AOSC Seminar by Dr. Sumant Nigam, 12/2/2021
Dr. Sumant Nigam
Title: The Mechanics of Surface Warming: A Tale of Two Continents
The Earth’s climate is warming: Surface air temperature over Northern continents has risen in the 20th-21st century, and sharply in recent decades, but not uniformly across seasons or regions. Over northwestern North America, the warming is pronounced in winter and spring but weak in summer and fall; Antarctic warming also shows seasonal and spatial structure. Although the origin of secular (i.e., centennial-scale) warming is certain – rising greenhouse gas concentrations – the reasons for its seasonal and sectoral preferences are not. The dynamic and thermodynamic processes generating the observed preferences – the mechanics of surface warming -- will be discussed.
The seasonal cycle of climate, despite its monotony, provides an expanded phase space – a prism – for the exposition of processes generating surface warming and a cost-effective strategy for assessing climate projection models. Surface warming in the IPCC-AR5 historical 20th-century climate simulations shows varied (and often unrealistic) strength and structure and significantly weaker seasonal variation.
Sumant Nigam is a Professor of Atmospheric and Oceanic Science at the University of Maryland. He studies climate variability and change, atmospheric general circulation and climate teleconnections, ocean-atmosphere interaction, monsoons, and droughts and desertification. Sumant led the drafting of the 2019 AMS Information Statement on Climate Change. He has served on NCAR and NSF-Geosciences advisory committees, and was a member of the Climate Research Committee and the Board of Atmospheric Sciences and Climate from 2008-2012. Sumant was a Jefferson Science Fellow of NAS and a Senior Science Advisor to the State Department during 2016-17, and a 2020 Fulbright-Nehru Fellow. Sumant received his Ph.D. in Geophysical Fluid Dynamics from Princeton University in 1984 and postdoctoral training at MIT.
Contact: Sumant Nigam
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Pre-seminar refreshment: N/A
Seminar: 3:30-4:30pm, Room: ATL 2400
Meet-the-Speaker: 4:30-5:00pm, Room: ATL 3400 [For AOSC Students only]