conversion from longitude to kilometres

[Basit Khan]

Hi there,
I want to plot a vertical cross section with height on y-axis and 
distance on x-axis. By default, GrADS prints longitudes on x-axis. I am 
just wondering if i can replace these longitudnal values with kilometres 
or grid point values without writing the conversion script.
Cheers,

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Basit A. Khan
PhD Candidate
Centre for Atmospheric Research
Department of Geography
University of Canterbury  Te Whare Wananga o Waitaha Private Bag 4800 
Christchurch 8020, New Zealand
Tel: (643) 364 2987 Ext. 3088
Fax: (643) 364 2907
bak41 at student.canterbury.ac.nz