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Re: [ferret_users] Projected data



Hi Tony,
You can plot this data with the curvilinear forms of the plotting commands. The variables LONGITUDE and LATITUDE are 2-dimensional curvilinear coordinate fields, so you can use this command to get the correct longitude and latitude labellings

fill temperature, longitude, latitude

The fact that the SHOW GRID has the axes of the variables like temperature labeled as longitude and latitude is misleading; the axes are just indices 1 to 792 and the coordinates are in the curvilinear coordinate variables. Look at the SHOW GRID output:

yes? show grid temperature
GRID GPI1
name axis # pts start end
X LONGITUDE 792 r 1E 72E(792)
Y LATITUDE 792 r 1N 792N
...

It has a latitude 1 N to 792N, and longitude 1 to 792 as well, which is clearly incorrect. The curvilinear graphics commands require that the X and Y axes of the variable field such as TEMPERATURE or SALINITY, and the X and Y axes of the coordinates LONGITUDE and LATITUDE agree and then it can draw the plot.

Ansley


Tony Jolibois wrote:

Hi all,

I have to plot some stereographic projected data (latitude 55N to 90N, projected in the netCDF), and I don't know how I can use it with longitude and latitude (instead of x and y).

Here is the ferret command I use to produce the plot attached. The axes are not good and I can not fill the land mask...

[console@rdp1-jaune arc]$ ferret -nojnl
NOAA/PMEL TMAP
FERRET v5.50
Linux 2.4.3-12smp - 01/15/03
12-Oct-05 09:40
yes? use mercatorPsy3v1R1v_arc_mean_20050923_R20051005.nc
yes? show data
currently SET data sets:
1> ./mercatorPsy3v1R1v_arc_mean_20050923_R20051005.nc (default)
name title I J K L
TEMPERATURE
temperature 1:792 1:792 1:43 ...
SALINITY salinity 1:792 1:792 1:43 ...
U zonal velocity 1:792 1:792 1:43 ...
V meridian velocity 1:792 1:792 1:43 ...
KZ vertical eddy diffusivity 1:792 1:792 1:43 ...
LONGITUDE
longitude 1:792 1:792 ... ...
LATITUDE latitude 1:792 1:792 ... ...
SSH sea surface height 1:792 1:792 ... ...
MLD temperature ocean mixed layer t 1:792 1:792 ... ...
MLP density ocean mixed layer thick 1:792 1:792 ... ...
TAUX windstress eastward Tx componen 1:792 1:792 ... ...
TAUY windstress northward Ty compone 1:792 1:792 ... ...
QTOT total net heat flux 1:792 1:792 ... ...
EMP water flux 1:792 1:792 ... ...
QSR surface downward solar heat flu 1:792 1:792 ... ...
yes? show grid temperature
GRID GPI1
name axis # pts start end
X LONGITUDE 792 r 1E 72E(792)
Y LATITUDE 792 r 1N 792N
DEPTH DEPTH (m) 43 i- 0 5500
normal T
yes? set region/x=1:792/y=1:792/z=0
yes? fill/levels=(-3,15,0.2) temperature

Best regards,
Tony

--
Tony Jolibois

CLS - Direction Océanographie Spatiale
8-10 rue hermès - 31520 Ramonville Saint-Agne
tjolibois@cls.fr

Tél : +33 (0) 561 393 797
Fax : +33 (0) 561 393 782


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