How does viscosity contrast influence phase mixing and strain localization?Andrew Cross, Philip Skemer, Hélène Couvy & Elizabeth Olree
Ultramylonites with well-mixed mineral phases are thought to be an essential feature of Earth-like plate tectonics, because coupled phase mixing and grain boundary pinning enable rocks to deform by grain-size-sensitive, self-softening creep mechanisms over long geologic timescales. In isoviscous two-phase composites (and in the absence of chemical exchange or reaction), bulk “geometric” phase mixing occurs via the sequential formation and disaggregation of compositional layering. However, the effects of viscosity contrast on the mechanism(s) and timescale(s)...
How variable is mixing efficiency in the abyss?Takashi Ijichi, Louis St. Laurent, Kurt L. Polzin & John Toole
This directory contains BBTRE/DoMORE processed data (“all_BBTRE.mat” and “all_DoMORE.mat”) that was used to produce all figures in the above research letter. Each mat file has two structure arrays named “location” and “patch10”. The “location” array includes microstructure profile information used in this study (Table D1). The “patch10” array includes 10-m patch-wise parameter estimates used in this study (Table D2). Note that bulk averaged parameters can be constructed from parameters saved in “patch10” (see the above...
Increased typhoon activity in the Pacific deep tropics driven by Little Ice Age circulation changesJames Bramante, Murray Ford, Paul Kench, Andrew D. Ashton, Michael Toomey, Richard M. Sullivan, Kristopher B. Karnauskas, Caroline C. Ummenhofer & Jeffrey P. Donnelly
The instrumental record reveals that tropical cyclone activity is sensitive to oceanic and atmospheric variability on inter-annual and decadal scales. However, our understanding of climate’s influence on tropical cyclone behavior is restricted by the short historical record and sparse prehistorical reconstructions, particularly in the western North Pacific where coastal communities suffer loss of life and livelihood from typhoons annually. Here we reconstruct three millennia of deep tropical North Pacific cyclogenesis and compare with other records...
Mechanisms of exchange flow in an estuary with a narrow, deep channel and wide, shallow shoalsW. Rockwell Geyer, David Ralston & Jia-Lin Chen
Delaware Bay is a large estuary with a deep, relatively narrow channel and wide, shallow banks, providing a clear example of a “channel-shoal” estuary. This numerical modeling study addresses the exchange flow in this channel-shoal estuary, specifically to examine how the lateral geometry affects the strength and mechanisms of exchange flow. We find that the exchange flow is exclusively confined to the channel region during spring tides, when stratification is weak, and it broadens laterally...
The rheological behavior of CO2 ice: application to glacial flow on MarsAndrew Cross, David L. Goldsby, Travis F. Hager & Isaac B. Smith
Vast amounts of solid CO2 reside in topographic basins of the south polar layered deposits (SPLD) on Mars and exhibit morphological features indicative of glacial flow. Previous experimental studies showed that coarse-grained CO2 ice is 1–2 orders of magnitude weaker than water ice under Martian polar conditions. Here we present data from a series of deformation experiments on high-purity, fine-grained CO2 ice over a broader range of temperatures than previously explored (158–213 K). The experiments...
Woods Hole Oceanographic Institution5
University of Pennsylvania1
University of Washington1
Texas A&M University – Central Texas1
National Cheng Kung University1
Washington University in St. Louis1
Simon Fraser University1
United States Geological Survey1
University of Auckland1
Massachusetts Institute of Technology1