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[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).
> 
The dataset is 280m in size, I will check it out next week from office.

> 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.
> 

The color table is linear, however, we should be able to pick up some details 
in the dataset through applying the certain scaling factor.

> 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.
> 

Basically, there is a default xml table to assign the default color table and 
range. You can always make the change to this table, or select different table 
after the image being created.

> 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.
> 
The IDV do have a formula to find the max and min in the grid dataset, but only 
in the time dimension if I remember correctly.



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


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