stomata resistance and solar zenith angle

[msulis]

Dear All,

I am experiencing some issue in running continental-scale simulations (approx. 6km resolution) across Europe (see attached plots). In particular, I am getting a weird pattern of the stomata resistance (both SHA and SUN components) during the sunrise and the sunset, with night-day switch across the domain. It seems that there is mismatch between the internally calculated solar zenith angle and the timing of the radiation forcing. Any feedback will be much appreciated. Thank you in advance!

Best,
Mauro

 

[oleson]

I guess I would suggest outputting some diurnal cycle output for incoming solar (FSDS), reflected solar (FSR), and the cosine of the solar zenith angle (COSZEN) and see how they are lining up. You might have to adjust your forcing data.

 

[nick]

[linking from this post]
Hi @msulis, did you get to the bottom of this? I'm seeing it as well in my global cases. @oleson I've looked at FSDS, FSR and COSZEN and they seem consistent at first glance (figs below). Looking at GSSUN evolve by time step, it does seem consistent with what @msulis says about these artefacts arising at sunset.

 

[oleson]

It doesn't look like gs_mol_sun (GSSUN) and gs_mol_sha (GSSHA) are being set at night in the code, so they are retaining the values from the last time step with sunlight. Perhaps they should be set to the Medlyn intercept value at night (minimum stomatal conductance).