scholarly journals Calibration and instrumental line shape characterization of a set of portable FTIR spectrometers for detecting greenhouse gas emissions

2015 ◽  
Vol 8 (7) ◽  
pp. 3047-3057 ◽  
Author(s):  
M. Frey ◽  
F. Hase ◽  
T. Blumenstock ◽  
J. Groß ◽  
M. Kiel ◽  
...  
Keyword(s):  
Line Shape ◽  
External Source ◽  
Calibration Procedure ◽  
Total Carbon ◽  
Instrumental Performance ◽  
Solar Absorption ◽  
Ground Pressure ◽  
Before And After ◽  
Instrumental Line ◽  
The Individual

Abstract. A comprehensive calibration procedure for mobile, low-resolution, solar-absorption FTIR spectrometers, used for greenhouse gases observations, is developed. These instruments commend themselves for campaign use and deployment at remote sites. The instrumental line shape (ILS) of each spectrometer has been thoroughly characterized by analyzing the shape of H2O signatures in open path spectra. A setup for the external source is suggested and the invariance of derived ILS parameters with regard to chosen path length is demonstrated. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Side-by-side solar observations before and after a campaign, which involved shipping of all spectrometers to a selected target site and back, are applied for verifying the temporal invariability of instrumental characteristics and for deriving intercalibration factors for XCO2 and XCH4, which take into account residual differences of instrumental characteristics. An excellent level of agreement and stability was found between the different spectrometers: the uncorrected biases in XCO2 and XCH4 are smaller than 0.01 and 0.15 %, respectively, and the drifts are smaller than 0.005 and 0.035 %. As an additional sensitive demonstration of the instrumental performance we show the excellent agreement of ground pressure values obtained from the total column measurements of O2 and barometric records. We find a calibration factor of 0.9700 for the spectroscopic measurements in comparison to the barometric records and a very small scatter between the individual spectrometers (0.02 %). As a final calibration step, using a co-located TCCON (Total Carbon Column Observation Network) spectrometer as a reference, a common scaling factor has been derived for the XCO2 and XCH4 products, which ensures that the records are traceable to the WMO in situ scale.

scholarly journals Calibration of sealed HCl cells used for TCCON instrumental line shape monitoring

2013 ◽  
Vol 6 (4) ◽  
pp. 7185-7215
Author(s):  
F. Hase ◽  
B. J. Drouin ◽  
C. M. Roehl ◽  
G. C. Toon ◽  
P. O. Wennberg ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Greenhouse Gases ◽  
Line Shape ◽  
Calibration Procedure ◽  
Total Carbon ◽  
Dry Air ◽  
Reference Cell ◽  
Instrumental Line ◽  
Shape Monitoring

Abstract. The TCCON (Total Carbon Column Observing Network) FTIR network provides highly accurate observations of greenhouse gases column-averaged dry-air mole fractions. As an important component of TCCON quality assurance measures, sealed cells filled with approx. 5 mbar of HCl are used for instrumental line shape (ILS) monitoring at all TCCON sites. Here, we introduce a calibration procedure for the HCl cells which applies a refillable, pressure-monitored reference cell filled with C2H2. Using this method, we identify residual variations of HCl purity between the TCCON cells as a non-negligible disturbance.

scholarly journals Calibration of sealed HCl cells used for TCCON instrumental line shape monitoring

2013 ◽  
Vol 6 (12) ◽  
pp. 3527-3537 ◽  
Author(s):  
F. Hase ◽  
B. J. Drouin ◽  
C. M. Roehl ◽  
G. C. Toon ◽  
P. O. Wennberg ◽  
...  
Keyword(s):  
Line Shape ◽  
Individual Cell ◽  
Calibration Procedure ◽  
Total Carbon ◽  
Effective Pressure ◽  
Error Source ◽  
Secondary Importance ◽  
Instrumental Line ◽  
Network Consistency ◽  
Shape Monitoring

Abstract. The TCCON (Total Carbon Column Observing Network) FTIR (Fourier transform infrared) network provides highly accurate observations of greenhouse gas column-averaged dry-air mole fractions. As an important component of TCCON quality assurance, sealed cells filled with approximately 5 mbar of HCl are used for instrumental line shape (ILS) monitoring at all TCCON sites. Here, we introduce a calibration procedure for the HCl cells which employs a refillable, pressure-monitored reference cell filled with C2H2. Using this method, we identify variations of HCl purity between the TCCON cells as a non-negligible disturbance. The new calibration procedure introduced here assigns effective pressure values to each individual cell to account for additional broadening of the HCl lines. This approach will improve the consistency of the network by significantly reducing possible station-to-station biases due to inconsistent ILS results from different HCl cells. We demonstrate that the proposed method is accurate enough to turn the ILS uncertainty into an error source of secondary importance from the viewpoint of network consistency.

scholarly journals Use of portable FTIR spectrometers for detecting greenhouse gas emissions of the megacity Berlin – Part 1: Instrumental line shape characterisation and calibration of a quintuple of spectrometers

2015 ◽  
Vol 8 (3) ◽  
pp. 2735-2766 ◽  
Author(s):  
M. Frey ◽  
F. Hase ◽  
T. Blumenstock ◽  
J. Groß ◽  
M. Kiel ◽  
...  
Keyword(s):  
Line Shape ◽  
Common Factor ◽  
Low Resolution ◽  
Ground Pressure ◽  
Before And After ◽  
Instrumental Line ◽  
Cross Calibration ◽  
Shape Characteristics ◽  
Level Of Agreement

Abstract. Several low resolution spectrometers were used to investigate the CO2 and CH4 emissions of the megacity Berlin. Before and after the campaign the instruments were tested side-by-side. An excellent level of agreement and stability was found between the different spectrometers: the drifts in XCO2 and XCH4 are within 0.005 and 0.035%, respectively. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Cross-calibration factors for XCH4 and XCO2 were established for each spectrometer. An empirical airmass correction factor has been applied. As a last calibration step, using a co-located TCCON spectrometer as a reference, a common factor has been derived for the low-resolution campaign spectrometers, which ensures that the records are compatible to the WMO in-situ scale. Finally as a first result of the Berlin campaign we show the excellent agreement of ground pressure values obtained from total column measurements and in situ records.

scholarly journals Technical note: Sensitivity of instrumental line shape monitoring for the ground-based high-resolution FTIR spectrometer with respect to different optical attenuators

2017 ◽  
Vol 10 (3) ◽  
pp. 989-997 ◽  
Author(s):  
Youwen Sun ◽  
Mathias Palm ◽  
Christine Weinzierl ◽  
Christof Petri ◽  
Justus Notholt ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Shape ◽  
Radiant Energy ◽  
Technical Note ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Incident Intensity ◽  
Instrumental Line ◽  
Ftir Spectrometer ◽  
Potential Strategy

Abstract. The TCCON (Total Carbon Column Observing Network) and most NDACC (Network for Detection of Atmospheric Composition Change) sites assume an ideal ILS (instrumental line shape) for analysis of the spectra. In order to adapt the radiant energy received by the detector, an attenuator or different sizes of field stop can be inserted in the light path. These processes may alter the alignment of a high-resolution FTIR (Fourier transform infrared) spectrometer, and may result in bias due to ILS drift. In this paper, we first investigated the sensitivity of the ILS monitoring with respect to application of different kinds of attenuators for ground-based high-resolution FTIR spectrometers within the TCCON and NDACC networks. Both lamp and sun cell measurements were conducted after the insertion of five different attenuators in front of and behind the interferometer. The ILS characteristics derived from lamp and sun spectra are in good agreement. ILSs deduced from all lamp cell measurements were compared. As a result, the disturbances to the ILS of a high-resolution FTIR spectrometer with respect to the insertion of different attenuators at different positions were quantified. A potential strategy to adapt the incident intensity of a detector was finally deduced.

scholarly journals Ship-borne measurements of XCO<sub>2</sub>, XCH<sub>4</sub>, and XCO above the Pacific Ocean and comparison to CAMS atmospheric analyses and S5P/TROPOMI

2020 ◽  
Author(s):  
Marvin Knapp ◽  
Ralph Kleinschek ◽  
Frank Hase ◽  
Anna Agustí-Panareda ◽  
Antje Inness ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Excellent Agreement ◽  
Total Carbon ◽  
Solar Absorption ◽  
The Pacific ◽  
Before And After ◽  
Infrared Spectral ◽  
Solar Tracker ◽  
The Pacific Ocean ◽  
Shortwave Infrared

Abstract. Measurements of atmospheric column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) have been collected across the Pacific ocean during the Measuring Ocean REferences 2 (MORE-2) campaign in June 2019. We deployed a ship-borne variant of the EM27/SUN Fourier Transform Spectrometer (FTS) on board the German research vessel Sonne which, during MORE-2, crossed the Pacific ocean from Vancouver, Canada, to Singapore. Equipped with a specially manufactured fast solar tracker, the FTS operated in direct-sun viewing geometry during the ship cruise reliably delivering solar absorption spectra in the shortwave infrared spectral range (4000 to 11 000 1/cm). After filtering and bias correcting the dataset, we report on XCO2, XCH4, and XCO measurements for 22 days along a trajectory that largely aligns with 30° N of latitude between 140° W and 120° E of longitude. The dataset has been scaled to the Total Carbon Column Observing Network (TCCON) station in Karlsruhe, Germany, before and after the MORE-2 campaign through side-by-side measurements. The precision for hourly means of XCO2, XCH4, and XCO during the campaign is found 0.24 ppm, 1.1 ppb, and 0.75 ppb, respectively. Comparing concentration fields analysed by the Copernicus Atmosphere Monitoring Service (CAMS) to our data, we find excellent agreement of 0.52 ± 0.31 ppm for XCO2, 0.9 ± 4.1 ppb for XCH4, and 3.2 ± 3.4 ppb for XCO (mean difference ± standard deviation of differences for entire record). Likewise, we find excellent agreement to within 2.2 ± 6.6 ppb with the XCO observations of the TROPOspheric MOnitoring Instrument (TROPOMI) on the Sentinel-5 Precursor satellite (S5P). The ship-borne measurements are accessible at https://doi.org/10.1594/PANGAEA.917240 (Knapp et al., 2020).

scholarly journals Shipborne measurements of XCO<sub>2</sub>, XCH<sub>4</sub>, and XCO above the Pacific Ocean and comparison to CAMS atmospheric analyses and S5P/TROPOMI

2021 ◽  
Vol 13 (1) ◽  
pp. 199-211
Author(s):  
Marvin Knapp ◽  
Ralph Kleinschek ◽  
Frank Hase ◽  
Anna Agustí-Panareda ◽  
Antje Inness ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Excellent Agreement ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Solar Absorption ◽  
The Pacific ◽  
Before And After ◽  
Infrared Spectral ◽  
Solar Tracker ◽  
The Pacific Ocean

Abstract. Measurements of atmospheric column-averaged dry-air mole fractions of carbon dioxide (XCO2), methane (XCH4), and carbon monoxide (XCO) have been collected across the Pacific Ocean during the Measuring Ocean REferences 2 (MORE-2) campaign in June 2019. We deployed a shipborne variant of the EM27/SUN Fourier transform spectrometer (FTS) on board the German R/V Sonne which, during MORE-2, crossed the Pacific Ocean from Vancouver, Canada, to Singapore. Equipped with a specially manufactured fast solar tracker, the FTS operated in direct-sun viewing geometry during the ship cruise reliably delivering solar absorption spectra in the shortwave infrared spectral range (4000 to 11000 cm−1). After filtering and bias correcting the dataset, we report on XCO2, XCH4, and XCO measurements for 22 d along a trajectory that largely aligns with 30∘ N of latitude between 140∘ W and 120∘ E of longitude. The dataset has been scaled to the Total Carbon Column Observing Network (TCCON) station in Karlsruhe, Germany, before and after the MORE-2 campaign through side-by-side measurements. The 1σ repeatability of hourly means of XCO2, XCH4, and XCO is found to be 0.24 ppm, 1.1 ppb, and 0.75 ppb, respectively. The Copernicus Atmosphere Monitoring Service (CAMS) models gridded concentration fields of the atmospheric composition using assimilated satellite observations, which show excellent agreement of 0.52±0.31 ppm for XCO2, 0.9±4.1 ppb for XCH4, and 3.2±3.4 ppb for XCO (mean difference ± SD, standard deviation, of differences for entire record) with our observations. Likewise, we find excellent agreement to within 2.2±6.6 ppb with the XCO observations of the TROPOspheric MOnitoring Instrument (TROPOMI) on the Sentinel-5 Precursor satellite (S5P). The shipborne measurements are accessible at https://doi.org/10.1594/PANGAEA.917240 (Knapp et al., 2020).

scholarly journals Sensitivity of instrumental line shape with respect to different optical attenuators and resulting error propagation into atmospheric trace gas retrievals

2016 ◽  
Author(s):  
Y. W. Sun ◽  
M. Palm ◽  
C. Weinzierl ◽  
C. Petri ◽  
J. Notholt ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Shape ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Spherical Mirror ◽  
Incident Intensity ◽  
Height Range ◽  
Entrance Aperture ◽  
Optical Attenuators ◽  
Instrumental Line

Abstract. The TCCON (Total Carbon Column Observing Network) and most NDACC (Network for Detection of Atmospheric Composition Change) assume an ideal ILS (Instrumental line shape) in spectra retrieval and insert an attenuator or select a smaller entrance aperture to take some intensities away if incident radiation is too strong. These processes may alter the alignment of a high resolution FTIR (Fourier transform infrared) spectrometer and may result in biases due to ILS drift. In this paper, we first investigated the sensitivity of ILS monitoring with respect to various typical optical attenuators for ground-based high resolution FTIR spectrometers within the TCCON and NDACC networks. Both lamp and sun cell measurements were conducted in this analysis via the insertion of five different attenuators before and behind the interferometer. We compared the HCl profile retrievals using an ideal ILS with those using an actual measured ILS. The results showed that the total column amounts were under-estimated by about 0.4 % if the ME (modulation efficiency) amplitude deviates by about –3.5 %. Furthermore, the retrieval errors increased and the obvious profile deviations are shown in a height range with a high retrieval sensitivity. ILSs deduced from all scenarios of lamp cell measurements were compared, and were further used to derive the HCl profile from the same spectrum. As a result, the disturbances to the ILS of a high resolution FTIR spectrometer with respect to inserting different attenuators before and behind the interferometer are quantified. The resulting ILS errors propagation into gas retrievals were also analyzed. In conclusion, the alignment of the optical parts before the interferometer is more critical than those behind the interferometer, and the entrance aperture (the focus of the entrance parabolic/spherical mirror) exhibited the most critical influence. An optimum method to adapt the incident intensity of a detector was finally deduced.

Official Advice Improves Mortgage-Holders’ Perceptions of Switching: Experimental Evidence

2019 ◽  
Author(s):  
Shane Timmons
Keyword(s):  
Interest Rate ◽  
Experimental Evidence ◽  
Consumer Protection ◽  
Policy Development ◽  
Switching Process ◽  
Competitive Markets ◽  
Protection Agency ◽  
Change Perceptions ◽  
Before And After ◽  
The Individual

Encouraging consumers to switch to lower-rate mortgages is important both for the individual consumer’s finances and for functioning competitive markets, but switching rates are low. Given the complexity of mortgages, one potential regulatory intervention that may increase switching rates is to provide independent advice on how to select good mortgage products and how to navigate the switching process. Working with a government consumer protection agency, we conducted an experiment with mortgage-holders to test whether such advice alters perceptions of switching. The experiment tested how (i) the attributes of the offer, (ii) perceptions about the switching process, (iii) individual feelings of competence and (iv) comprehension of the product affect willingness to switch to better offers, both before and after reading the official advice. The advice made consumers more sensitive to interest rate decreases, especially at longer terms. It also increased consumers’ confidence in their ability to select good offers. Overall, the findings imply that advice from policymakers can change perceptions and increase switching rates. Moreover, the experiment demonstrates how lab studies can contribute to behaviourally-informed policy development.

Quality of Life for Children with Persistent Sinonasal Symptoms

2003 ◽  
Vol 128 (1) ◽  
pp. 17-26 ◽  
Author(s):  
David J. Kay ◽  
Richard M. Rosenfeld
Keyword(s):  
Quality Of Life ◽  
Clinical Care ◽  
Longitudinal Change ◽  
Good Test ◽  
Routine Clinical Care ◽  
Before And After ◽  
The Mean ◽  
The Individual ◽  
Sinonasal Symptoms

OBJECTIVE: The goal was to validate the SN-5 survey as a measure of longitudinal change in health-related quality of life (HRQoL) for children with persistent sinonasal symptoms. DESIGN AND SETTING: We conducted a before and after study of 85 children aged 2 to 12 years in a metropolitan pediatric otolaryngology practice. Caregivers completed the SN-5 survey at entry and at least 4 weeks later. The survey included 5 symptom-cluster items covering the domains of sinus infection, nasal obstruction, allergy symptoms, emotional distress, and activity limitations. RESULTS: Good test-retest reliability ( R = 0.70) was obtained for the overall SN-5 score and the individual survey items ( R ≥ 0.58). The mean baseline SN-5 score was 3.8 (SD, 1.0) of a maximum of 7.0, with higher scores indicating poorer HRQoL. All SN-5 items had adequate correlation ( R ≥ 0.36) with external constructs. The mean change in SN-5 score after routine clinical care was 0.88 (SD, 1.19) with an effect size of 0.74 indicating good responsiveness to longitudinal change. The change scores correlated appropriately with changes in related external constructs ( R ≥ 0.42). CONCLUSIONS: The SN-5 is a valid, reliable, and responsive measure of HRQoL for children with persistent sinonasal symptoms, suitable for use in outcomes studies and routine clinical care.

scholarly journals General psychopathology links burden of recent life events and psychotic symptoms in a network approach

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Linda T. Betz ◽  
◽  
Nora Penzel ◽  
Lana Kambeitz-Ilankovic ◽  
Marlene Rosen ◽  
...  
Keyword(s):  
Life Events ◽  
Childhood Trauma ◽  
Negative Symptoms ◽  
Psychotic Symptoms ◽  
Network Approach ◽  
General Psychopathology ◽  
Recent Onset ◽  
Syndrome Scale ◽  
Before And After ◽  
The Individual

AbstractRecent life events have been implicated in the onset and progression of psychosis. However, psychological processes that account for the association are yet to be fully understood. Using a network approach, we aimed to identify pathways linking recent life events and symptoms observed in psychosis. Based on previous literature, we hypothesized that general symptoms would mediate between recent life events and psychotic symptoms. We analyzed baseline data of patients at clinical high risk for psychosis and with recent-onset psychosis (n = 547) from the Personalised Prognostic Tools for Early Psychosis Management (PRONIA) study. In a network analysis, we modeled links between the burden of recent life events and all individual symptoms of the Positive and Negative Syndrome Scale before and after controlling for childhood trauma. To investigate the longitudinal associations between burden of recent life events and symptoms, we analyzed multiwave panel data from seven timepoints up to month 18. Corroborating our hypothesis, burden of recent life events was connected to positive and negative symptoms through general psychopathology, specifically depression, guilt feelings, anxiety and tension, even after controlling for childhood trauma. Longitudinal modeling indicated that on average, burden of recent life events preceded general psychopathology in the individual. In line with the theory of an affective pathway to psychosis, recent life events may lead to psychotic symptoms via heightened emotional distress. Life events may be one driving force of unspecific, general psychopathology described as characteristic of early phases of the psychosis spectrum, offering promising avenues for interventions.

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