The paper introduces the OZFLUX network which is being established to study several Australian ec... more The paper introduces the OZFLUX network which is being established to study several Australian ecosystems, discusses the analysis of eddy covariance data from tower-based flux stations, and then examines use of the flux data and a SVAT model within an atmospheric transport model to estimate regional fluxes. Lack of energy closure by eddy covariance measurements is commonly observed for Euroflux and Ameriflux installations. Reasons for the underestimates of H+ lambda E may result from the way water vapor concentrations are determined using closed-path infrared gas analyzers. A comparison of open- and closed-path analyzers show that energy closure to better than 95% can be achieved with both systems when water vapor concentrations are expressed as mixing ratios in dry air, along with careful choice of the coordinate framework and the averaging periods used to calculate fluxes. Water, energy and carbon dioxide fluxes for two ecosystems are compared: 1) a 40 m tall, cool temperate Eucal...
ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release... more ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release of carbon and water by the terrestrial biosphere to quantify the sink and source strengths under current climatic conditions. In addition, understanding the consequences of a changing climate on the capacity of the biosphere to sequester carbon by using a certain amount of water and the impacts of disturbances on resilience and thresholds of the terrestrial biosphere is critical. Recently there has been increasing general interest in how human activities may be affecting Australia's natural carbon cycles. Quantification of carbon and water exchanges requires process understanding over long temporal and large spatial scales, but at fine levels of detail. This requires integration of long term, high frequency observations, models and information from process studies and can only be achieved through research infrastructure that can provide easy access to meta-data and data that have been collected in a systematic and standardized way. The Australian Terrestrial Ecosystem Research Network (TERN) provides such nationally networked infrastructure, along with multi-disciplinary capabilities and end-user-focused products to deliver better ways of measuring and estimating Australia's current and future environmental carbon stocks and flows. Multiple Facilities in TERN are studying carbon and water dynamics across a range of distance and time scales. OzFlux, the Australasian arm of the global initiative Fluxnet, is the most obvious deployment of field hardware in TERN with close to 30 flux towers and their associated micrometeorological instrumentation in place around the country, from Central Australia to the Alps, covering ecosystems ranging from rainforest to alpine grasslands to mulga. Intensive monitoring is carried out at the 10 TERN Supersites which carry a suite of environmental instrumentation and perform standardised vegetation, faunal, soil and water monitoring.TERN AusCover provides a national expert network and data delivery service for provision of Australian biophysical remote sensing time-series data, continental-scale map products, and select high-resolution datasets over TERN OzFlux and Supersites. Integration of data streams and modeling is carried out through the TERN eMAST Facility. This presentation will give an overview of the infrastructure related to research in biogeochemistry through TERN. We will show how the deployment of large-scale infrastructure, observations, the curation of data and assimilation and integration of data into modelling is enhancing our process understanding of carbon uptake and water use in a large range of ecosystems.
Even moderately complex topography can lead to significant horizontal and vertical advection and ... more Even moderately complex topography can lead to significant horizontal and vertical advection and a consequent underestimation of nocturnal CO2 fluxes derived from eddy covariance measurements on a single tower. The presence of advective transport is identified using the time series of CO2 concentrations. Given a continuous input of carbon (soil-, wood- and leaf respiration) into a control volume (CV) we
ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release... more ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release of carbon and water by the terrestrial biosphere to quantify the sink and source strengths under current climatic conditions. In addition, understanding the consequences of a changing climate on the capacity of the biosphere to sequester carbon by using a certain amount of water and the impacts of disturbances on resilience and thresholds of the terrestrial biosphere is critical. Recently there has been increasing general interest in how human activities may be affecting Australia's natural carbon cycles. Quantification of carbon and water exchanges requires process understanding over long temporal and large spatial scales, but at fine levels of detail. This requires integration of long term, high frequency observations, models and information from process studies and can only be achieved through research infrastructure that can provide easy access to meta-data and data that have been collected in a systematic and standardized way. The Australian Terrestrial Ecosystem Research Network (TERN) provides such nationally networked infrastructure, along with multi-disciplinary capabilities and end-user-focused products to deliver better ways of measuring and estimating Australia's current and future environmental carbon stocks and flows. Multiple Facilities in TERN are studying carbon and water dynamics across a range of distance and time scales. OzFlux, the Australasian arm of the global initiative Fluxnet, is the most obvious deployment of field hardware in TERN with close to 30 flux towers and their associated micrometeorological instrumentation in place around the country, from Central Australia to the Alps, covering ecosystems ranging from rainforest to alpine grasslands to mulga. Intensive monitoring is carried out at the 10 TERN Supersites which carry a suite of environmental instrumentation and perform standardised vegetation, faunal, soil and water monitoring.TERN AusCover provides a national expert network and data delivery service for provision of Australian biophysical remote sensing time-series data, continental-scale map products, and select high-resolution datasets over TERN OzFlux and Supersites. Integration of data streams and modeling is carried out through the TERN eMAST Facility. This presentation will give an overview of the infrastructure related to research in biogeochemistry through TERN. We will show how the deployment of large-scale infrastructure, observations, the curation of data and assimilation and integration of data into modelling is enhancing our process understanding of carbon uptake and water use in a large range of ecosystems.
Australian Journal of Experimental Agriculture, 2007
ABSTRACT Wind tunnel studies have been used to simulate hot dry wind events that occur in Mediter... more ABSTRACT Wind tunnel studies have been used to simulate hot dry wind events that occur in Mediterranean climates and to investigate their possible impact on field crop production. This study investigates the effects of wind speed, duration, flower development stage and soil moisture on flower abortion and pod set in faba bean ( Vicia faba L.) using a wind tunnel. At an air temperature of 30 C and relative humidity of 15 - 25%, rates of flower abortion increased with wind speed across a range of 2 to 12 m/ s with the proportion of flowers setting a healthy pod following treatment declining for all stages of flower development tested. At 12.5 m/ s, flower abortion reached close to the maximum observed, with a 35% reduction in pod set below that observed in the control plants at flower development stages up to and including anthesis. As the flowers develop, they become less sensitive to the hot windy conditions with abortion rates declining gradually from early developmental stages and showing a sharp decline in sensitivity after anthesis. Once the pod has set and extended beyond the withered petals, it is not vulnerable to extreme wind conditions and has a high chance of continuing to develop if moisture is available. Lower soil moisture levels and increased duration inconsistently increased the rate of flower abortion. When soil moisture is not limiting, hot dry wind will significantly contribute to flower abortion and may reduce crop yield. This level of flower abortion does not necessarily translate directly to yield reduction as pods that have already set on proximal nodes have a low vulnerability to adverse conditions and may remain unaffected by a severe wind event, while flowers at an early stage of development on distal nodes are vulnerable and may be affected leading to flower loss. If plant development is interrupted due to ending of the growing season, the more distal flowers may not have an opportunity to reach a harvestable stage and the impact of the wind event will not be expressed in the final yield. Net yield reduction therefore depends on seasonal conditions and the timing of the event. These results infer that the risk and extent of yield reduction in faba beans following severe climate events during the flowering phase could be minimised by creating sheltered zones of reduced wind speed with planted windbreaks.
In the last two decades substantial advances have been made in the understanding of the scientifi... more In the last two decades substantial advances have been made in the understanding of the scientific basis of urban climates. These are reviewed here with attention to sustainability of cities, applications that use climate information, and scientific understanding in relation to measurements and modelling. Consideration is given from street (micro) scale to neighbourhood (local) to city and region (meso) scale. Those areas where improvements are needed in the next decade to ensure more sustainable cities are identified. High- ...
The paper introduces the OZFLUX network which is being established to study several Australian ec... more The paper introduces the OZFLUX network which is being established to study several Australian ecosystems, discusses the analysis of eddy covariance data from tower-based flux stations, and then examines use of the flux data and a SVAT model within an atmospheric transport model to estimate regional fluxes. Lack of energy closure by eddy covariance measurements is commonly observed for Euroflux and Ameriflux installations. Reasons for the underestimates of H+ lambda E may result from the way water vapor concentrations are determined using closed-path infrared gas analyzers. A comparison of open- and closed-path analyzers show that energy closure to better than 95% can be achieved with both systems when water vapor concentrations are expressed as mixing ratios in dry air, along with careful choice of the coordinate framework and the averaging periods used to calculate fluxes. Water, energy and carbon dioxide fluxes for two ecosystems are compared: 1) a 40 m tall, cool temperate Eucal...
ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release... more ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release of carbon and water by the terrestrial biosphere to quantify the sink and source strengths under current climatic conditions. In addition, understanding the consequences of a changing climate on the capacity of the biosphere to sequester carbon by using a certain amount of water and the impacts of disturbances on resilience and thresholds of the terrestrial biosphere is critical. Recently there has been increasing general interest in how human activities may be affecting Australia's natural carbon cycles. Quantification of carbon and water exchanges requires process understanding over long temporal and large spatial scales, but at fine levels of detail. This requires integration of long term, high frequency observations, models and information from process studies and can only be achieved through research infrastructure that can provide easy access to meta-data and data that have been collected in a systematic and standardized way. The Australian Terrestrial Ecosystem Research Network (TERN) provides such nationally networked infrastructure, along with multi-disciplinary capabilities and end-user-focused products to deliver better ways of measuring and estimating Australia's current and future environmental carbon stocks and flows. Multiple Facilities in TERN are studying carbon and water dynamics across a range of distance and time scales. OzFlux, the Australasian arm of the global initiative Fluxnet, is the most obvious deployment of field hardware in TERN with close to 30 flux towers and their associated micrometeorological instrumentation in place around the country, from Central Australia to the Alps, covering ecosystems ranging from rainforest to alpine grasslands to mulga. Intensive monitoring is carried out at the 10 TERN Supersites which carry a suite of environmental instrumentation and perform standardised vegetation, faunal, soil and water monitoring.TERN AusCover provides a national expert network and data delivery service for provision of Australian biophysical remote sensing time-series data, continental-scale map products, and select high-resolution datasets over TERN OzFlux and Supersites. Integration of data streams and modeling is carried out through the TERN eMAST Facility. This presentation will give an overview of the infrastructure related to research in biogeochemistry through TERN. We will show how the deployment of large-scale infrastructure, observations, the curation of data and assimilation and integration of data into modelling is enhancing our process understanding of carbon uptake and water use in a large range of ecosystems.
Even moderately complex topography can lead to significant horizontal and vertical advection and ... more Even moderately complex topography can lead to significant horizontal and vertical advection and a consequent underestimation of nocturnal CO2 fluxes derived from eddy covariance measurements on a single tower. The presence of advective transport is identified using the time series of CO2 concentrations. Given a continuous input of carbon (soil-, wood- and leaf respiration) into a control volume (CV) we
ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release... more ABSTRACT It is essential to understand the drivers and processes that regulate uptake and release of carbon and water by the terrestrial biosphere to quantify the sink and source strengths under current climatic conditions. In addition, understanding the consequences of a changing climate on the capacity of the biosphere to sequester carbon by using a certain amount of water and the impacts of disturbances on resilience and thresholds of the terrestrial biosphere is critical. Recently there has been increasing general interest in how human activities may be affecting Australia's natural carbon cycles. Quantification of carbon and water exchanges requires process understanding over long temporal and large spatial scales, but at fine levels of detail. This requires integration of long term, high frequency observations, models and information from process studies and can only be achieved through research infrastructure that can provide easy access to meta-data and data that have been collected in a systematic and standardized way. The Australian Terrestrial Ecosystem Research Network (TERN) provides such nationally networked infrastructure, along with multi-disciplinary capabilities and end-user-focused products to deliver better ways of measuring and estimating Australia's current and future environmental carbon stocks and flows. Multiple Facilities in TERN are studying carbon and water dynamics across a range of distance and time scales. OzFlux, the Australasian arm of the global initiative Fluxnet, is the most obvious deployment of field hardware in TERN with close to 30 flux towers and their associated micrometeorological instrumentation in place around the country, from Central Australia to the Alps, covering ecosystems ranging from rainforest to alpine grasslands to mulga. Intensive monitoring is carried out at the 10 TERN Supersites which carry a suite of environmental instrumentation and perform standardised vegetation, faunal, soil and water monitoring.TERN AusCover provides a national expert network and data delivery service for provision of Australian biophysical remote sensing time-series data, continental-scale map products, and select high-resolution datasets over TERN OzFlux and Supersites. Integration of data streams and modeling is carried out through the TERN eMAST Facility. This presentation will give an overview of the infrastructure related to research in biogeochemistry through TERN. We will show how the deployment of large-scale infrastructure, observations, the curation of data and assimilation and integration of data into modelling is enhancing our process understanding of carbon uptake and water use in a large range of ecosystems.
Australian Journal of Experimental Agriculture, 2007
ABSTRACT Wind tunnel studies have been used to simulate hot dry wind events that occur in Mediter... more ABSTRACT Wind tunnel studies have been used to simulate hot dry wind events that occur in Mediterranean climates and to investigate their possible impact on field crop production. This study investigates the effects of wind speed, duration, flower development stage and soil moisture on flower abortion and pod set in faba bean ( Vicia faba L.) using a wind tunnel. At an air temperature of 30 C and relative humidity of 15 - 25%, rates of flower abortion increased with wind speed across a range of 2 to 12 m/ s with the proportion of flowers setting a healthy pod following treatment declining for all stages of flower development tested. At 12.5 m/ s, flower abortion reached close to the maximum observed, with a 35% reduction in pod set below that observed in the control plants at flower development stages up to and including anthesis. As the flowers develop, they become less sensitive to the hot windy conditions with abortion rates declining gradually from early developmental stages and showing a sharp decline in sensitivity after anthesis. Once the pod has set and extended beyond the withered petals, it is not vulnerable to extreme wind conditions and has a high chance of continuing to develop if moisture is available. Lower soil moisture levels and increased duration inconsistently increased the rate of flower abortion. When soil moisture is not limiting, hot dry wind will significantly contribute to flower abortion and may reduce crop yield. This level of flower abortion does not necessarily translate directly to yield reduction as pods that have already set on proximal nodes have a low vulnerability to adverse conditions and may remain unaffected by a severe wind event, while flowers at an early stage of development on distal nodes are vulnerable and may be affected leading to flower loss. If plant development is interrupted due to ending of the growing season, the more distal flowers may not have an opportunity to reach a harvestable stage and the impact of the wind event will not be expressed in the final yield. Net yield reduction therefore depends on seasonal conditions and the timing of the event. These results infer that the risk and extent of yield reduction in faba beans following severe climate events during the flowering phase could be minimised by creating sheltered zones of reduced wind speed with planted windbreaks.
In the last two decades substantial advances have been made in the understanding of the scientifi... more In the last two decades substantial advances have been made in the understanding of the scientific basis of urban climates. These are reviewed here with attention to sustainability of cities, applications that use climate information, and scientific understanding in relation to measurements and modelling. Consideration is given from street (micro) scale to neighbourhood (local) to city and region (meso) scale. Those areas where improvements are needed in the next decade to ensure more sustainable cities are identified. High- ...
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