2) Chase Chivers
Chase Chivers, Postdoctoral Scholar, Applied Ocean Physics & Engineering Woods Hole Oceanographic Institution
Chase Chivers, Postdoctoral Scholar, Applied Ocean Physics & Engineering Woods Hole Oceanographic Institution
Monday September 18th; 3 PM
Monday September 18th; 3 PM
Host: Ellyn Enderlin
Host: Ellyn Enderlin
Title: From Shells to Sheets and Shelves: Ice-Melt Interactions and Ice Dynamics Across the Solar System
Title: From Shells to Sheets and Shelves: Ice-Melt Interactions and Ice Dynamics Across the Solar System
Abstract: Ice is a ubiquitous and important material in the universe, including on our planet and in our solar system. On Earth, large ice sheets and their supporting floating shelves play a significant role in the climate system. On Jupiter’s moon Europa, in the frigid temperatures of the outer solar system (~100 K), ice covers the entire surface and extends 10s-100 km deep (the “ice shell”). Beneath the icy shell likely lies a ~100 km thick saline liquid-water ocean in contact with a silicate mantle beneath, providing a potentially habitable environment. While access to the ocean remains a technological feat for the future, we can turn to Europa’s marred surface for clues to the interior.
Abstract: Ice is a ubiquitous and important material in the universe, including on our planet and in our solar system. On Earth, large ice sheets and their supporting floating shelves play a significant role in the climate system. On Jupiter’s moon Europa, in the frigid temperatures of the outer solar system (~100 K), ice covers the entire surface and extends 10s-100 km deep (the “ice shell”). Beneath the icy shell likely lies a ~100 km thick saline liquid-water ocean in contact with a silicate mantle beneath, providing a potentially habitable environment. While access to the ocean remains a technological feat for the future, we can turn to Europa’s marred surface for clues to the interior.
The surface of Europa is highly modified by mostly endogenic processes, including the enigmatic, and geologically young chaos terrains and the related lenticulae. These appear as elliptically-shaped, <10 - >100 km in diameter surface disruptions and have been suggested to form above reservoirs of (saline) liquid water emplaced in the ice shell >1 km below the surface. To understand how the impact on the composition of the ice shell and regional surface geology over time, I quantify their longevity and explore the evolution of their saline chemistry using numerical models. Depending on the initial composition, I find that smaller reservoirs (≤10^3 km3) last only up to ~140 kyr, much more transient than previously thought, while larger reservoirs (~104 km3) may last >350 kyr. This suggests the possibility of a contemporary ice shell with liquid water near the surface. Furthermore, a characteristic chemical signature is left behind in the ice shell and thermal signature at the surface for detection by future missions.
The surface of Europa is highly modified by mostly endogenic processes, including the enigmatic, and geologically young chaos terrains and the related lenticulae. These appear as elliptically-shaped, <10 - >100 km in diameter surface disruptions and have been suggested to form above reservoirs of (saline) liquid water emplaced in the ice shell >1 km below the surface. To understand how the impact on the composition of the ice shell and regional surface geology over time, I quantify their longevity and explore the evolution of their saline chemistry using numerical models. Depending on the initial composition, I find that smaller reservoirs (≤10^3 km3) last only up to ~140 kyr, much more transient than previously thought, while larger reservoirs (~104 km3) may last >350 kyr. This suggests the possibility of a contemporary ice shell with liquid water near the surface. Furthermore, a characteristic chemical signature is left behind in the ice shell and thermal signature at the surface for detection by future missions.
Back on Earth, the stability of large ice sheets is threatened by a warming climate at present day and in the past. At the end of the last glacial maximum (~22 ka) sea levels rose periodically and rapidly in several meltwater pulse (MWP) events likely resulted from ice sheet elevation-climate feedbacks. In the present day, the Greenland Ice Sheet (GrIS) holds two conditions necessary to create an MWP: an ice saddle geometry in the southeast and positive elevation-mass balance feedback. I investigate the possibility of saddle collapse in the GrIS focusing on transient deglaciation using an ice sheet model by applying a simple elevation-mass balance saturation relationship. I find that the southern saddle collapses in most simulations causing, along with another saddle that transiently forms and collapses at the northern edge of the GrIS. Both saddle collapses create a MWP events, but the southern saddle contributes ~0.5 m SLE only over a few hundred to thousands of years alone.
Back on Earth, the stability of large ice sheets is threatened by a warming climate at present day and in the past. At the end of the last glacial maximum (~22 ka) sea levels rose periodically and rapidly in several meltwater pulse (MWP) events likely resulted from ice sheet elevation-climate feedbacks. In the present day, the Greenland Ice Sheet (GrIS) holds two conditions necessary to create an MWP: an ice saddle geometry in the southeast and positive elevation-mass balance feedback. I investigate the possibility of saddle collapse in the GrIS focusing on transient deglaciation using an ice sheet model by applying a simple elevation-mass balance saturation relationship. I find that the southern saddle collapses in most simulations causing, along with another saddle that transiently forms and collapses at the northern edge of the GrIS. Both saddle collapses create a MWP events, but the southern saddle contributes ~0.5 m SLE only over a few hundred to thousands of years alone.
Surface melt on Antarctica’s floating ice shelves represents one of the largest uncertainties in future projections of mass loss in Antarctica. As ice shelves provide stability to continental ice, melt features may play an outsized role in future sea level rise. “Ice dolines,” a feature caused by the rapid drainage of an englacial lake which creates a ~10 m depression, may be important for the future stability of some ice shelves but are relatively understudied. I will present a 50-year observational history of an ice doline on the Amery Ice Shelf, discussing the evolution of the ice doline prior to collapse, the environmental conditions surrounding the collapse and correlate the factors that lead to its abrupt drainage, as well its evolution after collapse."
Surface melt on Antarctica’s floating ice shelves represents one of the largest uncertainties in future projections of mass loss in Antarctica. As ice shelves provide stability to continental ice, melt features may play an outsized role in future sea level rise. “Ice dolines,” a feature caused by the rapid drainage of an englacial lake which creates a ~10 m depression, may be important for the future stability of some ice shelves but are relatively understudied. I will present a 50-year observational history of an ice doline on the Amery Ice Shelf, discussing the evolution of the ice doline prior to collapse, the environmental conditions surrounding the collapse and correlate the factors that lead to its abrupt drainage, as well its evolution after collapse."
Journal article link https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JE006692
