The impact of spatially varying wetland source signatures on the atmospheric variability of dD-CH4

2021 ◽  
Author(s):  
Angharad Stell ◽  
Peter Douglas ◽  
Matthew Rigby ◽  
Anita Ganesan
Keyword(s):  
Spatial Variation ◽  
Methane Emissions ◽  
Inverse Modelling ◽  
Large Impact ◽  
Atmospheric Variability ◽  
Model Studies ◽  
Modelling Studies ◽  
Spatially Varying ◽  
The Impact ◽  
Wetland Types

<p>We present the first spatially varying map of the δD-CH<sub>4 </sub>signature of wetland methane emissions and model its impact on atmospheric δD-CH<sub>4</sub>. The δD-CH<sub>4</sub> signature map is derived by relating the δD-H<sub>2</sub>O of precipitation to the measured δD-CH<sub>4</sub> of methane wetland emissions at a variety of wetland types and locations. Since the δD-H<sub>2</sub>O of precipitation is highly latitude-dependent, including this spatial variation has the potential to have a large impact on the distribution of δD-CH<sub>4</sub> observed in the atmosphere. This latitude-dependence means that wetland emissions at different latitudes can have very different impacts on atmospheric δD-CH<sub>4</sub>, which could provide a useful way to constrain the location of wetland methane emissions in future inverse modelling studies. Here, we assess the implications for model studies on the differences that arise by treating δD-CH<sub>4</sub> wetland source signatures as globally uniform rather than accounting for the large spatial variation. We also assess the potential for δD-CH<sub>4</sub> to provide an independent constraint on wetland emissions over the more abundant and widely measured δ<sup>13</sup>C-CH<sub>4</sub>.</p>

scholarly journals Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

2013 ◽  
Vol 13 (19) ◽  
pp. 9917-9937 ◽  
Author(s):  
R. Locatelli ◽  
P. Bousquet ◽  
F. Chevallier ◽  
A. Fortems-Cheney ◽  
S. Szopa ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Initial Conditions ◽  
Spatial Scales ◽  
Global Scale ◽  
Methane Emissions ◽  
Inverse Modelling ◽  
Model Errors ◽  
Inverse Systems ◽  
The Impact

Abstract. A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the three-component PYVAR-LMDZ-SACS (PYthon VARiational-Laboratoire de Météorologie Dynamique model with Zooming capability-Simplified Atmospheric Chemistry System) inversion system to produce 10 different methane emission estimates at the global scale for the year 2005. The same methane sinks, emissions and initial conditions have been applied to produce the 10 synthetic observation datasets. The same inversion set-up (statistical errors, prior emissions, inverse procedure) is then applied to derive flux estimates by inverse modelling. Consequently, only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg yr−1 at the global scale, representing 5% of total methane emissions. At continental and annual scales, transport model errors are proportionally larger than at the global scale, with errors ranging from 36 Tg yr−1 in North America to 7 Tg yr−1 in Boreal Eurasia (from 23 to 48%, respectively). At the model grid-scale, the spread of inverse estimates can reach 150% of the prior flux. Therefore, transport model errors contribute significantly to overall uncertainties in emission estimates by inverse modelling, especially when small spatial scales are examined. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher horizontal resolution in transport models. The large differences found between methane flux estimates inferred in these different configurations highly question the consistency of transport model errors in current inverse systems. Future inversions should include more accurately prescribed observation covariances matrices in order to limit the impact of transport model errors on estimated methane fluxes.

scholarly journals Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling

2013 ◽  
Vol 13 (4) ◽  
pp. 10961-11021
Author(s):  
R. Locatelli ◽  
P. Bousquet ◽  
F. Chevallier ◽  
A. Fortems-Cheney ◽  
S. Szopa ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Spatial Scales ◽  
Global Scale ◽  
Methane Emissions ◽  
Inverse Modelling ◽  
Model Errors ◽  
Inverse Systems ◽  
Set Up ◽  
The Impact

Abstract. A modelling experiment has been conceived to assess the impact of transport model errors on the methane emissions estimated by an atmospheric inversion system. Synthetic methane observations, given by 10 different model outputs from the international TransCom-CH4 model exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the PYVAR-LMDZ-SACS inverse system to produce 10 different methane emission estimates at the global scale for the year 2005. The same set-up has been used to produce the synthetic observations and to compute flux estimates by inverse modelling, which means that only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg CH4 per year at the global scale, representing 5% of the total methane emissions. At continental and yearly scales, transport model errors have bigger impacts depending on the region, ranging from 36 Tg CH4 in north America to 7 Tg CH4 in Boreal Eurasian (from 23% to 48%). At the model gridbox scale, the spread of inverse estimates can even reach 150% of the prior flux. Thus, transport model errors contribute to significant uncertainties on the methane estimates by inverse modelling, especially when small spatial scales are invoked. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher resolution models. The analysis of methane estimated fluxes in these different configurations questions the consistency of transport model errors in current inverse systems. For future methane inversions, an improvement in the modelling of the atmospheric transport would make the estimations more accurate. Likewise, errors of the observation covariance matrix should be more consistently prescribed in future inversions in order to limit the impact of transport model errors on estimated methane fluxes.

scholarly journals UNCERTAINTY OF NATURAL METHANE EMISSIONS FROM BOREAL WETLANDS

2020 ◽  
Vol 1 (5) ◽  
pp. 45-49
Author(s):  
S.N. Denisov ◽  
◽  
M.M. Arzhanov ◽  
Keyword(s):  
Land Surface ◽  
Moisture Transport ◽  
Methane Emissions ◽  
Hudson Bay ◽  
Atmospheric Variability ◽  
Methane Cycle ◽  
Model Cell ◽  
Heat And Moisture Transport ◽  
Heat And Moisture ◽  
The Impact

Current estimates of methane emissions from high latitude wetlands have significant intermodel variations, one reason for which may be internal atmospheric circulation variability. This paper analyzes the impact of internal atmospheric variability on variations in methane emissions from the Hudson Bay Lowland (HBL) area. The ensemble of numerical experiments with a joint model of the methane cycle and heat and moisture transport in soil was performed. An ensemble of 45 realizations of the multi-year data of meteorological variables at the land surface, calculated by the ECHAM5 for different initial and identical boundary conditions for a 34-year period (from 1.01.1979 to 31.12.2012) was specified as space-distributed input data. Necessary physical characteristics of the soil were calculated in the module of heat and moisture transport, supplemented with an interactive scheme for calculating the area of the model cell occupied by the wetlands. Wetlands are estimated to occupy 8–20 % (with 11.4 % ensemble mean) of HBL region area. The ensemble average of annual emissions for HBL over the estimated period equals 6.1 TgCH4/yr with – 0.1 TgCH4/yr trend. The obtained uncertainty associated with climate noise equals 32 % for average annual emissions, and 31–38 % for individual months. It is shown that a significant contribution to the high uncertainty of methane emissions is made by the climatically determined variability of the wetland area.

The impact of spatially varying wetland source signatures on the atmospheric variability of δ D-CH 4

2021 ◽  
Vol 379 (2210) ◽  
pp. 20200442
Author(s):  
Angharad C. Stell ◽  
Peter M. J. Douglas ◽  
Matthew Rigby ◽  
Anita L. Ganesan
Keyword(s):  
Spatial Information ◽  
Regional Scale ◽  
Atmospheric Model ◽  
Hemispheric Difference ◽  
Atmospheric Variability ◽  
Spatially Resolved ◽  
Global Atmospheric Model ◽  
Spatially Varying ◽  
The Impact ◽  
Global Mean

We present the first spatially resolved distribution of the δ D-CH 4 signature of wetland methane emissions and assess its impact on atmospheric δ D-CH 4 . The δ D-CH 4 signature map is derived by relating δ D-H 2 O of precipitation to measured δ D-CH 4 of methane wetland emissions at a variety of wetland types and locations. This results in strong latitudinal variation in the wetland δ D-CH 4 source signature. When δ D-CH 4 is simulated in a global atmospheric model, little difference is found in global mean, inter-hemispheric difference and seasonal cycle if the spatially varying δ D-CH 4 source signature distribution is used instead of a globally uniform value. This is because atmospheric δ D-CH 4 is largely controlled by OH fractionation. However, we show that despite these small differences, using atmospheric records of δ D-CH 4 to infer changes in the wetland emissions distribution requires the use of the more accurate spatially varying δ D-CH 4 source signature. We find that models will only be sensitive to changes in emissions distribution if spatial information can be exploited through the spatially resolved source signatures. In addition, we also find that on a regional scale, at sites measuring excursions of δ D-CH 4 from background levels, substantial differences are simulated in atmospheric δ D-CH 4 if using spatially varying or uniform source signatures. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 1)’.

The end of the laboratory developed test as we know it? Recommendations from a national multidisciplinary taskforce of laboratory specialists on the interpretation of the IVDR and its complications

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Paul C. D. Bank ◽  
Leo H. J. Jacobs ◽  
Sjoerd A. A. van den Berg ◽  
Hanneke W. M. van Deutekom ◽  
Dörte Hamann ◽  
...  
Keyword(s):  
Clinical Practice ◽  
The Netherlands ◽  
Medical Devices ◽  
Task Force ◽  
Large Impact ◽  
Guidance Document ◽  
Scientific Societies ◽  
Clinical Laboratories ◽  
The Impact

AbstractThe in vitro diagnostic medical devices regulation (IVDR) will take effect in May 2022. This regulation has a large impact on both the manufacturers of in vitro diagnostic medical devices (IVD) and clinical laboratories. For clinical laboratories, the IVDR poses restrictions on the use of laboratory developed tests (LDTs). To provide a uniform interpretation of the IVDR for colleagues in clinical practice, the IVDR Task Force was created by the scientific societies of laboratory specialties in the Netherlands. A guidance document with explanations and interpretations of relevant passages of the IVDR was drafted to help laboratories prepare for the impact of this new legislation. Feedback from interested parties and stakeholders was collected and used to further improve the document. Here we would like to present our approach to our European colleagues and inform them about the impact of the IVDR and, importantly we would like to present potentially useful approaches to fulfill the requirements of the IVDR for LDTs.

scholarly journals The Impact of Microclimate on the Reproductive Phenology of Female Populus tomentosa in a Micro-Scale Urban Green Space in Beijing

2021 ◽  
Vol 13 (6) ◽  
pp. 3518
Author(s):  
Xiaoyi Xing ◽  
Li Dong ◽  
Cecil Konijnendijk ◽  
Peiyao Hao ◽  
Shuxin Fan ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Spatial Variation ◽  
Air Temperature ◽  
Green Space ◽  
Populus Tomentosa ◽  
Early Spring ◽  
Reproductive Phenology ◽  
Primary Role ◽  
Micro Scale ◽  
The Impact

The spatial variation of poplars’ reproductive phenology in Beijing’s urban area has aggravated the threat of poplar fluff (cotton-like flying seeds) to public health. This research explored the impact of microclimate conditions on the reproductive phenology of female Populus tomentosa in Taoranting Park, a micro-scale green space in Beijing (range <1 km). The observed phenophases covered flowering, fruiting, and seed dispersal, and ENVI-MET was applied to simulate the effect of the microclimate on SGS (start day of the growing season). The results showed that a significant spatial variation in poplar reproductive phenology existed at the research site. The variation was significantly affected by the microclimate factors DMT (daily mean temperature) and DMH (daily mean heat transfer coefficient), with air temperature playing a primary role. Specifically, the phenology of flowering and fruiting phenophases (BBB, BF, FF, FS) was negatively correlated with DMT (−0.983 ≤ r ≤ −0.908, p <0.01) and positively correlated with DMH (0.769 ≤ r ≤ 0.864, p < 0.05). In contrast, DSD (duration of seed dispersal) showed a positive correlation with DMT (r = 0.946, p < 0.01) and a negative correlation with DMH (r = −0.922, p < 0.01). Based on the findings, the increase in air convection with lower air temperature and decrease in microclimate variation in green space can be an effective way to shorten the seed-flying duration to tackle poplar fluff pollution in Beijing’s early spring.

scholarly journals Microbial drivers of methane emissions from unrestored industrial salt ponds

2021 ◽  
Author(s):  
Jinglie Zhou ◽  
Susanna M. Theroux ◽  
Clifton P. Bueno de Mesquita ◽  
Wyatt H. Hartman ◽  
Ye Tian ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Methane Flux ◽  
Methane Emissions ◽  
Metagenomic Data ◽  
Rrna Gene ◽  
Salt Ponds ◽  
Salt Pond ◽  
Reference Wetlands ◽  
Reference Wetland ◽  
The Impact

AbstractWetlands are important carbon (C) sinks, yet many have been destroyed and converted to other uses over the past few centuries, including industrial salt making. A renewed focus on wetland ecosystem services (e.g., flood control, and habitat) has resulted in numerous restoration efforts whose effect on microbial communities is largely unexplored. We investigated the impact of restoration on microbial community composition, metabolic functional potential, and methane flux by analyzing sediment cores from two unrestored former industrial salt ponds, a restored former industrial salt pond, and a reference wetland. We observed elevated methane emissions from unrestored salt ponds compared to the restored and reference wetlands, which was positively correlated with salinity and sulfate across all samples. 16S rRNA gene amplicon and shotgun metagenomic data revealed that the restored salt pond harbored communities more phylogenetically and functionally similar to the reference wetland than to unrestored ponds. Archaeal methanogenesis genes were positively correlated with methane flux, as were genes encoding enzymes for bacterial methylphosphonate degradation, suggesting methane is generated both from bacterial methylphosphonate degradation and archaeal methanogenesis in these sites. These observations demonstrate that restoration effectively converted industrial salt pond microbial communities back to compositions more similar to reference wetlands and lowered salinities, sulfate concentrations, and methane emissions.

Numerical modeling and analysis of the noncontacting impulse gas face seals

2018 ◽  
Vol 233 (8) ◽  
pp. 1139-1153
Author(s):  
Slawomir Blasiak
Keyword(s):  
Computer Software ◽  
Surface Modifications ◽  
Mechanical Seals ◽  
Face Surface ◽  
Modeling And Analysis ◽  
C Language ◽  
Model Studies ◽  
Face Seals ◽  
Radial Gap ◽  
The Impact

Noncontacting mechanical seals with various kinds of face surface modifications have established their position in the sealing technique. Over the last few years, a lot of works dedicated to the impact of various surface modifications on the dynamics of working rings have been created. This paper presents model studies regarding relatively unknown noncontacting impulse gas face seals. Here, a mathematical model of impulse gas face seals is developed including the nonlinear Reynolds equation and stator dynamics equations, which were solved simultaneously using numerical methods. An original computer software written in C + + language was developed. A number of numerical tests were conducted and the phenomena occurring in the radial gap during seal operation were analyzed. Final conclusions were drawn and several features were indicated characterizing impulse face seals. It should be emphasized that numerical research on this type of seals has not been published yet. The literature usually presents simplified models for the noncompressible medium, which can be solved with the use of analytical methods.

scholarly journals Multi-model study of mercury dispersion in the atmosphere: Vertical distribution of mercury species

2016 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
The Impact ◽  
The Vertical Distribution

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model inter-comparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground based observations of mercury concentration and deposition, here we investigate the vertical distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on inter-continental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including inter-hemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury (RM) patterns depending on altitude. High RM concentrations in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parametrizations in the chemistry transport models also proved to have a substantial impact on model results.

scholarly journals Studying the Impact of Radioactive Charging on the Microphysical Evolution and Transport of Radioactive Aerosols with the TOMAS-RC v1 framework

2017 ◽  
Author(s):  
Petros Vasilakos ◽  
Yong-Ηa Kim ◽  
Jeffrey R. Pierce ◽  
Sotira Yiacoumi ◽  
Costas Tsouris ◽  
...  
Keyword(s):  
Background Radiation ◽  
Atmospheric Transport ◽  
Long Range Transport ◽  
Radioactive Aerosol ◽  
Computationally Efficient ◽  
Radioactive Aerosols ◽  
Model Studies ◽  
Aerosol Mass ◽  
Range Transport ◽  
The Impact

Abstract. Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. The objective of this work is to determine the influence of radioactive charging on the vertical transport of radioactive aerosols in the atmosphere, through its effect on coagulation and deposition, as well as quantifying the impact of this charging on aerosol lifetime. The TwO-Moment Aerosol Sectional (TOMAS) microphysical model was extended to account for radioactive charging effects on coagulation in a computationally efficient way. The expanded model, TOMAS-RC (TOMAS with Radioactive Charging effects), was then used to simulate the microphysical evolution and deposition of radioactive aerosol (containing the isotopes 131I and 137Cs) in a number of idealized atmospheric transport experiments. Results indicate that radioactive charging can facilitate or suppress coagulation of radioactive aerosols, thus influencing the deposition patterns and total amount of radioactive aerosol mass available for long-range transport. Sensitivity simulations to uncertain parameters affirm the potential importance of radioactive charging effects. An important finding is that charging of neutral, coarse mode aerosol from background radiation can reduce coagulation rates and extend its lifetime in the atmosphere by up to a factor of 2.

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