FALL 2025
Fridays at 11:00 am, Rosenstiel School Auditorium / Virtual Auditorium
Aug 22: NO SEMINAR
Aug 29: NO SEMINAR
Sep 05: NO SEMINAR
Sep 12: NO SEMINAR
Sep 19: SPECIAL ATM & OCE FACULTY PRESENTATION SERIES
Dr. Igor Kamenkovich
Department of Ocean Sciences, Rosenstiel School
Beyond Diffusion: Capturing the Complexity of Mesoscale Eddy Transport
Recording Available at COMPASS ON DEMAND
Mesoscale eddies – ocean currents spanning tens to hundreds of kilometers – play a key role in transporting tracers across the world's oceans, shaping the large-scale distributions of temperature, salinity, and other properties. Yet most climate models cannot resolve these eddies, relying instead on parameterizations that reduce their impact to turbulent diffusion along tracer gradients. However, evidence from numerical simulations reveals that eddy-driven mixing is far more complex, with diagnosed turbulent diffusion varying by location, time, and direction. Moreover, eddies frequently sharpen tracer fronts and can produce up-gradient fluxes that defy traditional diffusive models. This work introduces a novel framework, blending generalized eddy-induced advection with isopycnal diffusion, to more accurately represent eddy effects on tracers. By capturing eddy-driven filamentation and the sharpening of oceanic fronts, this approach offers a path to more physically consistent parameterizations for coarse-resolution ocean models. Ultimately, these results suggest the need to move beyond purely diffusive approaches and toward methods that can truly capture the complexity of eddy transport, improving the representation of key eddy effects in climate simulations.
Sep 26: Dr. Ved Chirayath
Department of Ocean Sciences, Rosenstiel School
Updates From Your Neighborhood Aircraft Center for Earth Studies (ACES)
In this talk, I share several updates and research advances from the Aircraft Center for Earth Studies, introduce our new long endurance electric aircraft and research vessels, new NASA-funded drone center, courses, and highlights from recent expeditions and technology developments. ACES research focuses on inventing and developing next-generation in-situ and remote sensing technologies, airborne and spaceborne instruments, and artificial intelligence (AI) to better understand and protect our natural world, principally using space exploration technologies. Ultimately, my investigations aim to extend our capabilities for studying and protecting life on Earth as well as aiding in the search for life elsewhere in the universe. I seek to advance knowledge about the Earth system at planetary scales and inform analog research for planetary science at large. I extensively use Earth's Ocean, our largest biosphere, and extreme environments as analogs for planetary and space exploration. In a 2024 TEDx talk, I articulated my vision to map the world's oceans using NASA space exploration technologies I invented for an oceanography moonshot and pave the way for exploration of ocean worlds across the solar system. Most recently, as a Moore Inventor Fellow, I am inventing an advanced remote sensing technology that can see even deeper underwater, and was awarded a NASA Instrument Incubator Program grant to build a fluorescent LiDAR, FLOR-A, for airborne and spaceborne detection of biogenic markers and anthropogenic marine debris and plastics.
This talk will feature additional selected research highlights including our:
1) DoD SERDP project, Automated Airborne Detection of Underwater Munitions using NASA Multispectral Passive & Active MiDAR Fluid Lensing, which used Rosenstiel's Broad Key research station for the automated airborne detection and localization of underwater military munitions in a complex marine environment.
2) Automated Motile Marine Wildlife Detection in Coral Reefs using NASA Airborne Fluid Lensing, where we developed a new airborne fluid lensing-based marine wildlife detection algorithm to characterize moving underwater wildlife using raw fluid lensing data and solutions. The detector assesses marine animals by analyzing time series imagery, deriving and characterizing animal planform area, velocity, and abundance for keystone reef species across depths of ~0-20m, at the cm-scale, in complex coral reef ecosystems over dozens of square kilometers.
3) 2025 Antarctic Expedition Highlights, where several novel technology demonstrations were successfully executed to collect raw data for airborne fluid lensing and contemporaneous passive thermal infrared imaging of cetaceans, as well as demonstration of the airborne NASA MiDAR instrument in a suitable planetary analog environment.
4) NASA MarineVERSE Global Coral Reef Habitat Mapping Project that uses airborne fluid lensing and NeMO-Net, a crowd-sourced citizen science video game, to map and monitor change in reef ecosystems.
Additionally, highlights from my new course, MSC 332 – Planetary Science, the Search for Life, & Oceans across the Solar System, a research-experiential semester course that gives students first-hand lab experience with state-of-the-art NASA instruments, participating in field trips on an electric research vessel, telescope time for planetary observations, ocean biology labs, and physics and optics labs.
Oct 03: NO SEMINAR
Oct 10: Dr. Claudia Benitez-Nelson
School of the Earth, Ocean & Environment, University of South Carolina, Columbia
Invited Speaker of the Department of Ocean Sciences
Understanding Sinking Particle Flux and Composition in Coastal Marine Systems
Sinking particles play a critical role in the ocean by transporting material from the surface ocean to depth. The magnitude and composition of this downward flux influence a suite of processes, ranging from carbon storage and contaminant removal to microbial diversity and benthic foodwebs. Particle flux remains poorly understood, in part due to the stochastic nature of flux events and the multitude of abiotic and biogeochemical reactions that drive particle composition. This seminar will dive into our current understanding of particle export, focusing on connecting surface water measurements with those in underlying sediments. Time-series sediment trap deployments in the Cariaco and Santa Barbara Basins (and others) will be used as case studies.
Oct 17: NO SEMINAR
Oct 24: Dr. Rodrigo Duran
Planetary Science Institute, Tucson, Arizona (residing in Stuart, Florida)
Guest of Josefina Olascoaga, Department of Ocean Sciences
On the Physical Mechanisms Controlling Loop Current Eddy Separations
and Their Seasonality
Recording Available at COMPASS ON DEMAND
The Loop Current (LC) and its eddy-shedding dynamics profoundly impact the Gulf of Mexico, influencing hurricane intensity, offshore platform safety, algal blooms, and the fishing industry. However, the driving mechanisms behind the well-documented seasonality of eddy-shedding events have remained a long-standing open question. This study resolves that question by shifting from a descriptive kinematic view to a causal energetic framework. This breakthrough is achieved through the combination of three complementary methodologies: canonical energy transfers to reproducibly quantify key instabilities, information-flow theory to independently confirm causality, and vorticity transport barriers from nonlinear dynamical systems theory to explain the permanent separation mechanism. Using 30 years of altimetry data and a 22-year reanalysis, we trace a direct causal chain: The summer seasonal maximum in mean kinetic energy of the Yucatan Current drives intense cyclonic vorticity production via barotropic instability. This vorticity leads to LC frontal eddies that cut through the LC, and the formation of a vorticity transport barrier causing the separation to become final as it dynamically severs the new eddy from the main current. The rarity of December shedding events arises from the combined effects of reduced vorticity production and strong wind-driven damping of eddies. This framework reveals that the separation mechanism exists year-round, with seasonality emerging from the modulation of energy pathways, providing a theoretical foundation for LC dynamics and a physical basis for predicting critical events related to tropical cyclone intensification and offshore platform safety.
Oct 31: NO SEMINAR (Rosenstiel School faculty meeting)
Nov 07: STUDENT SEMINARS
Cameron Pine (ATM)
Using a Novel Tropical Cyclone Radar Database to Observe Moderately Sheared Storms
Early in a tropical cyclone's evolution, moderate vertical wind shear can tilt its inner core structure, leading to an asymmetric precipitation distribution, often prompting operational forecasting challenges. When hurricane hunter aircraft are unavailable to probe these developing systems, coastal Doppler radar networks in the U.S. can fill the gap by acting as "virtual hurricane hunters", providing critical observations in regions without aircraft reconnaissance. Our study examines 43 tropical cyclones (23 with dual-Doppler coverage), retrieving three-dimensional wind fields using the multi-Doppler analysis technique after rigorous quality control to ensure reliability. These frequent, high-resolution radar observations capture crucial inner-core processes – including how a tilted vortex slowly realigns, leading to subsequent intensification. We leverage our radar dataset to produce a composite observational analysis of storm structure, revealing common patterns in precipitation distribution, vortex tilt, and intensity change across numerous cases. Hurricanes Elsa and Nicholas (2021) serve as detailed examples within the broader dataset, illustrating how persistent shear influences rainfall asymmetry and vortex misalignment. In addition, we incorporate supplementary observations, including dropsonde-derived thermodynamic profiles, to examine the role of environmental dry air entrainment. The results demonstrate a clear benefit: Ground radar networks can provide continuous, detailed insights when other observational tools are absent, thereby advancing our scientific understanding of a storm's evolution in sheared environments.
Victoria Pizzini (ATM)
Validation and Intercomparison of SAR-Derived Wind Fields in Tropical Cyclones
Using In-Situ and Satellite Data
The National Oceanographic Partnership Program project "Hurricane Coastal Impacts" brings together over ten institutions from the U.S. and the Netherlands to improve the predictability of hurricane-induced damages. As part of this effort, our team at the Rosenstiel School and CSTARS focuses on rapid mapping of impacts on land and enhancing wind and wave field products over the ocean. A separate collaborative effort supporting this goal is NOAA's SARWIND project, which obtains very good synthetic aperture radar (SAR) coverage of tropical cyclones through coordination with the Canadian Space Agency. By aligning SAR satellite overpasses with NOAA P-3 aircraft reconnaissance missions, SARWIND enables collocated high-resolution SAR-based wind field retrievals and in situ measurements with dropsondes and Tail Doppler Radar (TDR). Using this unique combination of datasets, our study presents analyses from the 2016-2024 Atlantic hurricane seasons, with a detailed case study of Hurricane Helene, which featured an unprecedented triple overpass by RADARSAT-2, the RADARSAT Constellation Mission, and a European Sentinel-1 satellite within a one-minute window, coinciding with P-3 flight data. Preliminary results show a consistent positive bias of 1-3 m s⁻¹ in SAR-dropsonde wind speed comparisons, with the largest variability observed in the northeast storm quadrant. SAR vs. TDR analyses suggest that SAR tends to overestimate winds in deep convective regions, likely due to enhanced C-band backscatter from rain-induced surface roughness. These findings support the development of a robust validation framework for SAR-derived wind retrievals and contribute to our objective of advancing remote sensing tools for improved hurricane analysis.
Nov 14: STUDENT SEMINARS
Caitlin Martinez (ATM)
Diagnosing Ocean Memory in ENSO Initial Conditions:
Insights From CESM2 Release Experiments
Subsurface preconditioning – the buildup of anomalous ocean heat content in the equatorial Pacific – is widely considered necessary for ENSO (El Niño - Southern Oscillation) event development. But not all variability associated with ENSO can be explained by such deterministic dynamics. Recent studies reveal that ENSO-like events can be initiated and grow to substantial amplitude independently of preceding events, preconditioning, or large-scale wind stress triggers. Meanwhile, forecasts initialized from preconditioned states exhibit reduced spread and shifted outcome distributions, consistent with theoretical expectations. The extent to which this "ocean memory" constrains event evolution, however, remains unresolved. We test this concept in CESM2 (Community Earth System Model 2) with a suite of ensembles initialized from contrasting climate states within a predictability experiment context. Ensemble forecasts initialized from ENSO-neutral states generate balanced ENSO statistics, demonstrating that events readily develop without preconditioning. In contrast, ensembles initialized in March from a high-frequency, high-amplitude periodic ENSO simulation behave unexpectedly: Despite strong warm preconditioning, 40% evolve into La Niña by December, while 54% of cold-preconditioned members generate El Niño. This is a stark departure from previous work where preconditioning reliably constrains outcomes – warm preconditioned members produce warm events, cold preconditioned members produce cold events. What, exactly, in these initial conditions carries that ocean memory forward and shapes how events unfold months later? In this talk, we explore what characteristics of the preconditioned initial state determine whether ensemble members develop into events that match or oppose the subsurface signal. Understanding these initial condition sensitivities is critical for improving seasonal prediction when preconditioning should theoretically provide the greatest predictive advantage.
Christina Schuler (ATM)
Coupled Variability in the Gulf Stream-Nash System
and Its Influence on North Atlantic Tropical Cyclones
The intensity and position of the North Atlantic Subtropical High (NASH) and the Gulf Stream play prominent roles in determining the trajectory of North Atlantic tropical cyclones (TCs). A strengthening and southwest shift of the subtropical high is consistent with an increase in straight-moving tropical systems; however, the impact of the Gulf Stream on NASH variability and consequent feedback mechanisms are less understood. This research analyzes the coupled dynamics between the Gulf Stream and the subtropical high by incorporating 850-hPa geopotential heights, sea-surface temperature (SST), and zonal and meridional ocean current velocities. Maximum covariance analysis (MCA) is employed to determine dominant modes of variability among these fields and to display ocean-atmosphere interactions. Results demonstrate that stronger NASH-driven trade winds intensify the meridional SST dipole in the Atlantic and enhance northward heat transport. It further is hypothesized that an increase in northward heat transport reinforces the NASH, amplifying the likelihood for westward and/or straight-moving cyclones.
Shanna Chamhitt (ATM)
Investigating Non-Propagating Waves in the Outflow Layer of Tropical Cyclones
Using Geostationary Satellite Data
Increasing attention has been directed toward the upper outflow layer of tropical cyclones, where key dynamical processes remain poorly identified. Wave activity in this region is thought to be influenced by internal storm dynamics as well as its surrounding environment, and may provide insight into storm intensity, suggesting the need to better understand wave behavior in the outflow region. Studies by Nolan et al. (2017, 2020) that investigated spiral gravity waves in tropical-cyclone outflows also revealed the presence of another distinct wave pattern – non-propagating waves (NPWs). This study focuses on NPWs, which we define as features that resemble spiral gravity waves but lack their outward propagating motion. We investigate whether NPWs can be quantitatively identified using geostationary and mesoscale sector satellite data, while noting the environmental conditions and patterns in which they usually develop. Visible imagery from major West Pacific and North Atlantic tropical cyclones (2014-2024) are manually inspected, revealing NPWs in most storms, particularly during periods of intensification and low wind shear. Linear transects of normalized radiance are extracted to distinguish outward-propagating gravity waves from NPWs. Peaks in the radiance profiles, interpreted as individual waves, are identified and tracked to estimate propagation speeds. Although difficult to quantify directly, NPWs exhibited spatial and temporal continuity, supporting their identification as coherent wave-like features. This study represents an initial survey toward understanding NPWs, laying the groundwork for future efforts to objectively track and analyze their behavior in the tropical cyclone outflow.
Nov 21: Samantha Medina
Department of Ocean Sciences, Rosenstiel School
(one-hour OCE student seminar)
Insight Into the Growth and Decay of Wind-Driven Waves in Coastal Zones
Waves in coastal zones are affected by coastal winds, bathymetry, and coastal topography. Recent direct measurements of wind stress over the nearshore (Shabani et al., 2014, Ortiz-Suslow et al. 2015/2018, Grachev et al., 2018) have demonstrated the non-validity of COARE (a widely used drag coefficient parameterization) and Monin-Obukhov similarity theory (MOST) in some coastal regions – even for onshore winds. It is hypothesized that the interaction between onshore winds and coastal topography may be at fault for this disparity. As for offshore winds, the appropriate drag parameterizations to use are completely undefined due to the theoretical gaps and sparse measurements. Therefore, in-situ observations of wind and wave fields in coastal zones are key in understanding how wind-driven waves in the coastal zones propagate in the presence of swell. To observe coastal land-air-sea interaction processes, the Coastal Land-Air-Sea (CLASI) project was conducted over three years in Monterey Bay, California, and Pensacola, FL. By deriving the directional wave spectra of various coastal zones of interest, we can observe the growth and decay of wind-driven waves in fetch-limited cases. My research has examined the efficacy of various in-situ sensors (Air Sea Interaction Spar Buoys and Spotter buoys) in deriving the directional wave spectra of these sites of interest, and how these measurements compare to those derived by current wave spectral models. Once we understand the nuances of our in-situ measurements, we can then derive the relationship of wind to wave growth in the presence of swell for fetch-limited cases to develop "coast-aware" parameterizations to be used in current wave spectral models.
Nov 28: NO SEMINAR (Thanksgiving Recess)
Dec 05: SPECIAL ATM & OCE FACULTY PRESENTATION SERIES
Dr. Roland Romeiser
Department of Ocean Sciences, Rosenstiel School
SPRING 2026 PREVIEW
Jan 23: NO SEMINAR (High-Performance Computing Town Hall)
Mar 06: Dr. Jane Baldwin
Atmospheric Integrated Research, University of California Irvine
Guest of the Department of Atmospheric Sciences
Mar 20: NO SEMINAR (Rosenstiel School Research Day)
Apr 03: Dr. Peisen Tan
Department of Marine Sciences, University of Connecticut, Groton
