Airborne CO2 Research Articles

Urban greenhouse gas emissions from the Berlin area: A case study using airborne CO2 and CH4 in situ observations in summer 2018

Urban areas are recognised as a significant source of greenhouse gas emissions (GHG), such as carbon dioxide (CO2) and methane (CH4). The total amount of urban GHG emissions, especially for CH4, however, is not well quantified. Here we report on airborne in situ measurements using a Picarro G1301-m analyser aboard the DLR Cessna Grand Caravan to study GHG emissions downwind of the German capital Berlin. In total, five aircraft-based mass balance experiments were conducted in July 2018 within the Urban Climate Under Change [UC]2 project. The detection and isolation of the Berlin plume was often challenging because of comparatively small GHG signals above variable atmospheric background concentrations. However, on July 20th enhancements of up to 4 ppm CO2 and 21 ppb CH4 were observed over a horizontal extent of roughly 45 to 65 km downwind of Berlin. These enhanced mixing ratios are clearly distinguishable from the background and can partly be assigned to city emissions. The estimated CO2 emission flux of 1.39 ± 0.76 t s–1 is in agreement with current inventories, while the CH4 emission flux of 5.20 ± 1.70 kg s–1 is almost two times larger than the highest reported value in the inventories. We localized the source area with HYSPLIT trajectory calculations and the global/regional nested chemistry climate model MECO(n) (down to ~1 km), and investigated the contribution from sewage-treatment plants and waste deposition to CH4, which are treated differently by the emission inventories. Our work highlights the importance of strong CH4 sources in the vicinity of Berlin and shows, that there is limited understanding of CH4 emissions from urban regions, even for major cities in highly developed countries like Germany. Furthermore, we show that a detailed knowledge of GHG inflow mixing ratios is necessary to suitably estimate emission rates for Berlin.

Evaluation of Regional CO2 Mole Fractions in the ECMWF CAMS Real‐Time Atmospheric Analysis and NOAA CarbonTracker Near‐Real‐Time Reanalysis With Airborne Observations From ACT‐America Field Campaigns

AbstractThis study systematically examines the regional uncertainties and biases in carbon dioxide (CO2) mole fractions from two of the state‐of‐the‐art global CO2 analysis products, namely, the Copernicus Atmosphere Monitoring Service (CAMS) real‐time atmospheric analysis from the European Centre for Medium‐Range Weather Forecasts (ECMWF) and the CarbonTracker Near‐Real‐Time (CT‐NRT) reanalysis from the National Oceanic and Atmospheric Administration (NOAA), by evaluation against hundreds of hours of airborne in situ measurements from the summer 2016 and winter 2017 Atmospheric Carbon and Transport (ACT)‐America field campaigns. Both the CAMS and CT‐NRT analyses agree reasonably well with the independent ACT‐America airborne CO2 measurements in the free troposphere, with root‐mean‐square deviations (RMSDs) between analyses and observations generally between 1 and 2 ppm but show considerably larger uncertainties in the atmospheric boundary layer where the RMSDs exceed 8 ppm in the lowermost 1 km of the troposphere in summer. There are strong variations in accuracy and bias between seasons, and across three different subregions in the United States (Mid‐Atlantic, Midwest, and South), with the largest uncertainties in the Mid‐Atlantic region in summer. Overall, the RMSDs of the CAMS and CT‐NRT analyses against airborne data are comparable to each other and largely consistent with the differences between the two analyses. The current study provides uncertainty estimates for both analysis products over North America and suggests that these two independent estimates can be used to approximate regional CO2 analysis uncertainties. Both statistics are important in future studies in quantifying the uncertainties in regional CO2 mole fraction and flux estimates.

A new predictive model for Plants Photosynthesis Influenced by Major Climatic Conditions

Climate change, particularly global warming, is significantly affected by atmospheric CO2 dynamics. Plant photosynthesis is capable of fixing a large amount of airborne CO2 and converts it into vegetation biomass and thus alleviates the greenhouse effect from atmospheric CO2. However, how climate change and climate condition impact the dynamics of plant photosynthesis is still highly uncertain. Here we combined high frequency land surface measurements of photosynthetic CO2 fixation data and information theory to understand the casual relationship from climate drivers on the photosynthesis rate. We found that temperature and shortwave radiation dominated photosynthesis more at forest site, while precipitation dominated photosynthesis more at grass land site. More importantly, linear regression based analysis failed to identify such relationships, which confirmed the important role of information theory in identifying nonlinear relationship within a complex system.

Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing.

The springtime transition to regional-scale onset of photosynthesis and net ecosystem carbon uptake in boreal and tundra ecosystems are linked to the soil freeze-thaw state. We present evidence from diagnostic and inversion models constrained by satellite fluorescence and airborne CO2 from 2012 to 2014 indicating the timing and magnitude of spring carbon uptake in Alaska correlates with landscape thaw and ecoregion. Landscape thaw in boreal forests typically occurs in late April (DOY 111±7) with a 29±6day lag until photosynthetic onset. North Slope tundra thaws 3weeks later (DOY 133±5) but experiences only a 20±5day lag until photosynthetic onset. These time lag differences reflect efficient cold season adaptation in tundra shrub and the longer dehardening period for boreal evergreens. Despite the short transition from thaw to photosynthetic onset in tundra, synchrony of tundra respiration with snow melt and landscape thaw delays the transition from net carbon loss (at photosynthetic onset) to net uptake by 13±7days, thus reducing the tundra net carbon uptake period. Two global CO2 inversions using a CASA-GFED model prior estimate earlier northern high latitude net carbon uptake compared to our regional inversion, which we attribute to (i) early photosynthetic-onset model prior bias, (ii) inverse method (scaling factor+optimization window), and (iii) sparsity of available Alaskan CO2 observations. Another global inversion with zero prior estimates the same timing for net carbon uptake as the regional model but smaller seasonal amplitude. The analysis of Alaskan eddy covariance observations confirms regional scale findings for tundra, but indicates that photosynthesis and net carbon uptake occur up to 1month earlier in evergreens than captured by models or CO2 inversions, with better correlation to above-freezing air temperature than date of primary thaw. Further collection and analysis of boreal evergreen species over multiple years and at additional subarctic flux towers are critically needed.

Synergistic effect between ultrasound and fierce mechanical activation towards mineral extraction: A case study of ZnO ore

Though the positive role of ultrasound has been confirmed in the mineral extraction, its potential towards fiercely mechanically-activated mineral was not yet mentioned. In this study, as a novel mechanical activation style, bead milling (BM) was presented and ZnO ore was selected to determine its effectiveness. Results showed that median particle size of ZnO ore could be pulverized to as low as 1/164 of its original value (from ∼29.2 μm to ∼178 nm), indicating much higher activation potential of BM than that of conventional ball milling. Besides, structure destruction, even phase transformation with the direct participation of airborne CO2 occurred. All these processes rendered the superior activation capacity of BM. In view of the extraction promotion, the combination of ultrasound and BM exerted more pronounced effect than those of individual ones, indicating the synergistic effect between extra energy input (by ultrasound) and inner energy storage (by fierce BM). The classic shrinking core model with the product layer diffusion as the rate-controlling step was found to well model the extraction kinetics. The modeling disclosed high capability of ultrasound and BM combination in decreasing the activation energy (Ea) (from 54.6 kJ/mol to 26.4 kJ/mol), while ultrasound, BM could only decrease the Ea to 44.9 kJ/mol, 41.5 kJ/mol, respectively. The dual roles of ultrasound were specially highlighted: (i) participation in the extraction process via direct energy input, (ii) regulation of the aggregation that the activated ore suspension was confronted with.

Impact of home remediation and household education on indoor air quality, respiratory visits and symptoms in Alaska Native children

ABSTRACTAlaska Native children experience high rates of lower respiratory tract infections (LRTIs) and lung conditions, which are associated with substandard indoor air quality (IAQ). We conducted an intervention of home remediation and education to assess the impact on IAQ, respiratory symptoms and LRTI visits. We enrolled households of children 1–12 years of age with lung conditions. Home remediation included improving ventilation and replacing leaky woodstoves. We provided education about IAQ and respiratory health. We monitored indoor airborne particles (PM2.5), CO2, relative humidity and volatile organic compounds (VOCs), and interviewed caregivers about children’s symptoms before, and for 1 year after intervention. We evaluated the association between children’s respiratory visits, symptoms and IAQ indicators using multiple logistic regression. A total of 60 of 63 homes completed the study. VOCs decreased (coefficient = −0.20; p < 0.001); however, PM2.5 (coeff. = −0.010; p = 0.89) did not decrease. Burning wood for heat, VOCs and PM2.5 were associated with respiratory symptoms. After remediation, parents reported decreases in runny nose, cough between colds, wet cough, wheezing with colds, wheezing between colds and school absences. Children had an age-adjusted decrease in LRTI visits (coefficient = −0.33; p = 0.028). Home remediation and education reduced respiratory symptoms, LRTI visits and school absenteeism in children with lung conditions.

(Invited) The Molten Air Battery and the Multiple Electron Storage Advantage

We’ve demonstrated multiple electron per molecule processes yield higher battery storage capacity, introducing a variety of novel storage chemistries including high efficiency in-situ photoelectrochemical solar cells,1,2 aluminum sulfur battery,3 super-iron battery,4 ammonia useful for fuel cells,5 and zirconia on VB2 batteries.6 Unusual multiple electron opportunities abound. For example, not only redox active oxygen from air, but also redox active carbon dioxide from air can be utilized for charge storage.7,8 The Licht group has recently introduced a new class of multiple electrons per molecule battery: Molten Air Batteries.9-14 These new batteries use multi-electron charge storage, a molten electrolyte, are quasi-reversible (rechargeable), and have amongst the highest intrinsic battery storage capacities. This talk will focus on advances in the molten air class of rechargeable batteries including carbon (4 electron storage), iron (3 electron storage) and VB2 (11 electron storage). For example, uncommonly, the carbon molten air battery can utilize carbon dioxide directly from the air or from industrial smoke stacks: charging: CO2(g) -> C(solid) + O2(g) (1) discharging: C(solid) + O2(g) -> CO2(g) (2) 1) S. Licht, G. Hodes, R. Tenne, J. Manassen, A Light Variation Insensitive High Efficiency Solar Cell" Nature , 326, 863-864 (1987). 2) S. Licht, "A Description of Energy Conversion in Photoelectrochemical Solar Cells" Nature , 330, 148-151 (1987). 3) D. Peramunage, S. Licht, "A Novel Solid Sulfur Cathode for Aqueous Batteries" Science , 261, 1029-1032 (1993). 4) S. Licht, B. Wang, S. Ghosh, "Energetic Iron(VI) Chemistry: The Super-Iron Battery," Science , 285, 1039-1042 (1999). 5) S. Licht, B. Cui, B, Wang, F.-F. Li, J. Lau, S, Liu, "Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3," Science, 345 , 637-640, (2014). 6) S. Licht, H. Wu, X. Yu, Y. Wang, "Renewable Highest Capacity VB2/Air Energy Storage," Chemical Communication , 2008, 3257-3259 (2008). 7) S. Licht, A. Douglas, R. Carter, M. Lefler, C. L. Pint, C. “Carbon Nanotubes Produced from Ambient Carbon Dioxide for Environmentally Sustainable Lithium-Ion and Sodium-Ion Battery Anodes,” ACS Central Science , 2, 162-168 (2015). 8)J. Ren, S. Licht, “Tracking airborne CO2 mitigation and low cost transormation into valuable carbon nanotubes,” Scientific Reports, 6, 27760-1-11 (2016). 9) S. Licht, B. Cui, J. Stuart, B. Wang, J. Lau, "Molten Air Batteries - A new, highest energy class of rechargeable batteries," Energy & Environmental Science ,6, 3646-3657, with 2 pages supplementary information (2013). 10) B. Cui, S. Licht, "A Low Temperature Iron Molten Air Battery," Journal of Materials Chemistry A , 2, 10577-10580, with 3 pages supplementary (2014). 11) S. Liu, X. Li, B. Cui, X. Liu , Y. Hao, Q. Guo, P. Xu, S. Licht, "Critical advances for the iron molten air battery: A new lowest temperature, rechargeable, ternary electrolyte domain," Journal of Materials Chemistry A, 3, 21039-21043, with 2 page Supplementary Info (2015). 12) B. Cui, X. Xiang, S. Liu, H. Xin, X. Liu, and Stuart Licht, "A novel rechargeable zinc-air battery with molten salt electrolyte," Journal of Power Sources, 342, 435-441. (2017). 13) B. Cui, H. Xin, S. Liu, Xianjun Liu, Y. Hao, Q. Guo, and S. Licht, "Improved cycle iron molten air battery performance using a robust fin air electrode," Journal of the Electrochemical Society , 164, A88-A92 (2017). 14) Baochen Cui, Wei , Xiang, Shuzhi Liu, Hongyu Xin, Xianjun Liu, and Stuart Licht, "A long cycle life, high coulombic iron molten air battery," Sustainable Energy & Fuels , cover article, in press (2017).

HgCdTe avalanche photodiode detectors for airborne and spaceborne lidar at infrared wavelengths

We report results from characterizing the HgCdTe avalanche photodiode (APD) arrays developed for lidar at infrared wavelengths by using the high density vertically integrated photodiodes (HDVIP®) technique. The results show >90% quantum efficiencies between 0.8 μm and the cut-off wavelength, >600 APD gain, near unity excess noise factor, 6-10 MHz electrical bandwidth and <0.5 fW/Hz1/2 noise equivalent power (NEP). The detectors provide linear analog output with a dynamic range of 2-3 orders of magnitude at a fixed APD gain without averaging, and over 5 orders of magnitude by adjusting the APD gain settings. They have been used successfully in airborne CO2 and CH4 integrated path differential absorption (IPDA) lidar as precursors for use in space lidar.

Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes.

Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotube) synthesis transforms CO2-gas dissolved in a 750 °C molten Li2CO3, by electrolysis, into O2-gas at a nickel electrode, and at a steel cathode into CNTs or carbon or nanofibers, CNFs. CNTs are synthesized at a 100-fold price reduction compared to conventional chemical vapour deposition, CVD, synthesis. The low cost conversion to a stable, value-added commodity incentivizes CO2 removal to mitigate climate change. The synthesis allows morphology control at the liquid/solid interface that is not available through conventional CVD synthesis at the gas/solid interface. Natural abundance 12CO2 forms hollow CNTs, while equivalent synthetic conditions with heavier 13CO2 favours closed core CNFs, as characterized by Raman, SEM and TEM. Production ease is demonstrated by the first synthesis of a pure 13C multiwalled carbon nanofiber.

Lidar reflectance from snow at 2.05 μm wavelength as measured by the JPL Airborne Laser Absorption Spectrometer.

We report airborne measurements of lidar directional reflectance (backscatter) from land surfaces at a wavelength in the 2.05 μm CO₂ absorption band, with emphasis on snow-covered surfaces in various natural environments. Lidar backscatter measurements using this instrument provide insight into the capabilities of lidar for both airborne and future global-scale CO₂ measurements from low Earth orbit pertinent to the NASA Active Sensing of CO₂ Emissions over Nights, Days, and Seasons mission. Lidar measurement capability is particularly useful when the use of solar scattering spectroscopy is not feasible for high-accuracy atmospheric CO₂ measurements. Consequently, performance in high-latitude and winter season environments is an emphasis. Snow-covered surfaces are known to be dark in the CO₂ band spectral regions. The quantitative backscatter data from these field measurements help to elucidate the range of backscatter values that can be expected in natural environments.

Indoor particle dynamics in schools: Determination of air exchange rate, size-resolved particle deposition rate and penetration factor in real-life conditions

Indoor and outdoor airborne particles, CO, CO2 levels and comfort parameters were monitored at two naturally ventilated elementary schools (S1 and S2). This paper studies the variation of ventilation rate during lectures, recreations, lunchtime and after class. Additionally, mass balance equations were used to estimate the particle deposition rates and penetration factors for different particle size fractions. The originality of the present work resides in taking advantage of occupants’ activities as sources of indoor particles and tracer gas CO2 used to simultaneously estimate the above-mentioned parameters in different scenarios. This simple approach makes the determination of indoor particle dynamics more effective, and allows reducing the cost of indoor air quality studies. During the class, the ventilation rates at S1 and S2 fluctuated largely from day to day, with respective average values of 10.08 m3/h/p and 7.92 m3/h/p, significantly lower than the ASHRAE acceptable value (18 m3/h/p) in classrooms. The particle deposition loss rate coefficients for 0.3–10 µm particles dramatically increased from 0.16–0.18 h−1 for the 0.3–0.5 µm fraction to 1.81–2.31 h−1 for the 7.5–10 µm fraction, while their corresponding penetration factors declined from 0.94 to 0.30, respectively. The difference in deposition rate between schools was probably associated to discrepancies in particle density.

Structural controls on fluid pathways in an active rift system: A case study of the Aluto volcanic complex

In volcanically and seismically active rift systems, preexisting faults may control the rise and eruption of magma, and direct the flow of hydrothermal fluids and gas in the subsurface. Using high-resolution airborne imagery, field observations, and CO 2 degassing data on Aluto, a typical young silicic volcano in the Main Ethiopian Rift, we explore how preexisting tectonic and volcanic structures control fluid pathways and spatial patterns of volcanism, hydrothermal alteration and degassing. A new light detection and ranging (lidar) digital elevation model and evidence from deep geothermal wells show that the Aluto volcanic complex is dissected by rift-related extensional faults with throws of 50–100 m. Mapping of volcanic vent distributions reveals a structural control by either rift-aligned faults or an elliptical caldera ring fracture. Soil-gas CO 2 degassing surveys show elevated fluxes (>>100 g m –2 d –1 ) along major faults and volcanic structures, but significant variations in CO 2 flux along the fault zones reflect differences in near-surface permeability caused by changes in topography and surface lithology. The CO 2 emission from an active geothermal area adjacent to the major fault scarp of Aluto amounted to ∼60 t d –1 ; we estimate the total CO 2 emission from Aluto to be 250–500 t d –1 . Preexisting volcanic and tectonic structures have played a key role in the development of the Aluto volcanic complex and continue to facilitate the expulsion of gases and geothermal fluids. This case study emphasizes the importance of structural mapping on active rift volcanoes to understand the geothermal field as well as potential volcanic hazards.

Examination of geostatistical and machine-learning techniques as interpolators in anisotropic atmospheric environments

Selecting which interpolation method to use significantly affects the results of atmospheric studies. The goal of this study is to examine the performance of several interpolation techniques under typical atmospheric conditions. Several types of kriging and artificial neural networks used as spatial interpolators are here compared and evaluated against ordinary kriging, using real airborne CO2 mixing-ratio data and synthetic data. The real data were measured (on December 26, 2012) between Billings and Lamont, near Oklahoma City, Oklahoma, within and above the planetary boundary layer (PBL). Predictions were made all along the flight trajectory within a total volume of 5000 km3 of atmospheric air (27 × 33 × 5.6 km). We evaluated (a) universal kriging, (b) ensemble neural networks, (c) universal kriging with ensemble neural network outputs used as covariates, and (d) ensemble neural networks with ordinary kriging of the residuals as interpolation tools. We found that in certain cases, when the weaknesses of ordinary kriging interpolation schemes (based on an omnidirectional isotropic variogram presumption) became apparent, more sophisticated interpolation methods were in order. In this study, preservation of the potentially nonlinear relationship between the trend and coordinates (by using neural kriging output as a covariate in a universal kriging scheme) was attempted, with varying degrees of success (it was best performer in 4 out of 8 cases). The study confirmed the necessity of selecting an interpolation approach that includes a combination of expert understanding and appropriate interpolation tools. The error analysis showed that uncertainty representations generated by the kriging methods are superior to neural networks, but that the actual error varies from case to case.

Studies of the Negative Effects of Climate Change on Crop Productivity and Global Food Security

Climate change has a non-linearity effect on the global food supplies system when the atmospheric CO 2 reaches a new level. Although one may assume that higher CO 2 may increase the earth vegetations due to the need for CO 2 in photosynthesis, increase in CO 2 has negative effects on plant growth mostly because increases in CO 2 increases the earth temperature causing greater soil moisture evaporations affecting the plant growth. However in certain cases, the increase in warmth along with rain falls has resulted in improved plant growth via the sequestration of airborne CO 2 in plants.

Use of wood-based materials in beef bedded manure packs: 1. Effect on ammonia, total reduced sulfide, and greenhouse gas concentrations.

The objectives of this study were to determine the effect of using corn stover or three different wood-based bedding materials (kiln-dried pine wood chips, dry cedar chips, or green cedar chips) on airborne concentrations of NH, total reduced sulfides (TRS), CO, CH, and NO above lab-scaled bedded manure packs. Four bedded packs of each bedding material were maintained for two 42-d periods. Airborne NH, TRS, CO, CH, and NO were measured weekly. Bedded packs containing dry or green cedar had lower concentrations of NH (350.8 and 357.3 mg m, respectively; < 0.05) than bedded packs containing pine chips or corn stover (466.0 and 516.7 mg m, respectively). Airborne CO was also lower from bedded packs containing dry and green cedar (1343.7 and 1232.3 mg m, respectively; < 0.001) compared with bedded packs containing pine chips or corn stover (2000.2 and 1659.8 mg m, respectively). Air samples from bedded packs containing green cedar chips had a higher ( < 0.01) concentration of CH than bedded packs containing dry cedar chips, corn stover, or pine chips at Day 35 and 42. Initially, TRS concentration was similar among all bedding materials; at 28 to 42 d, TRS was higher ( < 0.001) from bedded packs containing the cedar products. Airborne NO was similar ( = 0.51) for all bedding materials. Pine chips and cedar products can be adequate substitutes for corn stover in deep-bedded barns, but cedar bedding may need to be removed more frequently.

2nd generation concrete construction: carbon footprint accounting

PurposeConstruction contractors and facility managers are being challenged to minimize the carbon footprint. Life cycle carbon‐equivalent (CO2‐e) accounting, whereby the potential emissions of greenhouse gases due to energy expenditure during construction and subsequent occupation of built infrastructure, generally ceases at the end of the service life. However, following demolition, recycling of demolition waste that becomes incorporated into 2nd generation construction is seldom considered within the management of the carbon footprint. This paper aims to focus on built concrete infrastructure, particularly the ability of recycled concrete to chemically react with airborne CO2, thereby significantly influencing CO2‐e estimates.Design/methodology/approachCO2‐e estimates were made in accordance with the methodology outlined in the Australian National Greenhouse Accounts (NGA) Factors and were based on the energy expended for each life cycle activity from audited records. Offsets to the CO2‐e estimates were based on the documented ability of concrete to chemically react with airborne carbon dioxide (“carbonation”) and predictions of CO2 uptake by concrete and recycled concrete was made using existing predictive diffusion models. The author's study focused on a built concrete bridge which was demolished and recycled at the end of the service life, and the recycled concrete was utilized towards 2nd generation construction. The sensitivity of CO2‐e and carbonation estimates were tested on several different types of source demolition waste as well as subsequent construction applications using recycled concrete (RCA). Whole‐of‐life CO2‐e estimates, including carbonation of RCA over the 1st and 2nd generations, were estimated and contrasted with conventional carbon footprints that end at the conclusion of the 1st generation.FindingsFollowing demolition, CO2 capture by RCA is significant due to the more permeable nature of the crushed RCA compared with the original built infrastructure. RCA also has considerably greater exposed surface area, relative to volume, than a built concrete structure, and therefore more highly exposed surface to react with CO2: it therefore carbonates more comprehensively. CO2‐e estimates can be offset by as much as 55‐65 per cent when including the contribution of carbonation of RCA built within 2nd generation infrastructure. Further offsets are achievable using blended fly ash or slag cement binders; however, this study has focused on concrete composed of 100 per cent OPC binders and the effects of RCA.Originality/valueConstruction project estimates of life cycle CO2‐e emissions should include 2nd generation applications that follow the demolition of the 1st generation infrastructure. Life cycle estimates generally end at the time of demolition. However, by incorporating the recycled concrete demolition waste into the construction of 2nd generation infrastructure, the estimated CO2‐e is significantly offset during the 2nd generation life cycle by chemical uptake of CO2 (carbonation). This paper provides an approach towards inclusion of 2nd generation construction applications into whole‐of‐life estimates of CO2‐e.

Airborne measurements of CO2 column absorption and range using a pulsed direct-detection integrated path differential absorption lidar

We report on airborne CO(2) column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO(2) line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 8-10 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

Direct CO2 capture from ambient air using K2CO3/Al2O3 composite sorbent

A composite sorbent K2CO3/γ-Al2O3 was synthesized and tested for direct carbon dioxide capture from ambient air. Composition and structure of the composite were characterized by means of atomic absorption spectroscopy, low-temperature nitrogen adsorption, X-ray diffraction and transmission electron microscopy, differential scanning calorimetry and thermogravimetry methods. CO2 absorption from air and desorption experiments were performed in a continuous-flow system. The effect of temperature on thermal regeneration of the composite was investigated. It was shown that stable CO2 absorption capacity of 4.0–4.9wt.% can be obtained in cycles with regeneration temperature of 250–300°C. The composite sorbent demonstrated a great stability of its CO2 absorption characteristics, therefore it should be considered as a promising material for direct carbon dioxide capture from air. The total energy required for air-borne CO2 capture and its subsequent methanation was assessed.

Validation of routine continuous airborne CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; observations near the Bialystok Tall Tower

Abstract. Since 2002 in situ airborne measurements of atmospheric CO2 mixing ratios have been performed regularly aboard a rental aircraft near Bialystok (53°08´ N, 23°09´ E), a city in northeastern Poland. Since August 2008, the in situ CO2 measurements have been made by a modified commercially available and fully automated non-dispersive infrared (NDIR) analyzer system. The response of the analyzer has been characterized and the CO2 mixing ratio stability of the associated calibration system has been fully tested, which results in an optimal calibration strategy and allows for an accuracy of the CO2 measurements within 0.2 ppm. Besides the in situ measurements, air samples have been collected in glass flasks and analyzed in the laboratory for CO2 and other trace gases. To validate the in situ CO2 measurements against reliable discrete flask measurements, we developed weighting functions that mimic the temporal averaging of the flask sampling process. Comparisons between in situ and flask CO2 measurements demonstrate that these weighting functions can compensate for atmospheric variability, and provide an effective method for validating airborne in situ CO2 measurements. In addition, we show the nine-year records of flask CO2 measurements. The new system, automated since August 2008, has eliminated the need for manual in-flight calibrations, and thus enables an additional vertical profile, 20 km away, to be sampled at no additional cost in terms of flight hours. This sampling strategy provides an opportunity to investigate both temporal and spatial variability on a regular basis.

Atmospheric CO2 budget over the Amazon basin: the role of convective systems

This work studies the atmospheric CO2 budget in the Amazon basin, focusing on the role of shallow and deep convective systems. The vertical redistribution of CO2 is numerically simulated using an Eulerian transport model coupled to the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS). The transport model includes grid-scale advection, diffusion in the PBL (Planetary Boundary Layer) and convective transport by sub-grid shallow and deep moist convection. In the simulation, the mass conservation equation is solved for six tracers, including or not the shallow and deep moist convection terms. The rectifier effect is also showed through simulation of the transport to the free troposphere of PBL air masses with low CO2 concentrations due to assimilation by vegetation during the afternoon, when both CO2 fixation and convection are at their peak. The model is applied to simulate July 2001 with a 30 km grid resolution covering the northwest part of South America. We compare the model results with airborne CO2 observations collected in the Amazon basin during the 2001 CLAIRE field campaign.