Mojtaba Sadegh


2022

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Coevolution of machine learning and process‐based modelling to revolutionize Earth and environmental sciences: A perspective
Saman Razavi, David M. Hannah, Amin Elshorbagy, Sujay V. Kumar, Lucy Marshall, Dimitri Solomatine, Amin Dezfuli, Mojtaba Sadegh, J. S. Famiglietti
Hydrological Processes, Volume 36, Issue 6

Abstract Machine learning (ML) applications in Earth and environmental sciences (EES) have gained incredible momentum in recent years. However, these ML applications have largely evolved in ‘isolation’ from the mechanistic, process‐based modelling (PBM) paradigms, which have historically been the cornerstone of scientific discovery and policy support. In this perspective, we assert that the cultural barriers between the ML and PBM communities limit the potential of ML, and even its ‘hybridization’ with PBM, for EES applications. Fundamental, but often ignored, differences between ML and PBM are discussed as well as their strengths and weaknesses in light of three overarching modelling objectives in EES, (1) nowcasting and prediction, (2) scenario analysis, and (3) diagnostic learning. The paper ponders over a ‘coevolutionary’ approach to model building, shifting away from a borrowing to a co‐creation culture, to develop a generation of models that leverage the unique strengths of ML such as scalability to big data and high‐dimensional mapping, while remaining faithful to process‐based knowledge base and principles of model explainability and interpretability, and therefore, falsifiability.

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Status and prospects for drought forecasting: opportunities in artificial intelligence and hybrid physical–statistical forecasting
Amir AghaKouchak, Baoxiang Pan, Omid Mazdiyasni, Mojtaba Sadegh, Shakil Jiwa, Wenkai Zhang, Charlotte Love, Shahrbanou Madadgar, Simon Michael Papalexiou, Steven J. Davis, Kuolin Hsu, Soroosh Sorooshian
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Volume 380, Issue 2238

Despite major improvements in weather and climate modelling and substantial increases in remotely sensed observations, drought prediction remains a major challenge. After a review of the existing methods, we discuss major research gaps and opportunities to improve drought prediction. We argue that current approaches are top-down, assuming that the process(es) and/or driver(s) are known—i.e. starting with a model and then imposing it on the observed events (reality). With the help of an experiment, we show that there are opportunities to develop bottom-up drought prediction models—i.e. starting from the reality (here, observed events) and searching for model(s) and driver(s) that work. Recent advances in artificial intelligence and machine learning provide significant opportunities for developing bottom-up drought forecasting models. Regardless of the type of drought forecasting model (e.g. machine learning, dynamical simulations, analogue based), we need to shift our attention to robustness of theories and outputs rather than event-based verification. A shift in our focus towards quantifying the stability of uncertainty in drought prediction models, rather than the goodness of fit or reproducing the past, could be the first step towards this goal. Finally, we highlight the advantages of hybrid dynamical and statistical models for improving current drought prediction models. This article is part of the Royal Society Science+ meeting issue ‘Drought risk in the Anthropocene’.

2020

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Climate Extremes and Compound Hazards in a Warming World
Amir AghaKouchak, Felicia Chiang, Laurie S. Huning, Charlotte Love, Iman Mallakpour, Omid Mazdiyasni, Hamed Moftakhari, Simon Michael Papalexiou, Elisa Ragno, Mojtaba Sadegh
Annual Review of Earth and Planetary Sciences, Volume 48, Issue 1

Climate extremes threaten human health, economic stability, and the well-being of natural and built environments (e.g., 2003 European heat wave). As the world continues to warm, climate hazards are expected to increase in frequency and intensity. The impacts of extreme events will also be more severe due to the increased exposure (growing population and development) and vulnerability (aging infrastructure) of human settlements. Climate models attribute part of the projected increases in the intensity and frequency of natural disasters to anthropogenic emissions and changes in land use and land cover. Here, we review the impacts, historical and projected changes,and theoretical research gaps of key extreme events (heat waves, droughts, wildfires, precipitation, and flooding). We also highlight the need to improve our understanding of the dependence between individual and interrelated climate extremes because anthropogenic-induced warming increases the risk of not only individual climate extremes but also compound (co-occurring) and cascading hazards. ▪ Climate hazards are expected to increase in frequency and intensity in a warming world. ▪ Anthropogenic-induced warming increases the risk of compound and cascading hazards. ▪ We need to improve our understanding of causes and drivers of compound and cascading hazards.