Passive continental margins make up many of the world’s densely populated coasts, hold 35% of the world’s largest oil reservoirs, sequester carbon, and are critical biodiversity hotspots. Human populations and infrastructure on passive margins are at risk from sea level rise, increased storm intensity, and sediment starvation. The geologic evolution of passive margins around the world is poorly understood due to a lack of models that couple terrestrial erosion with sediment deposition in the deep marine environment. The Atlantic Passive Margin (APM) of the eastern United States is exceptionally enigmatic; debate centers on how many (if any) pulses of exhumation occurred on the APM since the opening of the Atlantic Ocean 200 million years ago. Yet there has been no attempt to use mechanistic surface process models to extract APM exhumation history. I propose to build a new, coupled model of terrestrial and marine sediment transport and use it to invert the rich deep marine sedimentary record for APM exhumation history. I will develop a new model for continent-scale deep marine seascape and stratigraphy evolution over geologic time, which I will couple with existing models for terrestrial and shallow marine environments. I will validate the new model against an existing small-scale stratigraphy model as well as stratigraphy from the Bay of Biscay and the Ogooué Delta, Gabon. I will use the coupled model to invert the deep marine sedimentary record and resolve APM exhumation history over the past 200 Ma. Inversion results will provide novel constraints on the number, timing, and cause of exhumation pulses, and will be compared against thermochronologic data and geodynamic models. This approach is the first to quantitatively link the development of marine stratigraphy to APM landscape change. The proposed study will unlock the potential of deep marine deposits, the most complete sedimentary archives on Earth, to yield time-resolved records of changes to Earth’s surface.

Repeated glacial-interglacial cycles during the Quaternary have significantly impacted the topography of many mountain ranges around the world. Yet, the response of landscape evolution to repeated climate oscillations has not been well quantified. In recently deglaciated landscapes, the transition from glacial to fluvial/hillslope processes have induced progressive topographic adjustments, and the large amounts of sediments inherited from glacial periods and generated through landsliding of oversteepened glaciated topography may act as a fundamental control on the incision of postglacial rivers. These sediments can enhance fluvial incision rate by providing more tools for erosion, or inhibit incision by armoring the river bed. Characterizing when and where sediment enhances or inhibits fluvial incision in postglacial landscapes is critical for understanding the changes in postglacial landscape evolution rates over time and quantifying the response times of mountain ranges to deglaciation. In this project, I propose to develop a landscape evolution model to account for the complex impact of sediment dynamics on fluvial incision in postglacial landscapes. I will utilize this model to investigate the response of fluvial incision to changes in sediment supply and assess the effects of sediment on postglacial landscape evolution. I will apply the model to quantify response times of the deglaciated European Alp, leveraging the rich observational datasets in this region. The proposed work will provide a quantitative understanding of postglacial fluvial incision histories, which is critical for ecosystem management and natural hazard assessment in recently deglaciated mid-latitude mountain ranges and perhaps in high-latitude mountain ranges where continued climate change may eventually lead to deglaciation.

The magnetosphere is a natural plasma laboratory. Radiation belts in the magnetosphere are full of high energy particles. The energetic electrons in the Earth’s radiation belts can be hazardous to Earth-orbiting satellites and astronauts in space. Many of the space systems on which modern human society depends operate in this region. The fluxes of radiation belt electrons are very dynamic, which is not fully understood due to the delicate balance between various acceleration and loss processes. Wave-particle interactions are believed to play a crucial role in the acceleration and loss of these particles. To quantify the effect of different waves on the dynamics of radiation belt electrons, comprehensive wave models are needed. Currently, there are some wave models based on satellite measurements. However, the space coverage of these wave models is not sufficient due to the orbit limit of satellites. In this project, combining state-of-the-art measurements from multiple satellites, comprehensive wave models will be developed. We will improve our sophisticated physics-based radiation belt dynamic model by using the wave models developed in this project and calculate diffusion coefficients using more realistic background magnetic field and plasma density models for the first time. Furthermore, fundamental acceleration and loss of energetic electrons caused by different waves in the Earth's radiation belts will be quantified. We will systematically validate simulation results against satellite measurements to understand the competition between acceleration and loss caused by various mechanisms. All these improvements will be critically important for answering the overarching scientific question: Why do the Earth’s radiation belts respond differently to geomagnetic storms which have approximately the same intensity? The knowledge gained in this project can be useful for basics plasma physics and astronomy physics because the similar fundamental processes exist.