Calendar Event Details
AeroCenter + Cloud Precipitation Center - Tianle Yuan
Affiliation: GSFC 613 and JCET
Event Date: Tuesday, April 12, 2016
Location: G133
Time: 11:00 AM
Positive Low Cloud and Dust Feedbacks Help to Generate Tropical North Atlantic Multidecadal Variability
The North Atlantic sea surface temperature (NASST) can undergo large fluctuations on multidecadal time scales, commonly known as Atlantic Multidecadal Oscillation (AMO) or Atlantic Multidecadal Variability. While the tropical arm of AMO is responsible for many climatic impacts by AMO, it is often too weak or sometimes absent in current climate models simulations. Here we show, using both observational and model evidence, the role of positive feedbacks from low cloud and desert dust in generating the tropical arm of AMO. Estimates of the radiative effects by the feedbacks are strong enough to largely account for the tropical arm of AMO with the low cloud positive feedback more dominant. Two feedbacks can be understood in a consistent dynamic framework in which the response of tropical surface wind speed to midlatitude SST anomaly is the key. Most current models have difficulty in capturing either feedback in the tropical North Atlantic. The feedbacks provide an amplifying mechanism to generate the tropical arm of AMO and correctly simulating them may be critical for a range of studies and applications. We will show some preliminary results on how precipitation and clouds respond to AMO.
Posted or updated: Tuesday, April 5, 2016
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