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Re: How to draw data on multi-grid



Hi Zhi,
The 3-argument shade, fill, and contour commands can plot curvilinear data. If the curvilinear coordinate variables are geolon and geolat, and var is the field of values, then the syntax is

yes? use tripolar_data.nc
yes? shade var, geolon, geolat

See "curvilinear coordinates" in the Users Guide.

For your data in multiple files, you may be able to make a plot using overlays. If one file contained longitudes 0 to 180, and
another contains 181 to 360, for example, then,
yes? use file_1.nc
yes? shade/hlimits=0:360 var, geolon, geolat
yes? use file_2.nc
yes? shade/over/lev var, geolon, geolat

If there are discontinuous longitudes, then the SHADE command may scramble the plot. We are currently developing a SHADE/MOD curvilinear command, which will treat the longitudes as modulo coordinates. There is more development to do, to get truly modulo behavior from curviilnear coordinate data.


Zhi Liang wrote:

Hi,

I figured out why ferret can draw the graph of data from multi file. The reason is the axis data
of my files. The axis data is the index of the grid, not actual grid location. One reason is that
the axis grid is not the actual grid location when the grid is tripolar grid ( for same index j, latitude
may be different for some points and lontitude can be different for same index i). We want to push
user always to use the geographical grid to draw the graph. I don't know if ferret developer can
extend the ferret usage.

Thanks!

Zhi



Zhi Liang wrote:

Hi,

I have global data sets that are splitted into four files (the grid in each file is part of
the global grid). I want to plot the data in one picture using those four files (like using shade).
The grid is curvilinear. Is this possible?

Thanks!

Zhi








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