Alexandre Carrara is a physical volcanologist who focuses on the dynamics of magma reservoirs and the physics of magma. His research aims at understanding how physical processes occurring at the scale of the crystals or gas bubbles affect the dynamics and physical properties of magma reservoirs at a macroscopic scale (e.g., magma rheology, seismic waves velocities, flow dynamics). For this purpose, Alexandre uses both numerical and analytical approaches based on the fluid mechanics of multiphase flows. At the College of the Environment, he develops numerical simulations of the coupled flow of liquid and crystals to understand how the variety of crystal shapes affects the rheology of crystal-rich magmas. The numerical simulations employ the Computational Fluid Dynamics and Discrete Element Method (CFD-DEM). This method considers each crystal as a rigid body and computes its motion by calculating the external forces applied to it and solving Newton’s second law. CFD-DEM explicitly accounts for the presence of contact between crystals of various shapes and sizes. Simulations consist of the simple shearing of crystal-rich magmas and show that the crystals slowly align in the direction of the strain, which is accommodated by the successive activation of multiple shear bands. While focused on magmas, Alexandre’s research provides insights on the physics of multiphase flows that may also be applied to other phenomena across the earth and environmental sciences (e.g., debris flows, avalanches, CO₂ sequestration).

Citations

1. Carrara, A., Lesage, P., Burgisser, A., Annen, C., Bergantz, G.W., 2021. The dispersive velocity of compressional waves in magmatic suspensions. Geophys. J. Int. 228, 2122–2136. https://doi.org/10.1093/gji/ggab432

2. Carrara, A., Burgisser, A., Bergantz, G.W., 2020. The architecture of intrusions in magmatic mush. Earth Planet. Sci. Lett, 549, 116539. https://doi.org/10.1016/j.epsl.2020.116539.

3. Carrara, A., Burgisser, A., Bergantz, G.W., 2019. Lubrication effects on magmatic mush dynamics. J. Volcanol. Geotherm. Res. 380, 19–30. https://doi.org/10.1016/j.jvolgeores.2019.05.019

4. Carrara, A., Pinel, V., Bascou, P., Chaljub, E., De la Cruz-Reyna, S., 2019. Post-emplacement dynamics of andesitic lava flows at Volcán de Colima, Mexico, revealed by radar and optical remote sensing data. J. Volcanol. Geotherm. Res. 381, 1–15. https://doi.org/10.1016/j.jvolgeores.2019.05.019

Shearing of a crystal-rich magma. [A] Snapshot of a CFD-DEM simulation. The white elongated cuboids represent the crystals. First, the sample is compressed in the direction of the blue arrow. Then, shearing is imposed in the direction of the red arrow. The background color in the particle bed indicates the local shear rate and highlights the activation of a shear band. [B] Evolution of the ordering of the crystals. The graph plots the evolution of the order parameter for three sections as a function of time. The order parameter equals one when all the crystals are aligned in the same direction and tends to zero when they are randomly oriented. The orange, green, and blue curves correspond to the plane XZ, YZ (both vertical), and XY (horizontal), respectively. The upward trend of the curves emphasizes the progressive alignment of the crystals in the direction of the strain.

Sea ice is an inherent part of our climate system that responds rapidly to climate change. It is commonly conceptualized as a collection of many strongly interacting floes (sea ice fragments). However, climate models treat sea ice as a continuum, as resolving the complexity of floe-scale mechanical and thermodynamical processes is challenging. We created a conceptually new sea ice model (SubZero) that can explicitly simulate the life cycle of individual sea ice floes, including collisions, fractures, ridging and rafting, welding, and growth. The unique SubZero capabilities may improve the realism of sea ice modeling.

CITATIONS:

Example of two floes in contact leading to various possible outcomes, including welding, ridging/rafting, and fractures. The floe interaction forces are computed based on the geometry of the overlapping area. Collision forces define the homogenized floe stress tensor used in the fracture parameterization that splits the floe into several pieces. Welding occurs if a thermodynamic criterion is satisfied and leads to the merger of two floes into one. The ridging/rafting parameterization determines if the overlap area between the floes will be absorbed into increasing the thickness of one of the two floes in contact.

Eily (Andruszkiewicz) Allan is a researcher in the School of Marine and Environmental Affairs, where she uses environmental DNA (eDNA) to monitor aquatic species. A new method to census aquatic animals, eDNA works by identifying DNA left behind by organisms (e.g., their cells, feces, tissues) in the water column. Allan is interested in the technical side of eDNA research, including determining how much eDNA different species shed, how long eDNA persists in different environments, and how far eDNA can move with currents. She is also interested in using eDNA for applied ecological questions such as how aquatic communities change over space and time, or in response to stressors. Allan is using eDNA methods to monitor aquatic communities—and salmon specifically—before, during, and after the replacement of road culverts that prevent fish passage. She is also working to develop methods for rapid, on-site eDNA detection using simple technologies, which will allow for increased monitoring of rivers and other water bodies by citizen scientists, government agencies, or scientists in remote areas without access to extensive laboratory equipment.

Citations

1. Andruszkiewicz Allan, E., Zhang, W. G., Lavery, A. C., Govindarajan, A. F. 2020. Environmental DNA shedding and decay rates from diverse animal forms and thermal regimes. Environmental DNA, 3:141. https://onlinelibrary.wiley.com/doi/epdf/10.1002/edn3.141
2. Andruszkiewicz, E.A., Koseff, J.R., Fringer, O. B., Ouellette, N. T., Lowe, A. B., Edwards, C. A., Boehm, A. B. 2019. Modeling environmental DNA transport in the coastal ocean using Lagrangian particle tracking. Frontiers in Marine Science, 6:477. https://www.frontiersin.org/articles/10.3389/fmars.2019.00477/full
3. Andruszkiewicz, E. A., Sassoubre, L. M., Boehm, A. B. 2017. Persistence of marine fish environmental DNA and the influence of sunlight. PLOS ONE, 12(9): e0185043. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185043
4. Andruszkiewicz, E. A., Starks, H.A., Chavez, F. P., Sassoubre, L. M., Block, B. A., Boehm, A. B. 2017. Biomonitoring of marine vertebrates in Monterey Bay using eDNA metabarcoding. PLOS ONE, 12(4): e0176343. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0176343

Censusing animals by collecting residual environmental DNA (eDNA) in water samples requires consideration of many different biological and physical processes, including how animals move, how eDNA is shed from an animal, how eDNA decays, and how water moves eDNA around. These processes occur on different scales in time and space and can be highly variable. It is thus important to consider all relevant processes and their corresponding scales when interpreting eDNA results. (Figure from Allan et al. 2020).

Hauke Schulz is working with Prof. Robert Wood (UW Atmospheric Sciences) and Dr. Dongxiao Zhang (CICOES/NOAA PMEL) to better understand the atmospheric and oceanic processes leading to the organization of shallow convection in the trades. Dr. Schulz and his colleagues have recently discovered the importance of the meso-scale organization of shallow clouds for the net cloud-radiative effect and their ability to cool the atmosphere. The formation mechanism of these cloud formations remains, however, an open question. Dr. Schulz will use autonomous saildrones to particularly capture the processes at the air-sea interface to study the importance of small-scale processes like cold pools for the formation of meso-scale cloud structures. Paired with satellite observations and large-eddy simulations these measurements will shed light on how shallow clouds organize in the current climate, but also addresses the question on how the clustering of clouds will react and feedback in a future climate.

Citations:

Schulz, H., Eastman, R., & Stevens, B. (2021). Characterization and Evolution of Organized Shallow Convection in the Downstream North Atlantic Trades. Journal of Geophysical Research: Atmospheres, 126(17), e2021JD034575. https://doi.org/10.1029/2021JD034575

Schulz, H., & Stevens, B. (in review). On the representation of shallow convection in the trades by large-domain, hecto-meter, large-eddy simulations. https://doi.org/10.31223/X5H651

Bony, S., Schulz, H., Vial, J., & Stevens, B. (2020). Sugar, Gravel, Fish, and Flowers: Dependence of Mesoscale Patterns of Trade-Wind Clouds on Environmental Conditions. Geophysical Research Letters, 47(7), e2019GL085988. https://doi.org/10.1029/2019GL085988

Comparison of variability of trade-wind convection in observations (left) and large-eddy simulations (right) reveals current agreement and challenges that still need to be tackled.

Kalyan is a physical oceanographer exploring the physics of boundary layer processes in the ice-free/ice-aware upper ocean and atmospheric surface layer. He uses general circulation models (GCM), large eddy simulation (LES) models, and Lattice Boltzmann (LB) models to study various turbulent environmental flows. Currently, he is focused on understanding the interactions between sea ice and submesoscale ocean variability. The ocean surface is filled with fronts that can become unstable and lead to the formation of submesoscale eddies in the ocean mixed layer. These instabilities overturn the density fronts, releasing potential energy. The restratification process associated with the overturning of the density fronts strongly influences variations in the mixed layer depth. Hence, understanding the mixed layer restratification process is of first-order importance in improving the accuracy of global climate models. However, its current model parameterization in terms of an eddy-driven overturning streamfunction does not consider the presence of sea ice cover. Kalyan’s work is focused on improving this parameterization for ice-covered polar oceans, considering the effect of ice-ocean drag and making it explicitly dependent on sea ice concentration. The updated parameterization scheme predicts the reduction of overturning streamfunction up to a factor of 4 for fully ice-covered regions with the sharp transition of submesoscale eddy characteristics occurring at critical sea ice concentration. The inclusion of such parameterization in global climate models can improve the representation of ocean-ice interactions and consequently lead to more accurate sea ice predictions.

Citations
1. Shrestha, K., Manucharyan, G.E. 2021. Parameterization of submesoscale mixed layer restratification under sea ice. Journal of Physical Oceanography (in revision).
2. Shrestha, K., Anderson, W., Tejada-Martinez, A., Kuehl, J. 2019. Orientation of coastal-zone Langmuir cells forced by wind, wave, and mean current at variable obliquity. Journal of Fluid Mechanics, 879:716–743.
3. Shrestha, K., Anderson, W., Kuehl, J. 2018. Langmuir turbulence in coastal zones: structure and length scales. Journal of Physical Oceanography, 48(5):1089–1115.
4. Shrestha, K., Mompean, G., Calzavarini, E. 2016. Finite-volume versus streaming-based Lattice Boltzmann algorithm for fluid-dynamics simulations: A one-to-one accuracy and performance study. Physical Review E, 93(2):023306.

(A) Contours of eddy-induced overturning circulation represented by blue color (clockwise) and red color (anti-clockwise) illustrating how the presence of sea ice cover makes a difference in its intensity. Black contour lines denote lines connecting points of a specific density. (B) Non-dimensional overturning streamfunction (Y+) and sea ice-ocean drag induced dissipation (e+) as a function of sea ice concentration (c).

Kinya Toride is a hydro-meteorologist whose research focuses on mitigating the risk of natural hazards caused by extreme weather events. One of his research focuses is improving the sub-seasonal forecasts of atmospheric rivers. Atmospheric rivers are narrow bands of concentrated moisture that bring extreme precipitation and flooding to the US West Coast. The Madden-Julian Oscillation (MJO) in the tropical atmosphere modulates atmospheric river activity on timescales of 2–5 weeks. However, there is large uncertainty in atmospheric river forecasts due to various tropical-extratropical processes. Toride has demonstrated that the low-frequency variability of the Pacific/North American (PNA) mode could significantly improve forecasts. Differences in the phasing of baroclinic wave packets appear to be particularly important relative to the large-scale structure of the Pacific jet (see figure below). He is currently investigating the contributions of the MJO and extratropical processes independent of MJO on North American atmospheric river activity. His study has potential to improve the forecasting of hydrological disasters, which will benefit numerous sectors including water resources, energy, and agriculture.

Website: https://sites.google.com/view/kinya

Citations

3. Toride, K., Hakim, G.J. 2021. Influence of low-frequency PNA variability on MJO teleconnections to North American atmospheric river activity, Geophys. Res. Lett, 48, e2021GL094078, doi: 10.1029/2021GL094078​
4. Toride, K., Yoshimura, K., Tada, M., Diekmann, C., Ertl, B., Khosrawi, F., Schneider, M. 2021. Potential of mid-tropospheric water vapor isotopes to improve large-scale circulation and weather predictability, Geophys. Res. Lett, 48:e2020GL091698, doi: 10.1029/2020GL091698​
5. Toride, K., Iseri, Y., Warner, M.D., Frans, C.D., Duren, A.M., England, J.F., Kavvas, M.L. 2019. Model-based Probable Maximum Precipitation estimation: How to estimate the worst-case scenario induced by atmospheric rivers?, J. Hydrometeorol., 20(12):2383-2400, doi: 10.1175/JHM-D-19-0039.1
6. Toride, K., Neluwala, P., Kim, H., Yoshimura, K. 2017. Feasibility Study of the Reconstruction of Historical weather with Data Assimilation, Mon. Weather Rev., 145(9):3563-3580, doi: 10.1175/MWR-D-16-0288.1

The map shows the extratropical condition when MJO is in the same condition (phase 3) but different monthly PNA phases. The westerly jet-exit region (blue contours) is stretched to the east by more than 20° longitude for the PNA+ phase compared to the PNA- phase. The extension/retraction of the Pacific jet modulates baroclinic wave propagation across the North Pacific (black contours). When the jet exit region extends eastward during PNA+, baroclinic waves are zonally stretched and directed more poleward into North America such that atmospheric river activity increases over the Pacific Northwest.

Nils Hutter is a sea-ice physicist whose research focuses on how sea-ice deforms under the forcing of wind and ocean currents. The Arctic sea ice cover is broken into a mosaic of floes of different shapes, sizes, and thicknesses. The distribution of floes and their properties impacts most physical processes in ice. For example, floes determines the mechanical strength of sea ice as well as how fast ice melts in response to a warming ocean and atmosphere. Despite this important role, climate models currently are not able to simulate the floe character of sea ice. Nils explores new ways to resolve floes and floe-dependent processes in sea-ice models. At UW, he examines how sea ice breaks apart into smaller floes during a fracture event. A major challenge is the chaotic nature of ice fracture, which he addresses by applying machine learning techniques to the wealth of satellite observations of Arctic sea ice. In doing so, he constrains the two-way relationship between floe sizes and deformation: how fracture creates new floes and how this change in the distribution of floes weakens the ice to favor further deformation. These feedbacks will be included in a continuum sea-ice model to realistically simulate the evolution of the distribution of floes in all regions of the Arctic Ocean. Nils’s findings will increase our capabilities to predict sea-ice both short-term forecast and long-term climate projection by considering both dynamic and thermodynamic processes at floe scale.

Citations

1. Hutter, N. et al. Sea Ice Rheology Experiment (SIREx), Part II: Evaluating simulated linear kinematic features in high-resolution sea-ice simulations. Accepted (2022). J. Geophys. Res. Oceans. doi:10.1002/essoar.10507396.1.
2. Bouchat, A., Hutter, N. et al. Sea Ice Rheology Experiment (SIREx), Part I: Scaling and statistical properties of sea-ice deformation fields. Accepted (2022). J. Geophys. Res. Oceans. doi: 10.1002/essoar.10507397.1.
3. Hutter, N. & Losch, M. Feature-based comparison of sea ice deformation in lead-permitting sea ice simulations. Cryosphere 14, 93–113 (2020).
4. Hutter, N., Zampieri, L. & Losch, M. Leads and ridges in Arctic sea ice from RGPS data and a new tracking algorithm. Cryosphere 13, 627–645 (2019).
5. Hutter, N., Losch, M. & Menemenlis, D. Scaling Properties of Arctic Sea Ice Deformation in a High‐Resolution Viscous‐Plastic Sea Ice Model and in Satellite Observations. J. Geophys. Res. Oceans 123, 672–687 (2018).

Very high resolution (1 km) simulation of sea-ice where fracture of sea-ice and large floes are explicitly resolved. Simulations like this can be used to better understand the interplay between ice deformation and resulting floes to parameterize these effects in coarser resolution climate models.

Núria Viladrich Canudas explores the resilience and resistance of coral species to natural and human-induced impacts. Her research is focused on coral and gorgonians’ reproduction and energetics using a multidisciplinary approach combining field work, experimental studies, and laboratory analysis to best understand complex ecological phenomena. Her research encompasses the study of the reproductive processes of coral and gorgonian species, their larval ecology, nutritional condition (biochemical characterization), trophic ecology (fatty acids and stable isotopes), ecophysiology (respiration, excretion and calcification), and the viability of ecological restoration of populations. As a postdoc at both the Global Fellowship Marie-Curie at the University of Washington and the Universitat de Barcelona (Barcelona, Spain), she is continuing her work on ecophysiology and marine conservation, learning new genetic and modelling skills, and expanding her international network and research to other geographic areas. Her research in SAFS will allow for reliable prediction of future shifts in community structure of coral reefs, accounting for the energetic cost of adaptive mechanisms to ocean warming and acidification, and transgenerational effects that can undermine early-life history stages of coral species. The results of her research will improve coral species management and conservation by focusing protection and restoration efforts towards coral species with higher probability of survival in future conditions. Her research thus provides a fundamental tool to project future ecological trends in response to global change.

Citations

1. Viladrich N, Bramanti L, Tsounis G, Coppari M, Dominguez-Carrió C, Pruski AM, Rossi S (accepted, 2022). Estimations of free fatty acid (FFA) as a reliable proxy for larval performance in Mediterranean octocoral species. Mediterr. Mar. Sci.
2. Viladrich N, Bramanti L, Tsounis G, Martinez A, Rossi S (2017). Variation of lipid and free fatty acid contents during larval release in two temperate octocorals according to their trophic strategy. Mar. Ecol. Prog. Ser. 573:117–128.
3. Viladrich N, Bramanti L, Tsounis G, Chocarro B, Martinez A, Ambroso S, Madurell T, Rossi S (2016). Variation in lipid and free fatty acid content during spawning in two temperate octocorals with different reproductive strategies: surface versus internal brooder. Coral Reefs 35:1033–1045. (nominated by the editorial board as one of the best papers of the journal Coral Reefs 2016).

Mediterranean coral species during the reproductive event and their early-life history. (a) Eggs and fertilized eggs on the colony surface of Paramuricea clavate (a). Expanded polyps during the brooding period event for (b) Corallium rubrum (red coral) and (c) Eunicella singularis (White gorgonian). (d) Pink larvae of Eunicella singularis and (e) new recruits of Eunicella singularis.