Kirk,
my approach is very simple, I've taken the Biome-BGC code and I've modified the initialization part to conform to GRASS module style. The other thing I've done is to call the calculation code part from inside a for cicle on rows and columns. How to create a module? I downloaded from GRASS web site the Programmer's Manual, but the thing that helped me more was to have a look at how other modules are made. I warn you that I'm not so good in writing C code so I find very useful to have examples.
I simplified Biome-BGC in the initialization part and I took away the possibility to do spin-up simulations. I didn't do modifications to the calculation algorithms so at the end I didn't simplify it very much. Now the module works, or better, I think it works because I need to find the appropriate initialization parameters. I can tell you that at this moment it works only with regions smaller than 16x16 pixels and it takes few seconds to do the job. For bigger regions I get error messages like "too many raster open" or for much bigger region "segmentation fault". As you can see I have still some problems.
I hope to have been helpful.
Best Regards,
Chiara
Da: Kirk R. Wythers <kwythers@umn.edu>
Data: Mon, 2 Feb 2004 09:56:02 -0600
A: "chiara.sboarina@katamail.com" <chiara.sboarina@katamail.com>
Oggetto: Re: BGC GRASS module
Chiara,
I'd be very interested in learning more about your approach (right down
to the nitty gritty details). I have a big leaf ecosystem model with
which I would like to do something similar. Is there any documentation
(anywhere) that describes the process of "module" creation for grass?
If so where?
How much did you simplify Biome-BGC in your module? and if you have it
working, can you give an estimate on process time based on a number of
cells that you are analyzing?
Best Regards,
Kirk
On Jan 21, 2004, at 2:04 AM, chiara.sboarina@katamail.com wrote:
Kirk,
you are right I modified Biome-BGC of Running et al. . I simplified it
a lot because my aim is to calculate the amount of C stocked in a year
by forest of a region. So I chose as out put only totalc, vegc, soilc
and litterc. I removed the spinup simulation not to weight down the
module so the user must have many initialization parameters. Now I'm
testing the module to see if it works. If you need more informations
just tell me and I will try to answer you.
Bye
Chiara
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Kirk R. Wythers tel: 612.625.2261
Dept. of Forest Resources fax: 612.625.5212
University of Minnesota email: kwythers@umn.edu
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