Regridding 2-D lat/lons with the linint2 function

Hello,

I have two sea - ice models with limited domains and differing grids that I
will be using in a validation analysis. The model with the coarser grid is
an arctic cap model over the circumpolar region from 90 degrees_north down
to a latitude of 49 degrees_north. The dimensions of this arctic cap grid
are: [ lat | 120] x [ lon | 360]. Each latitude and longitude value per
grid cell is unique, in generalized curvilinear coordinates. This results
in a 2-D latitude array and a 2-D longitude array.

I'm wishing to regrid the aforementioned arctic cap model in a region that
overlaps with a higher-resolution model enveloping the Bering, Chukchi, and
Beaufort Seas. The regional model domain spans 45 to 75 degrees_north
latitude and 160 to 220 degrees_east longitude. The dimensions of the
regional grid over the region are: [lat | 876] x [lon | 751]. This grid is
rectangular and can be represented by 1-D latitude and longitudes arrays.

>From reading over the various regridding routines available through NCL,
I've determined that the linint2 function is appropriate and can handle
this transformation.

The code that I have started putting together for this task is as follows:

;**********************************************************************
; PIOMAS regridding script.
; - Regrid PIOMAS down to the ACNFS resolution.
;
; Created 01/17/2014
;**********************************************************************

load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/shea_util.ncl"

begin
; - - - Read in PIOMAS ice thickness climatology
ClimateFile = "1979-2000_PIOMAS_Climatology_.nc"
ClimatePath = "/Volumes/OLD_GREG/Research/Validation
Data/PIOMAS/Climatology/"
PIOMAS = addfile(ClimatePath + ClimateFile, "r")

; - - - Assign variables to file objects
hi = PIOMAS->hi(0,:,:)
lat = PIOMAS->lat(:,:)
lon = PIOMAS->lon(:,:)

printVarSummary(hi)
printVarSummary(lat)
printVarSummary(lon)

; - - - Create new grid dimensions to match ACNFS
minlon = 160
maxlon = 220
lonnum = 751
minlat = 40
maxlat = 75
latnum = 876

newlat = fspan(minlat, maxlat, latnum)
newlon = fspan(minlon, maxlon, lonnum)

; - - - Regrid with linint2 function
new_hi = linint2(lon,lat, hi, False, newlon, newlat,0)

end

The variable summaries and error message that I receive from this code is
this:

Variable: hi

Type: double

Total Size: 345600 bytes

            43200 values

Number of Dimensions: 2

Dimensions and sizes: [lat | 120] x [lon | 360]

Coordinates:

Number Of Attributes: 5

  time : 0

  standard_name : sea_ice_thickness

  units : m

  _FillValue : -9999

  missing_value : -9999

Variable: lat

Type: double

Total Size: 345600 bytes

            43200 values

Number of Dimensions: 2

Dimensions and sizes: [lat | 120] x [lon | 360]

Coordinates:

Number Of Attributes: 3

  standard_name : latitude

  units : degrees_north

  axis : Y

Variable: lon

Type: double

Total Size: 345600 bytes

            43200 values

Number of Dimensions: 2

Dimensions and sizes: [lat | 120] x [lon | 360]

Coordinates:

Number Of Attributes: 3

  standard_name : longitude

  units : degrees_east

  axis : X

fatal:linint2: If xi is not one-dimensional, then it must have one less
dimension than fi

Two questions here:
1) Why is there no list of coordinate variables and values after
"Coordinates:"? - Does this have something to do with the 2-D latitude and
longitude arrays?

2) How do I address the fatal error here? My first guess was to change
dimension of my ice thickness variable, hi, to [time | 366] x [lat | 120] x
[lon | 360] instead of bringing in one slice along the time dimension. I
did this by changing the line of code that assigned my ice thickness data.

old: hi = PIOMAS->hi(0,:,:)
new: hi = PIOMAS->hi

This then resulted in a new fatal error stating:

fatal:linint2: If xi is not one-dimensional, then its leftmost dimensions
must be the same as the leftmost dimensions of fi

This error I am not quite able to interoperate. It seems that I need to
switch the ordering of my array to lon x time x lat, which sounds
unreasonable.

Thank you for the help,
Greg

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
- - - - - - - -

Gregory J. Deemer
Graduate Research Assistant
Department of Atmospheric Sciences
University of Alaska Fairbanks
IARC 338K
Office: (907) 474-5430
Cell: (907) 750-1063

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Sat Jan 18 18:48:58 2014