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GeoCARB is a proposed instrument to measure column averaged concentrations of CO2, CH4 and CO from geostationary orbit using reflected sunlight in near-infrared absorption bands of the gases. The scanning options, spectral channels and noise characteristics of geoCARB and two descope options are described. The accuracy of concentrations from geoCARB data is investigated using end-to-end retrievals; spectra at the top of the atmosphere in the geoCARB bands are simulated with realistic trace gas profiles, meteorology, aerosol, cloud and surface properties, and then the concentrations of CO2, CH4 and CO are estimated from the spectra after addition of noise characteristic of geoCARB. The sensitivity of the algorithm to aerosol, the prior distributions assumed for the gases and the meteorology are investigated. The contiguous spatial sampling and fine temporal resolution that geoCARB could provide opens the possibility of monitoring localised sources such as power plants. Simulations of emissions from a power plant with a gaussian plume are conducted to assess the accuracy with which the emission strength may be recovered from geoCARB spectra. Scenarios for "clean" and "dirty" power plants are examined. It is found that a reliable estimate of the emission rate is possible, especially for power plants that have particulate filters, by averaging multiple snap-shots of the CO2 field surrounding the plant. The result holds even in the presence of partial cloud cover. [ABSTRACT FROM AUTHOR]

Laser Absorption Spectroscopy (LAS) has been used over the last several decades for the measurement of trace gasses in the atmosphere. For over a decade, LAS measurements from multiple sources and tens of retroreflectors have been combined with sparse-sample tomography methods to estimate the 2-D distribution of trace gas concentrations and underlying fluxes from pointlike sources. In this work, we consider the ability of such a system to detect and estimate the position and rate of a single point leak which may arise as a failure mode for carbon dioxide storage. The leak is assumed to be at a constant rate giving rise to a plume with a concentration and distribution that depend on the wind velocity. We demonstrate the ability of our approach to detect a leak using numerical simulation and a preliminary measurement. [ABSTRACT FROM AUTHOR]

The article discusses the study which estimates the quantification of the greenhouse gas methane emissions for anthropogenic activity and natural phenomena in global climate change. The study used the optical remote sensing instrument MAMAP data, which is operated from aircraft to better understand point sources of the greenhouse gases, carbon dioxide, and methane. The study utilised the added information from a turbulence probe operated on-board an aircraft to enhance the emission quality.

Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called "Onion Peeling DOAS" (ONPD) which combines an onion peeling approach with a weighting function DOAS (Differential Optical Absorption Spectroscopy) fit. By use of updated pointing information and optimisation of the data selection and of the retrieval approach the altitude range for reasonable CH4 could be extended to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5-10 % for CH4 and 2-3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002-April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated, which are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere. [ABSTRACT FROM AUTHOR]

The article presents a study which measures ground-based high-resolution fourier transform spectrometers through carbon dioxide and methane aircraft measurements. The study also compares the aforementioned measurements to Greenhouse Gases Observing Satellite (GOSAT) data measurement. It also gives details of the measurement instruments onboard the aircraft and ground sites.

The article presents a study which looks into the remote sensing of carbon dioxide (CO) and atmospheric methane (CH4) through solar absorption spectrometry. The study operates the high resolution instrument as part of the Total Carbon Column Observing Network (TCCON). It concludes that a low resolution Fourier Transform Spectrometry (FTS) instrument is effective in measuring XCO2.

A new coastal background site has been established for observations of greenhouse gases (GHGs) in the central Namib Desert at Gobabeb, Namibia. The location of the site was chosen to provide observations for a data-poor region in the global sampling network for GHGs. Semi-automated, continuous measurements of carbon dioxide, methane, nitrous oxide, carbon monoxide, atmospheric oxygen, and basic meteorology are made at a height of 21ma.g.l., 50 km from the coast at the northern border of the Namib Sand Sea. Atmospheric oxygen is measured with a differential fuel cell analyzer (DFCA). Carbon dioxide and methane are measured with an early-model cavity ring-down spectrometer (CRDS); nitrous oxide and carbon monoxide are measured with an off-axis integrated cavity output spectrometer (OA-ICOS). Instrument-specific water corrections are employed for both the CRDS and OA-ICOS instruments in lieu of drying. The performance and measurement uncertainties are discussed in detail. As the station is located in a remote desert environment, there are some particular challenges, namely fine dust, high diurnal temperature variability, and minimal infrastructure. The gas handling system and calibration scheme were tailored to best fit the conditions of the site. The CRDS and DFCA provide data of acceptable quality when base requirements for operation are met, specifically adequate temperature control in the laboratory and regular supply of electricity. In the case of the OA-ICOS instrument, performance is significantly improved through the implementation of a drift correction through frequent measurements of a working tank. [ABSTRACT FROM AUTHOR]

Planetary boundary layer (PBL) CO2 mole fraction data are needed by transport models and carbon budget models as both input and reference for validation. The height of in situ CO2 mole fraction measurements is usually different from that of the model levels where the data are needed; data from short towers, in particular, are dificult to utilize in atmospheric models that do not simulate the surface layer well. Tall tower CO2 mole fraction measurements observed at heights ranging from to 115ma.g.l. at a rural site in Hungary and regular airborne vertical mole fraction profile measurements (136 vertical profiles) above the tower allowed us to estimate how well a tower of a given height could estimate the CO2 mole fraction above the tower in the PBL. The statistical evaluation of the height-dependent bias between the real PBL CO2 mole fraction profile (measured by the aircraft) and the measurement at a given elevation above the ground was performed separately for the summer and winter half years to take into account the different dynamics of the lower troposphere and the different surface CO2 flux in the dif15 ferent seasons. The paper presents: (1) how accurately the vertical distribution of CO2 in the PBL can be estimated from the measurements on the top of a tower of height H, (2) how tall a tower would be needed for the satisfaction of different requirements on the accuracy of the estimation of the CO2 vertical distribution, (3) how accurate a CO2 vertical distribution estimation can be expected from the existing towers; and (4) how much improvement can be achieved in the accuracy of the estimation of CO2 vertical distribution applying the virtual tall tower concept. [ABSTRACT FROM AUTHOR]

The article discusses the study which compares the measurements of carbon dioxide CO2 δ(O2/N2) and δ13CO2 to assess the measurement compatibility of three European laboratories. It says that the standard deviation of the average differences between the laboratories are the same. It mentions that the required compatibility goals are not met by the laboratories.

The article discusses the study which assesses the cavity ring-down spectroscopy (CRDS) CO2CH4CO/H2O analyzer performance operating on an aircraft. The study used the CRDS analyzer to describe the system for making greenhouse gas measurements. Results show that the stability is not affected by pressure or temperature variation.

The article presents a study which evaluates the cavity ring-down spectrometer (CRDS) for 13carbon dioxide (CO)2's in situ observations. It states that a cylinder with known δ13CO2 was used to characterize the drift behavior and noise of the instrument. Results show that the performance of the laser detector and laser precision is governed by the noise.

The article discusses the measurement of dry mole fractions of greenhouse gases in humid air particularly carbon dioxide and methane. It says that greenhouse gas analyzers have been developed to provide high accuracy measurement of carbon dioxide, methane, and water vapor to meet the Global Atmospheric Watch program of the World Meteorological Organization (WMO/GAW) inter-laboratory compatibility goals. It adds that the dry-mole fraction measurements have met the compatibility goals of GAW.

The Geostationary Emission Explorer for Europe (G3E) is a concept for a geostationary satellite sounder that targets at constraining the sources and sinks of the greenhouse gases carbon dioxide (CO2) and methane (CH4) for continental-scale regions. Thereby, its primary focus is on Central Europe. G3E carries a spectrometer system that collects sunlight backscattered from the Earth's surface and atmosphere in the near-infrared (NIR) and shortwave-infrared (SWIR) spectral range. Solar absorption spectra allow for spatiotemporally dense observations of the column-average concentrations of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) including sampling of the diurnal variation with several measurements per day during summer. Here, we present the mission concept and carry out an initial performance assessment of the retrieval capabilities. The radiometric performance of the 4 grating spectrometers is tuned to reconcile small ground-pixel sizes (~ 2 km × 3 km at 50° latitude) with short single-shot exposures (~ 2.9 s) that allow for sampling continental regions such as Central Europe within 2 h while providing sufficient signal-to-noise. The noise errors to be expected for XCO2, XCH4, and XCO are assessed through retrieval simulations for a European trial ensemble. Generally, single-shot precision for the targeted XCO2 and XCH4 is better than 0.5% with some exception for scenes with low infrared surface albedo observed under low sun conditions in winter. For XCO, precision is generally better than 10%. Performance for aerosol and cirrus loaded atmospheres is assessed by mimicking G3E's slant view on Europe for an ensemble of atmospheric scattering properties used previously for evaluating nadir-viewing low-Earth-orbit (LEO) satellites. While retrieval concepts developed for LEO configurations generally succeed in mitigating aerosol and cirrus induced retrieval errors for G3E's setup, residual errors are somewhat greater in geostationary orbit (GEO) than in LEO. G3E's deployment in the vicinity of the Meteosat Third Generation (MTG) satellites suggests making synergistic use of MTG's sounding capabilities e.g. with respect to characterization of aerosol and cloud properties or with respect to enhancing carbon monoxide retrievals by combining G3E's solar and MTG's thermal infrared spectra. [ABSTRACT FROM AUTHOR]

An automated identification and integration method has been developed to investigate in-use vehicle emissions under real-world conditions. This technique was applied to high time resolution air pollutant measurements of in-use vehicle emissions performed under real-world conditions at a near-road monitoring station in Toronto, Canada during four seasons, through month-long campaigns in 2013-2014. Based on carbon dioxide measurements, over 100 000 vehicle-related plumes were automatically identified and fuel-based emission factors for nitrogen oxides; carbon monoxide; particle number, black carbon; benzene, toluene, ethylbenzene, and xylenes (BTEX); and methanol were determined for each plume. Thus the automated identification enabled the measurement of an unprecedented number of plumes and pollutants over an extended duration. Emission factors for volatile organic compounds were also measured roadside for the first time using a proton transfer reaction time-of-flight mass spectrometer; this instrument provided the time resolution required for the plume capture technique. Mean emission factors were characteristic of the light-duty gasoline dominated vehicle fleet present at the measurement site, with mean black carbon and particle number emission factors of 35 mgkg-1 and 7.7×1014 kg-1, respectively. The use of the plume-by-plume analysis enabled isolation of vehicle emissions, and the elucidation of coemitted pollutants from similar vehicle types, variability of emissions across the fleet, and the relative contribution from heavy emitters. It was found that a small proportion of the fleet (< 25 %) contributed significantly to total fleet emissions; 95, 93, 76, and 75% for black carbon, carbon monoxide, BTEX, and particle number, respectively. Emission factors of a single pollutant may help classify a vehicle as a high emitter. However, regulatory strategies to more efficiently target multi-pollutants mixtures may be better developed by considering the co-emitted pollutants as well. [ABSTRACT FROM AUTHOR]

Increased natural gas production in recent years has spurred intense interest in methane (CH4) emissions associated with its production, gathering, processing, transmission and distribution. Gathering and processing facilities (G&P facilities) are unique in that the wide range of gas sources (shale, coal-bed, tight gas, conventional, etc.) results in a wide range of gas compositions, which in turn requires an array of technologies to prepare the gas for pipeline transmission and distribution. We present an overview and detailed description of the measurement method and analysis approach used during a 20-week field campaign studying CH4 emissions from the natural gas G&P facilities between October 2013 and April 2014. Dual tracer flux measurements and onsite observations were used to address the magnitude and origins of CH4 emissions from these facilities. The use of a second tracer as an internal standard revealed plume-specific uncertainties in the measured emission rates of 20-47 %, depending upon plume classification. Combining downwind methane, ethane (C2H6), carbon monoxide (CO), carbon dioxide (CO2), and tracer gas measurements with onsite tracer gas release allows for quantification of facility emissions, and in some cases a more detailed picture of source locations. [ABSTRACT FROM AUTHOR]

The continuous in-situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C-CO2 measurement systems have been commercially available already for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier Transform InfraRed (FTIR) spectrometer also measures the 18O/16O ratio of CO2, but the precision and accuracy of the measurements has not been evaluated yet. Here we present a first analysis of δ18O-CO2 (and δ13C CO2) measurements with the FTIR in Heidelberg. We find that our spectrometer measures 18O in CO2 with a reproducibility of better than 0.3‰ at a temporal resolution of less than 10 min, as determined from surveillance gas measurements over a period of ten months. An Allan deviation test shows that the δ18O repeatability reaches 0.15‰ for half-hourly means. The compatibility of our spectroscopic measurements was determined by comparing FTIR measurements of calibration gases and ambient air to mass-spectrometric measurements of flask samples, filled with the cylinder gases or episodically collected over a diurnal cycle (event). We found that direct cylinder gas measurements agree to 0.01±0.04‰ (mean and standard deviation) for δ13C-CO2 and 0.01±0.11‰ for δ18O. Two weekly episodes of recent ambient air measurements, one in winter and one in summer, are discussed in view of the question, which potential insights and new challenges combined highly resolved δ18O-CO2 and δ13C-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes [ABSTRACT FROM AUTHOR]

In recent years, cavity ring-down spectrometry (CRDS) has been demonstrated to be a highly sensitive, stable and fast analytical technique for real-time in situ measurements of greenhouse gases. In this study, we propose the technique (which we call flask-CRDS) of analyzing whole air flask samples for CO2, CH4 and CO using a custom gas manifold designed to connect to a CRDS analyzer. Extremely stable measurements of these gases can be achieved over a large pressure range in the flask, from 175 to 760 Torr. The wide pressure range is conducive to flask sample measurement in three ways: (1) flask samples can be collected in low-pressure environments (e.g. high-altitude locations); (2) flask samples can be first analyzed for other trace gases with the remaining low-pressure sample for CRDS analysis of CO2, CH4 and CO; and (3) flask samples can be archived and re-analyzed for validation. The repeatability of this method (1α of 0.07 ppm for CO2, 0.4 ppb for CH4, and 0.5 ppb for CO) was assessed by analyzing five canisters filled with the same air sample to a pressure of 200 Torr. An inter-comparison of the flask-CRDS data with in-situ CRDS measurements at a high-altitude mountain baseline station revealed excellent agreement, with differences of 0.10±0.09 ppm (1α) for CO2 and 0.9±1.0 ppb for CH4. This study demonstrated that the flask-CRDS method was not only simple to build and operate but could also perform highly accurate and precise measurements of atmospheric CO2, CH4 and CO in flask samples. [ABSTRACT FROM AUTHOR]

A robust in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Tall Tower Greenhouse Gas Observing Network. The network uses very tall (> 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary layer trace gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The longterm stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures and flow rates that are inputs for automated alerts and quality control algorithms. These algorithms provide detailed and time-dependent uncertainty estimates for all of the gases and could be adapted to other species or analysis systems. The design emphasizes use of off the shelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with > 93% uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts. [ABSTRACT FROM AUTHOR]

The article focuses on a study which aims at measuring carbon dioxide (CO2) using integrated path differential absorption (IPDA) lidar. In the study, CO2 concentration is measured using detection sensitivity of a 2-µm IPDA lidar. It shows the importance of coherent IPDA lidar operating at a high pulse repetition frequency for measuring the CO2 concentration of the hard target.

The article discusses a study on the use of SCIAMACHY WFM-DOAS XCO2 to determine errors related to reduction of scattering. The study develops a new version of the retrieval algorithm (WFMDv2.2) to enhance the quality of the SCIAMACHY XCO2 data product. It validates the new XCO2 data using ground-based observations from the Total Carbon Column Observing Network (TCCON). It also compares NOAA's global CO2 modelling and assimilation system CarbonTracker.

The article presents a study which focuses on the development of a technique for the satellite remote sensing of greenhouse gases in the Canary Islands. It outlines the acquisition of global set of altitude-resolved concentration measurements via the absorption of short-wave infrared (SWIR) laser signals transmitted between counter-rotating satellites in low earth orbit. The measurement of carbon dioxide over an open path of 144 kilometers is also discussed.

Satellite measurements are often compared with higher-precision ground-based measurements as part of validation efforts. The satellite soundings are rarely perfectly coincident in space and time with the ground-based measurements, so a colocation methodology is needed to aggregate "nearby" soundings into what the instrument would have seen at the location and time of interest. We are particularly interested in validation efforts for satellite-retrieved total column carbon dioxide (XCO2), where XCO2 data from Greenhouse Gas Observing Satellite (GOSAT) retrievals (ACOS, NIES, RemoteC, PPDF, etc.) or SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCHIACHY) are often colocated and compared to ground-based column XCO2 measurement from Total Carbon Column Observing Network (TCCON). Current colocation methodologies for comparing satellite measurements of total column dry-air mole fractions of CO2 (XCO2) with ground-based measurements typically involve locating and averaging the satellite measurements within some latitudinal, longitudinal, and temporal window. We examine a geostatistical colocation methodology that takes a weighted average of satellite observations depending on the "distance" of each observation from a ground-based location of interest. The "distance" function that we use is a modified Euclidian distance with respect to latitude, longitude, time, and mid-tropospheric temperature at 700 hPa. We apply this methodology to XCO2 retrieved from Greenhouse Gas Observing Satellite (GOSAT) spectra by the ACOS team, cross-validate the results to TCCON XCO2 ground-based data, and present some comparison between our methodology and standard existing colocation methods showing that in general geostatistical colocation produces smaller mean-squared error. [ABSTRACT FROM AUTHOR]

Carbon dioxide flux measurements in ecosystem sciences are mostly conducted by eddy covariance technique or the closed chamber method. Also some comparisons have been performed. But there is a lack of detailed assessment of present differences and uncertainties. To determine underlying processes, a ten-day, side-by-side measurement of the net ecosystem exchange with both techniques was evaluated with regard to various atmospheric conditions during the diurnal cycle. It was found that, depending on the particular atmospheric condition, the chamber carbon dioxide flux was either: (i) equal to the carbon dioxide flux measured by the reference method eddy covariance, by day with well developed atmospheric turbulence, (ii) higher, in the afternoon in times of oasis effect, (iii) lower, predominantly at night while large coherent structure fluxes or high wind velocities prevailed, or, (iv) showed less variation in the flux pattern, at night while stable stratification was present. Due to lower chamber carbon dioxide fluxes at night, when respiration forms the net ecosystem exchange, and higher chamber carbon dioxide fluxes in the afternoon, when the ecosystem is still a net carbon sink, there are two complementary aspects resulting in an overestimation of the ecosystem sink capacity by the chamber of 40% in this study. [ABSTRACT FROM AUTHOR]

The article discusses a study on the use of Aura TES and TCCON instruments for profiling tropospheric carbon dioxide. The study aims to improve the capability of estimating regional fluxes and estimates near-surface carbon dioxide values from ground-based near infrared (NIR) measurements with space-based thermal infrared (TIR) measurements. It reveals the consistency of calculated random uncertainties in total column and boundary layer with actual uncertainties as compared to aircraft data.

The first ground-based experiment to prove the concept of a novel space-based observation technique for microwave and infrared-laser occultation between Low Earth Orbit satellites (LMIO) was performed in the Canary Islands between La Palma and Tenerife in July 2011. This experiment aimed to demonstrate the infrared-laser differential transmission principle for the measurement of greenhouse gases (GHGs) in the free atmosphere. Such global and long-term stable measurements of GHGs, accompanied also by measurements of thermodynamic parameters and line-of-sight wind in a self-calibrating way, have become very important for climate change monitoring. The experiment delivered promising initial data for demonstrating the new observation concept by retrieving volume mixing ratios of GHGs along a ~ 144 km signal path at altitudes of ~ 2.4 km. Here, we present a detailed analysis of the measurements, following a recent publication that introduced the experiment's technical setup and first results for an example retrieval of CO2. We present the observational and validation datasets, the latter simultaneously measured at the transmitter and receiver sites, the measurement data handling, and the differential transmission retrieval procedure. We also determine the individual and combined uncertainties influencing the results and present the retrieval results for 12CO2, 13CO2, C18OO, H2O and CH4. The new method is found to have a reliable basis for monitoring of greenhouse gases such as CO2, CH4, and H2O in the free atmosphere. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the peformance and design of a Nafion dryer for methane (CH4) and carbon dioxide (CO2) air monitoring sites. The study developed and tested a method that dried ambient air to under 0.2% mole fraction water (H2O) with the use of Nafion dryer. Results revealed that permeation of CH4 and CO2 was within the precision of 0.05 parts per million (ppm) CO2 analyzer measurements.

The article discusses a study regarding the preliminary validation of column-averaged volume mixing ratios of carbon dioxide and methane retrieved from Greenhouse gases Observing SATellite (GOSAT) Short-Wavelength InfraRed spectra (GOSAT SWIR XCO2 and XCH4). The study compares the spectra's data with high-resolution Fourier Transform Spectrometers (g-b FTSs). It reveals that latitudinal distributions of zonal means of the spectra show similar features to g-b FTS data.

The article presents a study on a retrieval algorithm for methane and carbon dioxide from the thermal and near infrared sensor for carbon observation-Fourier transform spectrometer. The study mentions steps in the algorithm which include the selection of cloud-free observational scenes, retrieval of column abundances of carbon dioxide and methane, and examination of the retrieval quality. It is inferred that interhemispherical differences go well with the column abundances of these gases.

Most anthropogenic carbon dioxide (CO2) emissions originate from urban areas. To improve understandings of urban and regional emissions, we design and construct a low-cost UAV coordinated carbon observation network (LUCCN) which uses mid-accuracy (±1 ppm) CO2 sensors. In this paper, we introduce our multi-variable non-linear regression method for calibrating the non-dispersive infrared (NDIR) CO2 sensors for LUCCN's ground stations. We tested our calibration method with concentration data collected at the Xinglong Atmospheric Background Observatory. With comparison against data simultaneously collected by a high-accuracy cavity ring-down spectrometer, we found the maximum standard deviation of LUCCN's sensors to be 0.782 ppm in a controlled laboratory environment with a 1-second window size and 0.53 ppm in an outdoor environment with a 1-hour running average window size. As validation of LUCCN's ground measurements, we identify and present consistent trends between local CO2 concentration variations and aerosol pollution events captured by the space-based moderate resolution imaging spectrometer (MODIS). [ABSTRACT FROM AUTHOR]

The article attempts to address the issue of inadequate sampling of natural concentration gradients in the temporal domain through the presentation of a measurement design especially in the case of carbon dioxide. In this study, gradients were thoroughly examined to gather information on the large range of temporal scales. Such was made possible through the use of a high sufficient high temporal resolution. The study also shows the uncertainties of the approach.

The Geostationary Carbon Cycle Observatory (GeoCarb) was selected as NASA's second Earth Venture Mission (EVM-2). The scientific objectives of GeoCarb are to advance our knowledge of the carbon cycle, in particular, landatmosphere fluxes of the greenhouse gases carbon dioxide (CO2) and methane (CH4), and the effects of these fluxes on the Earth's radiation budget. GeoCarb will retrieve column integrated amounts of CO2 (XCO2), CH4 (XCH4) and CO (XCO, important for understanding tropospheric chemistry), in addition to Solar-Induced Fluorescence (SIF), from hyperspectral resolution measurements in the O2 A-band at 0.76 µm, the weak CO2 band at 1.6 µm, the strong CO2 band at 2.06 µm, and a CH4/CO band at 2.32 µm. Unlike it's polar orbiting predecessors (OCO-2/3, GOSAT-1/2, TROPOMI), GeoCarb will be in a Geostationary orbit with a sub-satellite point centered over the Americas. This orbital configuration combined with its high spatial resolution imaging capabilities will provide an unprecedented view of these quantities on spatial and temporal scales accurate enough to resolve sources and sinks to improve land-atmosphere CO2 and CH4 flux calculations and reduce the uncertainty of these fluxes. This paper will present a description of the GeoCarb instrument and the L2 retrieval algorithms which will be followed by simulation experiments to determine a relatively comprehensive error budget for each target gas. Several sources of uncertainty will be explored including that from the instrument calibration parameters for radiometric gain, the instrument line shape (ILS), the polarization, and the geolocation pointing, in addition to, forward model parameters including that from meteorology and spectroscopy. The results indicate that the errors (1κ) are less than the instrument's multi-sounding precision requirements of 1.2 ppm, 10 ppb, and 12 ppb (10%), for XCO2, XCH4, and XCO, respectively. In particular, when considering the sources of uncertainty separately and in combination (all sources included), we find overall RMS errors of 1.06 ppm for XCO2, 8.2 ppb for XCH4, and 2.5 ppb for XCO, respectively. Additionally, we find that, as expected, errors in XCO2 and XCH4 are dominated by forward model and other systematic errors, while errors in XCO, like SIF, are dominated by measurement noise. [ABSTRACT FROM AUTHOR]

The identification of atmospheric CO2 observation data which are minimally influenced by very local emissions/removals is essential for trend analysis, for the estimation of regional sources and sinks, and for the modeling of long-range transport of CO2. In this study, four approaches are used to filter the atmospheric CO2 observation records from 2009 to 2011 at one World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) regional station (Lin'an, LAN) in China. The methods are based on the concentration of atmospheric black carbon (BC), on a statistical approach (robust extraction of baseline signal, REBS), on CH4 as an auxiliary tracer (AUX), and on meteorological parameters (MET). All approaches do suitably well to capture the seasonal CO2 cycle at LAN. Differences are observed in the average regional mole fractions with annual values in the REBS method at least 1.7 ± 0.2 ppm higher than the other methods. The BC method may underestimate the regional CO2 mole fractions during the winter-spring period and should be treated with caution. The REBS method is a purely statistical method and it may also introduce errors on the regional CO2 mole fraction evaluations, as the filtered trend may be influenced by the "noisy" raw data series. Although there are correlations between CH4 and CO2 mole fractions at LAN, the different source/sink regimes may introduce bias on the regional CO2 estimation in the AUX method, typically in summer. Overall, the MET method seems to be the most favorable because it mainly focuses on the influence of potential local sources and sinks, and considers diurnal variations and meteorological conditions. Using the MET method, the annual growth rate of regional CO2 at LAN is determined to be 3.1 ± 0.01 ppm yr-1 (standard error) from 2009 to 2011. [ABSTRACT FROM AUTHOR]

The article presents a study on the measurements of continuous low-maintenance CO2/CH4/H2 at the ZotinoTall Tower Observatory (ZOTTO) in Central Siberia. It states that the evaluated water vapor is used to assess the dilution and pressure-broadening results for the exact finding of dry air methane and carbon dioxide mixing ratios. It relates that the recurrent field tests showed the water vapor correction's stability.

The article focuses on the measurements of CO2 operated by Fourier Transform Spectroscopic (FTS) solar observatory in Darwin, Northern Territory in August 2005. It states that the laboratory is component of Total Carbon Column Network that evaluates the atmospheric profusion of CO2 and other types of gases. It says that retrievals of CO2 were calibrated via aircraft profiles gathered during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) campaign.

The article focuses on the study in the detection of atmospheric trace gases using the reconstructed Infrared Atmospheric Sounding Interferometer (IASI) radiances and examines the potential of principal component (PC) analysis for chemistry applications. Examples of reconstructed IASI radiances for several trace gases including the ammonia, sulphur dioxide, methane, and carbon dioxide are presented.

The article discusses the study on the development and establishment of an accurate, portable, dynamic calibration system for volatile organic compounds (VOC). A combination of catalytic reduction of VOCs to carbon dioxide (CO2) produced to standardize the calibration sources and the subsequent measurement of CO2 was used. It also notes that the photo-oxidation of VOCs will lead to the formation of ozone and organic aerosol that are both pollutants and may alter the earth's climate system.

The article focuses on the study on global monitoring of power plant carbon dioxide (CO2) emissions from space and its related applications using satellite remote sensing technology based on spectroscopic measurements of reflected solar radiation in the short-waved infrared (SWIR) and near-infrared (NI) spectral regions. The Kyoto protocol requires current emission reporting based on the technical and economical information.

The article discusses the study proposing the use of total column differential absorption LiDAR (TC-DIAL), a remote sensing technique for making total column measurements of atmospheric carbon dioxide (CO2) from space. The principle of TC-DIAL is the differential retrieval of scattered intensities from two laser transmissions of standardized wavelengths. Results have shown the lower bound errors found in DIAL retrieval as consequence of the earth's reflectance variability.