Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO ...is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend similar to -1 % yr super(-1) in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.
Saline aquifers have been used for CO2 storage as a dedicated greenhouse gas mitigation strategy since 1996. Depleted gas fields are now being planned for large-scale CCS projects. Although basalt ...host reservoirs are also going to be used, saline aquifers and depleted gas fields will make up most of the global geological repositories for CO2. At present, depleted gas fields and saline aquifers seem to be treated as if they are a single entity, but they have distinct differences that are examined here. Depleted gas fields have far more pre-existing information about the reservoir, top-seal caprock, internal architecture of the site, and about fluid flow properties than saline aquifers due to the long history of hydrocarbon project development and fluid production. The fluid pressure evolution paths for saline aquifers and depleted gas fields are distinctly different because, unlike saline aquifers, depleted gas fields are likely to be below hydrostatic pressure before CO2 injection commences. Depressurised depleted gas fields may require an initial injection of gas-phase CO2 instead of dense-phase CO2 typical of saline aquifers, but the greater pressure difference may allow higher initial injection rates in depleted gas fields than saline aquifers. Depressurised depleted gas fields may lead to CO2-injection-related stress paths that are distinct from saline aquifers depending on the geomechanical properties of the reservoir. CO2 trapping in saline aquifers will be dominated by buoyancy processes with residual CO2 and dissolved CO2 developing over time whereas depleted gas fields will be dominated by a sinking body of CO2 that forms a cushion below the remaining methane. Saline aquifers tend to have a relatively limited ability to fill pores with CO2 (i.e., low storage efficiency factors between 2 and 20%) as the injected CO2 is controlled by buoyancy and viscosity differences with the saline brine. In contrast, depleted gas fields may have storage efficiency factors up to 80% as the reservoir will contain sub-hydrostatic pressure methane that is easy to displace. Saline aquifers have a greater risk of halite-scale and minor dissolution of reservoir minerals than depleted gas fields as the former contain vastly more of the aqueous medium needed for such processes compared to the latter. Depleted gas fields have some different leakage risks than saline aquifers mostly related to the different fluid pressure histories, depressurisation-related alteration of geomechanical properties, and the greater number of wells typical of depleted gas fields than saline aquifers. Depleted gas fields and saline aquifers also have some different monitoring opportunities. The high-density, electrically conductive brine replaced by CO2 in saline aquifers permits seismic and resistivity imaging, but these forms of imaging are less feasible in depleted gas fields. Monitoring boreholes are less likely to be used in saline aquifers than depleted gas fields as the latter typically have numerous pre-existing exploration and production well penetrations. The significance of this analysis is that saline aquifers and depleted gas fields must be treated differently although the ultimate objective is the same: to permanently store CO2 to mitigate greenhouse gas emissions and minimise global heating.
Chemical transport models (CTMs) driven with high-resolution meteorological fields can better resolve small-scale processes, such as frontal lifting or deep convection, and thus improve the ...simulation and emission estimates of tropospheric trace gases. In this work, we explore the use of the GEOS-Chem four-dimensional variational (4D-Var) data assimilation system with the nested high-resolution version of the model (0.5 degree 0.67 degree ) to quantify North American CO emissions during the period of June 2004-May 2005. With optimized lateral boundary conditions, regional inversion analyses can reduce the sensitivity of the CO source estimates to errors in long-range transport and in the distributions of the hydroxyl radical (OH), the main sink for CO. To further limit the potential impact of discrepancies in chemical aging of air in the free troposphere, associated with errors in OH, we use surface-level multispectral MOPITT (Measurement of Pollution in The Troposphere) CO retrievals, which have greater sensitivity to CO near the surface and reduced sensitivity in the free troposphere, compared to previous versions of the retrievals. We estimate that the annual total anthropogenic CO emission from the contiguous US 48 states was 97 Tg CO, a 14 % increase from the 85 Tg CO in the a priori. This increase is mainly due to enhanced emissions around the Great Lakes region and along the west coast, relative to the a priori. Sensitivity analyses using different OH fields and lateral boundary conditions suggest a possible error, associated with local North American OH distribution, in these emission estimates of 20 % during summer 2004, when the CO lifetime is short. This 20 % OH-related error is 50 % smaller than the OH-related error previously estimated for North American CO emissions using a global inversion analysis. We believe that reducing this OH-related error further will require integrating additional observations to provide a strong constraint on the CO distribution across the domain. Despite these limitations, our results show the potential advantages of combining high-resolution regional inversion analyses with global analyses to better quantify regional CO source estimates.
Deeply buried reservoirs containing chlorite-coated quartz sand grains commonly have higher than expected porosity and permeability, although prediction of such positive anomalies still remains ...elusive. A total of 54 published examples based on information and data from 62 scientific papers was collated. Quantification of some of the most common parameters including depositional environment, age and latitude of sand deposition, effect on reservoir quality and chemical composition of chlorite is presented.
The dataset indicates that chlorite-coats are found in sandstones deposited in a range of depositional environments, but most commonly occur in delta-related environments (44%), with fluvial environments the second most common (19%). Age relationships indicate that there is an overall exploration bias in published examples, with chlorite-coats becoming increasingly common through time. The latitude at the time of deposition of sands with chlorite-coats is wide (60°N–60°S), and indicates that temperate and tropical climates are important for the generation of this clay mineral. Chlorite can have a variable effect on reservoir quality, but is typically positive. Iron-rich chlorites occur overwhelmingly in coastal environments, while mixed iron- and magnesium-rich chlorites are principally found in marine and terrestrial sandstones.
Analysis of these factors suggests that hinterland geology, basinal soil development and geochemical weathering, and proximity to river systems are essential to the formation of chlorite precursor phases. These characteristics have been combined to define situations where chlorite-coats were more likely or more unlikely to form. These parameters will provide insights into the formation of chlorite and to further refine predictive models for the presence or absence of chlorite-coated sandstones.
► Chlorite-coats in petroleum sandstone reservoirs can have a positive effect on reservoir quality. ► We examine common parameters of chlorite-coated reservoir sandstone examples to better predict where chlorite may occur. ► Chlorite-coats predominantly occur in delta environments and other fluvial associated environments. ► Other factors such as latitude and age of sand formation are also important. ► Hinterland geology, soil development and proximity to river systems are key to chlorite precursor formation.
Using both thermal infrared (TIR) and near infrared (NIR) channels of MOPITT (Measurements of Pollution in the Troposphere) on EOS‐Terra, we demonstrate the first coincident multispectral retrievals ...of carbon monoxide (CO) from space. Exploiting both TIR and NIR channels has been possible due to recent progress in characterizing NIR channel radiance errors. This has allowed us to trade off sensitivity to near surface CO for larger random errors in the combined retrieval. By examining retrieval diagnostics such as DFS (degrees of freedom for signal) and averaging kernels for the multispectral retrieval (TIR + NIR) as compared to the TIR‐only retrieval, we find that adding the NIR channel to the retrieval significantly increases sensitivity to CO, especially near the surface, but with high spatial variability due to surface albedo variations. The cases with the largest increases in DFS are over regions with low thermal contrast between the surface and lower atmosphere. In the tropics (23.4°S–23.4°N), the fraction of daytime land cases with at least 0.4 DFS in the surface layer (surface to 800 hPa) is 20% for TIR‐only retrievals compared to 59% for multispectral retrievals. Vertical resolution for the surface layer is also improved, in some cases from around 6 km for TIR‐only to roughly 1 km for TIR + NIR. Since we apply a single a priori CO profile (unlike MOPITT V4) and error covariance in all the retrievals reported here, these increases are due solely to the addition of the NIR channel. Enhanced sensitivity to near surface CO is especially evident in a case study for central/east Asia where source regions for urban areas with high population density are clearly identifiable. Although these retrievals are still a research product and require further validation and scientific evaluation, they demonstrate the increased sensitivity to CO in the lowermost troposphere that can be obtained from multispectral MOPITT data.
We have analyzed Sentinel‐5 Precursor TROPOspheric Monitoring Instrument (TROPOMI) data over the Copperbelt mining region (Democratic Republic of Congo and Zambia). Despite high background values, ...annual 2019–2022 means of TROPOMI NO2 (nitrogen dioxide) show local enhancements consistent with six point sources (four copper/cobalt mines, two cities) where high‐emission industrial activities take place. We have quantified annual NOx (nitrogen oxides) emissions from these point sources, identified temporal trends in emissions, and found strong correlations with production data from colocated mines and one oil refinery. The Copernicus Atmosphere Monitoring Service Global Anthropogenic (CAMS‐GLOB‐ANT) version 5 inventory underpredicts TROPOMI‐derived emissions and lacks the temporal trends observed in TROPOMI and mine/refinery production. These results demonstrate the potential for satellite monitoring of mining and other industrial activities, often unreported or underestimated, which impact the air quality of local communities. This is particularly important for Africa, where mining is increasing aggressively.
Plain Language Summary
We show for the first time that annual NOx gas pollution emitted by individual copper/cobalt mines can be measured with TROPOMI satellite data, even in the presence of high background pollution from biomass burning and other sources. This is important for monitoring the air quality of local communities, particularly when these industrial activities proliferate in close proximity to population centers (as is the case in the Copperbelt mining region and in other African regions) and without sufficient ground measurements of air pollution levels. Additionally, we show for the first time that the annual amount of NOx pollution emitted by these single point sources is strongly correlated with annual production from individual, colocated copper/cobalt mines and one oil refinery. Studies like this can be used to estimate mine/oil refinery production before companies release their annual reports or (for non‐publicly traded companies) in the absence of such reports. Insufficient emissions from mines claiming high production could indicate production from a different source. Joint analysis of satellite‐derived emissions and mine production reports could be useful in improving the traceability of minerals extracted in conflict areas.
Key Points
We quantified annual TROPOspheric Monitoring Instrument (TROPOMI)‐derived NOx emissions from point sources corresponding to copper/cobalt mines, despite high background values
Annual emissions from individual point sources are strongly correlated with annual production from colocated single mines, one oil refinery
TROPOMI is relevant to monitoring air quality and mining/industrial production in remote regions where these activities are growing rapidly
Measurements made by the MOPITT (“Measurements of Pollution in the Troposphere”) instrument on the NASA Terra polar-orbiting platform enable the retrieval of tropospheric carbon monoxide (CO) ...concentrations. As determined by the Terra orbit and MOPITT swath width, the frequency of MOPITT observations at a specific location, or measurement sampling frequency, is typically about once every three to four days. However, because the MOPITT retrieval algorithm is only applicable to clear-sky scenes, MOPITT retrieval sampling frequency strongly depends on regional cloudiness and can be much smaller than the measurement sampling frequency. Moreover, highly polluted scenes, characterized by high aerosol optical depths, can be confused with cloudy scenes and thus be discarded unnecessarily by the MOPITT cloud detection algorithm. Herein are described revisions to this algorithm which substantially increase retrieval sampling over land in varying pollution conditions. The performance of the revised cloud detection algorithm is evaluated through validation, case studies, and continental-scale maps of retrieval sampling frequency. Presented case studies illustrate (1) why the current operational MOPITT cloud detection algorithm excludes extended areas of potentially valuable cloud-free MOPITT observations and (2) how, for the same scenes, improved retrieval coverage benefits analyses of regional CO variability. Maps of retrieval sampling frequency for South America and Asia exhibit well-defined improvements, especially in regions with poor sampling frequency in the current product.
•The current MOPITT cloud detection algorithm is often overly conservative.•Algorithm revisions resulting in improved sampling are described and evaluated.•Case studies illustrate improved retrieval coverage in both clean and polluted scenes.
Understanding changes in the burden and growth rate of atmospheric methane (CH4) has been the focus of several recent studies but still lacks scientific consensus. Here we investigate the role of ...decreasing anthropogenic carbon monoxide (CO) emissions since 2002 on hydroxyl radical (OH) sinks and tropospheric CH4 loss. We quantify this impact by contrasting two model simulations for 2002–2013: (1) a Measurement of the Pollution in the Troposphere (MOPITT) CO reanalysis and (2) a Control‐Run without CO assimilation. These simulations are performed with the Community Atmosphere Model with Chemistry of the Community Earth System Model fully coupled chemistry climate model with prescribed CH4 surface concentrations. The assimilation of MOPITT observations constrains the global CO burden, which significantly decreased over this period by ~20%. We find that this decrease results to (a) increase in CO chemical production, (b) higher CH4 oxidation by OH, and (c) ~8% shorter CH4 lifetime. We elucidate this coupling by a surrogate mechanism for CO‐OH‐CH4 that is quantified from the full chemistry simulations.
Key Points
Decreases in tropospheric CO from 2002 to 2012 indicate an increase in CH4 chemical loss
There is a positive trend in the chemical production of CO from CH4 in the tropics
We infer a reduced growth rate in CH4 burden due to decreases in anthropogenic CO emissions
We describe the approach for the estimation of the atmospheric state, e.g., temperature, water, ozone, from calibrated, spectral radiances measured from the Tropospheric Emission Spectrometer (TES) ...onboard the Aura spacecraft. The methodology is based on the maximum a posteriori estimate, which mathematically requires the minimization of the difference between observed spectral radiances and a nonlinear model of radiative transfer of the atmospheric state subject to the constraint that the estimated state must be consistent with an a priori probability distribution for that state. The minimization techniques employed here are based on the trust-region Levenberg-Marquardt algorithm. An analysis of the errors for this estimate include smoothing, random, spectroscopic, "cross-state", representation, and systematic errors. In addition, several metrics and diagnostics are introduced that assess the resolution, quality, and statistical significance of the retrievals. We illustrate this methodology for the retrieval of atmospheric and surface temperature, water vapor, and ozone over the Gulf of Mexico on November 3, 2004.
The isotopic composition of sulfate in the rock record has been frequently used to track the changes in the Earth's surface environments. By considering isotopic fractionation imparted by microbial ...sulfate reduction (MSR) and thermochemical sulfate reduction (TSR), in this study, we aim to develop a holistic understanding of the mixed effects of MSR and TSR on δ34S signals in sulfate‐rich carbonate systems. We report the occurrence of various types of sulfur‐bearing components from the Cambrian‐Ordovician carbonate system in the Tarim Basin, NW China, coupled with a well‐established diagenesis framework for these rocks. Our results indicate that most of the sulfur‐bearing species possess δ34S values slightly lower than both the source sulfate and the sulfide generated by TSR, yet these sulfur‐bearing species have substantially higher δ34S values than sulfide that resulted from MSR. Hence, a combination of sulfides sourced from MSR and TSR can adequately explain the sulfur isotope data in the studied interval. Building upon this hypothesis, we developed a new sulfur diagenesis model in order to quantify the accumulated H2S from the combined effects of MSR and TSR. Our new model can be used to explain the origin of sulfur‐bearing species in many other deep burial carbonate systems, including the Sichuan Basin, China, and the Gulf of Mexico, USA. We propose that greater attention should be paid to isotopic modulation through mixed diagenetic processes in order to gain a better mechanistic understanding of the primary geochemistry signals (e.g., δ34S) in marine carbonates.
Key Points
A new sulfur cycling diagenesis model was built based on sulfur‐bearing species generated during progressive burial
This new model advanced the quantification of accumulated H2S from sulfate reductions in many global deep burial basins
This new sulfur cycling model can be used to better define the origins of superheavy pyrite commonly present in the Neoproterozoic Era
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