[ferret_users] plotting along-track sea level anomaly

[Prasad Thoppil <thoppil@xxxxxxxxxxxxxxx>]

Hi

I have downloaded along-track sea level anomalies from
ftp://ftp.cls.fr/pub/oceano/AVISO/SSH/duacs/global/nrt/sla/en/

The data file looks something like this:

currently SET data sets:
res_oer_en_20346_20364.nc  (default)
name     title                             I         J         K         L
DELTAT   Time gap between two measuremen  ...       ...       ...       ...
NBPOINTS Number of measurements for each  ...       ...       ... 
1:472
CYCLES   Cycle numbers for each pass      1:1       ...       ... 
1:472
LONGITUDES
         Longitude of each measurement    1:185877  ...       ...       ...
LATITUDES
         Latitude of each measurement     1:185877  ...       ...       ...
BEGINDATES
         Date of first measurement for e  1:1       ...       ... 
 1:472
DATAINDEXES
         Data index in theoretical pass   1:185877  ...       ...       ...
SLA      Sea Level Anomaly                1:1       1:185877  ...       ...


I want to plot SLA over a small region say 50E-70E, 0-10N using go 
polymark script. Here is what I used

plot/vs/hlim=50:70/vlim=0:10 LONGITUDES,latitudes
go polymark polygon/hlim=50:70/vlim=0-10N/ov longitudes latitudes sla square

then it gives me "  Too much polygon data to plot at once"

No plot is generated. I use v5.8 Linux(g77) ferret version.

Any help would be appreciated.

Thanks,

Prasad