_Frazil.dox

1/*! \page Frazil_Ice Frazil Ice Formation

2

3\section section_frazil Frazil Ice Formation

4

5Frazil ice forms in the model when the in situ temperature drops below

6the local freezing point, taking into account the in situ salinity and

7pressure. Starting at the bottom and working up through the water column,

8if the water is below freezing, set it to freezing and add the heat

9required to the heat deficit. If the water above is warmer than freezing,

10use that heat to take away the heat deficit and to cool the water. If

11you get all the way to the surface with a heat deficit, that quantity

12is passed to the ice model as a heat flux it will need to provide to

13the ocean.

14

15The local freezing point code is provided by the equation of state being

16used by MOM6. See \ref section_TFREEZE for the MOM6 options.

17

18The salinity is adjusted only at the surface when frazil ice is

19formed. This happens when the ice model creates ice with the heat deficit,

20taking salt out of the surface waters. We inherit this behavior from

21older versions of MOM, but the effect of not adjusting the in situ

22salinity is thought to be small.

23

24Note that versions simply whisking all the heat deficit to the surface

25without checking for warm water above tended to produce rapidly-melting

26ice floes in warm waters. This was deemed unphysical and was corrected.

27

28A similar process that we are also omitting is the formation of salt

29crystals when the salinity becomes too high. The salt crystals should

30form and sink, leaving a layer on the bed that will be diluted when the

31salinity drops again. This process can be seen in a lake in Death Valley.

32

33*/