AOSC Seminar by Dr. Akash Koppa, 09/11/2025
AOSC Seminar
Akash Koppa
UMD, Environmental Science and Technology
Title
Vegetation–climate interactions from hours to millennia
Abstract
From sub-seasonal droughts to decadal scale aridification, the response of vegetation and its feedback into the climate plays a crucial role in modulating these drying phenomena. By controlling the opening and closing of stomata - small pores on the surface of leaves - plants regulate latent heat flux, and consequently the rate of atmospheric drying through feedbacks. Thus, accurately predicting stomatal behavior at sub-hourly timescales can help us better understand how vegetation can impact the atmospheric condition at longer timescales. While a range of semi-empirical to optimality-based parameterizations of stomatal behavior are common, I will show a deep learning-based variant trained using a large sample of flux observations from eddy covariance towers spread across the globe. The novel model not only predicts stomatal behavior accurately but, when embedded within a physics-based model, improves estimates of latent heat flux at global scales. Furthermore, the talk will highlight the importance of studying how the local response of vegetation to drying events can propagate downwind through advection of moisture and heat. In this context, I will show how persistent drying of the atmosphere over drylands, over the last four decades, has played an important role in their expansion.
Bio
Akash Koppa is an assistant professor in the Dept. of Environmental Science & Technology at the University of Maryland College Park. Dr. Koppa’s primary research interest in in understanding how land–atmosphere interactions shape both climate and land surface processes at a range of spatial and temporal scales. He is particularly interested in understanding how atmospheric aridity propagates into the biosphere and how consequent changes in vegetation feeds back into local and remote climates. For addressing these research questions, Dr. Koppa employs hybrid land surface models, which combine physics with machine learning, to quantify local changes in latent and sensible heat fluxes. He combines them with atmospheric transport models to understand how these changes propagate downwind through heat and moisture advection. Trained as a civil engineer in India, he received his PhD in Hydrology and Water Resources from the University of California Los Angeles.
Contact
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AOSC Seminar
Pre-seminar refreshment: N/A
Seminar: 3:30-4:30pm, Room: ATL 2400(only when in-person)
Meet-the-Speaker: 4:30-5:00pm, Room: ATL 3400(only when in-person) [For AOSC Students only]
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