scholarly journals Natural and anthropogenic methane fluxes in Eurasia: a meso-scale quantification by generalized atmospheric inversion

2014 ◽  
Vol 11 (10) ◽  
pp. 14587-14637 ◽  
Author(s):  
A. Berchet ◽  
I. Pison ◽  
F. Chevallier ◽  
J.-D. Paris ◽  
P. Bousquet ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Region Of Interest ◽  
Methane Emissions ◽  
Surface Fluxes ◽  
Atmospheric Methane ◽  
Mixing Ratios ◽  
Methane Fluxes ◽  
Meso Scale ◽  
Atmospheric Inversion

Abstract. Eight surface observation sites providing quasi-continuous measurements of atmospheric methane mixing ratios have been operated since the mid-2000's in Siberia. For the first time in a single work, we assimilate all of these in situ data in an atmospheric inversion. Our objective is to quantify methane surface fluxes from anthropogenic and wetland sources at the meso-scale in the Siberian Lowlands for the year 2010. To do so, we first inquire into the way the inversion uses the observations and the fluxes are constrained by the observation sites. As atmospheric inversions at the meso-scale suffer from mis-quantified sources of uncertainties, we follow recent innovations in inversion techniques and use a new inversion approach which quantifies the uncertainties more objectively than the previous inversions. We find that, due to errors in the representation of the atmospheric transport and redundant pieces of information, only one observation every few days is found valuable by the inversion. The remaining high-resolution signals are representative of very local emission patterns. An analysis of the use of information by the inversion also reveals that the observation sites constrain methane emissions within a radius of 500 km. More observation sites are necessary to constrain the whole Siberian Lowlands. Still, the fluxes within the constrained areas are quantified with objectified uncertainties. At the end, the tolerance intervals for posterior methane fluxes are of roughly 20% (resp. 50%) of the fluxes for anthropogenic (resp. wetland) sources. About 50–70% of emissions are constrained by the inversion on average on an annual basis. Extrapolating the figures on the constrained areas to the whole Siberian Lowlands, we find a regional methane budget of 5–28 Tg CH4 for the year 2010, i.e. 1–5% of the global methane emissions. As very few in situ observations are available in the region of interest, observations of methane total columns from the Greenhouse Gas Observing SATellite (GOSAT) are used for the evaluation of the inversion results, but they exhibit marginal signal from the fluxes within the region of interest.

scholarly journals Natural and anthropogenic methane fluxes in Eurasia: a mesoscale quantification by generalized atmospheric inversion

2015 ◽  
Vol 12 (18) ◽  
pp. 5393-5414 ◽  
Author(s):  
A. Berchet ◽  
I. Pison ◽  
F. Chevallier ◽  
J.-D. Paris ◽  
P. Bousquet ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Region Of Interest ◽  
Methane Emissions ◽  
Surface Fluxes ◽  
Atmospheric Methane ◽  
Methane Fluxes ◽  
In Situ Observations ◽  
Atmospheric Inversion ◽  
The Way

Abstract. Eight surface observation sites providing quasi-continuous measurements of atmospheric methane mixing ratios have been operated since the mid-2000's in Siberia. For the first time in a single work, we assimilate 1 year of these in situ observations in an atmospheric inversion. Our objective is to quantify methane surface fluxes from anthropogenic and wetland sources at the mesoscale in the Siberian lowlands for the year 2010. To do so, we first inquire about the way the inversion uses the observations and the way the fluxes are constrained by the observation sites. As atmospheric inversions at the mesoscale suffer from mis-quantified sources of uncertainties, we follow recent innovations in inversion techniques and use a new inversion approach which quantifies the uncertainties more objectively than the previous inversion systems. We find that, due to errors in the representation of the atmospheric transport and redundant pieces of information, only one observation every few days is found valuable by the inversion. The remaining high-resolution quasi-continuous signal is representative of very local emission patterns difficult to analyse with a mesoscale system. An analysis of the use of information by the inversion also reveals that the observation sites constrain methane emissions within a radius of 500 km. More observation sites than the ones currently in operation are then necessary to constrain the whole Siberian lowlands. Still, the fluxes within the constrained areas are quantified with objectified uncertainties. Finally, the tolerance intervals for posterior methane fluxes are of roughly 20 % (resp. 50 %) of the fluxes for anthropogenic (resp. wetland) sources. About 50–70 % of Siberian lowlands emissions are constrained by the inversion on average on an annual basis. Extrapolating the figures on the constrained areas to the whole Siberian lowlands, we find a regional methane budget of 5–28 TgCH4 for the year 2010, i.e. 1–5 % of the global methane emissions. As very few in situ observations are available in the region of interest, observations of methane total columns from the Greenhouse Gas Observing SATellite (GOSAT) are tentatively used for the evaluation of the inversion results, but they exhibit only a marginal signal from the fluxes within the region of interest.

scholarly journals TransCom N<sub>2</sub>O model inter-comparison – Part 1: Assessing the influence of transport and surface fluxes on tropospheric N<sub>2</sub>O variability

2014 ◽  
Vol 14 (2) ◽  
pp. 2307-2362 ◽  
Author(s):  
R. L. Thompson ◽  
P. K. Patra ◽  
K. Ishijima ◽  
E. Saikawa ◽  
M. Corazza ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Large Scale ◽  
Atmospheric Transport ◽  
Lower Troposphere ◽  
Vertical Gradient ◽  
Surface Fluxes ◽  
Meridional Transport ◽  
Mixing Ratios

Abstract. We present a comparison of chemistry-transport models (TransCom-N2O) to examine the importance of atmospheric transport and surface fluxes on the variability of N2O mixing ratios in the troposphere. Six different models and two model variants participated in the inter-comparison and simulations were made for the period 2006 to 2009. In addition to N2O, simulations of CFC-12 and SF6 were made by a subset of four of the models to provide information on the models proficiency in stratosphere-troposphere exchange (STE) and meridional transport, respectively. The same prior emissions were used by all models to restrict differences among models to transport and chemistry alone. Four different N2O flux scenarios totalling between 14 and 17 Tg N yr−1 (for 2005) globally were also compared. The modelled N2O mixing ratios were assessed against observations from in-situ stations, discrete air sampling networks, and aircraft. All models adequately captured the large-scale patterns of N2O and the vertical gradient from the troposphere to the stratosphere and most models also adequately captured the N2O tropospheric growth rate. However, all models underestimated the inter-hemispheric N2O gradient by at least 0.33 ppb (equivalent to 1.5 Tg N), which, even after accounting for an overestimate of emissions in the Southern Ocean of circa 1.0 Tg N, points to a likely underestimate of the Northern Hemisphere source by up to 0.5 Tg N and/or an overestimate of STE in the Northern Hemisphere. Comparison with aircraft data reveal that the models overestimate the amplitude of the N2O seasonal cycle at Hawaii (21° N, 158° W) below circa 6000 m, suggesting an overestimate of the importance of stratosphere to troposphere transport in the lower troposphere at this latitude. In the Northern Hemisphere, most of the models that provided CFC-12 simulations captured the phase of the CFC-12, seasonal cycle, indicating a reasonable representation of the timing of STE. However, for N2O all models simulated a too early minimum by 2 to 3 months owing to errors in the seasonal cycle in the prior soil emissions, which is still not adequately represented by terrestrial biosphere models. In the Southern Hemisphere, most models failed to capture the N2O and CFC-12 seasonality at Cape Grim, Tasmania, and all failed at the South Pole, whereas for SF6, all models could capture the seasonality at all sites, suggesting that there are large errors in modeled vertical transport in high southern latitudes.

scholarly journals Atmospheric CO<sub>2</sub> modeling at the regional scale: an intercomparison of 5 meso-scale atmospheric models

2007 ◽  
Vol 4 (3) ◽  
pp. 1923-1952 ◽  
Author(s):  
C. Sarrat ◽  
J. Noilhan ◽  
A. J. Dolman ◽  
C. Gerbig ◽  
R. Ahmadov ◽  
...  
Keyword(s):  
Regional Scale ◽  
Potential Temperature ◽  
Surface Fluxes ◽  
Systematic Evaluation ◽  
Atmospheric Models ◽  
Experimental Protocol ◽  
Intercomparison Exercise ◽  
Meteorological Models ◽  
Meso Scale

Abstract. Atmospheric CO2 modeling in interaction with the surface fluxes, at the regional scale is developed within the frame of the European project CarboEurope-IP and its Regional Experiment component. In this context, five meso-scale meteorological models participate in an intercomparison exercise. Using a common experimental protocol that imposes a large number of rules, two days of the CarboEurope Regional Experiment Strategy (CERES) campaign are simulated. A systematic evaluation of the models is done in confrontation with the observations, using statistical tools and direct comparisons. Thus, temperature and relative humidity at 2 m, wind direction, surface energy and CO2 fluxes, vertical profiles of potential temperature as well as in-situ CO2 concentrations comparisons between observations and simulations are examined. This intercomparison exercise shows also the models ability to represent the meteorology and carbon cycling at the synoptic and regional scale in the boundary layer, but also points out some of the major shortcomings of the models.

scholarly journals Mapping pan-Arctic methane emissions at high spatial resolution using an adjoint atmospheric transport and inversion method and process-based wetland and lake biogeochemical models

2015 ◽  
Vol 15 (22) ◽  
pp. 32469-32518 ◽  
Author(s):  
Z. Tan ◽  
Q. Zhuang ◽  
D. K. Henze ◽  
C. Frankenberg ◽  
E. Dlugokencky ◽  
...  
Keyword(s):  
High Resolution ◽  
Atmospheric Transport ◽  
Methane Emissions ◽  
The Arctic ◽  
Inversion Method ◽  
Methane Cycle ◽  
Mixing Ratios ◽  
Biogeochemical Models ◽  
Northern Russia ◽  
And Inversion

Abstract. Understanding methane emissions from the Arctic, a fast warming carbon reservoir, is important for projecting changes in the global methane cycle under future climate scenarios. Here we optimize Arctic methane emissions with a nested-grid high-resolution inverse model by assimilating both high-precision surface measurements and column-average SCIAMACHY satellite retrievals of methane mole fraction. For the first time, methane emissions from lakes are integrated into an atmospheric transport and inversion estimate, together with prior wetland emissions estimated by six different biogeochemical models. We find that, the global methane emissions during July 2004–June 2005 ranged from 496.4 to 511.5 Tg yr−1, with wetland methane emissions ranging from 130.0 to 203.3 Tg yr−1. The Arctic methane emissions during July 2004–June 2005 were in the range of 14.6–30.4 Tg yr−1, with wetland and lake emissions ranging from 8.8 to 20.4 Tg yr−1 and from 5.4 to 7.9 Tg yr−1 respectively. Canadian and Siberian lakes contributed most of the estimated lake emissions. Due to insufficient measurements in the region, Arctic methane emissions are less constrained in northern Russia than in Alaska, northern Canada and Scandinavia. Comparison of different inversions indicates that the distribution of global and Arctic methane emissions is sensitive to prior wetland emissions. Evaluation with independent datasets shows that the global and Arctic inversions improve estimates of methane mixing ratios in boundary layer and free troposphere. The high-resolution inversions provide more details about the spatial distribution of methane emissions in the Arctic.

scholarly journals The formaldehyde budget as seen by a global-scale multi-constraint and multi-species inversion system

2012 ◽  
Vol 12 (3) ◽  
pp. 6909-6955
Author(s):  
A. Fortems-Cheiney ◽  
F. Chevallier ◽  
I. Pison ◽  
P. Bousquet ◽  
M. Saunois ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Organic Compounds ◽  
Global Scale ◽  
Surface Fluxes ◽  
Atmospheric Methane ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Satellite Retrievals ◽  
Surface Measurements ◽  
First Time

Abstract. For the first time, carbon monoxide (CO) and formaldehyde (HCHO) satellite retrievals have been used together with methane (CH4) and methyl choloroform (CH3CCl3 or MCF) surface measurements in a complex inversion system. The CO and HCHO are, respectively from MOPITT and OMI instruments. The multi-species and multi-satellite dataset inversion is done for the 2005–2008 period. The robustness of our results is evaluated by comparing our posterior-modeled concentrations with several sets of independent measurements of atmospheric mixing ratios. The inversion results lead to significant changes from the prior to the posterior, in terms of magnitude and seasonality of the CO and CH4 surface fluxes and of the 3-D HCHO production by non-methane volatile organic compounds (NMVOCs). The latter is significantly decreased, indicating an overestimation of the biogenic NMVOCs emissions, such as isoprene, in the GEIA inventory. CO and CH4 surface emissions are increased by the inversion, from 1037 to 1409 Tg CO and from 489 to 528 TgCH4 on average for the 2005–2008 period. CH4 emissions present significant interannual variability and a joint CO–CH4 fluxes analysis reveals that tropical biomass burning probably played a role in the recent increase of atmospheric methane.

Quantifying methane emissions from fossil fuel sources using a Bayesian inverse model and observations of ethane with an uncertain emissions ratio

2021 ◽  
Author(s):  
Alice Ramsden ◽  
Anita Ganesan ◽  
Luke Western ◽  
Alistair Manning ◽  
Matthew Rigby ◽  
...  
Keyword(s):  
Fossil Fuel ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Synthetic Data ◽  
Methane Emissions ◽  
Inverse Model ◽  
Anthropogenic Sources ◽  
Atmospheric Methane ◽  
Livestock Farming ◽  
Emission Ratio

&lt;p&gt;Methane is an important greenhouse gas with a range of anthropogenic sources, including livestock farming and fossil fuel production. It is important that methane emissions can be correctly attributed to their source, to aid climate change policy and emissions mitigation efforts. For source attribution, many &amp;#8216;top-down&amp;#8217; models of atmospheric methane use spatial maps of sources from emissions inventory data coupled with an atmospheric transport model. However, this can cause difficulties if sources are co-located or if there is uncertainty in the sources&amp;#8217; spatial distributions.&lt;/p&gt;&lt;p&gt;To help with this issue and reduce overall uncertainty in estimates of methane emissions, recent methods have used observations of a secondary trace gas and its correlation with methane to infer methane emissions from a target sector. Most previous work has assumed a fixed emissions ratio between the two gases, which often does not reflect the true range of possible emission ratios. In this work, measurements of atmospheric ethane and its emissions ratio relative to methane are used to infer emissions of methane from fossil fuel sources. Instead of assuming a fixed emission ratio, our method allows for uncertainty in the emission ratio to be statistically propagated through the inverse model and incorporated into the sectoral estimates of methane emissions. We further demonstrate the inaccuracies that can result in an assessment of fossil fuel methane emissions if this uncertainty is not considered.&lt;/p&gt;&lt;p&gt;We present this novel method for modelling sectoral methane emissions with examples from a synthetic data experiment and give results from a case study of UK methane emissions. Methane and ethane observations from a tall tower network across the UK were used with this model to produce monthly estimates of UK fossil fuel methane emissions with improved uncertainty characterisation.&lt;/p&gt;

Significant fluxes of methane over tropical wetlands and their associated δ13C isotopic source signatures

2020 ◽  
Author(s):  
James L. France ◽  
Anna Jones ◽  
Tom Lachlan-Cope ◽  
Alex Weiss ◽  
Marcos Andrade ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Mixed Boundary ◽  
Ground Level ◽  
Isotopic Analysis ◽  
Isotopic Signature ◽  
Direct Access ◽  
Atmospheric Methane ◽  
Tropical Wetlands ◽  
Mixing Ratios ◽  
Methane Fluxes

&lt;p&gt;Tropical wetlands have been proposed as a potential driver for the recent rise in global atmospheric methane. However, direct access and quantification of emissions is difficult. In March 2019, a pilot study was given permission to overfly the Bolivian Llanos de Moxos wetlands to measure atmospheric mixing ratios of methane and collect spot samples for isotopic analysis. Combined with this was a short ground campaign to collect isotopic samples directly above the wetland edge to compare with the integrated atmospheric signature.&lt;/p&gt;&lt;p&gt;Atmospheric mixing ratios of methane reached a maximum of 2400 ppb (500 ppb above baseline concentrations) in the well mixed boundary layer flying at 400m above the wetland. Upwind and downwind transects were a maximum of 300 km, and methane mixing ratios increased roughly linearly with distance downwind. The isotopic data from the airborne surveys and ground surveys give a bulk isotopic signature for &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CH4&lt;/sub&gt; of ~-59 &amp;#8240; &amp;#177; 4, which is less negative than Amazon floodplain work focusing on emission of methane through trees, but match well with bulk isotopic values from the Amazon Basin. Ground based wetland samples taken concurrently near Trinidad, Bolivia, gave a source signature of -56 &amp;#8240; &amp;#177; 4 re-enforcing the likelihood that the atmospheric enhancements measured are related to the wetland emissions. For comparison, tropical wetlands measured at ground level during a recent Ugandan and Zambian campaign gave heavier &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CH4&lt;/sub&gt; isotopic source signatures of -50 to -54 &amp;#8240;. Based on this snap shot study, flux estimations suggest that the Bolivian wetlands could be emitting ~10mg CH&lt;sub&gt;4&lt;/sub&gt; m&lt;sup&gt;-2 &lt;/sup&gt;h&lt;sup&gt;-1&lt;/sup&gt;. The observed mole fractions will be compared to model simulations to determine how well the Bolivian wetland methane fluxes are represented.&lt;/p&gt;

scholarly journals FLEXINVERT: an atmospheric Bayesian inversion framework for determining surface fluxes of trace species using an optimized grid

2014 ◽  
Vol 7 (5) ◽  
pp. 2223-2242 ◽  
Author(s):  
R. L. Thompson ◽  
A. Stohl
Keyword(s):  
Dispersion Model ◽  
Particle Dispersion ◽  
Linear Process ◽  
Surface Fluxes ◽  
Bayesian Inversion ◽  
Mixing Ratios ◽  
Trace Species ◽  
Methane Fluxes ◽  
Spatio Temporal ◽  
Atmospheric Loss

Abstract. We present a new modular Bayesian inversion framework, called FLEXINVERT, for estimating the surface fluxes of atmospheric trace species. FLEXINVERT can be applied to determine the spatio-temporal flux distribution of any species for which the atmospheric loss (if any) can be described as a linear process and can be used on continental to regional and even local scales with little or no modification. The relationship between changes in atmospheric mixing ratios and fluxes (the so-called source–receptor relationship) is described by a Lagrangian Particle Dispersion Model (LPDM) run in a backwards-in-time mode. In this study, we use FLEXPART but any LPDM could be used. The framework determines the fluxes on a nested grid of variable resolution, which is optimized based on the source–receptor relationships for the given observation network. Background mixing ratios are determined by coupling FLEXPART to the output of a global Eulerian model (or alternatively, from the observations themselves) and are also optionally optimized in the inversion. Spatial and temporal error correlations in the fluxes are taken into account using a simple model of exponential decay with space and time and, additionally, the aggregation error from the variable grid is accounted for. To demonstrate the use of FLEXINVERT, we present one case study in which methane fluxes are estimated in Europe in 2011 and compare the results to those of an independent inversion ensemble.

scholarly journals Arctic regional methane fluxes by ecotope as derived using eddy covariance from a low-flying aircraft

2017 ◽  
Vol 17 (13) ◽  
pp. 8619-8633 ◽  
Author(s):  
David S. Sayres ◽  
Ronald Dobosy ◽  
Claire Healy ◽  
Edward Dumas ◽  
John Kochendorfer ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Surface Flux ◽  
Methane Emissions ◽  
Surface Fluxes ◽  
The Arctic ◽  
Observation System ◽  
Permafrost Region ◽  
Aircraft Measurements ◽  
The North ◽  
Methane Fluxes

Abstract. The Arctic terrestrial and sub-sea permafrost region contains approximately 30 % of the global carbon stock, and therefore understanding Arctic methane emissions and how they might change with a changing climate is important for quantifying the global methane budget and understanding its growth in the atmosphere. Here we present measurements from a new in situ flux observation system designed for use on a small, low-flying aircraft that was deployed over the North Slope of Alaska during August 2013. The system combines a small methane instrument based on integrated cavity output spectroscopy (ICOS) with an air turbulence probe to calculate methane fluxes based on eddy covariance. We group surface fluxes by land class using a map based on LandSat Thematic Mapper (TM) data with 30 m resolution. We find that wet sedge areas dominate the methane fluxes with a mean flux of 2.1 µg m−2 s−1 during the first part of August. Methane emissions from the Sagavanirktok River have the second highest at almost 1 µg m−2 s−1. During the second half of August, after soil temperatures had cooled by 7 °C, methane emissions fell to between 0 and 0.5 µg m−2 s−1 for all areas measured. We compare the aircraft measurements with an eddy covariance flux tower located in a wet sedge area and show that the two measurements agree quantitatively when the footprints of both overlap. However, fluxes from sedge vary at times by a factor of 2 or more even within a few kilometers of the tower demonstrating the importance of making regional measurements to map out methane emissions spatial heterogeneity. Aircraft measurements of surface flux can play an important role in bridging the gap between ground-based measurements and regional measurements from remote sensing instruments and models.

scholarly journals Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

2006 ◽  
Vol 6 (2) ◽  
pp. 283-301 ◽  
Author(s):  
A. Engel ◽  
H. Bönisch ◽  
D. Brunner ◽  
H. Fischer ◽  
H. Franke ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Trace Gases ◽  
Potential Temperature ◽  
Data Set ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Trace Species ◽  
Wide Range ◽  
Tropopause Region

Abstract. During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35° N and 75° N in the European longitude sector (10° W–20° E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N2O, CH4, CO, CO2, CFC12, H2, SF6, NO, NOy, O3 and H2O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature-equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O3 and NOy and the lowest mixing ratios of N2O and SF6. The lowest mixing ratios of NOy and O3 are observed during autumn, together with the highest mixing ratios of N2O and SF6 indicating a strong tropospheric influence. For H2O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies.

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