for pass #444 on 2023-12-30 is available here as a map and a CSV file:

https://ftp.odl.bzh/odl/sherleda/for_cla...nc_raw.png

https://ftp.odl.bzh/odl/sherleda/for_cla...nc_raw.csv

3) (SLA - mean) on 2023-12-30
When the mean map computed in step 1) is subtracted from the 2023-12-30 SLA extracted in step 2), only small scale variations remain:

https://ftp.odl.bzh/odl/sherleda/for_cla...efault.png

All values are negative, so the initial range is not suitable anymore. I made another plot after adapting the min/max to see more details (previous plots use [-0.05, 0.20] whereas this one uses the [-0.25, 0.0] range):

https://ftp.odl.bzh/odl/sherleda/for_cla...231230.png

and the corresponding CSV file: https://ftp.odl.bzh/odl/sherleda/for_cla...231230.csv

The exact same map rendered with a different color scheme with a bit more contrast: https://ftp.odl.bzh/odl/sherleda/for_cla...stncar.png

One last version where the range of the colormap has been narrowed down to [-0.15, -0.05] so that details in the immediate vicinity of the island stand out more: https://ftp.odl.bzh/odl/sherleda/for_cla...trange.png

---

Please let me know if there is something I misunderstood, or if these plots need to be changed/improved (I could add titles and units to make them easier to interpret).

Cheers,

Sylvain