P1.84
Comparing the Antarctic bipolar seesaw under glacial and interglacial conditions
Katherine A. Pingree, Plymouth State University, Plymouth, NH; and C. Morrill
The National Center for Atmospheric Research's Community Climate System Model version 3 (CCSM3) was used to simulate and examine the 8.5 ka (interglacial time period) and 21 ka (Last Glacial Maximum) global climates following an influx of freshwater into the North Atlantic Ocean that compromised the thermohaline circulation. For both simulations, hosing was conducted by adding freshwater to the North Atlantic Ocean between 50°N and 70°N at a rate of 1 Sv (10E6 m^3/s) for 100 years which caused a significant reduction in the Atlantic Meridional Overturning Circulation. The 8.5 ka and 21 ka simulations were then allowed to recover for 300 years and 500 years, respectively, in order to see how the global climate responded and then recovered. To determine how the global climate changed due to the hosing, the end of the 100 years of hosing was compared to the control run (no hosing) at the end of the same 100 year interval. In this research, the two simulations were then compared and the two unique bipolar seesaw responses were studied in order to understand why the 21 ka signal was significantly stronger than the 8.5 ka signal in the Southern Ocean and Antarctica.
Two simulations run by the CCSM3 in which bipolar seesaws occurred showed differing strengths of the Antarctic warming despite the bipolar seesaws being initiated by identical freshwater influxes into the North Atlantic. Simulations of 21 ka (glacial conditions) and 8.5 ka (interglacial conditions) both saw bipolar seesaws resulting from 100 years of hosing at a rate of 1 Sv, however, the 21 ka simulation saw a significantly stronger warming in the Antarctic in comparison to the 8.5 ka simulation. This research studied the difference in strength of the Antarctic bipolar seesaw between glacial and interglacial conditions.
This research was performed under appointment to the NOAA Ernest F. Hollings Undergraduate Scholarship Program administered by Oak Ridge Institute for Science and Education for the U.S. Department of Commerce.
Poster Session 1, Student Conference General Poster Session
Sunday, 20 January 2008, 5:30 PM-7:00 PM, Exhibit Hall B
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