SPRING 2026
Fridays at 11:00 am, Rosenstiel School Auditorium / Virtual Auditorium
(unless stated otherwise)
Jan 16: NO SEMINAR
Jan 23: NO SEMINAR (High-Performance Computing Town Hall)
Jan 30: NO SEMINAR
Feb 06: NO SEMINAR (Recruitment Weekend)
Feb 13: NO SEMINAR (Rosenstiel School Faculty Meeting)
Feb 20: STUDENT SEMINARS
Sam Ephraim (MPO)
Closed-to-Open-Celled Mixed-Phase Cloud Transition Over the Nordic Seas
Under High Aerosol Loading
Closed-cell to open-cell mixed-phased cloud transitions within marine cold air outbreaks (MCAO) remain challenging to model and predict, in part because underlying coupled processes (microphysics, turbulence, and radiation) remain poorly observed at process-level scales. While aerosol concentrations in the Arctic are typically low, the Cold Air Outbreak Experiment in the Sub-Arctic Region (CAESAR) observed a closed to open-celled transition within a MCAO over the Nordic Seas with boundary layer aerosol and cloud condensation nuclei concentrations surpassing 650 cm–3, likely sourced from industrial emissions in Siberia. We find that liquid-cloud processes govern the production of frozen precipitation, even at cloud temperatures colder than –15°C, pivotal for forming cold pools and initiating cloud breakup. High aerosol concentrations within a boundary layer containing a closed-celled convective cloud deck initially result in small drop sizes (cloud top effective radius of 6 µm), limiting riming efficiencies. Precipitation is all ice, with an initial dominant habit consisting of dendrites and aggregates. As closed-celled clouds deepen, aerosol depletes to concentrations of 380 cm–3 through precipitation scavenging and dilution with clean free tropospheric air, resulting in increased drop sizes. Increased riming efficiency increases the prevalence of rimed dendrites and small graupel (~1 mm) that reach the surface and form cold pools breaking up the cloud deck into open-celled convection. Depleted aerosol concentrations (~125 cm–3) within open-cells support larger drop sizes (15-30 µm) and sporadic in-cloud freezing drizzle. Heavy precipitation shafts contain abundant large graupel (~5 mm) with liquid equivalent precipitation intensities reaching 2 mm hr–1.
Ian Gifford (MPO)
ENSO Phase Prediction in a Warming Climate
Recent years have seen an apparent disconnect between oceanic signatures in the ENSO key monitoring region and the expected atmospheric response. Recent studies have concluded a new proxy for ENSO phase monitoring and prediction is necessary to accommodate an ocean whose tropics are warming too quickly for the use of decadal climatologies as a baseline to measure anomalous temperatures. Increased warming has led to an overestimate of the ENSO warm phase amplitude and consequently the expected impact patterns on global regions most sensitive to ENSO. Naturally, underestimates for the ENSO cold phase are inherent and have also been noted. This study examines the teleconnection capture ability between the traditional Oceanic Niño Index, and the newly developed relative Oceanic Niño Index. Also investigated are the equatorial Pacific zonal sea surface temperature gradient and the area of the equatorial Pacific cold tongue. The latter two indices feature the advantage of not requiring the use of long-term means. Statistical methods utilized include pattern correlation, which isolates expected patterns on ENSO sensitive regions as a response to equatorial Pacific Ocean surface conditions. Precipitation, geopotential height anomalies, and the Rossby wave source are used to diagnose each index's ability to represent the expected response from conditions in the equatorial Pacific.
Steven Akin (MPO)
Near-Inertial Wave Propagation in a Cyclonic Eddy Barrier Layer
Cyclonic eddies (CE) are common features in the Gulf that have been observed to affect anticyclonic eddy (AE) shedding, tropical cyclone (TC) intensity, and lateral transport of freshwater from the Mississippi River Plume. The literature suggests that wind-driven shear within a CE reaches a maximum at the base of the mixed layer (ML), often resulting in entrainment and cooling through near-inertial currents and shear instabilities. By contrast, barrier layers (BL) can form between the ML and isothermal layer (ILD) depths that can impede vertical motions and fluxes. In this scenario, the MLD is decoupled from the pycnocline (temperature and salinity), and wind-driven shear maxima are found at the depth of the maximum salinity gradient, often corresponding to the BL's lower interface. High-resolution observations of well-resolved near-inertial currents, buoyancy frequencies, and shear instabilities reveal enhanced stratification and the CE's positive relative vorticity modulated near-inertial wave propagation. That is, these energetic near-inertial wave packets impacted the BL's variability in the days following Hurricane Michael (2018). These results have important implications for TC development and upper-ocean mixing.
Feb 27: AVAILABLE Week of AGU Ocean Sciences Meeting!
Mar 06: Dr. Kathy Pegion
School of Meteorology, National Weather Center, University of Oklahoma
Guest of Emily Becker and Ben Kirtman
Mar 13: NO SEMINAR (Spring Recess)
Mar 20: NO SEMINAR (Rosenstiel School Research Day)
Mar 27 (MSC 123): Dr. Igal Berenshtein
Department of Marine Biology, School of Marine Sciences, University of Haifa, Israel
Guest of Claire Paris, Department of Ocean Sciences
Apr 03: STUDENT SEMINARS
Katie Simi (OCE)
Paloma Cartwright (OCE)
Hanna Chaja (ATM)
Apr 10: STUDENT SEMINARS
Trina Rosing (OCE)
Gabby Ricche (OCE)
Snigdha Samantaray (MPO)
Apr 17: STUDENT SEMINARS
Rachel Sampson (MPO)
Michael Perez (ATM)
Dailen Jeng (OCE)
Apr 24: STUDENT SEMINARS
Josiah Kaiser (ATM)
Jessie Yang (OCE)
Sabrina Glynn (OCE)
