Uday and others:

PAR is not a required input for the calculation of PET based on
FAO-Penman.  However, you will need recorded data for TDEW and WINDSP.  If
you do not have this information, the model will make some assumptions with
respect to the values for these inputs.  I would not recommend that you
FAO-Penman unless you have the required input data.

Kind regards,

Gerrit Hoogenboom


At 11:30 PM 5/31/2002 +0530, you wrote:
>Dear Members,
>
>During simulation of DSSAT3.5 I am using option of "FAO-Penman " under
>"Simulation control: Methods, Evaporation"  instead of Ritchie modified
>Priestly Taylor. I think my weather file should have input values for
>TDEW, PAR in addition to SRAD, TMAX, TMIN, RAIN and  WINDSP.
>
>In the absence of measured data for Dew Point Temperature(including dry
>bulb and wet bulb temp), is it possible to calculate Dew Point
>Temperature(TDEW) from the measured values RH(Min & Max), Temp(Min & Max)
>and psycrometry.
>
>What is PAR (Photosynthetic active radiation) and how should I get these
>values?
>
>I will appreciate if someone suggests.
>
>Thanks,
>
>Uday Khodke