Please note - at this time, in-person seminars in the APAM Department are only open to Columbia University ID holders. Others are invited to participate remotely. Email [email protected] for the Zoom link.
 

Speaker: Isaac Held, NOAA GFDL/Princeton

TItle: "Possible connection between the Ozone Hole and ENSO trends: A stratospheric causal chain"

Abstract: The evolution of the tropical Pacific over the past few decades has been surprising, with a trend favoring the La Nina phase, unlike that forced in most models by increasing CO2.  Whether this discrepancy is due to internal variability or errors in the response to external forcing is of central importance to the future evolution of regional climate and estimates of climate sensitivity.  There are several hints that the Antarctic Ozone Hole has been responsible for this anomalous behavior of the Pacific.  I will discuss a possible stratospheric causal chain, passing through lower stratospheric equatorial temperatures,  that could be partially responsible for this connection.  The talk will be speculative, with the goal of encouraging others to look at some of the links in this chain.

Bio: Isaac Held retired in 2020 from the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration on Princeton’s Forrestal Campus, and from teaching in the Atmospheric and Oceanic Sciences (AOS) Program, but retains an affiliation with AOS. He is an HMEI and a PACM (Program in Applied and Computational Mathematics) Associated Faculty. His research covers climate modeling and atmospheric and oceanic fluid dynamics, specifically the theory for the large-scale structure of the atmospheric circulation. He has written extensively and continues research on various aspects of climate change, including the hydrological cycle and tropical cyclones. He was elected to the United States National Academy of Sciences in 2003.