Fall 2019

Tuesdays at 3:30 PM
Natural Science Annex 101

October 1, 2019

Speaker: Scott Jasechko, UC Santa Barbara

Title: Drilling deeper wells only a short term ‘solution’ to water stress


Host: Margaret Zimmer

October 8, 2019

Speaker: Adi Torfstein, Hebrew Univeristy, Jerusalem

Title: Late Quaternary shifts in dust and rain patterns across the Levant and the Sahara Desert: lessons towards a warming world


Host: Adina Paytan

October 15, 2019

Speaker: Donna Blackman, UC San Diego

Title: Oceanic Core Complexes- use of their geophysical structure to assess interplay between tectonics, magmatism, and seawater circulation at slow-spreading centers


Host: Andrew Fisher

October 22, 2019

Speaker: Laura Schaefer, Stanford

Title: Atmosphere-Mantle feedbacks: importance of mantle oxidation state on atmospheric evolution

Abstract: The oxidation state of a rocky planet’s mantle has a strong influence on the composition of secondary atmospheres formed through outgassing. Understanding how mantle oxidation state depends on planetary bulk composition and how it changes with time due to planetary differentiation, atmospheric outgassing, and interactions with a planet’s volatile envelope is crucial to accurately predicting atmospheric compositions of rocky exoplanets. Distinguishing biosignature gases from geosignatures (false positive biosignatures produced by natural geological processes) will depend on understanding the geological processes operating on planets of different size and composition compared to the Earth. In this talk, I discuss models that explore how bulk composition, atmospheric escape and planetary differentiation (metal-silicate separation) influence mantle oxidation state and the resulting outgassed atmosphere. These and future models can help select the best exoplanetary targets for detailed characterization by future telescopes like the James Webb Space Telescope (JWST) by identifying planets with lower chances for producing false positive biosignatures.


Host: Jacob Abrahams

Special WES Seminar - October 24, 2019
2:00PM in A340

Speaker: Genevieve Coffey, Lamont-Doherty Earth Observatory

Title: Fault structure and mechanics through the lens of biomarkers

Host: Stephanie Taylor

October 29 , 2019

Speaker: Baptiste Journaux, University of Washington

Title: Astro-glaciology and habitability of planetary abysses : Experimental exploration of the richness of aqueous systems thermodynamics at high pressures


Host: Jason Ott and Myriam Telus

November 5, 2019

Speaker: Julie Meachen, Des Moines University

Title: Rappelling into the Pleistocene: A study of faunal response to a changing world


Host: Adrienne Ricker and Paul Koch

November 12, 2019

Speaker: Carlie Pietsch, San Jose State University

Title: Paleocene Eocene Thermal Maximum shows little impact on shallow marine mollusks


Host: Matthew Clapham

November 19, 2019

Speaker: Bradley Gooch, UC Davis

Title: The Grapes of Recharge - Flood-Managed Aquifer Recharge in a Vineyard Setting Along the Cosumnes River, CA


Host: Adam Price and Jenny Pensky

November 26, 2019

Speaker: Aditi Sheshadri, Stanford

Title: Midlatitude jet variability: forcing from above and below

Abstract: I will discuss aspects of midlatitude eddy-driven jet variability and its response to forcing from the stratosphere and by orography, starting with a zonal mean picture and then focusing on the Atlantic basin. Stratosphere–troposphere interactions are conventionally characterized using the first empirical orthogonal function (EOF) of fields such as zonal-mean zonal wind. Perpetual-winter integrations of an idealized model are used to contrast the vertical structures of EOFs with those of principal oscillation patterns (POPs; the modes of a linearized system governing the evolution of zonal flow anomalies). POP structures are shown to be insensitive to pressure weighting of the time series of interest, a factor that is particularly important for a deep system such as the stratosphere and troposphere. In contrast, EOFs change from being dominated by tropospheric variability with pressure weighting to being dominated by stratospheric variability without it. The analysis reveals separate tropospheric and stratospheric modes in model integrations that are set up to resemble midwinter variability of the troposphere and stratosphere in both hemispheres. Movies illustrating the time evolution of POP structures show the existence of a fast, propagating tropospheric mode in both integrations, and a pulsing stratospheric mode with a tropospheric extension in the Northern Hemisphere–like integration. The atmospheric jet stream over the North Atlantic exhibits three 'preferred positions', latitudes where the jet maximum occurs more frequently than others. Using a state-of-the-art atmosphere model, the forcing of these preferred positions by upper-atmosphere circulation and northern hemisphere mountain ranges are explored. Changes in the latitude of the time-mean jet manifest as changes in the relative probabilities of the preferred positions, not changes in the preferred latitudes. I will present strong evidence that the Greenland ice sheet is responsible for the northern preferred latitude.


Host: Nicole Feldl

December 3, 2019

Speaker: Ariana Ortiz, UCSC and UC Berkeley

Title: Carbon Sequestration in Wetlands: an interplay between burial and export


Host: Margaret Zimmer