Special seminar: Tropical Pacific SST Pattern Problem

Changes in the sea surface temperature (SST) pattern in the tropical Pacific modulate radiative feedbacks to greenhouse gas forcing, the pace of global warming, and regional climate impacts. Therefore, elucidating the drivers of the pattern is critically important for reducing uncertainties in future projections. However, the causes of observed changes over recent decades, an enhancement of the zonal SST contrast coupled with a strengthening of the Walker circulation, are still debated. While noting a potentially important contribution of internal climate variability, here we focus on the role of external forcing and review existing mechanisms of the forced response categorized as either an energy perspective that adopts global/hemispheric energy budget constraints or a dynamical perspective that examines the atmosphere-ocean coupled processes. Based on our  recent synthetic assessment of the relative contributions of individual mechanisms to the tropical Pacific SST pattern changes, we propose a narrative that reconciles the past strengthening and future weakening of the zonal SST contrast. Namely, multiple lines of evidence suggest that the mechanisms leading to strengthening of the zonal SST contrast have been efficient in the past and those leading to a weakening were less efficient but will become dominant in the future climate.




15:15–16:45 Uhr


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Dirk Olonscheck
Sarah Kang

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