부산대학교 도서관

The Community Earth System Model (CESM) version 2.0 was launched in June 2018 –improving both the physical parameterizations and numerical methods in the CESMcomponents (e.g. ocean, atmosphere, ice). However, we do not know yet what is theperformance of the ocean component in this new CESM version for oceanic waters aroundGreenland. Greenland is a key place to study due to its high sensitivity to the climate change.The Greenland Ice Sheet is losing mass by, approximately, 35 Gt/yr, which 30% is dueto the ice discharge. The highest rates of ice discharge are observed at tidewaterglaciers. Thus, in this presentation we evaluate CESM 2.0 in simulating the ocean circulation inthe Greenland vicinity, both in terms of present-day simulation and sensitivity toanthropogenic greenhouse forcing, with the ultimate goal of assessing the sensitivity of theGreenland ice sheet mass budget to future changes in the ocean conditions. For this purpose,we analyze results from simulations under three different scenarios with static and/orinteractive Greenland ice sheets: i) pre-industrial (PI) control - no anthropogenic effect, ii)one-percent CO2 concentration (1pct CO2), where the concentration of CO2 increases onepercent per time step until reaches four times the PI atmospheric CO2 level (1140 ppm) andiii) four times PI CO2 levels (abrupt 4xCO2). Thus, we can evaluate the response of the oceanin stable, intermediate and extreme scenarios. Three sites (each close to three mainGreenland outlet glaciers: Helheim, Kangerlussuaq and Jakobshavn Isbrae) are chosen toevaluate the water masses signature. These tidewater glaciers have been shown to besensitive to ocean forcing change, with increased discharge to the ocean and majorcontribution to sea level rise in the last decade (van den Broeke et al., 2016). A longertransect from Greenland to Iceland is also presented to evaluate the North AtlanticMeridional Overturning Circulation (NAMOC). Preliminary results show that in the1pct CO2 scenario the Atlantic Meridional Overturning Circulation (AMOC) indexdecreases 0.087 Sv/yr and 0.16 Sv/yr for the 4xCO2 scenario. In the latter, the signatureof the NAMOC is so weak that suggests a shutting down of the NAMOC. Themodeled southern hemisphere part of the AMOC (SAMOC) is enhanced in the 4xCO2scenario. The main water masses identified around Greenland in the pre-industrial simulation arethe Polar Water at the surface, Atlantic Water subsurface/intermediate water and Deep waterin the vicinity of the Helheim and Kangerlussuaq; and a fresh surface water and LabradorIntermediate Water around Jakobshavn glacier. In the 1pct CO2 and 4xCO2 scenarioswas observed an increase, in the Atlantic Water temperature (about 150 m depth),by approximately 2.5 and 8.5oC, respectively and a deepening of approximately350 m of the thermocline in the average of the last 30 years of each simulation. [ABSTRACT FROM AUTHOR]