>Date:  Mon, 9 Jun 1997 09:41:30 -1000
>From:  jess carl brown <[log in to unmask]>
>X-Sender: [log in to unmask]
>To:    [log in to unmask]
>Subject: CO2 (fwd)
>
>I sent this note originally to Gordon Tsuji. I would welcome any input
>from any source, however. Thanks. Jess Brown
>
>---------- Forwarded message ----------
>Date: Fri, 6 Jun 1997 11:53:31 -0500 (CDT)
>From: jess carl brown <[log in to unmask]>
>To: Gordon Tsuji <[log in to unmask]>
>Subject: CO2
>
>Hello again Mr. Imamura.  I have a couple questions
>about the CO2 component of the DSSAT v3 model. I have been simulating
>climate change scenarios for a sensitivity analysis (for maize). I have
>been looking at combinations of temperature increases (0, 2, & 4 degrees
>C), precipitation drops (-10, 20, 30, 40, & 50%), and increases in CO2
>(350, 550, 700). One strange result of all the runs has been that above
>550ppm CO2, maize yield is largely insensitive to temperature and precip.
>changes. For example, at 700 ppm CO2, maize yield is the same for a
>0% change in rain and a -40% change in rain. This is even the case for the
>unirrigated scenario. I
>was wondering if this was what you've found to be typical of any similar
>DSSAT output that you know of. Perhaps I am doing somethings wrong with
>the model. I've tried several things to make CO2 less dominant, but have
>been unsuccessful. I was also wondering what the CO2 component of the model
> was based on -- some type of regression analysis, etc. If you have any
>ideas, please let me know. Thanks very much.
>
>Sincerely,
>
>Jess Brown
>
>
>
Daniel Imamura                         Computer Specialist
University of Hawaii-Manoa             Email: [log in to unmask]
2500 Dole Street, Krauss Hall rm 118   Phone: (808)956-2713
Honolulu, Hawaii 96822                 http://everex.ibsnat.hawaii.edu