Help with HYCOM WMS

[Shipman, Gregory W]

Hello Hycom,

 

I’ve successfully connected to your WMS for HYCOM_GLBa0.08_expt91.0 (as well as 91.1 and 91.2) with ArcGIS, but I can’t tell how best to use it.

 

I’m able to display various coverages (current velocity, sea temp, etc), however, I don’t see how I can refine my view to look at a specific day.  When I inquire on the map to find cell values, all inquiries seem to tell me that it is the last day in the period covered by the export (April 8, 2014 in the case of export 91.0). 

 

Do you have any guidance as to how I can query specific dates and other ways to use this information in a more intelligent way?

 

Thank you,

 

Gregory W. Shipman

Geoscience Technician

S1.2A.425

(832) 624-9688

 

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[Michael McDonald]

Gregory,

Sorry about the lack of response to this inquiry. In general the
"GLBa0.08/expt_x.xx" outputs are in a different format that is not
easily ingested into GIS applications. There the lat/lon is unique and
the grid spacing is not consistent. There's a summary here,
https://hycom.org/dataserver/gofs-3pt0/analysis

To alleviate this issue in GIS (and many other applications) the
outputs for the GLBu0.08/GLBv0.08 experiments are on a uniform grid,
which makes for easier use.

https://hycom.org/dataserver/gofs-3pt1/analysis

Take a look at the WMS access for any of the "GOFS 3.1: 41-layer HYCOM
+ NCODA Global 1/12 degree Analysis (NRL)" datasets here,

http://tds.hycom.org/thredds/catalog.html

> I’ve successfully connected to your WMS for HYCOM_GLBa0.08_expt91.0 (as well
> as 91.1 and 91.2) with ArcGIS, but I can’t tell how best to use it.
>
>
>
> I’m able to display various coverages (current velocity, sea temp, etc),
> however, I don’t see how I can refine my view to look at a specific day.
> When I inquire on the map to find cell values, all inquiries seem to tell me
> that it is the last day in the period covered by the export (April 8, 2014
> in the case of export 91.0).
>
>
>
> Do you have any guidance as to how I can query specific dates and other ways
> to use this information in a more intelligent way?

--
Michael McDonald
HYCOM.org Administrator

[Shipman, Gregory W]

Thanks for getting back to me. I've connected to one of those WMS, but the problem remains:

I cannot seem to easily query by date at all. How can I see data from a specific date rather than only the last date of the coverage?

Any guidance is appreciated.

Thank you,
Greg Shipman

[Michael McDonald]

Greg,

I am not 100% sure on this (hycom forum users with more WMS experience
might want to chime in), as my experience with ArcGIS and WMS is very
limited, but the documentation for WMS (link below) outlines some of
the "known limitations" for the WMS service,

http://docs.geoserver.org/stable/en/user/data/cascaded/wms.html#limitations

One of them being certain dimensions, like "time" cannot be used...

quote from "Limitations" at bottom:
* Extra request parameters (time, elevation, cql_filter, etc.) cannot be used.


(( After reading this I am wondering if we need to disable advertising
the WMS service access option for all of our aggregated datasets, as
selecting time/date dimensions is not allowed...? )) We would still
keep this active for our unaggregated files.


So, the simplest option to get you working again in ArcGIS is to use
*single* time slice WMS URLs (i.e., non aggregated datasets) so that
you are only returned a single time value.

Start with our THREDDS catalog
(http://tds.hycom.org/thredds/catalog.html) and at the very top is " *
Unaggregated * / All Data"

Drill down to the dataset you want, the experiment you want, and then
you will see the individual files that all have a WMS Access/service
enable for them.

e.g., see "WMS" Access method here,

ssh for 20180331 @ 12Z

http://tds.hycom.org/thredds/catalog/datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/catalog.html?dataset=datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/hycom_glbv_930_2018033112_t000_ssh.nc


temperature & salinity for 20180331 @ 12Z

http://tds.hycom.org/thredds/catalog/datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/catalog.html?dataset=datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/hycom_glbv_930_2018033112_t000_ts3z.nc


u & v (currents) for 20180331 @ 12Z

http://tds.hycom.org/thredds/catalog/datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/catalog.html?dataset=datasets/GLBv0.08/expt_93.0/data/hindcasts/2018/hycom_glbv_930_2018033112_t000_uv3z.nc