[ncl-talk] Subsetting a circle of data

[Jake Huff]

Hello,

I am working on reading in precipitation data that corresponds to a radius
of a 500km around a tropical cyclone. I have a variable that contains
precipitation over the Eastern US and into the Atlantic Ocean. Below is
some of my code.

;Snippet of code

obtracks = addfile("Allstorms.ibtracs_wmo.v03r05.nc","r") ;Read in IBTrACS

lat_wmo = short2flt(obtracks->lat_wmo) ;(storm,time)

lon_wmo = short2flt(obtracks->lon_wmo) ;(storm,time)



; Read in Precipitation Files


precipfile = addfile("TRMMdata.nc","r")

AvgYearlyTRMM = precipfile->AvgYearlyTRMM   ;(time,lat,lon)

clat = new(61,float)

clon = new(61,float)

radius = 5.0


lat_location = lat_wmo(0,0) ; location for 1st TC and time step

lon_location = lon_wmo(0,0) ; location for 1st TC and time step

nggcog(lat_location,lon_location,radius,clat,clon) ;calculate circle


min_lat = min(clat)

max_lat = max(clat)

min_lon = min(clon)

max_lon = max(clon)


newTRMMyearly = AvgYearlyTRMM(0,{min_lat:max_lat},{min_lon:max_lon}) ;reads
in square of data


So the above reads in the data correctly but gives me a square of data
instead of the circle that I create with the nggcog function above since
I'm using the min/max of the circle.



I was wanting to know if anyone knows of a way to read in the clat/clon
from my AvgYearlyTRMM dataset. I have attempted some indexing of the
clat/clon varibles to put the index into AvgYearlyTRMM, but then the
lat/lon arrays are no longer monotonic so trying to use gsn_csm_contour_map
doesn't work.


Thanks for any help.

Jake
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