Warren Lecture with Ardeshir Ebtehaj

Ardeshir Ebtahaj
Civil, Environmental, and Geo- Engineering, University of Minnesota
"Unraveling Changes of Global Water Cycle using Satellite Data"

ABSTRACT: Satellite observations of the Earth’s radiation in microwave bands play an indispensable role, not only for unraveling the impacts of climate change on the global water cycle but also for accurate prediction of droughts and extreme storms. On the one hand, satellite remote sensing of the water cycle involves inversion of radiative transfer equations that link the amount of water in land and atmosphere to radiation intensity, observed by spaceborne radiometers at the top of the atmosphere. On the other hand, improved predictability of the hydrologic cycle requires optimal integration of satellite observations with the outputs of Earth System Models (ESMs). Ebtehaj presents recent advances in physically informed inversion of land emission models and in multi-satellite statistical learning for high-resolution remote sensing of soil moisture and snowstorms from space. Furthermore, he presents a new paradigm for satellite data assimilation over a Riemannian manifold equipped with the Wasserstein metric. Unlike classic approaches over the Euclidean space, this new framework can formally penalize geophysical biases in a non-Gaussian state space. The advantages of this approach for improved geophysical forecasts are demonstrated using chaotic dynamical systems, representing atmospheric circulation.