scholarly journals Retrieval of xCO<sub>2</sub> from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON

2015 ◽  
Vol 8 (10) ◽  
pp. 10523-10548 ◽  
Author(s):  
M. Buschmann ◽  
N. M. Deutscher ◽  
V. Sherlock ◽  
M. Palm ◽  
T. Warneke ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Seasonal Cycle ◽  
Atmospheric Composition ◽  
Composition Change ◽  
Solar Absorption ◽  
Mid Infrared ◽  
Infra Red ◽  
Infrared Spectral ◽  
Ftir Spectrometer ◽  
Total Column

Abstract. High resolution solar absorption spectra, taken within the Network for the Detection of Atmospheric Composition Change (NDACC) in the mid-infrared spectral region are used to infer partial or total column abundances of many gases. In this paper we present the retrieval of a column averaged mole fraction of carbon dioxide from NDACC-IRWG spectra taken with a Fourier-Transform-Infra-Red (FTIR) spectrometer at the site in Ny-Ålesund, Spitsbergen. The retrieved time series is compared to co-located standard TCCON measurements of total column CO2. Comparing the NDACC and TCCON retrievals we find that the sensitivity of the NDACC retrieval is lower in the troposphere (by a factor of two) and higher in the stratosphere, compared to TCCON. Thus, the NDACC retrieval is less sensitive to tropospheric changes (e.g. the seasonal cycle) in the column average.

scholarly journals Retrieval of xCO<sub>2</sub> from ground-based mid-infrared (NDACC) solar absorption spectra and comparison to TCCON

2016 ◽  
Vol 9 (2) ◽  
pp. 577-585 ◽  
Author(s):  
Matthias Buschmann ◽  
Nicholas M. Deutscher ◽  
Vanessa Sherlock ◽  
Mathias Palm ◽  
Thorsten Warneke ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Seasonal Cycle ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Composition Change ◽  
Solar Absorption ◽  
Mid Infrared ◽  
Infrared Spectral ◽  
Ftir Spectrometer ◽  
Total Column

Abstract. High-resolution solar absorption spectra, taken within the Network for the Detection of Atmospheric Composition Change Infrared Working Group (NDACC-IRWG) in the mid-infrared spectral region, are used to infer partial or total column abundances of many gases. In this paper we present the retrieval of a column-averaged mole fraction of carbon dioxide from NDACC-IRWG spectra taken with a Fourier transform infrared (FTIR) spectrometer at the site in Ny-Ålesund, Spitsbergen. The retrieved time series is compared to colocated standard TCCON (Total Carbon Column Observing Network) measurements of column-averaged dry-air mole fractions of CO2 (denoted by xCO2). Comparing the NDACC and TCCON retrievals, we find that the sensitivity of the NDACC retrieval is lower in the troposphere (by a factor of 2) and higher in the stratosphere, compared to TCCON. Thus, the NDACC retrieval is less sensitive to tropospheric changes (e.g., the seasonal cycle) in the column average.

scholarly journals Source brightness fluctuation correction of solar absorption Fourier Transform mid infrared spectra

2011 ◽  
Vol 4 (1) ◽  
pp. 443-459
Author(s):  
T. Ridder ◽  
T. Warneke ◽  
J. Notholt
Keyword(s):  
Spectral Region ◽  
Near Infrared ◽  
Trace Gas ◽  
Solar Absorption ◽  
Mid Infrared ◽  
Infrared Spectral Region ◽  
Infrared Spectral ◽  
Brightness Fluctuation ◽  
Precision And Accuracy ◽  
Total Column

Abstract. Solar absorption Fourier Transform infrared spectrometry is considered a precise and accurate method for the observation of trace gases in the atmosphere. The precision and accuracy of such measurements are dependent on the stability of the light source. Fluctuations in the source brightness reduce the precision and accuracy of the trace gas concentrations, but cannot always be avoided. Thus, a strong effort is made within the community to reduce the impact of source brightness fluctuations by applying a correction on the spectra following the measurements. So far, it could be shown that the precision and accuracy of CO2 total column concentrations could be improved by applying a source brightness fluctuation correction to spectra in the near infrared spectral region. The analysis of trace gas concentrations obtained from spectra in the mid infrared spectral region is fundamental. However, spectra below 2000 cm−1 are generally considered uncorrectable, if they are measured with a MCT detector. Such measurements introduce an unknown offset to MCT interferograms, which prevents a source brightness fluctuation correction. Here, we show a method of source brightness fluctuation correction, which can be applied on spectra in the whole infrared spectral region including spectra measured with a MCT detector. We present a solution to remove the unknown offset in MCT interferograms allowing MCT spectra for an application of source brightness fluctuation correction. This gives an improvement in the quality of MCT spectra and we demonstrate an improvement in the retrieval of O3 profiles and total column concentrations. For a comparison with previous studies, we apply our source brightness fluctuation correction method on spectra in the near infrared spectral region and show an improvement in the retrieval of CO2 total column concentrations.

scholarly journals Validation of IASI FORLI carbon monoxide retrievals using FTIR data from NDACC

2012 ◽  
Vol 5 (11) ◽  
pp. 2751-2761 ◽  
Author(s):  
T. Kerzenmacher ◽  
B. Dils ◽  
N. Kumps ◽  
T. Blumenstock ◽  
C. Clerbaux ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atmospheric Composition ◽  
Satellite Measurements ◽  
Solar Absorption ◽  
Mean Values ◽  
Significant Bias ◽  
Ftir Spectrometer ◽  
The Mean ◽  
The Individual ◽  
Total Column

Abstract. Carbon monoxide (CO) is retrieved daily and globally from space-borne IASI radiance spectra using the Fast Optimal Retrievals on Layers for IASI (FORLI) software developed at the Université Libre de Bruxelles (ULB). The IASI CO total column product for 2008 from the most recent FORLI retrieval version (20100815) is evaluated using correlative CO profile products retrieved from ground-based solar absorption Fourier transform infrared (FTIR) observations at the following FTIR spectrometer sites from the Network for the Detection of Atmospheric Composition Change (NDACC): Ny-Ålesund, Kiruna, Bremen, Jungfraujoch, Izaña and Wollongong. In order to have good statistics for the comparisons, we included all IASI data from the same day, within a 100 km radius around the ground-based stations. The individual ground-based data were adjusted to the lowest altitude of the co-located IASI CO profiles. To account for the different vertical resolutions and sensitivities of the ground-based and satellite measurements, the averaging kernels associated with the various retrieved products have been used to properly smooth coincident data products. It has been found that the IASI CO total column products compare well on average with the co-located ground-based FTIR total columns at the selected NDACC sites and that there is no significant bias for the mean values at all stations.

scholarly journals Validation of IASI FORLI carbon monoxide retrievals using FTIR data from NDACC

2012 ◽  
Vol 5 (3) ◽  
pp. 3973-4002 ◽  
Author(s):  
T. Kerzenmacher ◽  
B. Dils ◽  
N. Kumps ◽  
T. Blumenstock ◽  
C. Clerbaux ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atmospheric Composition ◽  
Satellite Measurements ◽  
Solar Absorption ◽  
Mean Values ◽  
Significant Bias ◽  
Ftir Spectrometer ◽  
The Mean ◽  
The Individual ◽  
Total Column

Abstract. Carbon monoxide (CO) is retrieved daily and globally from space-borne IASI radiance spectra using the Fast Optimal Retrievals on Layers for IASI (FORLI) software developed at the Université Libre de Bruxelles (ULB). The IASI CO total column product for 2008 from the most recent FORLI retrieval version (20100815) is evaluated using correlative CO profile products retrieved from ground-based solar absorption Fourier transform infrared (FTIR) observations at the following FTIR spectrometer sites from the Network for the Detection of Atmospheric Composition Change (NDACC): Ny Ålesund, Kiruna, Bremen, Jungfraujoch, Izaña and Wollongong. In order to have good statistics for the comparisons, we included all IASI data from the same day, within a 100 km radius around the ground-based stations. The individual ground-based data were adjusted to the lowest altitude of the co-located IASI CO profiles. To account for the different vertical resolutions and sensitivities of the ground-based and satellite measurements, the averaging kernels associated with the various retrieved products have been used to properly smooth coincident data products. It has been found that the IASI CO total column products compare well on average with the co-located ground-based FTIR total columns at the selected NDACC sites and that there is no significant bias for the mean values at all stations.

scholarly journals Construction of merged satellite total O<sub>3</sub> and NO<sub>2</sub> time series in the tropics for trend studies and evaluation by comparison to NDACC SAOZ measurements

2014 ◽  
Vol 7 (10) ◽  
pp. 3337-3354 ◽  
Author(s):  
M. Pastel ◽  
J.-P. Pommereau ◽  
F. Goutail ◽  
A. Richter ◽  
A. Pazmiño ◽  
...  
Keyword(s):  
Time Series ◽  
Lower Stratosphere ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Composition Change ◽  
Long Time ◽  
Uv Visible ◽  
The Tropics ◽  
Lower Noise ◽  
Total Column

Abstract. Long time series of ozone and NO2 total column measurements in the southern tropics are available from two ground-based SAOZ (Système d'Analyse par Observation Zénithale) UV-visible spectrometers operated within the Network for the Detection of Atmospheric Composition Change (NDACC) in Bauru (22° S, 49° W) in S-E Brazil since 1995 and Reunion Island (21° S, 55° E) in the S-W Indian Ocean since 1993. Although the stations are located at the same latitude, significant differences are observed in the columns of both species, attributed to differences in tropospheric content and equivalent latitude in the lower stratosphere. These data are used to identify which satellites operating during the same period, are capturing the same features and are thus best suited for building reliable merged time series for trend studies. For ozone, the satellites series best matching SAOZ observations are EP-TOMS (1995–2004) and OMI-TOMS (2005–2011), whereas for NO2, best results are obtained by combining GOME version GDP5 (1996–2003) and SCIAMACHY – IUP (2003–2011), displaying lower noise and seasonality in reference to SAOZ. Both merged data sets are fully consistent with the larger columns of the two species above South America and the seasonality of the differences between the two stations, reported by SAOZ, providing reliable time series for further trend analyses and identification of sources of interannual variability in the future analysis.

scholarly journals Comparison of ground-based FTIR and Brewer O<sub>3</sub> total column with data from two different IASI algorithms and from OMI and GOME-2 satellite instruments

2011 ◽  
Vol 4 (3) ◽  
pp. 535-546 ◽  
Author(s):  
C. Viatte ◽  
M. Schneider ◽  
A. Redondas ◽  
F. Hase ◽  
M. Eremenko ◽  
...  
Keyword(s):  
Atmospheric Composition ◽  
Composition Change ◽  
Neural Network Analysis ◽  
Ozone Monitoring Instrument ◽  
Atmospheric Sounding ◽  
Infrared Spectrometer ◽  
Operational Algorithm ◽  
Ozone Monitoring ◽  
Total Column ◽  
Observing Systems

Abstract. An intercomparison of ozone total column measurements derived from various platforms is presented in this work. Satellite data from Infrared Atmospheric Sounding Interferometer (IASI), Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment (GOME-2) are compared with data from two ground-based spectrometers (Fourier Transform Infrared spectrometer FTIR and Brewer), located at the Network for Detection of Atmospheric Composition Change (NDACC) super-site of Izaña (Tenerife), measured during a campaign from March to June 2009. These ground-based observing systems have already been demonstrated to perform consistent, precise and accurate ozone total column measurements. An excellent agreement between ground-based and OMI/GOME-2 data is observed. Results from two different algorithms for deriving IASI ozone total column are also compared: the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT/ESA) operational algorithm and the LISA (Laboratoire Inter-universitaire des Systèmes Atmosphériques) algorithm. A better agreement was found with LISA's analytical approach based on an altitude-dependent Tikhonov-Philips regularization: correlations are 0.94 and 0.89 compared to FTIR and Brewer, respectively; while the operational IASI ozone columns (based on neural network analysis) show correlations of 0.90 and 0.85, respectively, compared to the O3 columns obtained from FTIR and Brewer.

scholarly journals Comparison of ground-based FTIR and Brewer O<sub>3</sub> total column with data from two different IASI algorithms and from OMI and GOME-2 satellite instruments

2010 ◽  
Vol 3 (6) ◽  
pp. 5833-5865
Author(s):  
C. Viatte ◽  
M. Schneider ◽  
A. Redondas ◽  
F. Hase ◽  
M. Eremenko ◽  
...  
Keyword(s):  
Atmospheric Composition ◽  
Composition Change ◽  
Neural Network Analysis ◽  
Ozone Monitoring Instrument ◽  
Atmospheric Sounding ◽  
Infrared Spectrometer ◽  
Operational Algorithm ◽  
Ozone Monitoring ◽  
Total Column ◽  
Observing Systems

Abstract. An intercomparison of ozone total column measurements derived from various platforms is presented in this work. Satellite data from Infrared Atmospheric Sounding Interferometer (IASI), Ozone Monitoring Instrument (OMI) and Global Ozone Monitoring Experiment (GOME-2) are compared with data from two ground-based spectrometers (Fourier Transform Infrared spectrometer FTIR and Brewer), located at the Network for Detection of Atmospheric Composition Change (NDACC) super-site of Izaña (Tenerife), measured during a campaign from March to June 2009. These ground-based observing systems have already been demonstrated to perform consistent, precise and accurate ozone total column measurements. An excellent agreement between ground-based and OMI/GOME-2 data is observed. Results from two different algorithms for deriving IASI ozone total column are also compared: the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT/ESA) operational algorithm and the LISA (Laboratoire Interuniversitaire des Systèmes Atmosphériques) algorithm. A better agreement was found with LISA's analytical approach based on an altitude-dependent Tikhonov-Philips regularization: correlations are 0.94 and 0.89 compared to FTIR and Brewer, respectively; while the operational IASI ozone columns (based on neural network analysis) show correlations of 0.90 and 0.85, respectively, compared to the O3 columns obtained from FTIR and Brewer.

scholarly journals Characterisation and potential for reducing optical resonances in FTIR spectrometers of the Network for the Detection of Atmospheric Composition Change (NDACC)

2020 ◽  
Author(s):  
Thomas Blumenstock ◽  
Frank Hase ◽  
Axel Keens ◽  
Denis Czurlok ◽  
Orfeo Colebatch ◽  
...  
Keyword(s):  
Beam Splitter ◽  
Background Level ◽  
Air Gap ◽  
Atmospheric Composition ◽  
Composition Change ◽  
Infrared Source ◽  
Optical Components ◽  
Optical Resonances ◽  
Ftir Spectrometer

Abstract. Although optical components in Fourier transform infrared (FTIR) spectrometers are preferably wedged, in practice, infrared spectra typically suffer from the effects of optical resonances (“channeling”) affecting the retrieval of weakly absorbing gases. This study investigates the level of channeling of each FTIR spectrometer within the Network for the Detection of Atmospheric Composition Change (NDACC). Dedicated spectra were recorded by more than twenty NDACC FTIR spectrometers using a laboratory mid-infrared source and two detectors. In the InSb detector domain (1900–5000 cm−1), we find that the amplitude of the most pronounced channeling frequency amounts to 0.1 to 2.0 ‰ of the spectral background level, with a mean of (0.68 ± 0.48) ‰ and a median of 0.60 ‰. In the HgCdTe detector domain (700–1300 cm−1), we find even stronger effects, with the largest amplitude ranging from 0.3 to 21 ‰ with a mean of (2.45 ± 4.50) ‰ and a median of 1.2 ‰. For both detectors, the leading channeling frequencies are 0.9 and 0.11 or 0.23 cm−1 in most spectrometers. These observed spectral frequencies correspond to the optical thickness of the air gap in between the beam splitter and compensator plate (0.9 cm−1) and the beam splitter substrate itself (0.11 and 0.23 cm−1). Since the air gap is a significant source of channeling and the corresponding amplitude differs strongly between spectrometers, we propose new beam splitters with the wedge of the air gap increased to at least 0.8°. We tested the insertion of spacers in a beam splitter’s air gap to demonstrate that increasing the wedge of the air gap decreases the 0.9 cm−1 channeling amplitude significantly. This study shows the potential for reducing channeling in the FTIR spectrometers operated by the NDACC, thereby increasing the quality of recorded spectra across the network.

scholarly journals XCO<sub>2</sub>-measurements with a tabletop FTS using solar absorption spectroscopy

2012 ◽  
Vol 5 (4) ◽  
pp. 5691-5724 ◽  
Author(s):  
M. Gisi ◽  
F. Hase ◽  
S. Dohe ◽  
T. Blumenstock ◽  
A. Simon ◽  
...  
Keyword(s):  
Low Cost ◽  
Total Carbon ◽  
Fourier Transform Spectrometer ◽  
Promising Candidate ◽  
Solar Absorption ◽  
Solar Tracker ◽  
Ftir Spectrometer ◽  
Field Campaigns ◽  
Total Column ◽  
Comparison Period

Abstract. A commercial low-resolution (0.5 cm−1) Fourier-Transform-Spectrometer (FTS) has been modified and is used for determining the total column XCO2 of the atmosphere by analyzing direct solar radiation. The spectrometer has a small home-built solar tracker attached, so that it is a ready-to-use instrument. The results are validated with temporally coinciding on-site measurements taken with a high-resolution Total Carbon Column Observing Network (TCCON) FTIR-spectrometer. For the whole comparison period of 5 months (26 measurement days) an agreement with TCCON-results of (0.12 ± 0.08)% is achieved. This makes the spectrometer a promising candidate for a low-cost addition to the TCCON core FTIR sites, especially suitable for locations with limited infrastructure. An impressive mechanical and thermal stability is proved, enabling the spectrometer for use in field campaigns and for the monitoring of local sources.

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