Quadratic solution error: b^2 -4ac is negative

[syang]

Dear all,

I successfully run the case I2000CLm50BgcCruGs with my own forcing data (0.05x0.05 degree, year 2000-2018) and surface data with -crop mode. However, when I do the spin-up with crop mode for 100 years, an error called "quadratic solution error:b^2 -4ac is negative" showed up when the model run to year 2014. I would like to know how come this error show up here? Is that because of my forcing data? and what does b and a,c refer to?

I attached the cesm.log, atm.log, lnd.log below.

I really appreciate it if anyone can help me with this. THANKS!!!

 

[oleson]

a, b, and c are the terms in the quadratic equation for stomatal resistance. See equation 2.9.26 in the CLM technical note:

2.9. Stomatal Resistance and Photosynthesis — ctsm CTSM master documentation

If you haven't made any other changes to the model then perhaps the forcing data is the culprit. We haven't come across any errors like this in the standard model with standard forcing for quite a while.