I try to increase convective precipitation in Grell scheme. According to Giorgi et al. (2012, 1993b), large value of Peff (the fraction of precipitation efficiency) leads to less precipitation. So I would like to decrease the value of Peff.

However, I could not find the parameter in the input namelist for Grell Cumulus scheme. 

I did a try to increase minimum/maximum shear effect  and minimum/maximum precipitation efficiency. But I could not see any significant increase in precipitation. (please see attached)

Could you please let me know how to increase convective precipitation in Grell scheme?

Thank you very much!

- Guangshan