scholarly journals Characterization of lower-cost medium precision atmospheric CO<sub>2</sub> monitoring systems for urban areas using commercial NDIR sensors

2018 ◽  
Author(s):  
Emmanuel Arzoumanian ◽  
Felix R. Vogel ◽  
Ana Bastos ◽  
Bakhram Gaynullin ◽  
Olivier Laurent ◽  
...  
Keyword(s):  
High Precision ◽  
Urban Areas ◽  
Lower Cost ◽  
Co2 Concentration ◽  
Calibration Method ◽  
Atmospheric Co2 ◽  
Precision Instrument ◽  
Empirical Calibration ◽  
Paris Area ◽  
The Difference

Abstract. CO2 emission estimates from urban areas can be obtained with a network of in-situ instruments measuring atmospheric CO2 combined with high-resolution (inverse) transport modeling. The distribution of CO2 emissions being highly heterogeneous in space and variable in time in urban areas, gradients of atmospheric CO2 need to be measured by numerous instruments placed at multiple locations around and possibly within these urban areas, which calls for the development of lower-cost medium precision sensors to allow a deployment at required densities. Medium precision is here set to be a random error (uncertainty) on hourly measurements of ±1 ppm or less, a precision requirement based on previous studies of network design in urban areas. Here we present tests of a HPP commercial NDIR sensors manufactured by Senseair AB performed in the laboratory and at actual field stations, the latter for CO2 concentration in the Paris area. The lower-cost medium precision sensors are shown to be sensitive to atmospheric pressure and temperature conditions. The sensors respond linearly to CO2 when measuring calibration tanks, but the regression slope between measured and true CO2 differs between individual sensors and changes with time. In addition to pressure and temperature variations, humidity impacts the measurement of CO2, all causing systematic errors. In the field, an empirical calibration strategy is proposed based on parallel measurements with the lower-cost medium precision sensors and a high-precision instrument cavity ring-down instrument during 6 month. This empirical calibration method consists of using a multiple regression approach to create a model of the errors defined as the difference of CO2 measured by the lower-cost medium precision sensors relative to a calibrated high-precision instrument, based on predictors of air temperature, pressure and humidity. This error model shows good performances to explain the observed drifts of the lower-cost medium precision sensors on time scales of up to 1–2 months when trained against 1–2 weeks of high-precision instrument time series. Residual errors are contained within the ±1 ppm target, showing the feasibility to use networks of HPP instruments for urban CO2 networks, provided that they could be regularly calibrated against one anchor reference high-precision instrument.

scholarly journals Characterization of a commercial lower-cost medium-precision non-dispersive infrared sensor for atmospheric CO<sub>2</sub> monitoring in urban areas

2019 ◽  
Vol 12 (5) ◽  
pp. 2665-2677 ◽  
Author(s):  
Emmanuel Arzoumanian ◽  
Felix R. Vogel ◽  
Ana Bastos ◽  
Bakhram Gaynullin ◽  
Olivier Laurent ◽  
...  
Keyword(s):  
High Precision ◽  
Urban Areas ◽  
Lower Cost ◽  
Co2 Flux ◽  
Atmospheric Co2 ◽  
Precision Instrument ◽  
Transport Modelling ◽  
Dry Air ◽  
Empirical Calibration ◽  
Paris Area

Abstract. CO2 emission estimates from urban areas can be obtained with a network of in situ instruments measuring atmospheric CO2 combined with high-resolution (inverse) transport modelling. Because the distribution of CO2 emissions is highly heterogeneous in space and variable in time in urban areas, gradients of atmospheric CO2 (here, dry air mole fractions) need to be measured by numerous instruments placed at multiple locations around and possibly within these urban areas. This calls for the development of lower-cost medium-precision sensors to allow a deployment at required densities. Medium precision is here set to be a random error (uncertainty) on hourly measurements of ±1 ppm or less, a precision requirement based on previous studies of network design in urban areas. Here we present tests of newly developed non-dispersive infrared (NDIR) sensors manufactured by Senseair AB performed in the laboratory and at actual field stations, the latter for CO2 dry air mole fractions in the Paris area. The lower-cost medium-precision sensors are shown to be sensitive to atmospheric pressure and temperature conditions. The sensors respond linearly to CO2 when measuring calibration tanks, but the regression slope between measured and assigned CO2 differs between individual sensors and changes with time. In addition to pressure and temperature variations, humidity impacts the measurement of CO2, with all of these factors resulting in systematic errors. In the field, an empirical calibration strategy is proposed based on parallel measurements with the lower-cost medium-precision sensors and a high-precision instrument cavity ring-down instrument for 6 months. The empirical calibration method consists of using a multivariable regression approach, based on predictors of air temperature, pressure and humidity. This error model shows good performances to explain the observed drifts of the lower-cost medium-precision sensors on timescales of up to 1–2 months when trained against 1–2 weeks of high-precision instrument time series. Residual errors are contained within the ±1 ppm target, showing the feasibility of using networks of HPP3 instruments for urban CO2 networks. Provided that they could be regularly calibrated against one anchor reference high-precision instrument these sensors could thus collect the CO2 (dry air) mole fraction data required as for top-down CO2 flux estimates.

scholarly journals Observed decreases in on-road CO<sub>2</sub> concentrations in Beijing during COVID-19 restrictions

2021 ◽  
Vol 21 (6) ◽  
pp. 4599-4614
Author(s):  
Di Liu ◽  
Wanqi Sun ◽  
Ning Zeng ◽  
Pengfei Han ◽  
Bo Yao ◽  
...  
Keyword(s):  
Urban Areas ◽  
Low Cost ◽  
Working Hours ◽  
Weather Conditions ◽  
Co2 Concentration ◽  
Mobile Platforms ◽  
Local Standard ◽  
Transportation Emissions ◽  
Enhancement Method ◽  
The Difference

Abstract. To prevent the spread of the COVID-19 epidemic, restrictions such as “lockdowns” were conducted globally, which led to a significant reduction in fossil fuel emissions, especially in urban areas. However, CO2 concentrations in urban areas are affected by many factors, such as weather, biological sinks and background CO2 fluctuations. Thus, it is difficult to directly observe the CO2 reductions from sparse ground observations. Here, we focus on urban ground transportation emissions, which were dramatically affected by the restrictions, to determine the reduction signals. We conducted six series of on-road CO2 observations in Beijing using mobile platforms before (BC), during (DC) and after (AC) the implementation of COVID-19 restrictions. To reduce the impacts of weather conditions and background fluctuations, we analyze vehicle trips with the most similar weather conditions possible and calculated the enhancement metric, which is the difference between the on-road CO2 concentration and the “urban background” CO2 concentration measured at the tower of the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences. The results showed that the DC CO2 enhancement was decreased by 41 (±1.3) parts per million (ppm) and 26 (±6.2) ppm compared to those for the BC and AC trips, respectively. Detailed analysis showed that, during COVID-19 restrictions, there was no difference between weekdays and weekends during working hours (09:00–17:00 local standard time; LST). The enhancements during rush hours (07:00–09:00 and 17:00–20:00 LST) were almost twice those during working hours, indicating that emissions during rush hours were much higher. For DC and BC, the enhancement reductions during rush hours were much larger than those during working hours. Our findings showed a clear CO2 concentration decrease during COVID-19 restrictions, which is consistent with the CO2 emissions reductions due to the pandemic. The enhancement method used in this study is an effective method to reduce the impacts of weather and background fluctuations. Low-cost sensors, which are inexpensive and convenient, could play an important role in further on-road and other urban observations.

scholarly journals Intercomparison of two cavity ring-down spectroscopy analyzers for atmospheric <sup>13</sup>CO<sub>2</sub>  ∕ <sup>12</sup>CO<sub>2</sub> measurement

2016 ◽  
Vol 9 (8) ◽  
pp. 3879-3891 ◽  
Author(s):  
Jiaping Pang ◽  
Xuefa Wen ◽  
Xiaomin Sun ◽  
Kuan Huang
Keyword(s):  
Water Vapor ◽  
Co2 Concentration ◽  
Calibration Method ◽  
Vapor Concentration ◽  
Water Vapor Concentration ◽  
Mixing Ratio ◽  
Ambient Conditions ◽  
Significant Linear Correlation ◽  
The Difference ◽  
Water Vapor Mixing Ratio

Abstract. Isotope ratio infrared spectroscopy (IRIS) permits continuous in situ measurement of CO2 isotopic composition under ambient conditions. Previous studies have mainly focused on single IRIS instrument performance; few studies have considered the comparability among different IRIS instruments. In this study, we carried out laboratory and ambient measurements using two Picarro CO2δ13C analyzers (G1101-i and G2201-i (newer version)) and evaluated their performance and comparability. The best precision was 0.08–0.15 ‰ for G1101-i and 0.01–0.04 ‰ for G2201-i. The dependence of δ13C on CO2 concentration was 0.46 ‰ per 100 ppm and 0.09 ‰ per 100 ppm, the instrument drift ranged from 0.92–1.09 ‰ and 0.19–0.37 ‰, and the sensitivity of δ13C to the water vapor mixing ratio was 1.01 ‰ ∕ % H2O and 0.09 ‰ ∕ % H2O for G1101-i and G2201-i, respectively. The accuracy after correction by the two-point mixing ratio gain and offset calibration method ranged from −0.04–0.09 ‰ for G1101-i and −0.13–0.03 ‰ for G2201-i. The sensitivity of δ13C to the water vapor mixing ratio improved from 1.01 ‰ ∕ % H2O before the upgrade of G1101-i (G1101-i-original) to 0.15 ‰ ∕ % H2O after the upgrade of G1101-i (G1101-i-upgraded). Atmospheric δ13C measured by G1101-i and G2201-i captured the rapid changes in atmospheric δ13C signals on hourly to diurnal cycle scales, with a difference of 0.07 ± 0.24 ‰ between G1101-i-original and G2201-i and 0.05 ± 0.30 ‰ between G1101-i-upgraded and G2201-i. A significant linear correlation was observed between the δ13C difference of G1101-i-original and G2201-i and the water vapor concentration, but there was no significant correlation between the δ13C difference of G1101-i-upgraded and G2201-i and the water vapor concentration. The difference in the Keeling intercept values decreased from 1.24 ‰ between G1101-i-original and G2201-i to 0.36 ‰ between G1101-i-upgraded and G2201-i, which indicates the importance of consistency among different IRIS instruments.

CSIRO High-precision Measurement of Atmospheric CO2 Concentration in Australia. Part 2: Cape Grim, Surface CO2 Measurements and Carbon Cycle Modelling

2017 ◽  
Vol 28 (2) ◽  
pp. 126 ◽  
Author(s):  
Graeme I. Pearman ◽  
Paul J. Fraser ◽  
John R. Garratt
Keyword(s):  
Carbon Cycle ◽  
High Precision ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Political Activity ◽  
High Precision Measurement ◽  
Aerosol Composition ◽  
North West ◽  
Research Activities ◽  
Cape Grim

A companion paper discusses the history of, and rationale for, the development of a CSIRO programme of atmospheric carbondioxide (CO2) concentration measurements in Australia based on aircraft air sampling, field and laboratory measurements.1 Here, we describe parallel efforts to establish a permanent, ground-based atmospheric Baseline Station at Cape Grim, north-west Tasmania, the political activity required for its establishment, and the work undertaken to select a site commensurate with its long-term objectives. Additional CO2 measurements undertaken to complement the aircraft and Cape Grim measurements are discussed. The development of the Australian Baseline Station was part of an emerging international effort to obtain high-precision measurements of trace gas and aerosol composition of the atmosphere, and to quantify any changes in composition that might be occurring and their possible impact on global climate.We discuss the early development of global carbon cycle models, including the representations of atmospheric transport, and the interpretation of modern atmospheric CO2 data and historic air samples encapsulated in Antarctic ice and firn. The accumulated knowledge from these research activities, together with that collected by international colleagues, forms the basis of our understanding of changes occurring in CO2 concentration. It has contributed to an understanding of the mechanisms of the past and present biogeochemical cycling of CO2, providing predictions of future changes in CO2 concentration.

scholarly journals Inter-comparison of two cavity ring-down spectroscopy analyzers for atmospheric <sup>13</sup>CO<sub>2</sub> / <sup>12</sup>CO<sub>2</sub> measurement

2016 ◽  
Author(s):  
Jiaping Pang ◽  
Xuefa Wen ◽  
Xiaomin Sun ◽  
Kuan Huang
Keyword(s):  
Water Vapor ◽  
Co2 Concentration ◽  
Calibration Method ◽  
Vapor Concentration ◽  
Mixing Ratio ◽  
Ambient Conditions ◽  
Significant Linear Correlation ◽  
Before And After ◽  
The Difference ◽  
Water Vapor Mixing Ratio

Abstract. The isotope ratio infrared spectroscopy (IRIS) permits in situ and continuous measurements of CO2 isotopic composition under ambient conditions. Previous studies mainly focused on single IRIS instrument performance, few studies have paid attention to the comparability among different IRIS instruments. In this study, we carried out laboratory and ambient measurements of two Picarro CO2 δ13C analyzers (G1101-i and G2201-i), and evaluated their performance and comparability. The best precision were 0.08 ~ 0.15 ‰ and 0.01 ~ 0.04 ‰, the dependence of δ13C on CO2 concentration were 0.46 ‰ per 100 ppm and 0.09 ‰ per 100 ppm, the instrument drift ranged from 0.92 ~ 1.09 ‰ and 0.19 ~ 0.37 ‰. After upgradation of G1101-i, the sensitivity of δ13C on water vapor mixing ratio were 0.15 ‰ / % H2O and 0.13 ‰ / % H2O for the G1101-i and G2201-i, respectively. The accuracy after corrected by the two-point mixing ratio gain and offset calibration method ranged from −0.04 ~ 0.09 ‰ and −0.13 ~ 0.03 ‰ for G1101-i and G2201-i, respectively. Atmospheric δ13C measurements captured the rapidly changing atmospheric δ13C signals, with the difference of 0.07 ± 0.24 ‰ and 0.05 ± 0.30 ‰ between G1101-i upgraded before and after and G2201-i. Before upgradation of G1101-i, a significant linear correlation was observed between the δ13C difference and water vapor concentration, but there is no significant correlation after upgradation of G1101-i. The difference of Keeling intercept values between G1101-i and G2201-i decrease from 1.24 ‰ to 0.36 ‰, which indicate the importance of consistency among different IRIS instruments.

CSIRO High-precision Measurement of Atmospheric CO2 Concentration in Australia. Part 1: Initial Motivation, Techniques and Aircraft Sampling

2017 ◽  
Vol 28 (2) ◽  
pp. 111 ◽  
Author(s):  
Graeme I. Pearman ◽  
John R. Garratt ◽  
Paul J. Fraser
Keyword(s):  
High Precision ◽  
Precision Measurement ◽  
Measurement Techniques ◽  
Ice Cores ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
High Precision Measurement ◽  
Concentration Data ◽  
Atmospheric Co2 Concentration ◽  
The Impact

The potential for carbon dioxide (CO2) in the atmosphere to influence global surface temperatures was first recognized in the mid-nineteenth century. Even so, high-precision measurements of atmospheric CO2 concentration were not commenced until the International Geophysical Year (1957–8), following concerns of the climatic impact of increased use of fossil fuels and the concomitant release of CO2 into the atmosphere. In Australia, an early (1960s–70s) interest in the high-precision measurement of CO2 concentration was stimulated by a study of the photosynthesis and respiration of awheat crop. This study conducted in north-easternVictoria during 19717–2 led two young CSIRO scientists, J. R. Garratt and G. I. Pearman, encouraged by their Chief, C. H. B. Priestley, to extend micro-environment CO2 studies to larger-scale measurements of CO2 concentration in the background atmosphere. The significant extension of the observation programme required refined measurement techniques to improve both the precision and absolute comparability with observations made by laboratories overseas. Joined in 1974 by P. J. Fraser, they identified the impact of pressure broadening on calibration techniques used in the non-dispersive infrared absorption method of CO2 concentration measurement. This, in turn, led to improved inter-comparability of CO2 concentration data collected around the globe. Acomprehensive aircraft-based air sampling programmewas established in the early 1970s, leading to increased understanding of the time and space variability of CO2 concentration throughout the depth of the troposphere and lower stratosphere in the mid-latitudes of the Southern Hemisphere. In turn this led to: (i) the establishment of a permanent ground-based observatory at Cape Grim, north-western Tasmania; (ii) the development of carbon cycle models; and (iii) measurements of 12CO2, 13CO2 and 14CO2 relative abundances in current and past atmospheres, the last from air samples trapped in ice cores (described in Part 2, the companion paper). The accumulated data from these studies, together with those collected by international colleagues, form the basis of our understanding of the changes of CO2 concentration over thousands of years. In addition, the data have contributed to our understanding of the mechanisms of past and present biogeochemical cycling of CO2 that provides the predictive basis for future changes in CO2 concentration.

scholarly journals Long-term steady state <sup>13</sup>C labelling to investigate carbon turnover in plant soil systems

2007 ◽  
Vol 4 (2) ◽  
pp. 797-821 ◽  
Author(s):  
K. Klumpp ◽  
J. F. Soussana ◽  
R. Falcimagne
Keyword(s):  
Steady State ◽  
Urban Areas ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Organic C ◽  
Plant Soil ◽  
Soil Systems ◽  
The Mean ◽  
The Difference

Abstract. We have set up a facility allowing steady state 13CO2 labeling of short stature vegetation (12 m2) for several years. 13C labelling is obtained by scrubbing the CO2 from outdoors air with a self-regenerating molecular sieve and by replacing it with 13C depleted (−34.7±0.03‰) fossil-fuel derived CO2 The facility, which comprises 16 replicate mesocosms, allows tracing the fate of photosynthetic carbon in plant-soil systems in natural light and at outdoors temperature. This method was applied during 2 yrs to temperate grassland monoliths (0.5×0.5×0.4 m) sampled in a long term grazing experiment. During daytime, the canopy enclosure in each mesocosm was supplied in an open flow (0.67–0.88 volume per minute) with modified air (43% scrubbed air and 57% cooled and humidified ambient air) at mean CO2 concentration of 425 µmol mol−1 and δ13C of −21.5±0.27‰. Above and belowground CO2 fluxes were continuously monitored. The difference in δ13C between the CO2 at the outlet and at the inlet of each canopy enclosure was not significant (−0.35±0.39‰). Due to mixing with outdoors air, the CO2 concentration at enclosure inlet followed a seasonal cycle, often found in urban areas, where δ13C of CO2 is lower in winter than in summer. Mature C3 grass leaves were sampled monthly in each mesocosm, as well as leave from pot-grown control C4 (Paspalum dilatatum). The mean δ13C of fully labelled C3 and C4 leaves reached −41.4±0.67 and −28.7±0.39‰ respectively. On average, the labelling reduced by 12.7‰ the δ13C of C3 grass leaves. The isotope mass balance technique was used to calculate the fraction of "new" C in the soil organic matter (SOM) above 0.2 mm. A first order exponential decay model fitted to "old" C data showed that reducing aboveground disturbance by cutting increased from 22 to 31 months the mean residence time of belowground organic C (>0.2 mm) in the top soil.

scholarly journals Sensitivity of simulated CO<sub>2</sub> concentration to regridding of global fossil fuel CO<sub>2</sub> emissions

2014 ◽  
Vol 7 (3) ◽  
pp. 3575-3593
Author(s):  
X. Zhang ◽  
K. R. Gurney ◽  
P. Rayner ◽  
Y. Liu ◽  
S. Asefi-Najafabady
Keyword(s):  
Co2 Emissions ◽  
Urban Areas ◽  
Fossil Fuel ◽  
Atmospheric Transport ◽  
Co2 Concentration ◽  
Point Sources ◽  
Atmospheric Co2 ◽  
Atmospheric Co2 Concentration ◽  
Dynamical Consistency ◽  
Oceanic Carbon

Abstract. Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Finite grid resolution can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. We test these mismatches by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are: (1) a commonly-used method that allocates emissions to gridcells with no attempt to ensure dynamical consistency with atmospheric transport; (2) an improved method that reallocates emissions to gridcells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from −30.3 Tg C gridcell−1 yr−1 (−3.39 kg C m−2 yr−1) to +30.0 Tg C gridcell−1 yr−1 (+2.6 kg C m−2 yr−1) along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding −32 ppm. The differences implied by not accounting for this dynamical consistency problem are largest at monitoring sites proximal to large coastal urban areas and point sources. These results suggest that studies comparing simulated to observed atmospheric CO2 concentration, such as atmospheric CO2 inversions, must take measures to correct for this potential problem and ensure flux and dynamical consistency.

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