The Physics of Oceans and Atmospheres (POA) research discipline contains two core subdisciplines: Physical oceanography and atmospheric sciences.
Teaching and Research Faculty
Andrea Allan, Jack Barth, Jesse Cusack, Simon de Szoeke, Edward Dever, Melanie Fewings, Jonathan Fram, Amrapalli Garanaik, Jessica Garwood, Jennifer Hutchings, Andrea Jenney, Mike Kosro, Jim Lerczak, Ricardo Matano, Phil Mote, Jonathan Nash, Larry O'Neill, Tuba Özkan-Haller, Brodie Pearson, David Rupp, Roger Samelson, Andreas Schmittner, Kipp Shearman, Karen Shell, Emily Shroyer, Nick Siler, Eric Skyllingstad, Yvette Spitz, Justin Wettstein, Greg Wilson, Ed Zaron, Seth Zippel
POA Email Lists
Go to the CEOAS Email Lists Box Note and search for "poa" using Ctrl-F (Windows, Linux, Chrome OS), ⌘-F (Mac), or tap (upload) then Find on Page (phone or tablet).
Physics of Oceans and Atmospheres Seminar Series
Tuesdays from 3:30 to 4:30 p.m. in Burt 193 (except where noted)
Fall Term 2024
- Tuesday, September 24, Shih-Nan Chen, Asymmetry in the zonal drift of mesoscale vortices: From single vortex to vortex clusters
- Tuesday, October 8 – Inés Leyba, Air-sea interaction in the South Atlantic and its role in precipitation in southern South America
Abstract: This seminar presents an in-depth analysis of air-sea interactions in the South Atlantic Ocean and its role in precipitation variability in southeastern South America across multiple time scales, including daily, seasonal, interannual, and long-term trends.Our study focuses on trends in sea surface temperature (SST) and air-sea heat fluxes, which show strong regional and seasonal variability, with the most pronounced changes occurring in the Brazil Current and its extension into the Brazil-Malvinas Confluence. We also explore interannual SST variability and its relationship with precipitation patterns in southern South America, highlighting the South Atlantic as a critical moisture source. Using numerical simulations with the Dynamic Recycling Model, we identified three main regions in the South Atlantic contributing to continental moisture: the Tropical Atlantic, Subtropical Atlantic, and Southwestern Atlantic. Our results further show how these regions influence daily precipitation events in southeastern South America.
- Tuesday, October 15 – Takenobu Toyota, Interannual variability of sea ice dynamics conditions in the northern hemisphere
~ Did the regime shift in ice conditions affect the sea ice dynamics? ~
Abstract: Recently sea ice conditions have been changing rapidly in the northern hemisphere (NH). The sea ice extent has decreased significantly especially in summer, resulting in the decrease in multi-year ice (MYI) fraction and the spread of seasonal ice zones. Associated with the loss of MYI, mean ice thickness in the Arctic Ocean also decreased significantly. These significant changes in ice conditions have accompanied changes in sea ice dynamical properties such as increases in ice drift speed. Our motivation of this study is to examine the change in sea ice dynamics processes from the perspective of deformation processes, which has not been fully understood yet but is an important issue to predict the sea ice conditions in the future. This issue is closely related to sea ice rheology. While traditionally the Viscous-Plastic (VP) rheology (Hibler model) has been adopted in many numerical sea ice models, its validity was not necessarily confirmed from observational data. To address this pr
oblem, we examined the regional characteristics and their interannual variability of parameters related to sea ice dynamics, focusing on the shape (aspect ratio: e) of the elliptical yield curve and deformation conditions in winter of NH using AMSR-E&2 derived gridded ice drift datasets with a grid spacing of 60 km for the period of 2002 to 2022.
The results are summarized as follows: (1) VP rheology in Hibler model appears to work efficiently in most cases (mean optimal e = 1.97±0.25), but some regionality was found in optimal e values. Relatively high values are estimated in Greenland Sea (2.6) and Beaufort Sea (2.1). (2) An increasing trend was observed for optimal e values in the Beaufort Sea as well as for shear component of strain rate. It seems consistent if we consider that energy consumption due to lateral friction is becoming more significant there. (3) Overall, the likelihood of ridging is shown to have a slightly increasing trend in NH except for several areas (e.g. Sea of Okhotsk).
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- Thursday, October 17, 2:30 to 3:30 p.m. in Burt 193 – William Xu, Parameterization of frequency-dependent internal wave drag
Abstract: Input of tidal energy into the world’s oceans is approximately 3.5 TW, of which about 30% is dissipated in the open ocean due to internal wave generation at rough topographic features. This process converts barotropic tidal energy into internal wave (baroclinic) energy, and the effect on the barotropic current is similar to that of a linear drag. In coarse resolution global ocean models, the barotropic-to-baroclinic energy conversion (i.e., the internal wave drag) must be parameterized. One of the difficulties in developing such a parameterization scheme is that the internal wave drag is frequency dependent. In order to properly represent the internal wave drag without affecting any non-tidal, low-frequency motions, the instantaneous tidal velocities must be calculated while the model is running. In this talk, I will show that the instantaneous tidal velocities can be obtained by band-pass filtering the model output, utilizing a second order ODE that is configured as a streaming filter and coupled to the governing equations of the model. The algorithm allows us to control the drag applied to the diurnal and semi-diurnal frequency bands separately. The simulation results suggest that, by adjusting the strength of the drag applied to the M2 velocity, wecan change the resulting M2 elevation without affecting the K1 elevation. - Tuesday, October 22 – Emily Hayden, Characterizing the role of the atmosphere in Bering Sea temperature variability
Abstract: The Bering Sea is experiencing accelerated rates of change relative to the rest of the globe and has been subject to multiple instances of historic climate extremes in recent years. In addition, it has been impacted by the near global increase in marine heatwaves, a trend that is projected to be amplified under continued climate change. The role of air-sea coupling in driving amplified polar climate variability remains poorly quantified, largely due to a lack of satellite and in-situ observations of key variables describing these interactions and their role in climate variability. Our work seeks to address these open questions through an analysis approach that leverages reanalysis data sources to understand the impact of high-latitude air-sea interactions on the physical state of the Bering Sea.
We characterize the relationship between the atmospheric state and air-sea heat flux variability using ECMWF ERA5 fields and investigate the seasonal evolution of the heat flux terms and their influence on the annual heating cycle of the Bering Sea. We show strong evidence that the surface winds and air temperature drive much of the Bering Sea upper ocean temperature variability through mediation of the surface turbulent heat fluxes. We focus on the period 2010-2022, which is coincident with a period of intense regional climate extremes, including record warm ocean temperatures, multiple years of historically low sea ice extent, and an increase in air-sea heat exchange variability. Our results advance fundamental understanding of the role that the large-scale atmosphere plays in the thermal state of the Bering Sea.
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