The Energy Balance of Contrasting Vegetation Types on a Subtropical Sand Island
In subtropical coastal environments little is known about the nature of surface-atmosphere interactions and the transfer of mass and energy in the lower atmosphere. This project will contribute towards filling this knowledge gap by using the eddy covariance methodology to provide concurrent measurements of three contrasting groundwater dependent vegetation types on Bribie Island, a subtropical sand island off the coast of South East Queensland, Australia. Quantification of the energy balance will provide new insight into the relationship between coastal subtropical vegetation and background meteorological conditions, for example, the vegetative response to different air mass characteristics.
Bushfire Convective Plume Experiment: A Mobile X-band Field Campaign into Fire-Driven Convection in Australia
The prediction of pyroconvection presents complex problems for meteorologists and wildfire managers, given that plume-driven feedback processes between fire and atmosphere can lead to unpredictable and dangerous wildfire behaviour. In particular, plume dynamics is a significant factor in the transport of burning debris leading to new fires often many kilometres in advance of the main fire front in a process known as spotting. Here we present the initial findings of the Bushfire Convective Plume Experiment (BCPE), using portable dual-polarized X-band radar (from The University of Queensland; UQ-XPOL) to study fire-driven convection in Australia. Coupled with portable Automatic Weather Station observations, time-lapse photography, airborne multispectral imaging and spot-fire mapping, the design of the BCPE enables quantitative analysis of pyroconvection and its role in fire behaviour. The results to date include observations of three significant wildfires and one prescribed burn, with insights into deployment strategy, plume evolution, vortex generation, dual polarisation signatures and pyrocumulonimbus initiation. The findings demonstrate the suitability of portable, dual-polarized X-band Doppler radar for this application. There is an emerging space for the use of the X-band frequency matched with fire behaviour data where the nature of the in-plume scatterers remains poorly understood.
Trees Effect on Snowpack Energetics Experiment
The Snowy Mountains of Southeast Australia are home to mild temperatures, wet winters, and a marginal snowpack that sits precariously on the edge of complete ablation for the majority of the winter season. Small fluctuations in energy to the snowpack can cause dramatic increases in melt or storage during the winter. This project aims to examine and quantify the impacts of Eucalyptus pauciflora trees on snowpack energetics through exhaustive measurement of energy transfer in forested regions of the Snowy Mountains. Effects of single trees as well as those of living and dead (burned) tree stands on snow accumulation, ablation, and snow water equivalent (SWE) will be investigated over a variety of spatiotemporal scales. This study will be crucial to water management in the region and could be considered a pilot study for changes to forested snowpacks that will accompany climate change as it impacts the mountainous regions in the mid- and upper-latitude regions of the world.
Developing a Physical Model to Estimate Hail Trajectories
Hail nowcasting and climatology efforts currently rely on projecting hail detected aloft directly onto the ground underneath. When surface hail swaths produced in this manner are compared to surface hail observations, significant deviations are observed, likely due to storm generated advection of hail as it falls. This effect is particularly apparent for loss reports, motivating the need to improve hail retrievals for fine scale assessment by the insurance industry. The method proposed in this study uses a physical model to calculate hail trajectories in order to estimate where and when each detected hail particle above the freezing level will fall to the ground. Either a maximum hail size or hail intensity parameter is produced for each grid-point on the ground based on hail trajectories. Dual-polarised hail detection techniques are employed and considerations are made for changes in terminal velocities and size due to melting below the freezing level. In addition to improving impact mapping of hail events, this technique is aimed at improving operational nowcasting by providing a better indication of where hail will land with a lead-time sufficient to issue warnings. Additionally, the work is of significant importance to emergency services and the private sector to better guide post-storm assistance efforts and provide more accurate climatology information.
Southeasterly Change Observational Experiment: Observing the variability in structure and thermodynamics of the southeasterly wind change through SEQ
The importance of southeasterly change as a key catalyst for enhancing or hindering thunderstorm activity in southeast Queensland (SEQ) is recognised across a number of studies and BoM reports. Although well known, very little is actually documented about the structure, dynamics and thermodynamics of the wind change and the interactions with warm season thunderstorms in SEQ. Recent research has detailed how four of the most damaging and expensive convective storm events to hit SEQ have also coincided with a southeasterly change event. While the southeasterly change observational experiment (SECOE) is considered to be a pilot study that is unique to SEQ, it will lay the foundations to begin understanding the variability of the change which is hoped will lead to improved forecasting of these events which correspond with convective environments.