There are fundamental problems with the Grenfell and Maykut formulation of surface transmission parameter in sea ice. Some of these issues are described in the publication of Lebrun et al (in press @JGR, available soon online)Lebrun_et_al_JGR22.pdf.
Part of these issues were identified during conversations with specialists in ice optics (namely Christian Katlein, AWI and Bonnie Light, APL, Marcel Babin, ULaval). Following these, we concluded that the formulation of GM77 should be replaced in the near future. 1) the relations were obtained from obsolete instruments, 2) the definitions of io are inconsistent with the model framework, 3) there are physical limitations, outlined in the paper - basically, the scheme as it is ignores snow, ponds and Chl-a, all important drivers of sea ice optics.
The paper of Lebrun proposes an updated framework for radiative transfer in sea ice, mostly based on a revision of attenuation and surface transmission coefficients, which were tuned to transmittance observations, based on a very large Arctic sea ice data set (350 records). The scheme is available in SI3 but not in his final version. First, the coefficients currently in the code for the "Lebrun" scheme are not up to date with the last version of the paper and should be updated from the latest version. Second, an issue when using this scheme has been reported by several groups (Paris, Reading) that surface melting is excessively reduced when using that scheme. This is an issue that should be analyzed. A ULaval student (Christophe Perron) will likely work on this in the course of his Phd studies during a stay at Locean.
Thanks for raising that issue and sorry it has not been better explained at an appropriate place. For these reasons (and possibly also that ice age is pretty ambiguous), I would not recommend to incorporate the FY/MY contrast in the current formulation of io.
Martin Vancoppenolle (80f9f8fc) at 14 May 08:36
Consider rafting in strength calculation
Martin Vancoppenolle (d30fcaab) at 13 May 14:39
No need to define rn_pe_rdg twice
Merci Guillaume!
yes go for it, there is an ambiguity we should clarify anyway
Closes #26
Martin Vancoppenolle (c6cc7a5d) at 04 Mar 08:33
Update icedyn_rhg_evp.F90
Martin Vancoppenolle (b6f56da1) at 04 Mar 08:30
miss lbclnk on zshear in EVP + _wp
miss lbclnk on zshear in EVP + _wp
miss lbclnk on zshear in EVP + _wp
Martin Vancoppenolle (14c4e8e1) at 03 Mar 16:10
Tentative numéro 2
Closes #22
Martin Vancoppenolle (2c2c8a48) at 24 Feb 17:00
Martin Vancoppenolle (14c4e8e1) at 24 Feb 16:57
Merge forge.nemo-ocean.eu:nemo/nemo into HEAD
... and 5 more commits
Martin Vancoppenolle (374b5442) at 24 Feb 16:10
Update icedyn_rhg_evp.F90
Closes #22
Martin Vancoppenolle (50847f11) at 23 Feb 16:07
ADD all files related to commit
Closes #22