scholarly journals When does temperature matter for ecosystem respiration?

2021 ◽  
Author(s):  
Cristian Gudasz ◽  
Jan P Karlsson ◽  
David Bastviken
Keyword(s):  
Temperature Sensitivity ◽  
Temperature Effects ◽  
Temperature Increase ◽  
Ecosystem Respiration ◽  
Temperature Response ◽  
Effect Of Temperature ◽  
Respiration Rates ◽  
Sediment Respiration ◽  
Temperature Ranges ◽  
Temperature Factors

Abstract The temperature response of ecosystem processes is key to understand and predict impacts of climate change. This is especially true for respiration, given its high temperature sensitivity and major role in the global carbon cycle. However, similar intrinsic temperature sensitivity for respiration does not mean comparable temperature effects across ecosystems and biomes because non-temperature factors can be more important. Here we analyzed soil and sediment respiration data and found that in temperature ranges corresponding to high latitude mean temperatures, absolute respiration rates are more sensitive to non-temperature factors than to projected direct temperature effects. However, at higher temperatures (>20 °C) the direct effect of temperature mediated by temperature sensitivity will likely be more important over changes in non-temperature factors in shaping how respiration change over time. This supports past suggestions that the relatively small projected temperature increase at low (tropical) latitudes may have a large direct impact on absolute respiration. In contrast, absolute respiration rates at high (boreal/arctic) latitudes will likely be more sensitive on the development of the non-temperature factors than on the direct effects of the large projected temperature increase there.

scholarly journals Temperature requirements for growth and ripening of apples.

1988 ◽  
Vol 36 (1) ◽  
pp. 23-33
Author(s):  
H.G. Kronenberg
Keyword(s):  
Simple Model ◽  
Federal Republic ◽  
Positive Reaction ◽  
High Temperatures ◽  
Temperature Effects ◽  
Temperature Response ◽  
Effect Of Temperature ◽  
German Federal Republic ◽  
Temperature Requirements

The effect of temperature on the growth and ripening of fruits of up to ten cultivars grown at 4 different sites (2 in Netherlands, 1 in German Federal Republic and 1 in Denmark) was studied using a simple model. The period between flowering and harvest could be divided into 3 phases of differing temperature response. In most cases the first month after the beginning of the flowering and the period immediately before harvest showed a positive reaction towards high temperatures. During the period in between, which varied from 1-2 months in early cultivars to 5-6 months in late ones, no temperature effects were found in most cultivars. Temperature sums found in the first and third response periods did not show any relationship with earliness or lateness of crops. On the contrary, early and late cultivars had appoximately the same sums. Base monthly temperatures accounted for 0 to 89% of the differences in days between the different phases of growth of a fruit on the tree. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Temperature response of soil respiration largely unaltered with experimental warming

2016 ◽  
Vol 113 (48) ◽  
pp. 13797-13802 ◽  
Author(s):  
Joanna C. Carey ◽  
Jianwu Tang ◽  
Pamela H. Templer ◽  
Kevin D. Kroeger ◽  
Thomas W. Crowther ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Temperature Sensitivity ◽  
Boreal Forests ◽  
Temperature Response ◽  
Experimental Warming ◽  
Climatic Warming ◽  
Ambient Temperatures ◽  
Respiration Rates ◽  
Temperature Manipulation ◽  
Scientific Attention

The respiratory release of carbon dioxide (CO2) from soil is a major yet poorly understood flux in the global carbon cycle. Climatic warming is hypothesized to increase rates of soil respiration, potentially fueling further increases in global temperatures. However, despite considerable scientific attention in recent decades, the overall response of soil respiration to anticipated climatic warming remains unclear. We synthesize the largest global dataset to date of soil respiration, moisture, and temperature measurements, totaling >3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over 2 decades of warming. Our analysis reveals no significant differences in the temperature sensitivity of soil respiration between control and warmed plots in all biomes, with the exception of deserts and boreal forests. Thus, our data provide limited evidence of acclimation of soil respiration to experimental warming in several major biome types, contrary to the results from multiple single-site studies. Moreover, across all nondesert biomes, respiration rates with and without experimental warming follow a Gaussian response, increasing with soil temperature up to a threshold of ∼25 °C, above which respiration rates decrease with further increases in temperature. This consistent decrease in temperature sensitivity at higher temperatures demonstrates that rising global temperatures may result in regionally variable responses in soil respiration, with colder climates being considerably more responsive to increased ambient temperatures compared with warmer regions. Our analysis adds a unique cross-biome perspective on the temperature response of soil respiration, information critical to improving our mechanistic understanding of how soil carbon dynamics change with climatic warming.

The Effect of Temperature on the Mechanical Properties of CA Mortar

2012 ◽  
Vol 557-559 ◽  
pp. 860-864
Author(s):  
Li Wang ◽  
Wang Ping ◽  
Xiao Hui Zeng ◽  
Rong Chen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Temperature Sensitivity ◽  
Temperature Increase ◽  
Great Influence ◽  
Effect Of Temperature ◽  
Temperature Conditions ◽  
Ca Mortar

The compressive strength and the flexural strength of CA mortar at different temperature conditions were all tested. We have found that temperature has great influence on the mechanical properties of CA mortar. As the temperature increase from -40°C to 60°C, its compressive strength decrease from 31.7MPa to 1.5MPa for CRTS I type CA mortar, while the same rule can be found to the flexural strength. Results also showed that as the content of asphalt in mortar increases, the temperature sensitivity of mechanical properties increases.

scholarly journals Pyrolysis and Oxidation of PAN in Dry Air. Thermoanalytical Methods

1970 ◽  
Vol 17 (1) ◽  
pp. 38-42
Author(s):  
Anna BIEDUNKIEWICZ ◽  
Pawel FIGIEL ◽  
Marta SABARA
Keyword(s):  
Temperature Increase ◽  
Heating Rates ◽  
Linear Change ◽  
Dry Air ◽  
Isothermal Conditions ◽  
Gaseous Products ◽  
Heterogeneous Processes ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
Kinetics Of

The results of investigations on pyrolysis and oxidation of pure polyacrylonitrile (PAN) and its mixture with N,N-dimethylformamide (DMF) under non-isothermal conditions at linear change of samples temperature in time are presented. In each case process proceeded in different way. During pyrolysis of pure PAN the material containing mainly the product after PAN cyclization was obtained, while pyrolysis of PAN+DMF mixture gave the product after cyclization and stabilization. Under conditions of measurements, in both temperature ranges, series of gaseous products were formed.For the PAN-DMF system measurements at different samples heating rates were performed. The obtained results were in accordance with the kinetics of heterogeneous processes theory. The process rates in stages increased along with the temperature increase, and TG, DTG and HF function curves were shifted into higher temperature range. This means that the process of pyrolysis and oxidation of PAN in dry air can be carried out in a controlled way.http://dx.doi.org/10.5755/j01.ms.17.1.246

Temperature Sensitivity Analysis of Extended Source Double Gate Tunnel Field Effect Transistor

2021 ◽  
Author(s):  
Dharmender Nishad ◽  
Kaushal Nigam ◽  
Satyendra Kumar
Keyword(s):  
Temperature Sensitivity ◽  
Computer Aided Design ◽  
Field Effect ◽  
Field Effect Transistor ◽  
Effect Of Temperature ◽  
Double Gate ◽  
Extended Source ◽  
Temperature Variations ◽  
Effect Transistor ◽  
Tunnel Field Effect Transistor

Abstract Temperature-induced performance variation is one of the main concerns of the conventional stack gate oxide double gate tunnel field-effect transistor (SGO-DG-TFET). In this regard, we investigate the temperature sensitivity of extended source double gate tunnel field-effect transistor (ESDG-TFET). For this, we have analyzed the effect of temperature variations on the transfer characteristics, analog/RF, linearity and distortion figure of merits (FOMs) using technology computer aided design (TCAD) simulations. Further, the temperature sensitivity performance is compared with conventional SGO-DG-TFET. The comparative analysis shows that ESDG-TFET is less sensitive to temperature variations compared to the conventional SGO-DG-TFET. Therefore, this indicates that ESDG-TFET is more reliable for low-power, high-frequency applications at a higher temperature compared to conventional SGO-DG-TFET.

scholarly journals Effect of Temperature on Stiffness of Sandstones from the Deep North Sea Basin

2020 ◽  
Author(s):  
Tobias Orlander ◽  
Katrine Alling Andreassen ◽  
Ida Lykke Fabricius
Keyword(s):  
North Sea ◽  
Temperature Effects ◽  
Mass Density ◽  
Thermal Strain ◽  
High Stress ◽  
Testing Temperature ◽  
Effect Of Temperature ◽  
Stress Regime ◽  
The North

Abstract Development of high-pressure, high-temperature (HPHT) petroleum reservoirs situated at depths exceeding 5 km and in situ temperature of 170 °C increases the demand for theories and supporting experimental data capable of describing temperature effects on rock stiffness. With the intention of experimentally investigating temperature effects on stiffness properties, we investigated three sandstones from the deep North Sea Basin. As the North Sea Basin is presently undergoing substantial subsidence, we assumed that studied reservoir sandstones have never experienced higher temperature than in situ. We measured ultrasonic velocities in a low- and high-stress regime, and used mass density and stress–strain curves to derive, respectively, dynamic and static elastic moduli. We found that in both regimes, the dry sandstones stiffens with increasing testing temperature and assign expansion of minerals as a controlling mechanism. In the low-stress regime with only partial microcrack closure, we propose closure of microcracks as the stiffening mechanism. In the high-stress regime, we propose that thermal expansion of constituting minerals increases stress in grain contacts when the applied stress is high enough for conversion of thermal strain to thermal stress, thus leading to higher stiffness at in situ temperature. We then applied an extension of Biot’s effective stress equation including a non-isothermal term from thermoelastic theory and explain test results by adding boundary conditions to the equations.

scholarly journals How Asian aerosols impact regional surface temperatures across the globe

2020 ◽  
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Effects ◽  
Energy Transport ◽  
Temperature Response ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Temperature Responses ◽  
Global Surface

Abstract. South and East Asian anthropogenic aerosols mostly reside in an air mass extending from the Indian Ocean to the North Pacific. Yet the surface temperature effects of Asian aerosols spread across the whole globe. Here, we remove Asian anthropogenic aerosols from two independent climate models (ECHAM6.1 and NorESM1) using the same representation of aerosols via MACv2-SP (a simple plume implementation of the 2nd version of the Max Planck Institute Aerosol Climatology). We then robustly decompose the global distribution of surface temperature responses into contributions from atmospheric energy flux changes. We find that the horizontal atmospheric energy transport strongly moderates the surface temperature response over the regions where Asian aerosols reside. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the temperature effects efficiently across the Northern hemisphere, and to a lesser extent also over the Southern hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26 ± 0.04 °C (0.22 ± 0.03 for ECHAM6.1 and 0.30 ± 0.03 °C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01 ± 0.01 for ECHAM6.1 and 0.05 ± 0.01 °C for NorESM1) and shortwave cloud (0.03 ± 0.03 for ECHAM6.1 and 0.07 ± 0.02 °C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the Northern hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and weakest during the Arctic summer. We estimate that under a strong Asian aerosol mitigation policy tied with strong climate mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years' worth of current day global warming during the next few decades.

scholarly journals Rewetting of Three Drained Peatlands Drives Congruent Compositional Changes in Pro- and Eukaryotic Soil Microbiomes Through Environmental Filtering

2019 ◽  
Author(s):  
Micha Weil ◽  
Haitao Wang ◽  
Mia Bengtsson ◽  
Daniel Köhn ◽  
Anke Günther ◽  
...  
Keyword(s):  
Community Composition ◽  
Ecosystem Respiration ◽  
Abiotic Factors ◽  
Environmental Filtering ◽  
Network Analyses ◽  
Respiration Rates ◽  
Control Community ◽  
Methane Fluxes ◽  
Compositional Changes ◽  
Shed Light

AbstractDrained peatlands are significant sources of the greenhouse gas (GHG) carbon dioxide. Rewetting is a proven strategy to protect carbon stocks; however, it can lead to increased emissions of the potent GHG methane. The response to rewetting of soil microbiomes as drivers of these processes is poorly understood, as are biotic and abiotic factors that control community composition.We analyzed the pro- and eukaryotic microbiomes of three contrasting pairs of minerotrophic fens subject to decade-long drainage and subsequent rewetting. Also, abiotic soil properties including moisture, dissolved organic matter, methane fluxes and ecosystem respiration rates.The composition of the microbiomes was fen-type-specific, but all rewetted sites showed higher abundance of anaerobic taxa compared to drained sites. Based on multi-variate statistics and network analyses we identified soil moisture as major driver of community composition. Furthermore, salinity drove the separation between coastal and freshwater fen communities. Methanogens were more than tenfold more abundant in rewetted than in drained sites, while their abundance was lowest in the coastal fen, likely due to competition with sulfate reducers. The microbiome compositions were reflected in methane fluxes from the sites. Our results shed light on the factors that structure fen microbiomes via environmental filtering.

Deposition Effects on the Ultimate Strength of Tungsten Alloy

2014 ◽  
Vol 887-888 ◽  
pp. 857-860
Author(s):  
Ying Ge Xu ◽  
Ze Wei Wu
Keyword(s):  
Mechanical Properties ◽  
Ultimate Strength ◽  
Temperature Effects ◽  
Tensile Tests ◽  
Tungsten Alloy ◽  
Fracture Modes ◽  
Fracture Surfaces ◽  
Temperature Ranges

The temperature effects on the ultimate strength of 93WNiFe alloy have been investigated systematically through tensile tests, fracture surfaces and microstructure. The temperature ranges from 10 to 900 degrees. The results show that the ultimate strength decreases with the increase of temperature, and there is a platform in 300 to 600 degrees .The deposition has been observed in fracture surfaces from 500 to 600 degrees. The fracture modes influence the ultimate strength,deposition can improve mechanical properties of W-W and W-M interfaces, it is the cause of the ultimate strength platform.

Insights into temperature effects on structural deformation of a cable-stayed bridge based on structural health monitoring

2018 ◽  
Vol 18 (3) ◽  
pp. 778-791 ◽  
Author(s):  
Yi Zhou ◽  
Limin Sun
Keyword(s):  
Thermal Expansion ◽  
Health Monitoring ◽  
Temperature Effects ◽  
Temperature Response ◽  
Field Measurements ◽  
Structural Deformation ◽  
Linear Superposition ◽  
Thermally Induced ◽  
Diurnal Cycles ◽  
Cable Stayed Bridge

Structural deformation is an important consideration in the health monitoring of bridges, and its dependence on temperature variations is quite complex. Based on field measurements performed for an operational cable-stayed bridge, the proposed study investigates mechanisms of thermally induced variations in girder length and mid-span deflection through plane geometric and finite element analyses. The objective of this study is to understand the behaviour of such bridges over annual and diurnal cycles. It has been observed that the girder length and mid-span deflection of a cable-stayed bridge exhibit different modes of the temperature–response correlation. Thermally induced changes in girder length are solely governed by the average girder temperature, and its annual variation in amplitude is significantly larger compared to the diurnal variation. However, thermally induced mid-span deflections are simultaneously influenced by the cable temperature and average girder temperature, and these do not vary monotonously with temperature, thereby resulting in nearly equal variation amplitudes over both annual and diurnal cycles. Temperature-induced deformations of a cable-stayed bridge could well be approximated through multiple linear superposition of thermal-expansion effects of individual components. Besides thermal-expansion coefficients of structural materials, the temperature dependency of mid-span deflection of a symmetrical twin-tower cable-stayed bridge is closely related to the ratio of tower height above the deck to central span of the girder as well as span ratio of the side span to central span. The proposed simplified formulae to estimate the sensitivities of temperature effects could be readily extended to other cable-stayed bridges with different geometric arrangements, thereby providing valuable insights into thermally induced deformation of such bridges.

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