[ncl-talk] plot spatial distribution of BELD3 data, proj-provided lat/lon is good enough!
Rick Brownrigg
brownrig at ucar.edu
Thu Feb 7 13:46:02 MST 2019
I'm not sure I understand this question. Are you talking about regridding
the data so that it is on the same grid as the WRF data? NCL's ESMF
regridding tools should do the job for you. I'm not completely familiar
with them, but I suspect your input grid would have to be in geographical
coordinates. This gets tricky -- the projected coordinates are not explicit
in your file -- they are implied by an origin (in meters) and by a delta as
one steps across rows/columns. The corresponding geographical coords
would be curvilinear due to the Lambert projection, and these would need to
be computed and stored explicitly in the file before the ESMF gridding
could be applied. Software like ArcGIS *might* be able to help you with
the first step -- ArcGIS does read and write NetCDF.
I unfortunately don't know all the steps offhand -- it would take some
experimentation to find out what works :-/
Rick
On Thu, Feb 7, 2019 at 9:16 AM xiaoming Hu <yuanfangcan at hotmail.com> wrote:
> Rick
>
> Now I can plot correctly. Another question, how can I interpolate
> this dataset to other domains, for example WRF domain with lat2d/lon2d?
>
> Thanks a lot!
> Xiaoming
>
> ------------------------------
> *From:* ncl-talk <ncl-talk-bounces at ucar.edu> on behalf of xiaoming Hu <
> yuanfangcan at hotmail.com>
> *Sent:* Thursday, February 7, 2019 10:07 AM
> *To:* Rick Brownrigg; Hu, Xiaoming; Ncl-talk
> *Subject:* Re: [ncl-talk] plot spatial distribution of BELD3 data,
> proj-provided lat/lon is good enough!
>
> Rick
> Thank you so much! using the lower-left corner of -102.7/26.2, I am
> able to get the following figure, which I believe it is good enough!
> Nice Proj4 command! I tried on my machine, why do I get:
> $ proj +proj=lcc +lon_0=-90 +lat_0=40 +lat_1=30 +lat_2=60
> Rel. 4.9.1, 04 March 2015
> <proj>:
> projection initialization failure
> cause: major axis or radius = 0 or not given
> program abnormally terminated
> $ invproj +proj=lcc +lat_0=40 +lat_1=30 +lat_2=60 +lon_0=-90 -f "%.6f"
> Rel. 4.9.1, 04 March 2015
> <invproj>:
> projection initialization failure
> cause: major axis or radius = 0 or not given
> program abnormally terminated
>
> Thanks a lot!
> Xiaoming
>
>
> ------------------------------
> *From:* ncl-talk <ncl-talk-bounces at ucar.edu> on behalf of Rick Brownrigg <
> brownrig at ucar.edu>
> *Sent:* Thursday, February 7, 2019 9:41 AM
> *To:* Hu, Xiaoming; Ncl-talk
> *Subject:* Re: [ncl-talk] plot spatial distribution of BELD3 data, NetCDF
> data online
>
> Hi Xiaoming,
>
> Please let's keep this conversation on the ncl_talk, unless we really need
> to take it offline.
>
> Are you familiar with Proj4? Playing around with that, I tried:
>
> $ proj +proj=lcc +lon_0=-90 +lat_0=40 +lat_1=30 +lat_2=60
> -90 40 <---input
> 0.00 0.00 <----returned value
>
> This is a specification for a lambert conformal projection, with
> parameters:
> +lon_0=-90 longitude at center of projection
> +lat_0=40 latitude at center of projection
> +lat_1=30 1st standard parallel
> +lat_2=60 2nd standard parallel
>
> I enter the lon/lat pair -90 40 and get back 0 0 in units of meters,
> which checks out as the center of the projection.
>
> So, the inverse "de-projection" using the XORG/YORG values in your file
> yields:
>
> $ invproj +proj=lcc +lat_0=40 +lat_1=30 +lat_2=60 +lon_0=-90 -f "%.6f"
> -1296000 -1404000 <---- input
> -102.797916 26.266793 <---returned value
>
> Which I can believe -102.7/26.2 is the lower-left corner of tile #9, just
> eyeing the tilemap
>
> That all said, I'm still not certain you are going to get good alignment
> across your area-of-interest just by specifying LL/UR corners, due to the
> distortion inherent to the lamber conformal. If you find that to be the
> case, the "native grids" approach I mentioned previously may be required.
>
> Hope that helps...
> Rick
>
>
>
> On Thu, Feb 7, 2019 at 7:48 AM Hu, Xiaoming <xhu at ou.edu> wrote:
>
> Rick
>
> Thanks for your reply, I think I agree with all your interpretation.
>
> I tried to plot Juniper for tile 9 in this map:
> https://www.cmascenter.org/sa-tools/documentation/4.2/html/smoke_bio_inputs.html
> using
> http://www.caps.ou.edu/micronet/temp/forJianPing/plot_xhu_BELD3_Juniper.ncl
> The data is at
> http://www.caps.ou.edu/micronet/temp/forJianPing/b3_a.tile9.nzero.ncf
>
> Based on my current technique, I need
> ; res at mpLeftCornerLatF = lat2d(0,0)
> ; res at mpLeftCornerLonF = lon2d(0,0)
> to plot accurately to match tile 9 in
> https://www.cmascenter.org/sa-tools/documentation/4.2/html/smoke_bio_inputs.html
>
> I wonder if you have a solution.
>
> I am ccing to Dennis if he'd like to give it a try.
>
> Thanks a lot
> Xiaoming
>
> On 2/7/19 8:32 AM, Rick Brownrigg wrote:
>
> Hi Xiaoming,
>
> Yes, NCL could interpret this -- in principle -- but not without more
> information. The data appear to be in a projected coordinate space. See
> the examples at
>
> http://ncl.ucar.edu/Applications/native.shtml
> <https://urldefense.proofpoint.com/v2/url?u=http-3A__ncl.ucar.edu_Applications_native.shtml&d=DwMFaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=W32uvgk4VvmL2B6mi-37Lg&m=Rm0xpdrfxUY-YcoOdw7qGfGdEQxejDWnG_-7sJ75n0k&s=n80Mqz4HlpboRb4qhkfzNfZbPlcC7HtYajvc66OEtFA&e=>
>
> The precise cartographic projection parameters are not immediately evident
> from the metadata given above, although we can make some guesses (it would
> be better to know for certain!).
>
> These parameters:
> :XCENT = -90. ;
> :YCENT = 40. ;
> :XORIG = -1296000. ;
> :YORIG = -1404000. ;
> :XCELL = 1000. ;
> :YCELL = 1000. ;
>
> XCELL/YCELL affirm the data are at 1 1km spacing. The XCENT/YCENT and
> XORIG/YORIG give the correspondence between the projected and geographical
> spaces for the geographical location 90W/40N, a central location in North
> America.
>
> These parameters:
>
> :P_ALP = 30. ;
> :P_BET = 60. ;
> :P_GAM = -90. ;
>
> Looking at some of the maps at the EPA site you reference, these could
> very well be projection parameters for a Lambert Conformal projection, with
> P_ALP/P_BET being more commonly referred to as "standard parallels" and
> P_GAM being the "standard meridian". The values look quite right for North
> America, but again all of this is conjecture.
>
> Hope this helps...
> Rick
>
> On Thu, Feb 7, 2019 at 5:08 AM xiaoming Hu <yuanfangcan at hotmail.com>
> wrote:
>
> I try to plot spatial distribution of BELD data from
> https://www.epa.gov/air-emissions-modeling/biogenic-emissions-landuse-database-version-3-beld3
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.epa.gov_air-2Demissions-2Dmodeling_biogenic-2Demissions-2Dlanduse-2Ddatabase-2Dversion-2D3-2Dbeld3&d=DwMFaQ&c=qKdtBuuu6dQK9MsRUVJ2DPXW6oayO8fu4TfEHS8sGNk&r=W32uvgk4VvmL2B6mi-37Lg&m=Rm0xpdrfxUY-YcoOdw7qGfGdEQxejDWnG_-7sJ75n0k&s=Ye9wZ_kUZae0pNvfQ_2QtXtPV5s87-kpy-5IXyYyuqM&e=>
>
> the NetCDF files don't provide latitude/longitude, only with information of
> :P_ALP = 30. ;
> :P_BET = 60. ;
> :P_GAM = -90. ;
> :XCENT = -90. ;
> :YCENT = 40. ;
> :XORIG = -1296000. ;
> :YORIG = -1404000. ;
> :XCELL = 1000. ;
> :YCELL = 1000. ;
> :VGTYP = -9999 ;
> :VGTOP = -9.e+36f ;
> :VGLVLS = 0.f, 0.f ;
> :GDNAM = "BELD3_TILE9 " ;
>
> It there anyway NCL could interpret this ?
>
> Thanks
> Xiaoming
>
>
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