Title: Cold Jets in the Solar System with Focus on Mars and Enceladus
Abstract: MARS: Spring on Mars is a time of active changes in its polar areas, at latitudes covered by seasonal CO2 ice. The volatile nature of the CO2 sublimation in spring leads to cold jet eruptions that erode the surface, redistribute loose material, and lift dust into the atmosphere. I will summarize 6 Martian Years of observations of this seasonal activity in the southern and northern Martian polar areas.
ENCELADUS: Southern polar regions of a small satellite of Saturn Enceladus are source of cold jets too, while of a very different scale. The jets of Enceladus were observed by Cassini spacecraft for more than 12 years. I will focus on their water vapor component, its modeling that was done to analyze UV observations, and the questions Cassini left unanswered.
Learn more about Jack Holt
Informal weekly presentations by UTIG students and researchers. Bring your lunch!
Title: Why is projecting the sea level contribution from ice sheets so tricky?
Abstract: The Greenland and Antarctic ice sheets are the largest reservoir of freshwater on Earth, and the dominant source of uncertainty when projecting sea level. Remote sensed observations have revealed that the contemporary ice sheets are losing mass, and that their current contribution to sea level is accelerating. Whether the rate of sea level rise from the ice sheets will continue at the same pace, or what future sea level should our society prepare for, are questions that are very tricky to answer. In this presentation, I review the challenges faced by ice sheet models, along with developments that are required to make meaningful projections of Greenland and Antarctica on the timescale of the next IPCC assessment report. Finally, I will introduce the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), which has the key objective of improving projections of sea level from the Greenland and Antarctic ice sheets, along with increasing our understanding of the cryosphere in a changing climate. These goals map into both “Melting Ice and Global Consequence” and “Regional Sea-level Change” Grand Challenges relevant to the World Climate Research Program.
Learn more about Dr. Nowicki.
Host: Ginny Catania
Title: An adaptive Bayesian inversion for upper mantle structure using surface waves and scattered body waves
Abstract: I will present a methodology for 1-D imaging of upper mantle structure using a Bayesian approach that incorporates a novel combination of seismic data types and an adaptive parameterisation based on piecewise discontinuous splines. This inversion algorithm lays the groundwork for improved seismic velocity models of the lithosphere and asthenosphere by harnessing the recent expansion of large seismic arrays and computational power alongside sophisticated data analysis. Careful processing of P- and S-wave arrivals isolates converted phases generated at velocity gradients between the mid-crust and 300 km depth. This data is allied with ambient noise and earthquake Rayleigh wave phase velocities to obtain detailed VS and VP velocity models. Synthetic tests demonstrate that converted phases are necessary to accurately constrain velocity gradients, and S-p phases are particularly important for resolving mantle structure, while surface waves are necessary for capturing absolute velocities. We apply the method to several stations in the northwest and north-central United States, finding that the imaged structure improves upon existing models by sharpening the vertical resolution of absolute velocity profiles, offering robust uncertainty estimates, and revealing mid-lithospheric velocity gradients indicative of thermochemical cratonic layering. This flexible method holds promise for increasingly detailed understanding of the upper mantle.
Learn more about Dr. Eilon.
Host: Harm Van Avendonk
Hurricane Harvey dumped thirteen trillion gallons of rain on southeast Texas in August of 2017. Do extreme storm events like Harvey impact the coral reefs off Texas’ coast, in the Flower Garden Banks National Marine Sanctuary? Dr. Correa shares ongoing research connecting the Gulf Coast, extreme weather, and reef ecosystems. Supported by the Leon Jones Hot Science - Cool Talks Endowment. Free but registration required or watch the event live at www.hotsciencecooltalks.org
Title: Ice and mud: how sediment dynamics drive periodicity in tidewater glaciers
Abstract: Many tidewater glaciers in Alaska, such as Hubbard, Taku, and Yahtse, are growing despite a warming atmosphere and ocean. At the same time, close neighbors such as Columbia glacier are undergoing dramatic retreats, which cannot be accounted for by climate change. What drives this apparent disparity in glacier behavior? A hypothesized process known as the tidewater glacier cycle provides an explanation: movement of sediment by subglacial streams produces a shoal at the glacier front, decreasing the amount of iceberg calving and allowing the glacier to advance over several hundred years. Eventually the glacier becomes overextended, floats, and quickly retreats to its initial shape. In this talk, I will show (with the help of computer model) that simple interactions of ice, water, and erosion can produce tidewater glacier cycles like the ones that are observed in coastal Alaska, and that these cycles occur even in a static climate and persist with warming. I argue that these cycles drive natural shifts in marine habitat and the fjord landscape at large and must be accounted for in interpretations of glaciers as climate proxies.
Learn more about Dr. Brinkerhoff
Host: Ginny Catania