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Greenland ice sheet: surface climate variability and ice dynamics

Yang, Lei
http://rave.ohiolink.edu/etdc/view?acc_num=osu1180121203

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Atmospheric Sciences.
The Polar Pennsylvania State University-National Center for Atmospheric Research Fifth Generation Mesoscale Model (Polar MM5) regional climate model was run over the North Atlantic region for 1958 - 2006. Polar MM5 V0 (1958 - 2004) simulated surface mass balance and temperature are used to compare with observations and investigate the co-variability of surface climate variability and measured ice sheet changes. The correlation between ice sheet thickness change due to surface mass balance anomalies and due to ice dynamics became higher and statistically more significant from 1993 to 2005. The correlation varies with different based periods chosen for surface mass balance estimates, which suggests a threshold when glaciers start to accelerate. Longer term model temperature data was extracted from Polar MM5 V1, which is run over Greenland and surrounding areas for 1958 - 2006. Model temperature data are validated and calibrated using station observation records. With the longer term model assimilation available, melt index anomalies were calculated relative to the 1961-1990 base period. The co-variability of ice velocities and melt index anomalies are investigated for 3 largest outlet glaciers in Greenland. April-September Positive Degree Day, spring and summer temperature anomalies are found to be significantly correlated with ice velocities, which indicate a correspondence between surface melting and ice dynamics. Different responses of glacier speed to melt index anomalies after break-up also indicate an influence from bed geometry and other dynamic characteristics unique to each glacier. The small or even negative correlation after break-up at Kangerdlugssuaq Gl., and Helheim Gl. suggests that ice dynamics took control after melt triggered acceleration and retreat to re-adjust the glaciers toward an new equilibrium. The co-variability of glacier ice discharges and climate variability is also examined by using Polar MM5 V1 modeled summer temperature and April-September Positive Degree Day (PDD) anomalies. Ice discharges from south Greenland glaciers are found to be sensitive to temperature change. Based on sensitivities of ice discharge to melt index anomalies, time series of total ice discharge from 28 major glaciers since 1958 are modeled. The global sea level rise contribution from Greenland ice sheet during past 50 years is estimated be ~ 0.6 mm/yr in average.
Jason Box (Advisor)

Recommended Citations

Citations

  • Yang, L. (2007). Greenland ice sheet: surface climate variability and ice dynamics [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1180121203

    APA Style (7th edition)

  • Yang, Lei. Greenland ice sheet: surface climate variability and ice dynamics. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1180121203.

    MLA Style (8th edition)

  • Yang, Lei. "Greenland ice sheet: surface climate variability and ice dynamics." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1180121203

    Chicago Manual of Style (17th edition)

osu1180121203
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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.