Re: US mapping mask

Dear Mary

   Got it! Thanks a lot!

Best
W

On Wed, Apr 3, 2013 at 4:28 PM, Mary Haley <haley@ucar.edu> wrote:

> Hi,
>
> I had started creating an example before I saw Rick's response. The filled
> dots show the original data grid. The red dots show the grid points that
> got masked.
>
> I tried the example with a 20m shapefile from "
> http://www.census.gov/geo/www/cob/". When I saw Rick's message, I
> downloaded the nationalatlas shapefile and tried that too. The census one
> runs faster because the shapefile is smaller and less detailed. (206 wall
> clock seconds versus 17 wall clock seconds).
>
> Which shapefile you use just depends on how coarse or fine your original
> data grid is. The nationalatlas shapefile is more detailed and might work
> better for finer grids.
>
> When you run the script, it will create and write a mask grid to a NetCDF
> file. You can then use this mask for other variables that are the same
> size, without having to create it every time. See the CREATE_MASK variable.
>
> --Mary
>
>
>
>
> On Apr 3, 2013, at 1:58 PM, Rick Brownrigg wrote:
>
> Hi,
>
> Examples 4 & 5 from the shapefiles examples page shows how to use a
> shapefile as mask to get what you want:
>
> http://www.ncl.ucar.edu/Applications/shapefiles.shtml
>
> In particular, check out the National Atlas for a national boundaries
> shapefile of the US:
>
> http://www.nationalatlas.gov/atlasftp.html
>
> I think this one in particular *might* do the trick (but untested):
>
> http://www.nationalatlas.gov/atlasftp-1m.html#nationp
>
> Hope that helps…
> Rick
>
> On Apr 3, 2013, at 10:14 AM, Wei Liu <wliu5ster@gmail.com> wrote:
>
> Hi there
>
> Could I ask question about the US masking? Say, I have global
> atmospheric ptrecipitaion.
> I want to calculate the mean precipitation over US. How can I get a US
> masking data file.
> Is there some US mask data available in NCL or other database?
>
>
> (I found in NCL, there is a Ncarg4_1 Earth 1 database, but how can I get
> the mask data
> or build a mask data?)
>
>
> Thanks a lot!
>
>
> Best
> W
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Received on Wed Apr 3 21:04:27 2013