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Re: [ferret_users] listing with projected data



Hi Jagadish,
I think what you want is the SAMPLEXY_CURV function which lets you specify curvilinear data with its grid, and a set of points. The output is the variable at those points.

Ansley

jagadish karmacharya wrote:
Dear ferreters,
 
I have model output in rotated mercator projection.I can plot the figure and correctly overlay the boundaries using map projection information.But I have difficulty listing the data at a specific location.

To elaborate my problem I have attached two figures with land mask. Data is correctly plotted in fig 1 using map projection information(ie shade ta[l=6,d=1]*ocnmsk -273, x_page,y_page); but figure 2 is plotted without map projection information (ie shade ta[l=6,d=1]*ocnmsk-273).
To illustrate, let consider a inland water body (in pink color) over Tibet lying at 100 parallel (in figure 1). Unprojected map (figure 2) shows same spot at about 97.5E.

List command shows (ocnmsk is for masking  land points)

 
list/x=96:102/y=35:40 ta[l=6,d=1]*ocnmsk-273
             VARIABLE : TA[L=6,D=SRF2000AVG]*OCNMSK-273
             SUBSET   : 14 by 13 points (LONGITUDE-LATITUDE)
             TIME     : 01-DEC-2000 00:00
               95.82E 96.3E  96.77E 97.25E 97.72E 98.2E  98.67E 99.15E 99.62E 100.09E100.57E101.04E101.51E101.99E
                92     93     94     95     96     97     98     99    100    101    102    103    104    105
 40.19N / 98:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 39.76N / 97:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 39.34N / 96:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 38.91N / 95:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 38.48N / 94:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 38.05N / 93:   ....   ....   ....   ....  7.593   ....   ....   ....   ....   ....   ....   ....   ....   ....
 37.62N / 92:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 37.19N / 91:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 36.76N / 90:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 36.33N / 89:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 35.89N / 88:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 35.46N / 87:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
 35.02N / 86:   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....   ....
ie it list the coordinate of the grid as 97.72E, 38.05N (in agreement with its position with respect to unprojected map) but its actual position is along 100E ( as plotted in project map )

This implies that if I specify the true lat/long position of say a city in list command then the listed value displayed for projected data is not for that location but for another location shifted by some distance.This shift will consequently affect the Arial average over a region as well!
!for example in above case
!list/x=100/y=38.3 ta[l=6,d=1]*ocnmsk-273
!  VARIABLE : TA[L=6,D=SRF2000AVG]*OCNMSK-273
             LONGITUDE: 100.1E(100.1)
             LATITUDE : 38.5N
             TIME     : 01-DEC-2000 00:00
        ....
Now My question is: how to list data from map projected model output such that it corresponds to true lat/long position (as displayed in projected map) (ie is there equivalent qualifier for list command like x_page,y_page for contour in plotting projected map?)
May be I need to use function CURV_TO_RECT but I couldn't correctly grasp the idea from the appendix/mail archieves.
Thanking in advance!
Jagadish
 =========================
 My data="">
 sh d
 currently SET data sets:
    1> ../SRF2000AVG.nc
 name     title                             I         J         K         L
 UA       Anemom Zonal Winds               1:118     1:109     ...       1:12
 VA       Anemom Merid Winds               1:118     1:109     ...       1:12
 TA       Anemom Temp                      1:118     1:109     ...       1:12
 QA       Anemom Spec Humidity             1:118     1:109     ...       1:12

 sh grid ta
 GRID GLM1
 name       axis              # pts   start                end
 LON       LONGITUDE          118mi   52.372E(52.373)      108.09E(108.09)
 LAT       LATITUDE           109 i   2.378S               44.79N
 normal    Z
 TIME      TIME                12 i   15-JAN-2000 00:00    15-DEC-2000 00:00
 
 
 
 
 


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