scholarly journals A practical approach for uncertainty quantification of high-frequency soil respiration using Forced Diffusion chambers

2015 ◽  
Vol 120 (1) ◽  
pp. 128-146 ◽  
Author(s):  
Martin Lavoie ◽  
C. L. Phillips ◽  
David Risk
Keyword(s):  
Soil Respiration ◽  
Uncertainty Quantification ◽  
High Frequency ◽  
Practical Approach ◽  
Diffusion Chambers ◽  
Forced Diffusion

scholarly journals A practical approach to storage and retrieval of high-frequency physiological signals

2020 ◽  
Vol 41 (3) ◽  
pp. 035008 ◽  
Author(s):  
Andrew J Goodwin ◽  
Danny Eytan ◽  
Robert W Greer ◽  
Mjaye Mazwi ◽  
Anirudh Thommandram ◽  
...  
Keyword(s):  
High Frequency ◽  
Physiological Signals ◽  
Practical Approach ◽  
Storage And Retrieval

scholarly journals Source partitioning of H<sub>2</sub>O and CO<sub>2</sub> fluxes based on high-frequency eddy covariance data: a comparison between study sites

2019 ◽  
Vol 16 (6) ◽  
pp. 1111-1132 ◽  
Author(s):  
Anne Klosterhalfen ◽  
Alexander Graf ◽  
Nicolas Brüggemann ◽  
Clemens Drüe ◽  
Odilia Esser ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Eddy Covariance ◽  
High Frequency ◽  
Canopy Height ◽  
Canopy Density ◽  
Partitioning Methods ◽  
Site Characteristics ◽  
Measurement Height ◽  
Study Sites ◽  
Source Partitioning

Abstract. For an assessment of the roles of soil and vegetation in the climate system, a further understanding of the flux components of H2O and CO2 (e.g., transpiration, soil respiration) and their interaction with physical conditions and physiological functioning of plants and ecosystems is necessary. To obtain magnitudes of these flux components, we applied source partitioning approaches after Scanlon and Kustas (2010; SK10) and after Thomas et al. (2008; TH08) to high-frequency eddy covariance measurements of 12 study sites covering different ecosystems (croplands, grasslands, and forests) in different climatic regions. Both partitioning methods are based on higher-order statistics of the H2O and CO2 fluctuations, but proceed differently to estimate transpiration, evaporation, net primary production, and soil respiration. We compared and evaluated the partitioning results obtained with SK10 and TH08, including slight modifications of both approaches. Further, we analyzed the interrelations among the performance of the partitioning methods, turbulence characteristics, and site characteristics (such as plant cover type, canopy height, canopy density, and measurement height). We were able to identify characteristics of a data set that are prerequisites for adequate performance of the partitioning methods. SK10 had the tendency to overestimate and TH08 to underestimate soil flux components. For both methods, the partitioning of CO2 fluxes was less robust than for H2O fluxes. Results derived with SK10 showed relatively large dependencies on estimated water use efficiency (WUE) at the leaf level, which is a required input. Measurements of outgoing longwave radiation used for the estimation of foliage temperature (used in WUE) could slightly increase the quality of the partitioning results. A modification of the TH08 approach, by applying a cluster analysis for the conditional sampling of respiration–evaporation events, performed satisfactorily, but did not result in significant advantages compared to the original method versions developed by Thomas et al. (2008). The performance of each partitioning approach was dependent on meteorological conditions, plant development, canopy height, canopy density, and measurement height. Foremost, the performance of SK10 correlated negatively with the ratio between measurement height and canopy height. The performance of TH08 was more dependent on canopy height and leaf area index. In general, all site characteristics that increase dissimilarities between scalars appeared to enhance partitioning performance for SK10 and TH08.

High-frequency analysis of the diel patterns of mineral soil respiration under different forest management

2017 ◽  
Vol 37 (1) ◽  
Author(s):  
郑永 ZHENG Yong ◽  
刘小飞 LIU Xiaofei ◽  
郑蔚 ZHENG Wei ◽  
周嘉聪 ZHOU Jiacong ◽  
苏瑞兰 SU Ruilan ◽  
...  
Keyword(s):  
Forest Management ◽  
Soil Respiration ◽  
Frequency Analysis ◽  
High Frequency ◽  
Mineral Soil ◽  
Diel Patterns

scholarly journals Analyzing High‐Frequency Soil Respiration Using a Probabilistic Model in a Semiarid, Mediterranean Climate

2019 ◽  
Vol 124 (3) ◽  
pp. 509-520
Author(s):  
H. Anjileli ◽  
H. R. Moftakhari ◽  
O. Mazdiyasni ◽  
H. Norouzi ◽  
S. Ashraf ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Probabilistic Model ◽  
High Frequency ◽  
Mediterranean Climate

scholarly journals Extreme heat events heighten soil respiration

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hassan Anjileli ◽  
Laurie S. Huning ◽  
Hamed Moftakhari ◽  
Samaneh Ashraf ◽  
Ata Akbari Asanjan ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Carbon Cycle ◽  
High Frequency ◽  
The Past ◽  
Extreme Heat Events ◽  
In Situ Observations ◽  
Terrestrial Feedback ◽  
The Relationship ◽  
Heat Events

AbstractIn the wake of climate change, extreme events such as heatwaves are considered to be key players in the terrestrial biosphere. In the past decades, the frequency and severity of heatwaves have risen substantially, and they are projected to continue to intensify in the future. One key question is therefore: how do changes in extreme heatwaves affect the carbon cycle? Although soil respiration (Rs) is the second largest contributor to the carbon cycle, the impacts of heatwaves on Rs have not been fully understood. Using a unique set of continuous high frequency in-situ measurements from our field site, we characterize the relationship between Rs and heatwaves. We further compare the Rs response to heatwaves across ten additional sites spanning the contiguous United States (CONUS). Applying a probabilistic framework, we conclude that during heatwaves Rs rates increase significantly, on average, by ~ 26% relative to that of non-heatwave conditions over the CONUS. Since previous in-situ observations have not measured the Rs response to heatwaves (e.g., rate, amount) at the high frequency that we present here, the terrestrial feedback to the carbon cycle may be underestimated without capturing these high frequency extreme heatwave events.

scholarly journals Source Partitioning of H<sub>2</sub>O and CO<sub>2</sub> Fluxes Based on High Frequency Eddy Covariance Data: a Comparison between Study Sites

2018 ◽  
Author(s):  
Anne Klosterhalfen ◽  
Alexander Graf ◽  
Nicolas Brüggemann ◽  
Clemens Drüe ◽  
Odilia Esser ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Eddy Covariance ◽  
High Frequency ◽  
Canopy Height ◽  
Canopy Density ◽  
Partitioning Methods ◽  
Site Characteristics ◽  
Measurement Height ◽  
Study Sites ◽  
Source Partitioning

Abstract. For an assessment of the role of soil and vegetation in the climate system, a further understanding of the flux components of H2O and CO2 (e.g., transpiration, soil respiration) and their interaction with physical conditions and physiological functioning of plants and ecosystems is necessary. To obtain magnitudes of these flux components, we applied the source partitioning approaches after Scanlon and Kustas (2010; SK10) and after Thomas et al. (2008; TH08) to high frequency eddy covariance measurements of twelve study sites including various ecosystems (croplands, grasslands, and forests) in a number of countries. Both partitioning methods are based on higher-order statistics of the H2O and CO2 fluctuations, but proceed differently to estimate transpiration, evaporation, net primary production, and soil respiration. We compared and evaluated the partitioning results obtained with SK10 and TH08 including slight modifications of both approaches. Further, we analyzed the interrelations between turbulence characteristics, site characteristics (such as plant cover type, canopy height, canopy density and measurement height), and performance of the partitioning methods. We could identify characteristics of a data set as prerequisite for a sufficient performance of the partitioning methods. SK10 had the tendency to overestimate and TH08 to underestimate soil flux components. For both methods, the partitioning of CO2 fluxes was more irregular than of H2O fluxes. Results derived with SK10 showed relatively large dependencies on estimated water use efficiency (WUE) at leaf-level, which is needed as an input. Measurements of outgoing longwave radiation used for the estimation of foliage temperature and WUE could slightly increase the quality of the partitioning results. A modification of the TH08 approach, by applying a cluster analysis for the conditional sampling of respiration/evaporation events, performed satisfactorily, but did not result in significant advantages compared to the other method versions (developed by Thomas et al., 2008). The performance of each partitioning approach was dependent on meteorological conditions, plant development, canopy height, canopy density, and measurement height. Foremost, the performance of SK10 correlated negatively with the ratio between measurement and canopy height. The performance of TH08 was more dependent on canopy height and leaf area index. It was found, that all site characteristics which increase dissimilarities between scalars enhance partitioning performance for SK10 and TH08.

Effects of simulated rainfall events on soil carbon transformation

Soil Research ◽  
2010 ◽  
Vol 48 (5) ◽  
pp. 404 ◽  
Author(s):  
Jiaying Zhang ◽  
Zhongbing Lin ◽  
Renduo Zhang ◽  
Jing Shen
Keyword(s):  
Soil Respiration ◽  
Water Content ◽  
High Frequency ◽  
Co2 Emission ◽  
Control Treatment ◽  
Microbial Biomass C ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
Soil C ◽  
Respiration Rates

The storage of carbon (C) in soils can be influenced by rainfall patterns that affect both inputs from plant productivity and losses through soil respiration. The aim of this study was to investigate the effect of rainfall on the soil C transformation. A laboratory experiment was conducted using soil columns with different treatments, including a control with constant water content, and rainfall treatments with applications of 3, 6, and 10 simulated rainfall events during an experimental period of 31 days. Results showed that pulses of soil respiration rates occurred after the first 3 rainfall events, associated with soil water content and CO2 concentration pulses in the soil profile, while subsequent rainfall events did not result in similar increases in CO2 concentrations and respiration rates. Relative to the control treatment, the treatments with low (3 rainfall events) and moderate (6 rainfall events) amounts of total water applied resulted in 181% and 72% increases, respectively, in cumulative CO2 emission. In contrast, the high frequency rainfall treatment with the greatest amount of water resulted in a 40% reduction in cumulative CO2 emission. Soil microbial biomass C slightly increased under treatments with low and moderate rainfall treatments, but decreased under the treatment with 10 rainfall events. The results indicate that rainfall events with a high frequency and increased amount of water, and associated saturation of soils, can significantly reduce soil C losses during the wet season. The rainfall frequency and amount are of importance in controlling soil C emissions and should be incorporated into models of soil C dynamics.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

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