Jorg Hacker | Flinders University of South Australia (original) (raw)

Papers by Jorg Hacker

ABSTRACT Approximately 13 million hectares of native vegetation in southwest Australia has been r... more ABSTRACT Approximately 13 million hectares of native vegetation in southwest Australia has been replaced by non-native, rain-fed agricultural species over the last several decades. Prior studies link land use change to reduction in convective cloudiness and precipitation in this region. However, recent aircraft observations also show that land use change and associated effects on ground water hydrology impacts the atmospheric CCN distribution, with distinct differences found between adjacent areas of native vegetation and agriculture. Over the agricultural areas, substantially higher concentrations of very small aerosols were observed during the morning hours. Smaller concentrations of larger aerosols were found over the native vegetation area in the morning. Even though the smaller particles over the agricultural area grow and the size distribution is shifted to higher particle size ranges in the afternoon, they are smaller and more numerous compared to those on the native vegetation area. Aircraft observations also show differences in cloud particle size distribution consistent with differences in aerosols, with larger droplet sizes existing in higher concentrations over the native vegetation region. The source of the small particles in the agricultural area was traced to salt lakes. Shallow rooted vegetation in the agricultural area, causing the rise of the water table and altering the lake geochemistry is a potential reason for the enhanced aerosol emissions over the lakes in the agricultural area. The impact of differing atmospheric CCN on cloud precipitation is being explored using numerical modeling and results from this analysis will also be presented.

Remote Sensing, 2021

Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a var... more Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a variety of morphodynamic processes and controlling mechanisms. They provide valuable inhabitable land for small island nations, critical habitat for numerous species, and are threatened by climate change. Aiming to investigate the controlling mechanisms dictating the evolution of One Tree Island (OTI), a rubble island in the Southern Great Barrier Reef, we combined different remotely-sensed data across varying timescales with wave data extracted from satellite altimetry and cyclone activity. Our findings show that (1) OTI had expanded by 7% between 1978 and 2019, (2) significant gross planform decadal adjustments were governed by the amount, intensity, proximity, and relative position of cyclones as well as El Niño Southern Oscillation (ENSO) phases, and (3) the mechanisms of island growth involve rubble spits delivering and redistributing rubble to the island through alongshore sediment tr...

This presentation will discuss the methods applied for the flight planning in order to achieve a ... more This presentation will discuss the methods applied for the flight planning in order to achieve a quasi-Lagrangian observation of the air mass in which the various sources are emitting methane and carbon dioxide. Over this dry area in sunny Queensland in springtime, the emissions were quickly mixed into a rather deep convective boundary layer. Although this is an advantage for regional mass balances (as long as the boundary layer growth is known), it is a challenge for source attribution. Furthermore, as already discussed in Hiller et al. (2014), the data is suggesting, that dry deposition and photochemical reactions during the transport cannot be neglected. In Yacovitch et al. (2018) we have also shown that the uncertainty of a regional emission estimate is large when the conditions are not ideal. All of these experiences allowed to improve the methods and flight strategies now applied in the Surat Basin.

The Journal of Island and Coastal Archaeology, 2019

Remote Sensing, 2020

Reef islands are some of the most highly sensitive landforms to the impacts of future environment... more Reef islands are some of the most highly sensitive landforms to the impacts of future environmental change. Previous assessments of island morphodynamics primarily relied on historical aerial and satellite imagery. These approaches limit analysis to two-dimensional parameters, with no ability to assess long-term changes to island volume or elevation. Here, we use high-resolution airborne LiDAR data to assess three-dimensional reef island features for 22 islands along the north-western coast of Australia. Our primary objective was to utilize two regional LiDAR datasets to identify characteristics indicative of island sensitivity and future vulnerability. Results show reef platform area to be an accurate predictor of island area and volume suggesting larger island volumes may reflect (1) increased carbonate production and supply from the reef platform and/or (2) enhanced shoreline protection by larger reef platforms. Locations of foredune scarping (an erosional signature) and island o...

Remote Sensing, 2019

In the face of rapid global change it is imperative to preserve geodiversity for the overall cons... more In the face of rapid global change it is imperative to preserve geodiversity for the overall conservation of biodiversity. Geodiversity is important for understanding complex biogeochemical and physical processes and is directly and indirectly linked to biodiversity on all scales of ecosystem organization. Despite the great importance of geodiversity, there is a lack of suitable monitoring methods. Compared to conventional in-situ techniques, remote sensing (RS) techniques provide a pathway towards cost-effective, increasingly more available, comprehensive, and repeatable, as well as standardized monitoring of continuous geodiversity on the local to global scale. This paper gives an overview of the state-of-the-art approaches for monitoring soil characteristics and soil moisture with unmanned aerial vehicles (UAV) and air- and spaceborne remote sensing techniques. Initially, the definitions for geodiversity along with its five essential characteristics are provided, with an explanat...

PeerJ, 2017

The abundant dinosaurian tracksites of the Lower Cretaceous (Valanginian-Barremian) Broome Sandst... more The abundant dinosaurian tracksites of the Lower Cretaceous (Valanginian-Barremian) Broome Sandstone of the Dampier Peninsula, Western Australia, form an important part of the West Kimberley National Heritage Place. Previous attempts to document these tracksites using traditional mapping techniques (e.g., surface overlays, transects and gridlines combined with conventional photography) have been hindered by the non-trivial challenges associated with working in this area, including, but not limited to: (1) the remoteness of many of the tracksites; (2) the occurrence of the majority of the tracksites in the intertidal zone; (3) the size and complexity of many of the tracksites, with some extending over several square kilometres. Using the historically significant and well-known dinosaurian tracksites at Minyirr (Gantheaume Point), we show how these issues can be overcome through the use of an integrated array of remote sensing tools. A combination of high-resolution aerial photography...

Boundary-Layer Meteorology

Conditional sampling is used to locate mixed layer thermals and surface layer plumes, as well as ... more Conditional sampling is used to locate mixed layer thermals and surface layer plumes, as well as their downward moving companions - downdrafts - in a large data set obtained from flights by an instrumented motorglider in convective boundary layers over Eyre Peninsula, South Australia. The high resolution and excellent spatial coverage of the data permits a detailed study of internal structure. A compositing technique is used to construct average intersections through thermals and plumes from aircraft runs of given heights and directions. Groups of composites are then combined to form horizontal and vertical cross-sections, revealing the flow patterns and distribution of physical variables within "typical" thermals and plumes and their environment. Surface layer plumes are found to have strong lateral inflow patterns, in which air from the horizontal plane channels around the sides and then in behind the microfront present at the upstream edge. Mixed layer thermal towers ha...

Tellus B: Chemical and Physical Meteorology, 2015

Four turbulence measurement campaigns were performed in the winter sub-tropical jet streams of so... more Four turbulence measurement campaigns were performed in the winter sub-tropical jet streams of south coastal Japan and Australia during 1998-2001 with the objective to capture the dynamics of severe refractive and clear air turbulence events. The aircraft used was the GROB 520T EGRETT, which is owned and operated by Airborne Research Australia a unit of Flinders University of South Australia.

22nd Internation …, 2004

ANATOMY OF CIRRUS CLOUDS James A.Whiteway~1~, Clive Cook~2~, Martin W. Ga11agher~3~, Reinhold Bus... more ANATOMY OF CIRRUS CLOUDS James A.Whiteway~1~, Clive Cook~2~, Martin W. Ga11agher~3~, Reinhold Busen~4~, Tom W. Choularton~3~, Keith Bower~3~, Paul Connolly~3~, Michael Flynn~3~, and Jorg Hacker~5~ 1Department of Earth and Space ...

Walker, JP, Balling, J., Bell, M., Berg, A., Berger, M., Biasoni, D., Botha, E., Boulet, G., Chen... more Walker, JP, Balling, J., Bell, M., Berg, A., Berger, M., Biasoni, D., Botha, E., Boulet, G., Chen, Y., Christen, E., et al., 2007. The National Airborne Field Experiment Data Sets. MODSIM07: International Congress of Modelling and Simulation., 2625-2631.

3D Recording and Interpretation for Maritime Archaeology, 2019

Journal of Geophysical Research, 1999

Journal of Geophysical Research, 2008

Identifying the sources and sinks of methane and carbon dioxide is important for understanding pr... more Identifying the sources and sinks of methane and carbon dioxide is important for understanding processes within the Earth's climate system. This paper attempts to use back trajectories to identify sources of atmospheric methane and carbon dioxide as measured by high resolution in situ gas analyzers during aircraft ascents and descents in Southern Australia. Results from the back trajectory analysis were

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009

ABSTRACT Approximately 13 million hectares of native vegetation in southwest Australia has been r... more ABSTRACT Approximately 13 million hectares of native vegetation in southwest Australia has been replaced by non-native, rain-fed agricultural species over the last several decades. Prior studies link land use change to reduction in convective cloudiness and precipitation in this region. However, recent aircraft observations also show that land use change and associated effects on ground water hydrology impacts the atmospheric CCN distribution, with distinct differences found between adjacent areas of native vegetation and agriculture. Over the agricultural areas, substantially higher concentrations of very small aerosols were observed during the morning hours. Smaller concentrations of larger aerosols were found over the native vegetation area in the morning. Even though the smaller particles over the agricultural area grow and the size distribution is shifted to higher particle size ranges in the afternoon, they are smaller and more numerous compared to those on the native vegetation area. Aircraft observations also show differences in cloud particle size distribution consistent with differences in aerosols, with larger droplet sizes existing in higher concentrations over the native vegetation region. The source of the small particles in the agricultural area was traced to salt lakes. Shallow rooted vegetation in the agricultural area, causing the rise of the water table and altering the lake geochemistry is a potential reason for the enhanced aerosol emissions over the lakes in the agricultural area. The impact of differing atmospheric CCN on cloud precipitation is being explored using numerical modeling and results from this analysis will also be presented.

Remote Sensing, 2021

Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a var... more Rubble islands are dynamic sedimentary features present on reef platforms that evolve under a variety of morphodynamic processes and controlling mechanisms. They provide valuable inhabitable land for small island nations, critical habitat for numerous species, and are threatened by climate change. Aiming to investigate the controlling mechanisms dictating the evolution of One Tree Island (OTI), a rubble island in the Southern Great Barrier Reef, we combined different remotely-sensed data across varying timescales with wave data extracted from satellite altimetry and cyclone activity. Our findings show that (1) OTI had expanded by 7% between 1978 and 2019, (2) significant gross planform decadal adjustments were governed by the amount, intensity, proximity, and relative position of cyclones as well as El Niño Southern Oscillation (ENSO) phases, and (3) the mechanisms of island growth involve rubble spits delivering and redistributing rubble to the island through alongshore sediment tr...

This presentation will discuss the methods applied for the flight planning in order to achieve a ... more This presentation will discuss the methods applied for the flight planning in order to achieve a quasi-Lagrangian observation of the air mass in which the various sources are emitting methane and carbon dioxide. Over this dry area in sunny Queensland in springtime, the emissions were quickly mixed into a rather deep convective boundary layer. Although this is an advantage for regional mass balances (as long as the boundary layer growth is known), it is a challenge for source attribution. Furthermore, as already discussed in Hiller et al. (2014), the data is suggesting, that dry deposition and photochemical reactions during the transport cannot be neglected. In Yacovitch et al. (2018) we have also shown that the uncertainty of a regional emission estimate is large when the conditions are not ideal. All of these experiences allowed to improve the methods and flight strategies now applied in the Surat Basin.

The Journal of Island and Coastal Archaeology, 2019

Remote Sensing, 2020

Reef islands are some of the most highly sensitive landforms to the impacts of future environment... more Reef islands are some of the most highly sensitive landforms to the impacts of future environmental change. Previous assessments of island morphodynamics primarily relied on historical aerial and satellite imagery. These approaches limit analysis to two-dimensional parameters, with no ability to assess long-term changes to island volume or elevation. Here, we use high-resolution airborne LiDAR data to assess three-dimensional reef island features for 22 islands along the north-western coast of Australia. Our primary objective was to utilize two regional LiDAR datasets to identify characteristics indicative of island sensitivity and future vulnerability. Results show reef platform area to be an accurate predictor of island area and volume suggesting larger island volumes may reflect (1) increased carbonate production and supply from the reef platform and/or (2) enhanced shoreline protection by larger reef platforms. Locations of foredune scarping (an erosional signature) and island o...

Remote Sensing, 2019

In the face of rapid global change it is imperative to preserve geodiversity for the overall cons... more In the face of rapid global change it is imperative to preserve geodiversity for the overall conservation of biodiversity. Geodiversity is important for understanding complex biogeochemical and physical processes and is directly and indirectly linked to biodiversity on all scales of ecosystem organization. Despite the great importance of geodiversity, there is a lack of suitable monitoring methods. Compared to conventional in-situ techniques, remote sensing (RS) techniques provide a pathway towards cost-effective, increasingly more available, comprehensive, and repeatable, as well as standardized monitoring of continuous geodiversity on the local to global scale. This paper gives an overview of the state-of-the-art approaches for monitoring soil characteristics and soil moisture with unmanned aerial vehicles (UAV) and air- and spaceborne remote sensing techniques. Initially, the definitions for geodiversity along with its five essential characteristics are provided, with an explanat...

PeerJ, 2017

The abundant dinosaurian tracksites of the Lower Cretaceous (Valanginian-Barremian) Broome Sandst... more The abundant dinosaurian tracksites of the Lower Cretaceous (Valanginian-Barremian) Broome Sandstone of the Dampier Peninsula, Western Australia, form an important part of the West Kimberley National Heritage Place. Previous attempts to document these tracksites using traditional mapping techniques (e.g., surface overlays, transects and gridlines combined with conventional photography) have been hindered by the non-trivial challenges associated with working in this area, including, but not limited to: (1) the remoteness of many of the tracksites; (2) the occurrence of the majority of the tracksites in the intertidal zone; (3) the size and complexity of many of the tracksites, with some extending over several square kilometres. Using the historically significant and well-known dinosaurian tracksites at Minyirr (Gantheaume Point), we show how these issues can be overcome through the use of an integrated array of remote sensing tools. A combination of high-resolution aerial photography...

Boundary-Layer Meteorology

Conditional sampling is used to locate mixed layer thermals and surface layer plumes, as well as ... more Conditional sampling is used to locate mixed layer thermals and surface layer plumes, as well as their downward moving companions - downdrafts - in a large data set obtained from flights by an instrumented motorglider in convective boundary layers over Eyre Peninsula, South Australia. The high resolution and excellent spatial coverage of the data permits a detailed study of internal structure. A compositing technique is used to construct average intersections through thermals and plumes from aircraft runs of given heights and directions. Groups of composites are then combined to form horizontal and vertical cross-sections, revealing the flow patterns and distribution of physical variables within "typical" thermals and plumes and their environment. Surface layer plumes are found to have strong lateral inflow patterns, in which air from the horizontal plane channels around the sides and then in behind the microfront present at the upstream edge. Mixed layer thermal towers ha...

Tellus B: Chemical and Physical Meteorology, 2015

Four turbulence measurement campaigns were performed in the winter sub-tropical jet streams of so... more Four turbulence measurement campaigns were performed in the winter sub-tropical jet streams of south coastal Japan and Australia during 1998-2001 with the objective to capture the dynamics of severe refractive and clear air turbulence events. The aircraft used was the GROB 520T EGRETT, which is owned and operated by Airborne Research Australia a unit of Flinders University of South Australia.

22nd Internation …, 2004

ANATOMY OF CIRRUS CLOUDS James A.Whiteway~1~, Clive Cook~2~, Martin W. Ga11agher~3~, Reinhold Bus... more ANATOMY OF CIRRUS CLOUDS James A.Whiteway~1~, Clive Cook~2~, Martin W. Ga11agher~3~, Reinhold Busen~4~, Tom W. Choularton~3~, Keith Bower~3~, Paul Connolly~3~, Michael Flynn~3~, and Jorg Hacker~5~ 1Department of Earth and Space ...

Walker, JP, Balling, J., Bell, M., Berg, A., Berger, M., Biasoni, D., Botha, E., Boulet, G., Chen... more Walker, JP, Balling, J., Bell, M., Berg, A., Berger, M., Biasoni, D., Botha, E., Boulet, G., Chen, Y., Christen, E., et al., 2007. The National Airborne Field Experiment Data Sets. MODSIM07: International Congress of Modelling and Simulation., 2625-2631.

3D Recording and Interpretation for Maritime Archaeology, 2019

Journal of Geophysical Research, 1999

Journal of Geophysical Research, 2008

Identifying the sources and sinks of methane and carbon dioxide is important for understanding pr... more Identifying the sources and sinks of methane and carbon dioxide is important for understanding processes within the Earth's climate system. This paper attempts to use back trajectories to identify sources of atmospheric methane and carbon dioxide as measured by high resolution in situ gas analyzers during aircraft ascents and descents in Southern Australia. Results from the back trajectory analysis were

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009