Spring 2017 Seminar Schedule

Physical Oceanography Seminars usually take place at 10:30 am on Fridays in the Corless auditorium.

Jan 27 canceled

Feb 3 Amy Bower WHOI
Title: Transport of ISOW through the Charlie-Gibbs Fracture Zone and the impact of the North Atlantic Current on ISOW transport variability

Feb 10 David Nieves WHOI (canceled)
Title: Non-hydrostatic, rapidly rotating and stably stratified flows

Feb 17 Jaime Palter GSO
Title: Global Climate Impacts of North Atlantic Ocean Variability

Feb 24 Zhitao Yu NRL
Title: The impact of ocean surface currents on Sverdrup transport in the mid-latitude North Pacific via the wind stress formulation

Mar 3 Rhys Parfitt WHOI
Title: To what extent do ocean frontal zones affect mid-latitude weather and climate?

Mar 10 Georgi Sutyrin GSO cancelled
Title: Nonlinear transformations of baroclinic eddies

Mar 17 Spring Break

Mar 24 Kelly Lombardo UCONN

Mar 31 Dong-PingWang SUNY

Apr 7 Michael Spall WHOI canceled
Title: Coupled Ocean-Atmosphere decay scale along eastern boundaries

Apr 13 Susan Lozier DUKE
Special Thursday lecture and reception
5th Annual Scott W. Nixon Lecture: A 21st Century Look at the Global Ocean Conveyor Belt
3:30 - 5:00 pm, Coastal Institute Auditorium; reception to follow at 5:00 pm in Studio Blue

Apr 14 no Friday seminar

Apr 21 Alexey Fedorov Yale 1:30 pm
Title: Is Arctic sea ice decline driving the slow-down of the Atlantic meridional overturning circulation?
Abstract: One of the consequences of ongoing climate change is the rapid loss of Arctic sea ice that occurred over the past several decades. This sea ice retreat exposes the ocean to additional heat and freshwater fluxes, generating positive anomalies in surface buoyancy fluxes over the Arctic. In this study, using an optimal flux perturbations framework, we first estimate the sensitivity of the Atlantic meridional overturning circulation (AMOC) to changes in surface buoyancy forcing over the Arctic and globally. We find that, whereas on a decadal timescale the subpolar North Atlantic region is the primarily driver of the AMOC weakening, on multi-decadal timescales (20 years and longer) it is the Arctic ocean that largely controls the AMOC intensity. On these longer timescales Arctic surface buoyancy fluxes are nearly twice as effective for weakening the AMOC as those in the North Atlantic. Furthermore, anomalous surface fluxes in the Arctic act to weaken ocean poleward heat transport in the entire Atlantic, which can explain the so-called 'Warming Hole' in the subpolar North Atlantic. A suite of numerical experiments using a global climate model (CESM) wherein we closely replicate the observed sea ice decline, as well as CMIP5 climate simulation, confirm that the remote control of the AMOC intensity and heat transport from the Arctic is indeed a robust feature of global climate change.

Apr 28 Claudia Cenedese WHOI
Title: Do Icebergs melt like Glaciers?
Abstract: Icebergs calving into Greenlandic Fjords frequently experience strongly sheared flows over their draft, but existing melt parameterizations do not consider the effect of relative velocity on the melting along the iceberg sides. We will discuss a series of novel laboratory experiments investigating the dependence of side submarine melt rates on relative velocity. We show, for the first time, that two distinct regimes of melting exist depending on the melt plume behavior (side-attached or side-detached), with correspondingly different meltwater spreading characteristics. In a homogeneous fluid, iceberg meltwater spreads at the surface for attached melt plumes and mixes as deep as the iceberg draft for detached plumes. Including this velocity dependence in melting parameterizations applied to observed icebergs increases iceberg side melt in a fjord environment by an order of magnitude, consistent with observations of iceberg submarine melt rates. We show that both attached and detached plume regimes are relevant to icebergs observed in a Greenland fjord.

May 5 David Nieves WHOI
Title: Non-hydrostatic, rapidly rotating and stably stratified flows

May 12 Viviane Menezes WHOI
Title: Accelerated freshening of Antarctic Bottom Water in the Southeast Indian Ocean
Abstract: Antarctic Bottom Water (AABW) is a key component of the ocean's overturning circulation and spreads into the abyss of the major ocean basins. Changes in its properties have been shown to affect the circulation, ocean heat content, sea level, and Earth's climate over decadal to glacial-interglacial time scales. In this study, the data collected during the third occupation of the GO-SHIP I08S hydrographic line in February-March 2016 are compared with previous observations collected in 1994 and 2007.  The comparison reveals a striking accelerated freshening of AABW between 2007 and 2016 in the Australian-Antarctic Basin, which is at least four times stronger than that found in the earlier period (1994-2007). It is conjectured that this strong freshening is linked to the abrupt iceberg (B9B)-glacier (Mertz Glacier Tongue) collision and calving event that occurred in 2010 on the George V/Adelie Land Coast, an AABW source region for the Antarctic-Australian Basin.

May 19 Katinka Bellomo LDEO 12 pm (noon)
Title: Changes in low-level clouds over the Pacific Ocean and implications for Pacific Decadal Variability
Abstract: Previous research shows that mechanisms of Pacific Decadal Variability are debated and there could be multiple drivers. However, even though mechanisms are uncertain, identifying processes that increase the persistence of Pacific Ocean SST anomalies on decadal timescales would lead to increased predictive skill. Here I focus on the role of stratocumulus cloud decks over the subtropical northeast and southeast Pacific. I will show that decadal variability in SST is associated with observed anomalies in cloud cover leading to positive cloud radiative effect at the surface, which suggests that low-level clouds provide a positive feedback on SST anomalies. From observations alone, however, it's not possible to quantify the effects of low-level clouds and isolate them from other processes. Using idealized model experiments in which I manipulate the strength of low-level cloud feedback, I will demonstrate that low-level cloud anomalies lead to increased persistence of SST on decadal timescales not only locally, but also basin-wide through coupling with large-scale atmospheric circulations and surface heat fluxes. Finally, I will discuss observed trends in cloud cover in surface and satellite observations and discuss implications for current and future Pacific climate. 

Last updated 05/14/2017