Units Conversion

I have field with the function type (time -> (Temperature, Precipatation))
Temperature is loaded in celcius, and Precipitation is in millimeters.
I have tried experimenting with adding two fields of this type together and
have found that the Temperature gets converted to Kelvin.
Is it possible to convert all the Temperatures in the result field to Celcius
again? and how do I go about it?

Thanks in advance.


-----------------------------------------------------
Cameron Shepherdley <C.Shepherdley@xxxxxxxxxx>
AutoTAF Project Developer 
Bureau of Meteorology, Melbourne, VIC 3001, Australia
Telephone: +613 9669 4652