Query on Sea Ice Heat Content

[srjocn@gmail_com]

Hi,

I would like to inquire about sea ice heat content per unit area (SIHC).
I obtained SIHC variable of CESM2-WACCM model output from CMIP6 data repository.
It would be a great help if you can share your comments on:

1) The significance of SIHC.
2) Is the variability of SIHC proportional to thickness variability.
3) When we estimate ocean heat content, we integrate over some specific
depth levels. However, here the ice pack (thickness) itself may vary
from grid to grid, so what are the things that we should be aware of
before deducing any information.
4) What are the impacts we can expect due to changes in heat content of
sea ice.

Thanks in advance,
Suraj

 

[dbailey]

The variable sihc is part of the SIMIP (CMIP) specification. That is, the majority of CMIP models should include this. Within CESM2-CICE, this is the sea ice enthalpy (qi) * sea ice volume (vice). The units should be J / m^2. One way to think about this is the energy needed to heat the sea ice to the salinity dependent melt point and then to change from solid to liquid. You can multiply by the grid cell area (tarea) to get the total J of heat content in the sea ice for each grid cell. That is about the extent (pun intended) of my knowledge on this. I would be curious to hear what you find in terms of CESM2 and other CMIP models for this quantity.

 

[srjocn@gmail_com]

Thank you for your reply. It was helpful.

We notice sea ice heat content being always negative is about -6 x10^8 in the Beaufort gyre and is -1.5 x 10^8 in the Barents Sea in March.
So my related query to this:

1. Should we interpret that a greater SIHC (i.e. less negative values) shows warming of ice and a tendency of greater melting?

2. Does zero value of SIHC indicates absence of sea ice ?

3. Is the unit of temperature used in the calculation of SIHC, degree Celsius or Kelvin?

 

[dbailey]

This quantity is always negative as it is considered a "heat potential". The more negative the value, the colder the ice is internally. A zero or missing value is absence of sea ice. Internally in the sea ice model we reference to Celsius. The conversion between SIHC and temperature requires the specific heat constant.