Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO
<p>The Total Carbon Column Observing Network (TCCON) is the baseline ground-based network of instruments that record solar absorption spectra from which accurate and precise column-averaged dry-air mole fractions of <span class="inline-formula">CO<sub>2</sub></sp...
| Main Authors: | , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-09-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/13/4791/2020/amt-13-4791-2020.pdf |
| _version_ | 1811325565513236480 |
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| author | M. K. Sha M. De Mazière J. Notholt T. Blumenstock H. Chen A. Dehn D. W. T. Griffith F. Hase P. Heikkinen C. Hermans A. Hoffmann M. Huebner N. Jones R. Kivi B. Langerock C. Petri F. Scolas Q. Tu D. Weidmann |
| author_facet | M. K. Sha M. De Mazière J. Notholt T. Blumenstock H. Chen A. Dehn D. W. T. Griffith F. Hase P. Heikkinen C. Hermans A. Hoffmann M. Huebner N. Jones R. Kivi B. Langerock C. Petri F. Scolas Q. Tu D. Weidmann |
| author_sort | M. K. Sha |
| collection | DOAJ |
| description | <p>The Total Carbon Column Observing Network (TCCON) is the baseline ground-based network of instruments that record solar absorption spectra from which accurate and precise column-averaged dry-air mole fractions of <span class="inline-formula">CO<sub>2</sub></span> (<span class="inline-formula">XCO<sub>2</sub></span>), <span class="inline-formula">CH<sub>4</sub></span> (<span class="inline-formula">XCH<sub>4</sub></span>), CO (XCO), and other gases are retrieved. The TCCON data have been widely used for carbon cycle science and validation of satellites measuring greenhouse gas concentrations globally. The number of stations in the network (currently about 25) is limited and has a very uneven geographical coverage: the stations in the Northern Hemisphere are distributed mostly in North America, Europe, and Japan, and only 20 % of the stations are located in the Southern Hemisphere, leaving gaps in the global coverage. A denser distribution of ground-based solar absorption measurements is needed to improve the representativeness of the measurement data for various atmospheric conditions (humid, dry, polluted, presence of aerosol), various surface conditions such as high albedo (<span class="inline-formula">>0.4</span>) and very low albedo, and a larger latitudinal distribution. More stations in the Southern Hemisphere are also needed, but a further expansion of the network is limited by its costs and logistical requirements. For this reason, several groups are investigating supplemental portable low-cost instruments. The European Space Agency (ESA) funded campaign Fiducial Reference Measurements for Ground-Based Infrared Greenhouse Gas Observations (FRM4GHG) at the Sodankylä TCCON site in northern Finland aims to characterise the assessment of several low-cost portable instruments for precise solar absorption measurements of <span class="inline-formula">XCO<sub>2</sub></span>, <span class="inline-formula">XCH<sub>4</sub></span>, and XCO. The test instruments under investigation are three Fourier transform spectrometers (FTSs): a Bruker EM27/SUN, a Bruker IRcube, and a Bruker Vertex70, as well as a laser heterodyne spectroradiometer (LHR) developed by the UK Rutherford Appleton Laboratory. All four remote sensing instruments performed measurements simultaneously next to the reference TCCON instrument, a Bruker IFS 125HR, for a full year in 2017. The TCCON FTS was operated in its normal high-resolution mode (TCCON data set) and in a special low-resolution mode (HR125LR data set), similar to the portable spectrometers. The remote sensing measurements are complemented by regular AirCore launches performed from the same site. They provide in situ vertical profiles of the target gas concentrations as auxiliary reference data for the column retrievals, which are traceable to the WMO SI<span id="page4792"/> standards. The reference measurements performed with the Bruker IFS 125HR were found to be affected by non-linearity of the indium gallium arsenide (InGaAs) detector. Therefore, a non-linearity correction of the 125HR data was performed for the whole campaign period and compared with the test instruments and AirCore. The non-linearity-corrected data (TCCONmod data set) show a better match with the test instruments and AirCore data compared to the non-corrected reference data. The time series, the bias relative to the reference instrument and its scatter, and the seasonal and the day-to-day variations of the target gases are shown and discussed. The comparisons with the HR125LR data set gave a useful analysis of the resolution-dependent effects on the target gas retrieval. The solar zenith angle dependence of the retrievals is shown and discussed. The intercomparison results show that the LHR data have a large scatter and biases with a strong diurnal variation relative to the TCCON and other FTS instruments. The LHR is a new instrument under development, and these biases are currently being investigated and addressed. The campaign helped to characterise and identify instrumental biases and possibly retrieval biases, which are currently under investigation. Further improvements of the instrument are ongoing. The EM27/SUN, the IRcube, the modified Vertex70, and the HR125LR provided stable and precise measurements of the target gases during the campaign with quantified small biases. The bias dependence on the humidity along the measurement line of sight has been investigated and no dependence was found. These three portable low-resolution FTS instruments are suitable to be used for campaign deployment or long-term measurements from any site and offer the ability to complement the TCCON and expand the global coverage of ground-based reference measurements of the target gases.</p> |
| first_indexed | 2024-04-13T14:35:28Z |
| format | Article |
| id | doaj.art-e13efa92271a416aab92731660758d37 |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-04-13T14:35:28Z |
| publishDate | 2020-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-e13efa92271a416aab92731660758d372022-12-22T02:43:03ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482020-09-01134791483910.5194/amt-13-4791-2020Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and COM. K. Sha0M. De Mazière1J. Notholt2T. Blumenstock3H. Chen4A. Dehn5D. W. T. Griffith6F. Hase7P. Heikkinen8C. Hermans9A. Hoffmann10M. Huebner11N. Jones12R. Kivi13B. Langerock14C. Petri15F. Scolas16Q. Tu17D. Weidmann18Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, BelgiumRoyal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, BelgiumInstitute of Environmental Physics, University of Bremen, Bremen, GermanyKarlsruhe Institute of Technology, IMK-ASF, Karlsruhe, GermanyCentre for Isotope Research, University of Groningen, Groningen, the NetherlandsEuropean Space Agency, ESA/ESRIN, Frascati RM, ItalySchool of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, AustraliaKarlsruhe Institute of Technology, IMK-ASF, Karlsruhe, GermanySpace and Earth Observation Centre, Finnish Meteorological Institute, Sodankylä, FinlandRoyal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, BelgiumSpace Science and Technology Department, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UKSpace Science and Technology Department, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UKSchool of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, AustraliaSpace and Earth Observation Centre, Finnish Meteorological Institute, Sodankylä, FinlandRoyal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, BelgiumInstitute of Environmental Physics, University of Bremen, Bremen, GermanyRoyal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, BelgiumKarlsruhe Institute of Technology, IMK-ASF, Karlsruhe, GermanySpace Science and Technology Department, STFC Rutherford Appleton Laboratory, Harwell Campus, Didcot, OX11 0QX, UK<p>The Total Carbon Column Observing Network (TCCON) is the baseline ground-based network of instruments that record solar absorption spectra from which accurate and precise column-averaged dry-air mole fractions of <span class="inline-formula">CO<sub>2</sub></span> (<span class="inline-formula">XCO<sub>2</sub></span>), <span class="inline-formula">CH<sub>4</sub></span> (<span class="inline-formula">XCH<sub>4</sub></span>), CO (XCO), and other gases are retrieved. The TCCON data have been widely used for carbon cycle science and validation of satellites measuring greenhouse gas concentrations globally. The number of stations in the network (currently about 25) is limited and has a very uneven geographical coverage: the stations in the Northern Hemisphere are distributed mostly in North America, Europe, and Japan, and only 20 % of the stations are located in the Southern Hemisphere, leaving gaps in the global coverage. A denser distribution of ground-based solar absorption measurements is needed to improve the representativeness of the measurement data for various atmospheric conditions (humid, dry, polluted, presence of aerosol), various surface conditions such as high albedo (<span class="inline-formula">>0.4</span>) and very low albedo, and a larger latitudinal distribution. More stations in the Southern Hemisphere are also needed, but a further expansion of the network is limited by its costs and logistical requirements. For this reason, several groups are investigating supplemental portable low-cost instruments. The European Space Agency (ESA) funded campaign Fiducial Reference Measurements for Ground-Based Infrared Greenhouse Gas Observations (FRM4GHG) at the Sodankylä TCCON site in northern Finland aims to characterise the assessment of several low-cost portable instruments for precise solar absorption measurements of <span class="inline-formula">XCO<sub>2</sub></span>, <span class="inline-formula">XCH<sub>4</sub></span>, and XCO. The test instruments under investigation are three Fourier transform spectrometers (FTSs): a Bruker EM27/SUN, a Bruker IRcube, and a Bruker Vertex70, as well as a laser heterodyne spectroradiometer (LHR) developed by the UK Rutherford Appleton Laboratory. All four remote sensing instruments performed measurements simultaneously next to the reference TCCON instrument, a Bruker IFS 125HR, for a full year in 2017. The TCCON FTS was operated in its normal high-resolution mode (TCCON data set) and in a special low-resolution mode (HR125LR data set), similar to the portable spectrometers. The remote sensing measurements are complemented by regular AirCore launches performed from the same site. They provide in situ vertical profiles of the target gas concentrations as auxiliary reference data for the column retrievals, which are traceable to the WMO SI<span id="page4792"/> standards. The reference measurements performed with the Bruker IFS 125HR were found to be affected by non-linearity of the indium gallium arsenide (InGaAs) detector. Therefore, a non-linearity correction of the 125HR data was performed for the whole campaign period and compared with the test instruments and AirCore. The non-linearity-corrected data (TCCONmod data set) show a better match with the test instruments and AirCore data compared to the non-corrected reference data. The time series, the bias relative to the reference instrument and its scatter, and the seasonal and the day-to-day variations of the target gases are shown and discussed. The comparisons with the HR125LR data set gave a useful analysis of the resolution-dependent effects on the target gas retrieval. The solar zenith angle dependence of the retrievals is shown and discussed. The intercomparison results show that the LHR data have a large scatter and biases with a strong diurnal variation relative to the TCCON and other FTS instruments. The LHR is a new instrument under development, and these biases are currently being investigated and addressed. The campaign helped to characterise and identify instrumental biases and possibly retrieval biases, which are currently under investigation. Further improvements of the instrument are ongoing. The EM27/SUN, the IRcube, the modified Vertex70, and the HR125LR provided stable and precise measurements of the target gases during the campaign with quantified small biases. The bias dependence on the humidity along the measurement line of sight has been investigated and no dependence was found. These three portable low-resolution FTS instruments are suitable to be used for campaign deployment or long-term measurements from any site and offer the ability to complement the TCCON and expand the global coverage of ground-based reference measurements of the target gases.</p>https://amt.copernicus.org/articles/13/4791/2020/amt-13-4791-2020.pdf |
| spellingShingle | M. K. Sha M. De Mazière J. Notholt T. Blumenstock H. Chen A. Dehn D. W. T. Griffith F. Hase P. Heikkinen C. Hermans A. Hoffmann M. Huebner N. Jones R. Kivi B. Langerock C. Petri F. Scolas Q. Tu D. Weidmann Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO Atmospheric Measurement Techniques |
| title | Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO |
| title_full | Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO |
| title_fullStr | Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO |
| title_full_unstemmed | Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO |
| title_short | Intercomparison of low- and high-resolution infrared spectrometers for ground-based solar remote sensing measurements of total column concentrations of CO<sub>2</sub>, CH<sub>4</sub>, and CO |
| title_sort | intercomparison of low and high resolution infrared spectrometers for ground based solar remote sensing measurements of total column concentrations of co sub 2 sub ch sub 4 sub and co |
| url | https://amt.copernicus.org/articles/13/4791/2020/amt-13-4791-2020.pdf |
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