[IDV #IYO-548353]: Request for links to hurricane bundles

Hi Dom,

re:
> Thanks for the guide, the precipitable water, when displayed as described,
> looks great. I've been trying look at the various settings as I've gone
> along to pick up a few hints and tips.

> Do you know off hand where this data comes from?

The data is from the Global Forecast System (GFS) model.  The display I
outlined used the 0.5 degree (55 km) resolution.

re:
> It would be great to get precipitable water with a longer time frame.

One can get LOTS of this data at the U.S. National Climactic Data Center
(NCDC).  The process is straightforward:  register an email address
and then select the type of data desired, parameters in that data (subset
of the full set of parameters that are possible), and times.  The files
will be put on disk for you to FTP.

re:
> I've also been busy trying to find and visualise various models and couple
> of issues/questions have popped up.
> 
> There are four models I'm keen to try and display at the moment:
> 
> 1) The Antarctic current model generated by Paul Holland at the British
>    Antarctic Survey, that I mentioned before
> 2) The Antarctic atmospheric model (AMPS) produced by Jordan Powers at UCAR
> 3) Global dust output produced by Natalie Mahowald at Cornell
> 4) Global current model ECCO2 generated at JPL NASA

OK.

re:
> 1) I'm still waiting to find out from Paul what the original output was. He
> did say that the 10 GB file didn't include grid points and sent through
> another file which he uses to map the data out (grid file). Below are the
> details for our FTP site, Paul's files are saved into the 'Holland' folder.
> As you mentioned, downloading a 10 GB file probably isn't the best, the grid
> file is about 1 GB.

This is easily doable.

re:
> It maybe that I just need to link the two files - they're both .nc?

This should be possible using the "aggregate by time" feature.

re:
> To upload/download files externally: ftp://Earthfromspace5575:address@hidden
> 
> FTP client details:
> 
> username: xxxx
> password: xxxx
> URL: ftp.endemoluk.com

Thanks.

re:
> 2) Jordan has uploaded a bit of the AMPS output for me to look at, it's only
> a portion (1.7 GB) of the total output that we'd be interested in and came
> as a .tar.gz file. Jordan has since taken the file off of his server, but
> it's in the Powers folder of our FTP if you fancy taking a look.
> 
> After unzipping I end up with a list of .nc files for hourly time points
> which seem to load up fine. I was thinking of using isosurfaces set to a
> particular wind speed to highlight the polar jet, I think I've seen
> something similar done by one of the visualisation teams at UCAR. How do I
> load multiple time points into IDV and tell IDV to put them into the same
> timeline?

The current output of AMPS and 4 days previous is made available online on
our motherlode.ucar.edu demonstration server:

motherlode.ucar.edu

  RAMADDA Data Repository
  http://motherlode.ucar.edu/repository

    Projects
    
http://motherlode.ucar.edu/repository/entry/show/RAMADDA/Projects?entryid=1c0cb8d1-5177-4028-b685-577cbbf44ef6

      Antarctic IDD
      
http://motherlode.ucar.edu/repository/entry/show/RAMADDA/Projects/Antarctic+IDD?entryid=2c55cb2c-82ff-4c1f-8215-1fdb14ae46da

The model output is available in GRIB in the folders under AMPS Model Output.
This is available directly in the IDV through the Catalogs selection.

re:
> 3) Natalie has shared her global dust model output. These are relatively
> small files and can be found here:
> 
> http://www.geo.cornell.edu/eas/PeoplePlaces/Faculty/mahowald/fordominic/
> 
> I'm particularly interested in DSTQ.00.nc as this contains data in 3
> dimensions. What I'd like to do is try and select an isosurface that shows
> how the dust rises and travels across the Atlantic (and other locations).
> The problem is that IDV doesn't seem to identify the Z component and gives
> it a null value. I can display each level individually though.

We will take a look to see what my be missing from the file(s).

re:
> Also, the dust range is fairly logarithmic, at the lower levels there are
> very small differences in dust concentration (e-12 to e-11) and when the
> default colour bar is used (in this range) you see nice eddies in the dust
> movement. However at higher levels the dust is in the e-8 range and the
> standard linear colour bar doesn't resolve the fine detail in the very low
> concentrations.

Yuan will need to comment on this.

re:
> Failing being able to visualise this in 3D I was thinking of displaying each
> level individually, which our CGI team can stack and fill in the gaps.
> Ideally the colour scale would be consistent through each level and be able
> to show the fine detail throughout the e-12 to e-4 range.
> 
> I'm guessing if isosurfaces are possible it's going to be limited to the
> higher dust concentrations and the detail would be lost anyway. Also, it
> might be a bit of a cheat showing values on the logarithmic scale, the finer
> stuff you wouldn't see!
> 
> On a side note, how does IDV decide on the default values for the colour
> scale? 

A default is assigned for each dataset, and this can be changed by the user.
I will let Yuan lead you through this.

re:
> And is there a way of browsing the values or a summary of the values
> in the data - like maximum and minimum values, mean distribution?

Again, this is a question for Yuan.

re:
> 4) The ECCO2 directory can be found here:
> http://ecco2.jpl.nasa.gov/data1/cube/cube92/
> 
> I need to double check with the PI which are the most relevant data sets to
> work with (is THETA commonly temperature?). In any case the data are
> presented in individual time steps (like Jordan's AMPS output) and are .data
> files. Are these recognised by IDV?
> 
> Sorry - loads of questions! I'm going to hold off finding more data sets, I
> think I'm better off getting to grips with these for the time being.

I agree.  It is best to learn enough to be able to use the IDV effectively
before drowning oneself in data.

re: 
> The Mac is struggling a bit, when I try to do a 'flythrough' it freezes and
> the various displays start going wrong. Even if Paul's 10 GB current file
> could be loaded I suspect it would crash. I guess it's a case of finding
> more RAM (8GB?)

Since everything in the IDV is inherently 3D, one needs to have a LOT of memory
if one is trying to use large datasets.  Our development machines here in
the UPC typically have 24 GB or more of RAM and we don't find that to be
too much :-)

re:
> Many thanks,

No worries.
Cheers,

Tom
--
****************************************************************************
Unidata User Support                                    UCAR Unidata Program
(303) 497-8642                                                 P.O. Box 3000
address@hidden                                   Boulder, CO 80307
----------------------------------------------------------------------------
Unidata HomePage                       http://www.unidata.ucar.edu
****************************************************************************


Ticket Details
===================
Ticket ID: IYO-548353
Department: Support IDV
Priority: Normal
Status: Open