This is Megan Essig of U Nebraska Lincoln. Collaboration between Ohio State and U Nebraska. The start of glaciation she is talking about 120k years ago. Cooling at this time. Took about 25k years. She is trying to generate perennial snow fields. Paleo Data is scarce. LGI caused by CO2 reduction & methane reduction. Milkanovitch too. Cool summers and cold , wet winters.
They ran this for the 115k years ago. 2 runs. Only changed/reduced the CO2. no change in methane. 2nd run close to ice core values for CO2. 1/2 methane. Dramatic temperature changes in 50 years (!) to get the equilibrium. Compared to NCAR pre industrial simulations. Cooling is mostly in northern hemisphere. Summer CO2 and orbital params work together to cause cooling. During winter, cooling happens, but through sea ice. Second run still have cooling in summer and less in winter. The southern hemisphere doesn't cool constantly! AH HA moment! Cool temperatures during the summer in the northern hemisphere, hitting freezing at times.
Snow build up started in Alaska in the model. Canadian archipelago has snow build up as well. Ditto in Scandinavia and Russia. Less support for the first, but the other two matches rl big time. Massive increase in the sea ice in the northern hemisphere. No so for southern hemisphere (!) even a slight decrease.
Prelim results. perennial snow fields do mostly match the geological record. Very sparse geological data though. Greenland ice change not very good in helping: too much disturbance and too few going back that age. Antarctic better, but coarser. Ocean drilling spotty.
Sim seems to be working pretty well for as far as they have done. Seems to match well, except Scandinavian (a little too little) and Alaska (controversial, very). Now working on sensitivity runs.
They ran this for the 115k years ago. 2 runs. Only changed/reduced the CO2. no change in methane. 2nd run close to ice core values for CO2. 1/2 methane. Dramatic temperature changes in 50 years (!) to get the equilibrium. Compared to NCAR pre industrial simulations. Cooling is mostly in northern hemisphere. Summer CO2 and orbital params work together to cause cooling. During winter, cooling happens, but through sea ice. Second run still have cooling in summer and less in winter. The southern hemisphere doesn't cool constantly! AH HA moment! Cool temperatures during the summer in the northern hemisphere, hitting freezing at times.
Snow build up started in Alaska in the model. Canadian archipelago has snow build up as well. Ditto in Scandinavia and Russia. Less support for the first, but the other two matches rl big time. Massive increase in the sea ice in the northern hemisphere. No so for southern hemisphere (!) even a slight decrease.
Prelim results. perennial snow fields do mostly match the geological record. Very sparse geological data though. Greenland ice change not very good in helping: too much disturbance and too few going back that age. Antarctic better, but coarser. Ocean drilling spotty.
Sim seems to be working pretty well for as far as they have done. Seems to match well, except Scandinavian (a little too little) and Alaska (controversial, very). Now working on sensitivity runs.
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