srflx in bulk_flux.F

General scientific issues regarding ROMS

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pwallhead
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Joined: Fri Jan 17, 2014 7:28 pm
Location: Norwegian Institute of Water Research

srflx in bulk_flux.F

#1 Post by pwallhead » Thu Dec 20, 2018 8:21 pm

I have a few questions about the Hedstrom code, perhaps someone can help me. Apologies if I missed something obvious:

1) It seems that ice does not affect the skin heating (SRad). Why not?

2) It seems that the ice/snow albedo is used to correct the shortwave entering the ice, but not the shortwave entering the water (srflx) after passing through the ice. In my Hedstrom code from last year, srflx is only corrected for water albedo and ice attenuation, not the ice albedo. However I see that in the latest Hedstrom code on Github, it looks like srflx is only corrected for ice attenuation if ICE_BIO is defined, otherwise there is a new variable "SW_thru_ice" that is corrected for ice albedo and ice attenuation. But don't we need to correct srflx for (ice albedo + ice attenuation + water albedo) when using it in heat budgets and (if applicable) for biological models?

3) It seems that the cloudiness/sun angle corrected water albedo (cawdir) is only available if ALBEDO_CLOUD is activated. This seems a shame because I understand that such corrections can be the difference between 6% (low latitudes and/or cloudy sky) and up to 20% for a sunny day at low sun angle (Mobley and Boss, 2012). Maybe the direct/diffuse model used in cawdir_eval.F can account for that (I hope). The effect in ALBEDO_CURVE seems far too weak to account for non-cloudy days at high latitudes. But I don't necessarily want to resort to astronomical formula + empirical cloud correction to set the surface downwelling shortwave (ANA_SRFLUX + ALBEDO_CLOUD). For that I would prefer a reanalysis product, averaged over 1 day, with a diurnal cycle imposed (DIURNAL_SRFLUX). But in that case, I can't use cawdir because it requires ALBEDO_CLOUD. A dilemma.

Cheers
Phil

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