Droughts and flooding rains – statistical methods for hydrological extremes
Wednesday the 17th of April 4pm-5pm
UNSW School of Mathematics and Statistics, Red Centre room 2060 (level 2)
Hydrological extremes by their very nature are rare events and require careful use of statistical methods to ensure robust and reliable predictions. This presentation focuses on two case studies of application of statistical methods in hydrological engineering. The first example is the use of discrete wavelet transforms to better understand the drivers of multi year droughts in the Murray Darling Basin and how the frequency and severity of these events will change in the future. The second case study focuses on the other side of the metaphorical hydrologic coin – flooding rains and application of extreme value statistics to quantify the risk of extreme rainfall events historically and into the future.
Fiona Johnson is a Senior Lecturer and Scientia Fellow in the Faculty of Engineering, School of Civil and Environmental Engineering. She is interested in changes to flooding, droughts and extreme events due to climate change and her research focuses on how best to use climate models in engineering design, with a particular interest in statistical methods that can answer these questions. Through her research, Fiona aims to provide sustainable solutions to the water engineering problems faced by communities, particularly those in developing countries.
Title: Convergent Estimates of Marine Nitrogen Fixation
Speaker: Francois Primeau (UC Irvine)
Date: Mon, 18/02/2019 – 4:00pm
Venue: RC-4082, The Red Centre (School of Mathematics and Statsitics), UNSW
Uncertainty in the global patterns of marine nitrogen fixation limits our understanding of the response of the ocean’s nitrogen and carbon cycles to environmental change. The geographical distribution and ecological controls on nitrogen fixation are difficult to constrain with limited in-situ measurements. Here Prof. Primeau will present an inverse model to constrain the residual mean circulation of the ocean and to estimate rates of marine nitrogen fixation. The results demonstrate strong spatial variability in the nitrogen to phosphorus ratio of exported organic matter that greatly increases the global nitrogen-fixation rate. It is found that new nitrogen supports up to 50% of export in subtropical gyres, that nitrogen fixation and denitrification are spatially decoupled and that current-era nitrogen sources and sinks largely balance on multidecadal timescales. These findings suggest higher than expected ocean carbon export and weaker stabilizing nitrogen-cycle feedbacks than previously thought.
Francois Primeau is a Professor of Earth System Science at the University of California, Irvine. His research is at the interface between physical oceanography and biogeochemistry where he develops computational methods to make better inferences from data and models about the physical and biogeochemical state of the ocean.
Monday November 5th, 4pm
RC-4082, The Red Centre, UNSW
Heatwaves are changing. What role does statistics have in understanding these changes?
Heatwaves are increasing in their frequency, intensity and duration. Loosely described as prolonged periods of excessive heat, statistical techniques underpin their measurement, understanding their changes, the physical mechanisms behind these changes, the role anthropogenic climate change plays, and estimates of uncertainty (or certainty) surrounding these factors. This talk will explore the vital role statistics has behind heatwaves, making our understanding of these high-impact events possible.
Dr Sarah Perkins-Kirkpatrick is an ARC Future Fellow at the Climate Change Research Centre, UNSW Sydney. Her background focuses on measuring heatwaves, what drives them, the role climate change plays and future projections in a warmer world. Sarah’s Future Fellowship is working towards improving the attribution methods of extreme events (such as heatwaves) to human influence, as well as determining whether the health impacts of heatwaves can be attributed to human influence on the climate. Since gaining her PhD in 2010, Sarah has published 60 peer reviewed scientific papers on climate extremes. She co-leads an expert team for the World Meteorological Organisation’s Commission for Climatology, and is a frequent voice in local and international media on all things climate change in heatwaves. Sarah has won numerous awards for her research, and was named one UNSW’s 20 rising stars who will change our world in 2016.
This seminar is part of the ‘Mathematics for Planet Earth’ initiative (mathsforearth.com) and is co-hosted by the Department of Statistic at the School of Mathematics and Statistics at UNSW, Sydney. Light refreshments will follow the seminar.
Patterns in dispersion and accumulation of plastic litter by ocean currents and eddies
Erik van Sebille, Institute for Marine and Atmospheric Research, Utrecht University, Netherlands
Mon, 15/10/2018 – 4:00pm
RC-3085, The Red Centre, UNSW
Ocean currents and eddies carry floating plastic litter from coastlines into the infamous garbage patches in the centres of the gyres. However, the time scales and pathways on which this happens are unknown. In order to assess the impact of the plastic, it is key to know where it gets carried through vulnerable ecosystems.
In this talk, Dr Van Sebille will first discuss how tracks of satellite-tracked drifting buoys can be used to create a Markov model of dispersion at the surface of the ocean. He will show that this simple model accurately simulates the formation of the garbage patches, and can be used as a quick and easy tool to assess pathways of floating stuff.
Dr Van Sebille will then introduce more complicated models of passive particulates in the ocean, based on a Lagrangian description of the flow field from high-resolution models. While Lagrangian particle tracking is widely used in oceanography to track tracers, here the challenge is to make the virtual particles actually ‘behave’ like plastic.
About the speaker:
Erik is an oceanographer and climate scientist. His research focuses on how ocean currents transport heat, nutrients, marine organisms and plastic litter between different regions of the ocean.
He currently leads the “Tracking Of Plastic In Our Seas” (TOPIOS) project, funded by a 5-year (2017-2022) European Research Council Starting Grant.
Erik is the winner of the 2016 European Geosciences Union (EGU) Ocean Division Outstanding Young Scientist Award. In 2013, Erik was awarded a Discovery Early Career Researcher Award (DECRA) by the Australian Research Council.
Erik is a strong science communicator, with appearances on international television, radio and newspapers. He was a Media Fellow with the Australian Government Climate Commission and has co-hosted a section on sea level rise in Tuvalu in the international documentary series Tipping Points.
He is a sought-after international expert on oceanography, having done over 250 interviews on ocean circulation and plastic pollution with media outlets including CCN, BBC, NBC, ABC, New York Times, Wall Street Journal, Guardian, TIME magazine, AP, and Reuters.
Erik also holds an honorary lectureship at Imperial College London’s Grantham Institute
The ocean is highly turbulent. Pathways of free-floating buoys are chaotic and circulation patterns are dominated by mesoscale eddies – the ocean’s equivalent to atmospheric storms. The ocean is at the same time organised.
Substances injected into the ocean follow broad and distinct routes near the sea surface from the Pacific to the Atlantic Ocean. As a result the North Pacific and North Atlantic Ocean’s are in marked contrast. The Pacific is cold and fresh and the Atlantic is warm and salty. Known as the thermohaline circulation, this helps maintain Europe’s relatively mild climate.
This project will explore the link between the asymmetry in northern hemisphere climates, the thermohaline circulation and the atmospheric forcing which sets the eventual temperature and salinity of sea-water. The project will pivot on the hypothesis that, by accident of geography and the position of southern hemisphere winds, warm saline water preferentially flows into the Atlantic. Moreover these effects will dictate the stability of the thermohaline circulation and European climate over coming centuries.
This project is supervised by Dr Jan Zika (UNSW Sydney). Please contact firstname.lastname@example.org for more information.
Submit your application by Oct 26 2018 for commencement in Term 1, 2019.