Category: M4PE Seminar

M4PE Seminar – Fiona Johnson: Droughts, floods and statistics

by jandavidzika, posted in Latest news, M4PE Seminar

Title:
Droughts and flooding rains – statistical methods for hydrological extremes

Date/Time:
Wednesday the 17th of April 4pm-5pm

Location:
UNSW School of Mathematics and Statistics, Red Centre room 2060 (level 2)

Talk summary
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.

Speaker Bio:
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.

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M4PE Seminar next Monday on Convergent Estimates of Marine Nitrogen Fixation to be delivered by visiting Professor Francois Primeau

by jandavidzika, posted in Latest news, M4PE Seminar, Uncategorized

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
Abstract: 

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. 

Speaker Biography:

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.

All welcome!

Upcoming seminar by Sarah Perkins-Kirkpatrick on Stats and Heatwaves

by jandavidzika, posted in Climate, Latest news, M4PE Seminar, Meteorology, Uncategorized, Water

Date/Time:
Monday November 5th, 4pm
Location:
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. 

Erik Van Sebille to present seminar on ocean dispersion with applications to ocean plastic

Featured by jandavidzika, posted in Latest news, M4PE Seminar
Title:
Patterns in dispersion and accumulation of plastic litter by ocean currents and eddies
Speaker:
Erik van Sebille, Institute for Marine and Atmospheric Research, Utrecht University, Netherlands
Date: 
Mon, 15/10/2018 – 4:00pm
Venue: 
RC-3085, The Red Centre, UNSW
Abstract
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

M4PE Seminar: August 27th, Bishakdhatta Gayen (ANU)

by Shane, posted in Climate, Latest news, M4PE Seminar, Oceans, Uncategorized

ARC Future Fellow Dr Bishak Gayen (ANU) will discuss his research in the M4PE seminar at UNSW Sydney on Monday 27 August 2018.

Title: Spanning 10 billion scales from millimetre turbulence to global circulation

Speaker: Bishakhdatta Gayen (Australian National University)

Date & Time: 4pm, Monday 27 August 2018. (Seminar will be followed by refreshments.)

Location: Red Centre room RC-3085, School of Mathematics and Statistics, UNSW Sydney

Abstract: The general ocean circulation, of crucial importance to the global climate, involves fluid motion on scales ranging from turbulence, internal waves, eddies and fronts, planetary Rossby waves and basin-scale gyre recirculation. Equilibrium is maintained between continuous large-scale forcing and energy dissipation. Understanding the physics of various dissipation mechanisms is important for improving the dynamical description of large-scale circulation. Large-scale ocean models do not accurately model turbulent convection, breaking waves, and turbulence, providing motivation to develop a better understanding of these mechanisms. In this presentation, my primary focus will be on understanding the role of turbulence and convection in ocean circulation.

In order to examine the effect of convection in ocean circulation, we have developed a model of circulation with flow driven by surface buoyancy in a closed basin using Direct Numerical Simulations. The circulation cell involves a horizontal boundary flow, turbulent plume motion and week interior return flow. We show that under planetary rotation, even in the absence of wind stress, the flow becomes three-dimensional with small-scale deep convection and broad basin-scale gyres. For the first time, DNS is used to model this circulation and quantify the heat transfer and flow energetics, demonstrating several dynamical regimes. I will also discuss the role of turbulent convection in melting of basal ice shelves and circulation around the Antarctic basin.

About the speaker: Dr Bishakhdatta Gayen is a Research Fellow at the Research School of Earth Sciences at Australian National University. His current research interests are nonlinear internal waves in the ocean, turbulent convection, modeling of Antarctic ice melting and Southern ocean dynamics. Bishak is a 2018 ARC Future Fellow, and has previously been awarded a 2013 ARC DECRA Fellowship. He has also received the RJL Hawke post-doctoral fellowship from the Australian Antarctic Science Program to study subsurface melting of ice shelves around Antarctica with implications for future sea-level rise.

About the main image: A snapshot from simulation of circulation in a closed ocean basin forced by imposed constant temperature having a variation with latitude, showing the kinetic energy on a horizontal plane near the upper boundary, temperature contours on a vertical section near the western boundary and vertical velocity on a vertical section near the northern boundary. Time averaged near-surface transport streamfunction is shown above.