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ECWAM land-sea mask

Dear all, 

I am trying to find info on ECWAM land-sea mask.

I recently downloaded wave data from ERA5, and noticed that some points on the southern hemisphere, possibly close to the mask boundaries, sometimes have values and sometimes it doesn't, making me believe that somehow the mask is a dynamic mask...maybe due to sea-ice variations ?

Anyway, I looked everywhere in the Confluence and can't find any clear info on ECWAM land-sea mask, only on ERA5 one.

 

Hope to have some feedback soon

Regards

J

3 comments

May be you don't have enough permissions in your Confluence instance. Ask your administrators.

Hi @Joana DeMedeiros ,

Having a look at the ERA5 and ECWAM land-sea mask documentation it seems data comes from an archived grid and from another source. And this data can be interpolated using different methods.

https://apps.ecmwf.int/codes/grib/param-db?id=172 describes the expected behaviour of Land-sea mask. Perhaps this will provide you with more information on what you are attempting on retrieving.

As this link (https://confluence.ecmwf.int/display/CKB/Land-sea+mask+in+ERA5+and+ERA-Interim) suggests, the data used may be retrieved from web APIs, therefore, you could:

  • if you are familiar with HTTP Request, open the Inspector and select the Network tab so you can see all XHR requests, trying to identify the one that gets the data consumed by ECWAM or ERA5.
  • install Atlassian REST API Browser checking if there is any REST API available to ECWAM or ERA5. You can try to perform the same request using this plugin.
  • enable DEBUG logging on org.apache.http.wire in Confluence. More information on Confluence - Configuring Logging
    (i) Please, notice this will generate a considerable amount of log entries to "atlassian-confluence.log" so perhaps you should consider running tests on a separate Confluence instance and not on a production environment.

You have mentioned that sometimes values are not present. Perhaps, if you could provide more information on what you are trying to achieve, the configuration you have and an example on when the value is present and another on when is not.

Alternatively, you could try getting in touch with https://www.ecmwf.int/en/about/contact-us providing them more information on the issue you are facing.

Kind regards,
Rafael

Thanks for the info, but I've been previously on all those links and found nothing. 

I found though, that ECWAM accounts for the impact of sea ice on the wave field by setting wave energy to zero for all points with ice concentration above 30%.”, “ECWAM imposes a sea ice mask at each time step at the 30% ice concentration contour” ,this might suggest the dynamic mask on the wave fields. Because that is what I am seeing near the poles. 

Let's take for example the year 2018:  for the point lat=-65.00, lon=-27 there is data from Jan-June, no data (NaN) from June-Nov, then data again on December. This seems to be following the sea-ice dynamic mask, where the sea-ice extent is bigger in winter (hence NaN values) and decreases in summer where we see values again. 

I think this might explain what I am seeing near the poles, but did't see any confirmation in any ERA5 wave fields documentation, in fact there is none ERA5 wave proper documentation,

Many Thanks

Regards

Joana

I'm afraid this is a question for the owners and administrators of your systems and content  - we are a community of people using Atlassian software, not your content owners!

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