[MITgcm-support] sea ice stresses multiplied by concentration or not?

[Manucharyan, Georgy E. (Georgy)]

Hi everyone,

A reviewer pointed out to me that, by default, the sea ice stresses are not multiplied by the sea ice concentration, i.e.

m_ice* Du/Dt = … + \tau, where  m_ice=h*c (sea ice mass per unit area) and  \tau=rho*Cd* (u_i-u_o)^2 (not multiplied by c!)

Documentation for the SEAICE package seems to state the same: http://mitgcm.org/public/r2_manual/latest/online_documents/node254.html#SECTION00762430000000000000

In this case, the ocean and atmosphere stresses exerted on the sea ice do not depend on its concentration, which seems physically wrong. At the same time the manual suggests that the ocean stress exerted by the sea ice is multiplied by the sea ice concentration (which does make sense). Since stress is a continuous quantity the ice-ocean stress =-ocean-ice stress and it seems wrong to have only one of these proportional to the concentration. Is this correct that the SEAICE package does not multiply the stresses by the concentration, or is there a bug in documentation or perhaps my interpretation of the sea ice equations is off?

The reviewer also implied that there is frag that one needs to explicitly set in order for the stresses to be multiplied by the concentration. Could someone point me to that flag?

Thanks for your help,
Georgy


-----------------------------
Georgy Manucharyan,
Stanback Postdoctoral Scholar,
Environmental Science and Engineering,
California Institute of Technology,
MS 131-24, 1200 California Blvd,
Pasadena, CA, 91125

Office: L+R, Room 226; Tel: (626) 395-8715
Web: http://www.its.caltech.edu/~gmanuch

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