Kenza Tazi
Hi! I’m a PhD student at the University of Cambridge studying the application of AI to environmental risk. I’m advised by Richard E. Turner at the Department of Engineering, Scott Hosking and Andrew Orr at the British Antarctic Survey, and Javier González at Microsoft Research Cambridge. In this website, you’ll find some of my recent projects and academic resources.
Publications
Kernel Learning for Explainable Climate Science
Vidhi Lalchand, Kenza Tazi, Talay M Cheema, Richard E Turner, Scott Hosking, 2022. (In 16th Bayesian Modelling Applications Workshop at UAI, 2022).
Abstract▼ URL
The Upper Indus Basin, Himalayas provides water for 270 million people and countless ecosystems. However, precipitation, a key component to hydrological modelling, is poorly understood in this area. A key challenge surrounding this uncertainty comes from the complex spatial-temporal distribution of precipitation across the basin. In this work we propose Gaussian processes with structured non-stationary kernels to model precipitation patterns in the UIB. Previous attempts to quantify or model precipitation in the Hindu Kush Karakoram Himalayan region have often been qualitative or include crude assumptions and simplifications which cannot be resolved at lower resolutions. This body of research also provides little to no error propagation. We account for the spatial variation in precipitation with a non-stationary Gibbs kernel parameterised with an input dependent lengthscale. This allows the posterior function samples to adapt to the varying precipitation patterns inherent in the distinct underlying topography of the Indus region. The input dependent lengthscale is governed by a latent Gaussian process with a stationary squared-exponential kernel to allow the function level hyperparameters to vary smoothly. In ablation experiments we motivate each component of the proposed kernel by demonstrating its ability to model the spatial covariance, temporal structure and joint spatio-temporal reconstruction. We benchmark our model with a stationary Gaussian process and a Deep Gaussian processes.
Identifying causes of Pyrocumulonimbus (PyroCb)
Emiliano Diaz, Kenza Tazi, Ashwin S Braude, Daniel Okoh, Kara Lamb, Duncan Watson-Parris, Paula Harder, Nis Meinert, 2022. (In NeurIPS Workshop on Causality for Real-world Impact).
Abstract▼ URL
A first causal discovery analysis from observational data of pyroCb (storm clouds generated from extreme wildfires) is presented. Invariant Causal Prediction was used to develop tools to understand the causal drivers of pyroCb formation. This includes a conditional independence test for testing Y conditionally independent of E given X for binary variable Y and multivariate, continuous variables X and E, and a greedy-ICP search algorithm that relies on fewer conditional independence tests to obtain a smaller more manageable set of causal predictors. With these tools, we identified a subset of seven causal predictors which are plausible when contrasted with domain knowledge: surface sensible heat flux, relative humidity at 850 hPa, a component of wind at 250 hPa, 13.3 micro-meters, thermal emissions, convective available potential energy, and altitude
Pyrocast: a machine learning pipeline to forecast pyrocumulonimbus (pyrocb) clouds
Kenza Tazi, Emiliano Díaz Salas-Porras, Ashwin Braude, Daniel Okoh, Kara D Lamb, Duncan Watson-Parris, Paula Harder, Nis Meinert, 2022. (NeurIPS Workshop on Tackling Climate Change with Machine Learning).
Abstract▼ URL
Pyrocumulonimbus (pyroCb) clouds are storm clouds generated by extreme wildfires. PyroCbs are associated with unpredictable, and therefore dangerous, wildfire spread. They can also inject smoke particles and trace gases into the upper troposphere and lower stratosphere, affecting the Earth’s climate. As global temperatures increase, these previously rare events are becoming more common. Being able to predict which fires are likely to generate pyroCb is therefore key to climate adaptation in wildfire-prone areas. This paper introduces Pyrocast, a pipeline for pyroCb analysis and forecasting. The pipeline’s first two components, a pyroCb database and a pyroCb forecast model, are presented. The database brings together geostationary imagery and environmental data for over 148 pyroCb events across North America, Australia, and Russia between 2018 and 2022. Random Forests, Convolutional Neural Networks (CNNs), and CNNs pretrained with Auto-Encoders were tested to predict the generation of pyroCb for a given fire six hours in advance. The best model predicted pyroCb with an AUC of 0.90±0.04.