Numerical and Statistical Modelling of Australian Severe Weather

Hartigan, Joshua

Numerical and Statistical Modelling of Australian Severe Weather

Hartigan, Joshua

Permalink

Publication Type:: Thesis
Issue Date:: 2022

Open Access

Copyright Clearance Process

Recently Added
In Progress
Open Access

This item is open access.

Adobe PDF

Download contents and abstractAdobe PDF (3.47 MB)

Adobe PDF

Download thesisAdobe PDF (41.25 MB)

View statistics

Full metadata record

Field	Value	Language
dc.contributor.author	Hartigan, Joshua
dc.date.accessioned	2023-03-13T00:43:40Z
dc.date.available	2023-03-13T00:43:40Z
dc.date.issued	2022
dc.identifier.uri	http://hdl.handle.net/10453/167113
dc.description	University of Technology Sydney. Faculty of Science.	en_US.UTF-8
dc.description.abstract	Communities around Australia are frequently impacted by severe weather, including drought, floods, bushfires, severe convective thunderstorms (SCTs) and tropical cyclones. Such events can have a significant effect on society with their probability of occurrence and severity likely increasing with global warming. Studying historical severe weather provides unique insights to their causes, relevant atmospheric and climate variables, and trends in occurrence and severity. Attributes of severe weather can be assessed with non-linear statistical methods, while the development of past severe weather events can be studied using numerical modelling. Both methodologies can provide valuable guidance to forecasting and emergency planning yet have seldom been applied in Australia. In this thesis, changes to drought vulnerability over southeast Australia are assessed using trend analysis techniques. Overall, there are concerning changes to precipitation mean and variance particularly over the cool season that, coupled with increasing mean temperatures, suggest reduced streamflow and a trend to more frequent and severe drought. The influence of potential climate drivers over time were assessed using wavelet analysis, with statistical modelling used to attribute the key climate drivers associated with precipitation in the region. These models generally performed better than climatology and highlighted the influence of global warming on the precipitation trends. These statistical modelling techniques also were used to determine the atmospheric variables closely associated with SCT hazards. The best performing models were applied to the Bureau of Meteorology’s BARRA reanalysis data set highlighting the regions of Australia most likely affected by each hazard. Eastern Australia appeared exposed to all three hazards, with a notable peak in hail and tornado environments from the central coast of NSW to southeast Queensland, and over far southeast Australia. Spatial changes in the frequency of SCT hazard environments also were analysed between two periods in the BARRA data set. High resolution simulations of a damaging SCT and associated tornado that impacted Sydney on 16 December 2015 were conducted using the Weather Research and Forecasting (WRF) model with ECMWF’s ERA5 reanalysis data for initial conditions. The results from simulations with the Morrison microphysics scheme are compared to those from the NSSL double-moment 4-ice microphysics scheme. Both simulations produced SCTs, with the NSSL scheme producing a storm of similar morphology to the Kurnell storm. The results highlight how supportive the atmosphere was for development of SCTs with the potential to produce tornadoes, and the applicability of the WRF for studying the causes of Australian SCTs.	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/167113/2/02whole.pdf
dc.rights	info:eu-repo/semantics/openAccess
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	© 2022 Joshua Hartigan
dc.rights	au.edu.uts.lib/ppc
dc.title	Numerical and Statistical Modelling of Australian Severe Weather	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

Communities around Australia are frequently impacted by severe weather, including drought, floods, bushfires, severe convective thunderstorms (SCTs) and tropical cyclones. Such events can have a significant effect on society with their probability of occurrence and severity likely increasing with global warming. Studying historical severe weather provides unique insights to their causes, relevant atmospheric and climate variables, and trends in occurrence and severity. Attributes of severe weather can be assessed with non-linear statistical methods, while the development of past severe weather events can be studied using numerical modelling. Both methodologies can provide valuable guidance to forecasting and emergency planning yet have seldom been applied in Australia. In this thesis, changes to drought vulnerability over southeast Australia are assessed using trend analysis techniques. Overall, there are concerning changes to precipitation mean and variance particularly over the cool season that, coupled with increasing mean temperatures, suggest reduced streamflow and a trend to more frequent and severe drought. The influence of potential climate drivers over time were assessed using wavelet analysis, with statistical modelling used to attribute the key climate drivers associated with precipitation in the region. These models generally performed better than climatology and highlighted the influence of global warming on the precipitation trends. These statistical modelling techniques also were used to determine the atmospheric variables closely associated with SCT hazards. The best performing models were applied to the Bureau of Meteorology’s BARRA reanalysis data set highlighting the regions of Australia most likely affected by each hazard. Eastern Australia appeared exposed to all three hazards, with a notable peak in hail and tornado environments from the central coast of NSW to southeast Queensland, and over far southeast Australia. Spatial changes in the frequency of SCT hazard environments also were analysed between two periods in the BARRA data set. High resolution simulations of a damaging SCT and associated tornado that impacted Sydney on 16 December 2015 were conducted using the Weather Research and Forecasting (WRF) model with ECMWF’s ERA5 reanalysis data for initial conditions. The results from simulations with the Morrison microphysics scheme are compared to those from the NSSL double-moment 4-ice microphysics scheme. Both simulations produced SCTs, with the NSSL scheme producing a storm of similar morphology to the Kurnell storm. The results highlight how supportive the atmosphere was for development of SCTs with the potential to produce tornadoes, and the applicability of the WRF for studying the causes of Australian SCTs.

Please use this identifier to cite or link to this item:

http://hdl.handle.net/10453/167113