SPRING 2025
Wednesdays at 3:00 pm, Seminar Room SLAB 103 / Virtual SLAB 103
(unless stated otherwise)
Jan 08 (2:45 pm): Dr. Sophia Brumer
Aerology Laboratory (LAERO), Toulouse, France
Guest of Milan Curcic, Department of Ocean Sciences
On Sub-Mesoscale Air-Sea Interactions in Extratropical Windstorms
Recording Available at COMPASS ON DEMAND
Windstorms associated with extratropical cyclones are destructive natural hazards. We are interested in elucidating the processes involved in the formation of near-surface extreme winds, and my focus is on wave and wave-breaking related processes. Though crucial for their societal impact, these processes are not well understood and too small-scale to be explicitly represented in numerical weather prediction models. Waves modulate air-sea exchanges, mix the upper ocean, and inject sea spray into the atmosphere when breaking. Air-sea fluxes of enthalpy and momentum greatly influence the dynamics of the marine atmospheric boundary layer (MABL). Waves increase the surface roughness but sea spray loading may act as a buffer layer reducing drag and stabilizing the MABL. Larger droplets increase air-sea enthalpy and decrease momentum transfers, thus promoting the intensification of tropical cyclones, but what of extratropical cyclones?
In this talk, I will give an overview of ongoing and planned work at the Laboratoire d'Aérologie (LAERO) in Toulouse, France, on sub-mesoscale ocean-wave-atmosphere interactions in extratropical cyclones. Ongoing work will be illustrated through three case studies: 1) the Mediterranean cyclone Adrian, where sub-mesoscale wind rolls show strong sensitivity to air-sea fluxes; 2) the North Atlantic storm Alex, where wave coupling influences mesoscale jets and the downward momentum transport; and 3) the cold wake producing medicane (Mediterranean Hurricane) Ianos, where the ocean induces a negative feedback similar to that seen in certain tropical cyclones.
Future work aims at establishing a coherent air-sea coupled framework for numerical weather predictions, which includes the impact of waves on roughness, of sea spray on the MABL, and takes into account relative alignment between the wind and wave systems. For this purpose, we are designing realistic coupled simulations with horizontal resolutions approaching those of Large Eddy Simulations. These will allow gauging the scale of impacts of non-resolved and poorly constrained processes, such as sea spray generation and subsequent heat and momentum exchanges within the MABL. Field measurements needed to evaluate these simulations will include the NAWDIC field campaign, which will sample North Atlantic storms over the winter of 2025/2026. Future campaigns in the Mediterranean / Ionian Sea and the south Indian Ocean are also under consideration.
Sophia Brumer is a CNRS researcher specialized in ocean-wave-atmosphere interactions at the Aerology Laboratory (LAERO) in Toulouse, France. She obtained her BSc degree from the University of Miami and her PhD from Columbia University, where she investigated the role of waves and wave breaking on air-sea gas transfer based on shipborne measurements. She then joined the Laboratoire d’Océanographie Physique et Spatiale (LOPS, Brest, France) for a series of postdocs revolving around the role of waves on an ocean tidal temperature front and the impact of sea spray on the marine atmospheric boundary layer using coupled models. Since September 2023, she is at the LAERO where her work seeks to understand and quantify the role of sea state, wave breaking, and sea spray on wind and rain extremes in low-pressure systems.
Jan 15: NO SEMINAR
Jan 22: Dr. Alina Nathanaël Dossa
Department of Ocean Sciences, Rosenstiel School
Global Analysis of Coastal Gradients of Sea Surface Salinity
Recording Available at COMPASS ON DEMAND
Sea surface salinity (SSS) is a key variable for ocean-atmosphere interactions and the water cycle. Due to its climatic importance, increasing efforts have been made for its global in-situ observation, and dedicated satellite missions have been launched more recently to allow homogeneous coverage at higher resolution. Cross-shore SSS gradients can bear the signature of different coastal processes such as river plumes, upwelling, or boundary currents, as we illustrate in a few regions. However, satellite performances are questionable in coastal regions. Here, we assess the skill of four gridded products derived from the Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active Passive (SMAP) satellites and the GLORYS global model reanalysis at capturing cross-shore SSS gradients in coastal bands up to 300 km wide. These products are compared with thermosalinography (TSG) measurements, which provide continuous data from the open ocean to the coast along ship tracks. The comparison shows various skills from one product to the other, decreasing as the coast gets closer. The bias in reproducing coastal SSS gradients is unrelated to how the SSS biases evolve with the distance to the coast. Despite limited skill, satellite products generally agree better with collocated TSG data than a global reanalysis and show a large range of coastal SSS gradients with different signs. Moreover, satellites reveal a global dominance of coastal freshening, primarily related to river runoff over shelves. This work shows a great potential of SSS remote sensing to monitor coastal processes, which would, however, require a jump in the resolution of future SSS satellite missions to be fully exploited.
Jan 29: SPECIAL ATM & OCE FACULTY PRESENTATION SERIES
Dr. Mariana Bernardi Bif
Department of Ocean Sciences, Rosenstiel School
From Rosenstiel School to Rosenstiel School: The Path of a Marine Biogeochemist
Leveraging BGC-Argo Data to Constrain Our Changing Oceans
Recording Available at COMPASS ON DEMAND
In this talk, I will begin by sharing my academic journey in oceanography, from starting at a federal university in Brazil to completing the PhD program in Ocean Sciences at the University of Miami's Rosenstiel School. I will then reflect on the lessons learned during six years outside academia at the Monterey Bay Aquarium Research Institute (MBARI), a cutting-edge non-profit research institute specializing in engineering innovations for ocean applications. At MBARI, I focused on developing chemical sensors for BGC-Argo floats and analyzing their global dataset. The deployment of thousands of these robotic floats equipped with chemical sensors in the global oceans is revolutionizing how we study and constrain biogeochemical cycles. To date, this technology has collected more profiles of nitrate – a key nutrient for ocean productivity – than all oceanographic cruises combined. These profiles are gathered at an unprecedented spatiotemporal resolution: every few days and every few meters of depth. I will provide an overview of BGC-Argo floats, the current state of the global array, and the potential of a multi-platform approach to observing marine biogeochemical cycles – particularly in systems sensitive to extreme events. Finally, I will outline my vision for my new role as faculty at the Rosenstiel School, where I will investigate marine systems using BGC-Argo floats and train the next generation of professionals to harness Argo data in combination with other large-scale ocean datasets.
Feb 05: NO SEMINAR
Feb 12: Dr. Yixin "Berry" Wen
Department of Geography, University of Florida, Gainesville
Guest of Brian Mapes, Department of Atmospheric Sciences
Taming AI for Meteorological Research: The Role of Interpretable AI in the AI Era
Recording Available at COMPASS ON DEMAND
As we enter the AI era, domain scientists face a critical question: What can we do to harness AI effectively for scientific discovery? AI has demonstrated remarkable capabilities, from accelerating simulations to uncovering hidden patterns in complex datasets. While these advancements offer unprecedented opportunities, they also raise concerns – AI models often function as "black boxes", making it difficult to connect their outputs to established scientific principles. This lack of interpretability can undermine trust and limit adoption, particularly in fields like meteorology where physical understanding is critical.
In this talk, I will explore how interpretable AI can bridge this gap, highlighting its potential to generate explicit, physically meaningful equations rather than opaque neural networks. Through three case studies from my lab, I will showcase how interpretable AI can enhance scientific understanding:
Satellite Precipitation Retrieval: Using AI-based approaches to interpret precipitation retrieval algorithms from AMSU data, we identified critical microwave channels (89 and 150 GHz) that directly link to physical processes in the atmosphere.
Quantitative Precipitation Estimation (QPE): By applying symbolic regression models to polarimetric radar data, we derived mathematical expressions that outperform traditional Z-R relationships and existing QPE algorithms, offering new insights into rainfall microphysics.
Tornado Probability Prediction: Leveraging reinforcement learning-based symbolic deep learning models, we developed interpretable equations that outperform the traditional Significant Tornado Parameter (STP) index, providing a clearer understanding of the relationships between key atmospheric variables and tornado risk.
Through these examples, I hope to spark discussion on the evolving role of domain scientists in the AI era and inspire new ways to integrate AI with physical understanding in atmospheric research.
Feb 19: NO SEMINAR (SLAB 103 not available)
Feb 26: Elizabeth Yanuskiewicz
Department of Ocean Sciences, Rosenstiel School
(one-hour OCE student seminar)
Sources and Transformation of Particulate Organic Matter
in the North Atlantic Spring Bloom
Recording Available at COMPASS ON DEMAND
The transport of particulate organic matter (POM) from the upper ocean to depth dominates carbon export and carbon sequestration. Various mechanisms affect the transport of POM to depth, making it difficult to quantify and accurately model carbon export on a global scale. In May 2021, the EXPORTS (EXport Processes in the Ocean from RemoTe Sensing) program sampled a declining phytoplankton bloom in the North Atlantic to understand the mechanisms controlling carbon export in a productive oceanic environment. Together, amino acids and carbohydrates constitute a major proportion of POM, and these organic compounds can provide information on the sources and transformation of POM. We measured the concentrations of carbohydrate monomers and the concentrations, nitrogen isotope ratios, and carbon isotope ratios of individual amino acids across various particle size classes collected from the surface to mid-mesopelagic (30-500 m) depths and over time during the bloom decline. In the euphotic zone, patterns in the isotope ratios of amino acids indicated that POM derived predominantly from phytoplankton, with specific phytoplankton groups influencing POM composition across the different particle size fractions. This phytoplankton-derived POM was transported from the upper ocean to depth, however, microbial and metazoan-related mechanisms altered POM with increasing depth. Results from this study highlight a significant contribution to sinking POM from microbial reworking / biomass, which is a degradative pathway absent from models.
Mar 05: Hope Elliott
Department of Atmospheric Sciences, Rosenstiel School
(one-hour OCE student seminar)
Estimating Aerosol-Derived Phosphorus and Iron Fluxes to the Surface Ocean:
Looking Beyond Mineral Dust to Understand the Aerosol Indirect Effect
on Biogeochemical Cycles
Recording Available at COMPASS ON DEMAND
While many factors affect climate via impacts on radiative forcing, the magnitude of impacts associated with aerosol-related processes remains the most uncertain. Two mechanisms through which aerosols impact radiative forcing have been considered in climate models and projections for decades. However, a third mechanism, the "aerosol indirect effect on biogeochemical cycles," has only been considered in the last 15 years. This mechanism describes aerosols' ability to impact atmospheric CO2 concentration via releasing nutrients that stimulate plant growth upon deposition. For example, in the North Atlantic Ocean, mineral dust deposition releases significant amounts of phosphorus (P) and iron (Fe), which stimulate phytoplankton production and CO2 drawdown. However, we lack definitive estimates for P and Fe bioavailability in mineral dust, and little is known about nutrient release from other aerosol types like volcanic ash. My work shows that P solubility in mineral dust deposited in the North Atlantic has declined since the mid-1990s due to air pollution regulations like the Clean Air Act. I also demonstrate that volcanic ash, in addition to mineral dust, can serve as a source of soluble and bioavailable P to seawater. Finally, Fe in mineral dust is nearly 10% bioavailable to marine phytoplankton, while Fe in volcanic ash is only about 6% bioavailable. I show that aerosol mineralogy and interaction with acidity prior to deposition are the dominant factors controlling aerosol Fe bioavailability. My work provides evidence that atmospheric aerosols besides mineral dust can provide important fluxes of soluble and bioavailable nutrients to the North Atlantic Ocean.
Mar 12: NO SEMINAR (Spring Recess)
Mar 19: Dr. Lorenzo Polvani
Department of Applied Physics and Applied Mathematics, Columbia University, New York
Guest of Brian Soden, Department of Atmospheric Sciences
Surface Warming Caused by Large Volcanic Eruptions?
We will critically re-examine the widely-held belief that large, low-latitude volcanic eruptions cause wintertime warming over the continents in the Northern Hemisphere, and present modeling and observational evidence that such warming – if it exists at all – is so small that post-eruption Eurasian winters are unremarkable, even for events much larger than the largest eruptions of the last millennium.
Mar 26: Victoria Schoenwald
Department of Atmospheric Sciences, Rosenstiel School
(one-hour ATM student seminar)
Understanding Regional Sea Level Rise Acceleration
Along the North American Eastern Seaboard
Sea level rise acceleration continues to be one of the most costly and complex consequences of global warming in recent decades. The East Coast of the United States has experienced higher rates of sea level rise acceleration compared to the global average, leading to increased coastal flooding in this region. Building on previous studies of North Atlantic Ocean climate variability, we investigate basin-wide oceanic and atmospheric influences on East Coast sea level. Regression analysis between NOAA tide gauge sea surface height (SSH) measurements and multiple reanalysis products reveals a consistent positive SSH trend in recent decades, however, the magnitude and spatial distribution of the trends vary across datasets. The Gulf Stream's influence on hot spots of SLR along the East Coast, which has been previously documented, was also investigated. Discrepancies in the magnitude of GS speed and position between observations and reanalysis products was shown raising questions about the role of basin-wide and local wind forcing in modulating the GS strength, position, and coastal sea level. To explore this, we apply anomalous wind stress forcing in the Community Earth System Model Version 1 (CESM1), demonstrating that local winds significantly impact SSH in both the south-Atlantic Bight (Key West, FL to Cape Hatteras, NC) and Mid-Atlantic Bight (Cape Hatteras, NC to Cape Cod, MA). With future projections of oceanic and atmospheric warming due to anthropogenic CO2 emissions, these findings highlight the need for improved representation of steric height trends, mass flux, and GS variability in reanalysis datasets. Additionally, the importance of evolving atmospheric circulation driving hot spots of SLR in conjunction with thermohaline and steric contributions.
Mar 28 (Friday, 9:30 am): Dr. Una Miller
Postdoctoral Fellow
Graduate School of Oceanography, University of Rhode Island
Invited Speaker of the Department of Ocean Sciences
Observing the Multi-Scale Processes Linked to High-Latitude Ocean Ventilation
At high latitudes, cold surface waters sink and spread through the abyss. This "ventilation" of the deep ocean creates a vast sink for anthropogenic carbon and replenishes oxygen to marine organisms at depth. Predictions of how ocean ventilation will respond to rising global temperatures and glacial melt remain uncertain, in part due to the sparsity of observations in the polar and subpolar regions.
Here, I leverage moored observations to examine the formation of two crucial water masses tied to ocean ventilation: Labrador Sea Water (LSW), which feeds into the lower limb of Atlantic Meridional Overturning Circulation, and High Salinity Shelf Water (HSSW), a precursor to Antarctic Bottom Water, a water mass that fills the lowest kilometer of the global ocean. Using a moored array of dissolved oxygen time series, I quantify the net export of oxygen from the Labrador Sea and show that LSW formation is a key contributor to North Atlantic ventilation. As LSW formation is partially decoupled from overturning across the broader subpolar North Atlantic region, a crucial implication is that the future of North Atlantic ventilation will not necessarily follow projected declines in the strength of AMOC. Turning to smaller scales, I use moored turbulence and salinity measurements to examine turbulent mixing of brine in the Terra Nova Bay Polynya, Ross Sea, Antarctica that facilitates the formation of HSSW. I find that Law of the Wall, a simple boundary layer scaling based on wind stress, sufficiently predicts the measurements of turbulence and yields a mixing time scale consistent with observed changes in salinity over depth. This holds despite pervasive Langmuir Circulation in the polynya, which is often thought to invalidate Law of the Wall due to its lack of terms accounting for wave-generated turbulence. Law of the Wall forms the basis for widely-used vertical mixing schemes in ocean models, and these results suggest that its use may not be a dominant source of error when simulating vertical upper ocean fluxes in the polynya, and possibly the upper ocean more broadly. Together, my findings highlight the multi-scale physical processes governing high-latitude ocean ventilation and inform efforts to improve predictions of a changing ocean-climate system.
Apr 02 (9:30 am): Dr. Franz Philip Tuchen
Postdoctoral Associate
CIMAS, Rosenstiel School / NOAA-AOML
Invited Speaker of the Department of Ocean Sciences
Advancing Our Understanding of Equatorial Atlantic Ocean Dynamics
The equatorial Atlantic Ocean plays a crucial role in the global climate system, being influenced by various modes of variability that have significant implications for weather and climate patterns. For over two decades, a comprehensive network of observational platforms - including moored surface buoys, repeat shipboard observations, Argo floats, surface drifters, and more - has been actively monitoring the mean state and variability of the tropical Atlantic. In this seminar, I will present key examples of how the tropical Atlantic observing system has enhanced our understanding of the region’s complex dynamics. Additionally, I will highlight the importance and success of recent interdisciplinary collaborations that combine physical and biogeochemical measurements, providing a more integrated and comprehensive perspective on key processes in the equatorial Atlantic. Looking ahead, I will discuss how sustained observations, along with targeted process studies using a set of innovative observational platforms, are essential for addressing some of the most pressing research questions in the field.
Apr 02: Samantha Medina
Department of Ocean Sciences, Rosenstiel School
(one-hour OCE student seminar)
Apr 09: Karen Papazian
Department of Atmospheric Sciences, Rosenstiel School
(one-hour ATM student seminar)
Apr 16: Dr. Milan Curcic
Department of Ocean Sciences, Rosenstiel School
A Theoretical Model for Wave Tearing by Wind
Apr 23: AVAILABLE
