Eref and CMD are NaN above ~68N latitude

[cmahony]

@kdaust i'm out of time but this needs an urgent fix. can you look into this?

[kdaust]

Very weird. Yep will do

[cmahony]

@kdaust, i'm taking a quick look at the calc_Eref script. hopefully i can take the troubleshooting a bit further.

[cmahony]

This is an artefact of the Hargreaves Eref equation.
line 64 in calc_Eref_CMD.R OM <- -atan(Z / sqrt(-Z * Z + 1)) + pi / 2 is solely related to latitude; the value of -Z * Z + 1 becomes negative above a latitude of ~68N.
i checked hargreaves 1985 and our script is correct.
makes rough sense that Hargreave's Eref wouldn't be valid at high elevation.
i havent' checked the behaviour in climateNA but i'll figure out what we should replace the NaNs with.
@kdaust no need for action on your part at this point

[carloscarroll]

Eref values from ClimateNA seem valid even above 68 degrees (ie not 0, <0, or NaN). (see attached arbitrary example from CNRM-ESM2-1_ssp585_2071).