From: Dennis Shea <shea_at_nyahnyahspammersnyahnyah>

Date: Wed Mar 27 2013 - 14:00:12 MDT

Date: Wed Mar 27 2013 - 14:00:12 MDT

Try the following.

http://www.ncl.ucar.edu/Document/Functions/Built-in/gc_qarea.shtml

There are a few points on the grid that have repetitve values but

at other location, I thin the following works ok.

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

re = 6.37122e06 ; [m] average radius of earth

re2 = re^2

diri = "./"

fili = "sic_OImon_MRI-CGCM3_historical_r1i1p1_185001-200512.nc"

f = addfile(diri+fili,"r")

sic = f->sic ; sic(time, rlat, rlon)

latv = f->lat_vertices ; latv(rlat, rlon, vertices)

lonv = f->lon_vertices ; lonv(rlat, rlon, vertices)

area = re2*gc_qarea(latv, lonv)

area!0 = latv!0

area!1 = latv!1

area@long_name = "area of grid cells"

area@units = "m^2"

printVarSummary(area)

print("area: min="+min(area)+" max="+max(area))

;if (any(isnan_ieee(area))) then

; value = 1.e20

; replace_ieeenan (area, value, 0)

; area@_FillValue = value

; printVarSummary(area)

; print("area: min="+min(area)+" max="+max(area))

;end if

On 03/27/2013 01:12 PM, Dennis Shea wrote:

*> Hi Tingting
*

*>
*

*> Can you please point me toward a dataset so I may look at it?
*

*> Ideally, the file would contain an area variable. For example,
*

*> the POP models have
*

*>
*

*> float TAREA(nlat, nlon) ;
*

*> TAREA:long_name = "area of T cells" ;
*

*> TAREA:units = "centimeter^2" ;
*

*> TAREA:coordinates = "TLONG TLAT" ;
*

*> TAREA:_FillValue = 9.96921e+36f ;
*

*> TAREA:missing_value = 9.96921e+36f ;
*

*>
*

*> Consider:
*

*>
*

*> x(time,nlat,nlon) [ dimension #s (0,1,2) ]
*

*>
*

*> A global weighted mean would be
*

*>
*

*> xAVG = dim_sum_n(x*conform(x,TAREA,(/1,2/)),0)/ sum(TAREA)
*

*>
*

*> Then xAVG(ntim)
*

*>
*

*> On 3/27/13 11:40 AM, tingting@ucar.edu wrote:
*

*>> Hello,
*

*>> I am doing the MRI-CGCM3 model output validation and need to calculate
*

*>> SIE(sea ice extent), the coordinates of MRI output are two-dimensional,
*

*>> while the NCL function(wgt_areasum2) seems to deal with data with regular
*

*>> coordinates, right?
*

*>> So,my question is that how to calculate the area sum? Or, do I need to
*

*>> regrid the MRI to regular-grid data?
*

*>> Thank you for any coming help in advance.
*

*>> Tingting
*

*>>
*

*>>
*

*>> _______________________________________________
*

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Received on Wed Mar 27 14:00:22 2013

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