scholarly journals Derivation of tropospheric methane from TCCON CH<sub>4</sub> and HF total column observations

2014 ◽  
Vol 7 (4) ◽  
pp. 3471-3501
Author(s):  
K. M. Saad ◽  
D. Wunch ◽  
G. C. Toon ◽  
P. Bernath ◽  
C. Boone ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Inverse Relationship ◽  
Total Carbon ◽  
Aircraft Measurements ◽  
Atmospheric Methane ◽  
Sources And Sinks ◽  
Stratospheric Dynamics ◽  
The Relationship ◽  
Total Column

Abstract. The Total Carbon Column Observing Network (TCCON) is a global ground-based network of Fourier transform spectrometers that produce precise measurements of column-averaged dry-air mole fractions of atmospheric methane (CH4). Temporal variability in the total column of CH4 due to stratospheric dynamics obscures fluctuations and trends driven by tropospheric transport and local sources and sinks. We remove the contribution of stratospheric variability from the total column average by subtracting an estimate of the stratospheric CH4 derived from simultaneous measurements of hydrogen fluoride (HF). HF provides a proxy for stratospheric CH4 because it resides solely in the stratosphere, has a nearly linear inverse relationship with stratospheric CH4, and is measured at most TCCON stations. The stratospheric partial column of CH4 is calculated as a function of the zonal and annual trends in the relationship between CH4 and HF in the stratosphere, which we determine from ACE-FTS satellite data. We also explicitly take into account the CH4 column averaging kernel to estimate the contribution of stratospheric CH4 to the total column. The resulting tropospheric CH4 columns are consistent with in situ aircraft measurements and augment existing observations in the troposphere.

scholarly journals Derivation of tropospheric methane from TCCON CH<sub>4</sub> and HF total column observations

2014 ◽  
Vol 7 (9) ◽  
pp. 2907-2918 ◽  
Author(s):  
K. M. Saad ◽  
D. Wunch ◽  
G. C. Toon ◽  
P. Bernath ◽  
C. Boone ◽  
...  
Keyword(s):  
Surface Fluxes ◽  
Total Carbon ◽  
Strongly Correlated ◽  
Aircraft Measurements ◽  
Atmospheric Methane ◽  
Sources And Sinks ◽  
Stratospheric Dynamics ◽  
The Relationship ◽  
Total Column

Abstract. The Total Carbon Column Observing Network (TCCON) is a global ground-based network of Fourier transform spectrometers that produce precise measurements of column-averaged dry-air mole fractions of atmospheric methane (CH4). Temporal variability in the total column of CH4 due to stratospheric dynamics obscures fluctuations and trends driven by tropospheric transport and local surface fluxes that are critical for understanding CH4 sources and sinks. We reduce the contribution of stratospheric variability from the total column average by subtracting an estimate of the stratospheric CH4 derived from simultaneous measurements of hydrogen fluoride (HF). HF provides a proxy for stratospheric CH4 because it is strongly correlated to CH4 in the stratosphere, has an accurately known tropospheric abundance (of zero), and is measured at most TCCON stations. The stratospheric partial column of CH4 is calculated as a function of the zonal and annual trends in the relationship between CH4 and HF in the stratosphere, which we determine from ACE-FTS satellite data. We also explicitly take into account the CH4 column averaging kernel to estimate the contribution of stratospheric CH4 to the total column. The resulting tropospheric CH4 columns are consistent with in situ aircraft measurements and augment existing observations in the troposphere.

scholarly journals Multiscale observations of NH<sub>3</sub> around Toronto, Canada

2021 ◽  
Vol 14 (2) ◽  
pp. 905-921
Author(s):  
Shoma Yamanouchi ◽  
Camille Viatte ◽  
Kimberly Strong ◽  
Erik Lutsch ◽  
Dylan B. A. Jones ◽  
...  
Keyword(s):  
Temporal Variability ◽  
Grid Point ◽  
Regional Scale ◽  
Model Performance ◽  
In Situ Measurements ◽  
Coefficient Of Determination ◽  
Spatial And Temporal Variability ◽  
Predictive Capacity ◽  
Total Column

Abstract. Ammonia (NH3) is a major source of nitrates in the atmosphere and a major source of fine particulate matter. As such, there have been increasing efforts to measure the atmospheric abundance of NH3 and its spatial and temporal variability. In this study, long-term measurements of NH3 derived from multiscale datasets are examined. These NH3 datasets include 16 years of total column measurements using Fourier transform infrared (FTIR) spectroscopy, 3 years of surface in situ measurements, and 10 years of total column measurements from the Infrared Atmospheric Sounding Interferometer (IASI). The datasets were used to quantify NH3 temporal variability over Toronto, Canada. The multiscale datasets were also compared to assess the representativeness of the FTIR measurements. All three time series showed positive trends in NH3 over Toronto: 3.34 ± 0.89 %/yr from 2002 to 2018 in the FTIR columns, 8.88 ± 5.08 %/yr from 2013 to 2017 in the surface in situ data, and 8.38 ± 1.54 %/yr from 2008 to 2018 in the IASI columns. To assess the representative scale of the FTIR NH3 columns, correlations between the datasets were examined. The best correlation between FTIR and IASI was obtained with coincidence criteria of ≤25 km and ≤20 min, with r=0.73 and a slope of 1.14 ± 0.06. Additionally, FTIR column and in situ measurements were standardized and correlated. Comparison of 24 d averages and monthly averages resulted in correlation coefficients of r=0.72 and r=0.75, respectively, although correlation without averaging to reduce high-frequency variability led to a poorer correlation, with r=0.39. The GEOS-Chem model, run at 2∘ × 2.5∘ resolution, was compared to FTIR and IASI to assess model performance and investigate the correlation of observational data and model output, both with local column measurements (FTIR) and measurements on a regional scale (IASI). Comparisons on a regional scale (a domain spanning 35 to 53∘ N and 93.75 to 63.75∘ W) resulted in r=0.57 and thus a coefficient of determination, which is indicative of the predictive capacity of the model, of r2=0.33, but comparing a single model grid point against the FTIR resulted in a poorer correlation, with r2=0.13, indicating that a finer spatial resolution is needed for modeling NH3.

scholarly journals Retrieval of atmospheric CH<sub>4</sub> vertical information from ground-based FTS near-infrared spectra

2019 ◽  
Vol 12 (11) ◽  
pp. 6125-6141 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Mahesh Kumar Sha ◽  
Nicolas Kumps ◽  
Christian Hermans ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Mole Fraction ◽  
Atmospheric Chemistry ◽  
Near Infrared ◽  
Satellite Observations ◽  
Total Carbon ◽  
Fourier Transform Spectrometer ◽  
Aircraft Measurements ◽  
Retrieval Software ◽  
Total Column

Abstract. The Total Carbon Column Observing Network (TCCON) column-averaged dry air mole fraction of CH4 (XCH4) measurements have been widely used to validate satellite observations and to estimate model simulations. The GGG2014 code is the standard TCCON retrieval software used in performing a profile scaling retrieval. In order to obtain several vertical pieces of information in addition to the total column, in this study, the SFIT4 retrieval code is applied to retrieve the CH4 mole fraction vertical profile from the Fourier transform spectrometer (FTS) spectrum at six sites (Ny-Ålesund, Sodankylä, Bialystok, Bremen, Orléans and St Denis) during the time period of 2016–2017. The retrieval strategy of the CH4 profile retrieval from ground-based FTS near-infrared (NIR) spectra using the SFIT4 code (SFIT4NIR) is investigated. The degree of freedom for signal (DOFS) of the SFIT4NIR retrieval is about 2.4, with two distinct pieces of information in the troposphere and in the stratosphere. The averaging kernel and error budget of the SFIT4NIR retrieval are presented. The data accuracy and precision of the SFIT4NIR retrievals, including the total column and two partial columns (in the troposphere and stratosphere), are estimated by TCCON standard retrievals, ground-based in situ measurements, Atmospheric Chemistry Experiment – Fourier Transform Spectrometer (ACE-FTS) satellite observations, TCCON proxy data and AirCore and aircraft measurements. By comparison against TCCON standard retrievals, it is found that the retrieval uncertainty of SFIT4NIR XCH4 is similar to that of TCCON standard retrievals with systematic uncertainty within 0.35 % and random uncertainty of about 0.5 %. The tropospheric and stratospheric XCH4 from SFIT4NIR retrievals are assessed by comparison with AirCore and aircraft measurements, and there is a 1.0 ± 0.3 % overestimation in the SFIT4NIR tropospheric XCH4 and a 4.0 ± 2.0 % underestimation in the SFIT4NIR stratospheric XCH4, which are within the systematic uncertainties of SFIT4NIR-retrieved partial columns in the troposphere and stratosphere respectively.

scholarly journals Total column CO<sub>2</sub> measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles

2010 ◽  
Vol 3 (2) ◽  
pp. 989-1021 ◽  
Author(s):  
N. M. Deutscher ◽  
D. W. T. Griffith ◽  
G. W. Bryant ◽  
P. O. Wennberg ◽  
G. C. Toon ◽  
...  
Keyword(s):  
Nir Spectroscopy ◽  
Solar Observatory ◽  
Total Carbon ◽  
Relative Precision ◽  
Mixing Ratios ◽  
Clear Sky ◽  
The World ◽  
Total Column ◽  
Good Agreement

Abstract. An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO2 and O2 and other gases. Measured CO2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January–February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clear-sky low airmass relative precision of 0.1% is demonstrated in the CO2 and O2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS XCO2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.

scholarly journals Retrieval of atmospheric CH<sub>4</sub> vertical information from TCCON FTIR spectra

2019 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Mahesh Kumar Sha ◽  
Nicolas Kumps ◽  
Christian Hermans ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Distinct Species ◽  
Satellite Observations ◽  
Total Carbon ◽  
Systematic Uncertainties ◽  
Time Period ◽  
Accuracy And Precision ◽  
Retrieval Software ◽  
Total Column

Abstract. TCCON (Total Carbon Column Observing Network) column-averaged dry air mole fraction of CH4 (XCH4) measurements have been widely used to validate satellite observations and to estimate model simulations. The GGG2014 code is the standard TCCON retrieval software performing a profile scaling retrieval. In order to obtain several vertical information in addition to total column, in this study, the SFIT4 retrieval code is applied to retrieve CH4 mole fraction vertical profile using TCCON spectra (SFIT4TCCON) at six sites (Ny-Ålesund, Sodankylä, Bialystok, Bremen, Orléans and St Denis) during the time period of 2016−2017. The retrieval strategy of SFIT4TCCON is investigated. The degree of freedom for signal of the SFIT4TCCON retrieval is about 2.4, with two distinct species of information in the troposphere and in the stratosphere. The averaging kernel and error budget of the SFIT4TCCON retrieval are presented. The data accuracy and precision of the SFIT4TCCON retrievals, including the total column and two partial columns (in the troposphere and stratosphere), are estimated by TCCON standard retrievals, ground-based in situ measurements, ACE-FTS satellite observations, TCCON proxy data and AirCore measurements. By comparison against TCCON standard retrievals, it is found that the retrieval uncertainty of SFIT4TCCON XCH4 is similar to that of TCCON standard retrievals with the systematic uncertainty within 0.35 % and the random uncertainty about 0.5 %. The tropospheric and stratospheric XCH4 from SFIT4TCCON retrievals are assessed by comparing with AirCore measurements at Sodankylä, and there is a 1.2 % overestimation in the SFIT4TCCON tropospheric XCH4 and a 4.0 % underestimation in the SFIT4TCCON stratospheric XCH4, which are within the systematic uncertainties of SFIT4TCCON retrieved partial columns in the troposphere and stratosphere, respectively.

scholarly journals Diagnosing spatial error structures in CO<sub>2</sub> mole fractions and XCO<sub>2</sub> column mole fractions from atmospheric transport

2019 ◽  
Author(s):  
Thomas Lauvaux ◽  
Liza I. Díaz-Isaac ◽  
Marc Bocquet ◽  
Nicolas Bousserez
Keyword(s):  
Atmospheric Transport ◽  
Horizontal Wind ◽  
Ensemble Prediction ◽  
Model Errors ◽  
Spatial Error ◽  
Near Surface ◽  
Sources And Sinks ◽  
The Impact ◽  
Total Column

Abstract. Atmospheric inversions inform about the magnitude and variations of greenhouse gas (GHG) sources and sinks from global to local scales. Deployment of observing systems such as spaceborne sensors and ground-based instruments distributed around the globe has started to offer an unprecedented amount of information to estimate surface exchanges of GHG at finer spatial and temporal scales. However, inversion methods still rely on imperfect atmospheric transport models of which error structures directly affect the inverse estimates of GHG fluxes. The impact of spatial error structures on the inverse fluxes increase concurrently with the density of the available measurements. In this study, we diagnose the spatial structures due to transport model errors affecting modeled in situ carbon dioxide (CO2) mole fractions and total column dry air mole fractions of CO2 (XCO2). We implemented a cost-effective filtering technique recently developed in the meteorological data assimilation community to describe spatial error structures using a small-size ensemble. This technique can enable ensemble-based error analysis for multi-year inversions of sources and sinks. The removal of noisy structures in our small-size ensembles is evaluated by comparison to larger-size ensembles. A second filtering approach for error covariances is proposed (Wiener filter), producing similar results over the 1-month simulation period than a Schur filter. We conclude that key information about error variances and spatial error correlation structures are recoverable from small-size ensembles of about ten (10) members down to five (5), improving the representation of transport errors in mesoscale inversions of CO2 fluxes. Moreover, error variances of in situ near-surface and free-tropospheric CO2 mole fractions differ significantly from total column XCO2 error variances. We conclude that error variances for remote sensing observations need to be quantified independently of in situ CO2 mole fractions due to the complexity of spatial error structures at different altitudes. However, we show the potential use of meteorological error structures such as the mean horizontal wind speed, directly available from Ensemble Prediction Systems, to approximate spatial error correlations of in situ CO2 mole fractions, with similarities in seasonal variations and characteristic error length scales.

scholarly journals Total column CO<sub>2</sub> measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles

2010 ◽  
Vol 3 (4) ◽  
pp. 947-958 ◽  
Author(s):  
N. M. Deutscher ◽  
D. W. T. Griffith ◽  
G. W. Bryant ◽  
P. O. Wennberg ◽  
G. C. Toon ◽  
...  
Keyword(s):  
Nir Spectroscopy ◽  
Solar Observatory ◽  
Total Carbon ◽  
Relative Precision ◽  
Mixing Ratios ◽  
Clear Sky ◽  
The World ◽  
Total Column ◽  
Good Agreement

Abstract. An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO2 and O2 and other gases. Measured CO2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January–February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clear-sky low airmass relative precision of 0.1% is demonstrated in the CO2 and O2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS XCO2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.

scholarly journals The Total Carbon Column Observing Network

2011 ◽  
Vol 369 (1943) ◽  
pp. 2087-2112 ◽  
Author(s):  
Debra Wunch ◽  
Geoffrey C. Toon ◽  
Jean-François L. Blavier ◽  
Rebecca A. Washenfelder ◽  
Justus Notholt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Near Infrared ◽  
Total Carbon ◽  
Global Network ◽  
Satellite Measurements ◽  
Accuracy And Precision ◽  
Science Investigations ◽  
Total Column ◽  
Better Than

A global network of ground-based Fourier transform spectrometers has been founded to remotely measure column abundances of CO 2 , CO, CH 4 , N 2 O and other molecules that absorb in the near-infrared. These measurements are directly comparable with the near-infrared total column measurements from space-based instruments. With stringent requirements on the instrumentation, acquisition procedures, data processing and calibration, the Total Carbon Column Observing Network (TCCON) achieves an accuracy and precision in total column measurements that is unprecedented for remote-sensing observations (better than 0.25% for CO 2 ). This has enabled carbon-cycle science investigations using the TCCON dataset, and allows the TCCON to provide a link between satellite measurements and the extensive ground-based in situ network.

scholarly journals Measurements of Pollution In The Troposphere (MOPITT) validation through 2006

2009 ◽  
Vol 9 (5) ◽  
pp. 1795-1803 ◽  
Author(s):  
L. K. Emmons ◽  
D. P. Edwards ◽  
M. N. Deeter ◽  
J. C. Gille ◽  
T. Campos ◽  
...  
Keyword(s):  
Aircraft Measurements ◽  
Commercial Aircraft ◽  
Field Campaigns ◽  
Terra Satellite ◽  
The Impact ◽  
Instrumental Drift ◽  
Total Column ◽  
Over Time

Abstract. Comparisons of aircraft measurements of carbon monoxide (CO) to the retrievals of CO using observations from the Measurements of Pollution in The Troposphere (MOPITT) instrument onboard the Terra satellite are presented. Observations made as part of the NASA INTEX-B and NSF MIRAGE field campaigns during March–May 2006 are used to validate the MOPITT CO retrievals, along with routine samples from 2001 through 2006 from NOAA and the MOZAIC measurements from commercial aircraft. A significant positive bias, around 20% for total column CO, in MOPITT CO was found in the comparison to in situ measurements during 2006. Comparisons to the long-term records of measurements from NOAA and MOZAIC revealed an increasing bias in the V3 MOPITT CO retrievals over time. The impact of an instrumental drift is illustrated through retrieval simulations.

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