Atmospheric Sciences


FALL 2017

(3:00 SLAB Seminar Room, unless stated otherwise)

Sep 6 --- Rodrigo Duran (Oregon State University)

"Quasi-steady structures organizing Lagrangian transport."

Lagrangian transport is a difficult oceanographic problem for which solutions are frequently needed. Sensitivity to initial conditions, to the precision of the velocity field or to the intrinsic variability of a chaotic flow, requires more attention to detail than we are usually able to afford. In a quest to bypass these complications, we ask if it is possible to find structures that evolve slowly relative to Lagrangian timescales, while organizing transport. A relatively simple approach capitalizing on recent advances on the theory of Lagrangian Coherent Structures, is successful in finding such structures. This conclusion is reached by direct comparisons with a model and observations, and indirect comparisons with previous observational and numerical studies.
Work in collaboration with F.J. Beron-Vera and M.J. Olascoaga.

Sep 13 --- Xinfeng Liang (USF)

Vertical Redistribution of the Global Oceanic Heat Content

Observations show that the upper ocean has been warming since the 1970s, and it is usually attributed to global warming that is associated with the increasing concentration of greenhouse gases in the atmosphere. The global ocean is implicitly considered as a passive heat reservoir, and it is assumed that the ocean was in equilibrium with the atmosphere before the anthropogenic global warming had occurred. However, the global ocean is a dynamically active heat exchanger involving processes of various temporal and spatial scales and has a memory of thousands of years. Not only the heat exchange between ocean and atmosphere but the vertical heat flux passing the lower face of the upper ocean contribute to the changes in the observed upper ocean heat content. In this talk, I will present the mean and the bidecadal change of the ocean vertical heat flux as well as the related physical processes from a dynamically consistent and data-constrained ocean state estimate – ECCO (Estimating the Circulation & Climate of the Ocean). Implications of the vertical redistribution of ocean heat on the changes of the upper and deep ocean heat contents, particularly the recently much-debated global warming “hiatus”, will also be discussed.

Oct 11 --- Dr. Lars Hole (Norwegian Meteorological Institute)

Nov 2 --- Dr. Thomas Wahl (University of South Florida)

Apr 11 --- Dr. Colwell