Hi-
I think you have your I's and j's mixed here:
Yours:
print("Requested: (" + pointLat + "," + pointLon + "), got (" +
lat2d(ival,jval) + "," + lon2d(ival,jval) + ")")
Mine:
print("Requested: (" + pointLat + "," + pointLon + "), got (" +
lat2d(jval,ival)+","+lon2d(jval,ival)+")")
The compare you are doing is slightly different because the 2 functions are slightly different.
Jimmyc
On 3/3/10 3:07 PM, "Jeff Steward" <jeffsteward@gmail.com> wrote:
Hi,
I have a 25km/5km/1km nested WRF model with a Lambert conformal
mapping projection that I am working with. I am trying to find the
nearest grid point to a met tower that I have access to in order to
validate the model. I am using the NCL function wrf_user_ll_to_ij but
I am getting a result that is significantly different than I expect.
Am I doing something wrong or is there a bug?
(Note that I have also tried this with the wrf_ll_to_ij function but
get the same result).
--------------------
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRFUserARW.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/wrf/WRF_contributed.ncl"
begin
path_to_domain_3_output_file = ".........."
a = addfile(path_to_domain_3_output_file,"r")
lat2d = a->XLAT(0,:,:)
lon2d = a->XLONG(0,:,:)
opt = True
opt@returnInt = True
print(opt)
pointLon = -87.9949
pointLat = 41.7012
loc = wrf_user_ll_to_ij (a, pointLon, pointLat, opt )
ival = loc(0)
jval = loc(1)
print("i: " + ival + ", jval: " + jval)
print("Requested: (" + pointLat + "," + pointLon + "), got (" +
lat2d(ival,jval) + "," + lon2d(ival,jval) + ")")
ival2 = ival-6
jval2 = jval+4
print("Compare: (" + lat2d(ival2,jval2) + "," + lon2d(ival2,jval2) + ")")
end
--------------------
The result I get is:
--------------------
(0) i: 192, jval: 187
(0) Requested: (41.7012,-87.9949), got (41.76,-88.0333)
(0) Compare: (41.7014,-87.9899)
--------------------
Note that the first distance between the point I requested and the
point I received is is 7.2814 km while the distance between the
requested and comparison points is only 0.4162 km according to the
distance calculator found here:
http://jan.ucc.nau.edu/~cvm/latlongdist.html
I would expect to get the comparison values instead of the values I
received. Am I doing something wrong?
Best wishes,
Jeff
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Received on Wed Mar 3 16:17:54 2010
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