[ncl-talk] New York Map issue(s)

Tue Feb 21 07:54:39 MST 2017

Hi Barry,
   It's sort of a cheating method. I have point data, that I want to interpolate to a grid so I can map it (say, temperature). Since I can choose the grid I map it to, I merely pick a grid that happens to have a western border of exactly where the NY western border *should* be.

Here's the relevant section of my script:

sitefile  = "currenttemp.dat"

sitedata = asciiread(sitefile,-1,"string")

delim = ","

sitelats  = tofloat(str_get_field(sitedata,1,delim))

sitelons  = tofloat(str_get_field(sitedata,2,delim))

sitetemp  = tofloat(str_get_field(sitedata,3,delim))

lonmin = -79.76332855224604

lonmax = -71.85635375976562

latmin = 40.4

latmax = 45.1

newlons = fspan(lonmin,lonmax,200)

newlats = fspan(latmin,latmax,200)

latsize=(dimsizes(newlats))

lonsize=(dimsizes(newlons))

newlons at units="degrees_east"

newlats at units="degrees_north"

newdata2 = dsgrid2(sitelats,sitelons,sitetemp,newlats,newlons)

newdata3 = natgrid(sitelats,sitelons,sitetemp,newlats,newlons)

newdata = (newdata3+newdata2)/2   ; take average

newdata!0="lat"

newdata!1="lon"

newdata&lon = newlons

newdata&lat = newlats

newdata at _FillValue = -999

Nick Bassill, PhD

Modeler & Meteorologist, New York State Mesonet

LC SB-28, 1400 Washington Ave.,

SUNY, University at Albany, NY 12222

(518) 442-6375

http://nysmesonet.org/

________________________________
From: Barry Lynn <barry.h.lynn at gmail.com>
Sent: Tuesday, February 21, 2017 2:15 AM
To: Bassill, Nicholas
Cc: ncl-talk at ucar.edu
Subject: Re: [ncl-talk] New York Map issue(s)

Hi Bassill:

How do you mask the incorrect western boundary?

Barry

On Mon, Feb 20, 2017 at 4:57 PM, Bassill, Nicholas <nbassill at albany.edu<mailto:nbassill at albany.edu>> wrote:

Hi Rick,
    Thanks for the reply. I guess I must have missed that masking doesn't work with the high-res datasets, so sorry about that.

I've played around with shapefiles a little, but in our case we're interested in making some production-quality images pretty much in real-time, so the issue of "missing" data near the state boundaries is kind of a deal-breaker. Since all we care about is plotting the data, I think the best bet for the moment is to mask with medium-res, and interpolate our data to the correct western NY boundary so that the incorrect portion does not plot. Something like this: http://www.atmos.albany.edu/facstaff/nbassill/live/regularmercator.png

Nick Bassill, PhD

Modeler & Meteorologist, New York State Mesonet

LC SB-28, 1400 Washington Ave.,

SUNY, University at Albany, NY 12222

(518) 442-6375<tel:(518)%20442-6375>

http://nysmesonet.org/

________________________________
From: Rick Brownrigg <brownrig at ucar.edu<mailto:brownrig at ucar.edu>>
Sent: Friday, February 17, 2017 5:24 PM
To: Bassill, Nicholas
Cc: ncl-talk at ucar.edu<mailto:ncl-talk at ucar.edu>
Subject: Re: [ncl-talk] New York Map issue(s)

Hi Nicholas,

Yes, you are right about the western border issue:  attached is a plot showing NCL's border (in white), and the Shapefile's border (in red).  (this map was very quickly put together, please ignore the lack of esthetics).  I'm not sure we can do anything about that in the short term.  I'll file a bug report.

As for the second issu, the docs do explicitly state that NCL's builtin masking functions do not work with the HighRes/RANGS map databases.

However, for both purposes, state boundaries and masking, you might want to consider using a shapefile as a source.  Check out the examples page for both a link to a good source of shapefiles, GADM, and for examples of how to use them to perform masking.

http://ncl.ucar.edu/Applications/shapefiles.shtml
NCL and Shapefiles<http://ncl.ucar.edu/Applications/shapefiles.shtml>
ncl.ucar.edu<http://ncl.ucar.edu>
Shapefiles. Shapefiles are a supported data format. in NCL, and hence can be read with addfile. Unlike other supported formats, however, a "shapefile" refers to a ...

Hope this helps...
Rick

On Fri, Feb 17, 2017 at 8:59 AM, Bassill, Nicholas <nbassill at albany.edu<mailto:nbassill at albany.edu>> wrote:

Hi All,
    New subscriber, so bear with me here. Two things - (1) a likely bug, and (2) a question. I'm using NCL 6.3.

(1) It appears that the state boundaries for New York are slightly off in the far western boundary. I'm attaching an image (NY.png) that plots the state of NY, but with data that is specifically limited by the *actual* western border to demonstrate this.

The relevant map settings are:

res at mpDataBaseVersion           = "Ncarg4_1"
res at mpDataSetName               = "Earth..4"
res at mpFillAreaSpecifiers        = (/"Land", "Land:North America:United States:Conterminous US:New York","Water"/)
res at mpSpecifiedFillColors       = (/"white","transparent",       "white"/)
res at mpInlandWaterFillColor      = 238
res at mpLandFillColor             = -1     ; transparent
res at mpOutlineOn                 = True
res at mpMaskOutlineSpecifiers =   (/"Land"/)
res at mpOutlineSpecifiers =   (/ "Land:North America:United States:Conterminous US:New York"/)
res at mpDataBaseVersion = "MediumRes"

(2) Partially based off of that, and in an effort to have a more detailed coastline, I decided to try the "HighRes" dataset. However, I am not able to successfully do any masking. In this case I want *only* a fill in the shape of NY. For this I'm attaching the dataset I'm using (currenttemp.dat), the script I'm using (temp.ncl, based largely on http://www.ncl.ucar.edu/Applications/Scripts/mask_8.ncl for the mask), and a sample image (current.png).

Any help with (2) would be greatly appreciated!

Nick Bassill, PhD

Modeler & Meteorologist, New York State Mesonet

LC SB-28, 1400 Washington Ave.,

SUNY, University at Albany, NY 12222

(518) 442-6375<tel:(518)%20442-6375>

http://nysmesonet.org/

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Barry H. Lynn, Ph.D
Senior Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
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