The Glaciation model began as a single geological column, and then multiplied into 18 columns at 5º latitudes in the northern hemisphere, and has now become a polyhedral model with 80 triangular faces, 24 of them representing continents, and 56 oceans.
At present, it is intended to only use the 56 oceanic areas to initially find ocean air temperatures throughout the year. It is assumed that snow does not build up on the oceans, and so ocean albedo remains constant at about 0.1.
The remaining 24 continental column heat flows are then calculated at 1-day, 5-day, or 73-day intervals. As snow settles at high latitudes (usually when air temperatures fall below 0º C), the change of albedo is used to find new air temperatures and surface temperatures. And from this a new global mean air temperature can be found.
There is no attempt to model air movement (winds) but instead an Air Mixing Factor is used as an approximation. When Air Mixing Factor equals 0, there is assumed to be no air movement, and the air temperature at any location is whatever is calculated from sunshine, surface albedo, etc. If Air Mixing Factor equals 1, all regions are assumed to have the same global mean air temperature. Values between 0 and 1 are used to provide air temperatures between local air temperature and global mean air temperature.
With no Air Mixing, the regions behave independently from each other, with snow building up and melting at different rates.. When there is some degree of Air Mixing, the different regions tend to become entrained, and to grow and contract at the roughly the same rate.
The result, with an Air Mixing Factor of 0.25, is that there are cycles of glaciation followed by deglaciation at roughly 7,000 year intervals. Snow depth in metres is shown in each region.
The graph below shows air temperatures and surface rock temperatures in the triangular “Europe” region. And it also shows the number of glaciated regions::
This shows subglacial surface rock temperatures slowly rising during the glaciated period, and melting the overlying snow after about 7,000 years. During the brief interglacial period, subglacial surface rock temperatures rapidly fall back to a low level, eventually allowing snow to start settling again, and a new period of glaciation to commence.
The snowfall regime in this model is at present the same constant amount in every region, If air temperatures are above 0º C, the snow is assumed to fall as rain, and to run off the surface. Precipitation, as snow or water, continues throughout both glacial and interglacial periods, and is about 25 m every 300 years in order to not to have too many snow layers in the snow sheets.
In reality, terrestrial glacial cycles last about 100,000 years, with 10,000 year interglacials. It’s hoped that with improvements in the model, glaciation cycles can be extended.
This is a new model, that was only got working in January 2020, and needs to be further refined.
[Glaciation.java Source Code]
[y120k.hcm (standard continental geological column)]