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See detailAssessing the losses of HCFC-22 using ACE-FTS measurements
Kolonjari, F.; Walker, K.A.; Boone, C.D. et al

Scientific conference (2012, November 09)

The annual springtime minimum in stratospheric ozone over the Antarctic is primarily caused by catalytic reactions of ozone and chlorine. The Montreal Protocol on Substances that Deplete the Ozone Layer ... [more ▼]

The annual springtime minimum in stratospheric ozone over the Antarctic is primarily caused by catalytic reactions of ozone and chlorine. The Montreal Protocol on Substances that Deplete the Ozone Layer (with its subsequent amendments) restricts the emissions of ozone depleting substances. HCFC-22 has been the primary replacement for both CFC-11 and CFC-12, which has led to an increase in its atmospheric abundance. The Atmospheric Chemistry Experiment (ACE) is a mission on-board the Canadian satellite SCISAT. The primary instrument on SCISAT is a highresolution infrared Fourier Transform Spectrometer (ACE-FTS). With its wide spectral range, the ACE-FTS is capable of measuring an extensive range of gases including key CFC and HCFC species. The altitude distribution from the ACE-FTS profiles provides information that is complementary to the ground-based measurements that have been used to monitor these species. The ACE-FTS measurements compare well with surface in situ and balloon measurements. A preliminary validation of HCFC-22 using ground-based FTSs is discussed. The zonal mean distribution of HCFC-22 as observed by ACE-FTS is presented. The global distributions of HCFC-22 have been compared to the Global Modelling Initiative (GMI) Combined Stratospheric-Tropospheric Model, a chemistry and transport model. Large differences between the model and ACE-FTS measurements of HCFC-22 reveal issues with the boundary value mixing ratios. The comparison of stratospheric measurements with GMI suggest that there may be a missing loss process in the stratosphere, some issues with transport circulation and polar cap averaging in the current run, or a combination of the two processes. We propose the reaction of HCFC-22 with atomic chlorine as a potentially important loss process in the lowermost stratosphere and the lower stratosphere. [less ▲]

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See detailValidation of ACE-FTS using ground-based FTIR measurements of CFC-11, CFC-12 and HCFC-22
Kolonjari, F.; Mahieu, Emmanuel ULg; Walker, K.A. et al

Poster (2012, July 24)

Satellite data can be an effective global monitoring tool for long-lived compounds in the atmosphere. The Atmospheric Chemistry Experiment (ACE) is a mission on-board the Canadian satellite SCISAT. The ... [more ▼]

Satellite data can be an effective global monitoring tool for long-lived compounds in the atmosphere. The Atmospheric Chemistry Experiment (ACE) is a mission on-board the Canadian satellite SCISAT. The primary instrument on SCISAT is a high-resolution infrared Fourier Transform Spectrometer (ACE-FTS) which is capable of measuring a wide range of gases including key chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) species. These families of species are of interest because of their significant contribution to anthropogenic ozone depletion and to global warming. To assess the quality of data derived from satellite measurements, validation using other data sources is critical. Ground-based Fourier transform infrared spectrometers (FTIRs) are particularly useful for this purpose. In this study, five FTIRs located at four sites around the world are used to validate the CFC- 11, CFC-12, and HCFC-22 data products from ACE-FTS. These species are related; HCFC-22 was the primary replacement for CFC-11 and CFC-12 in refrigerant and propellant applications. The five FTIR instruments used in this study record solar absorption spectra at Eureka, Canada, Jungfraujoch, Switzerland, Poker Flat, USA, and Toronto, Canada. Details on the instrumentation at each site will be provided. The retrieval of CFC-11, CFC-12, and HCFC-22 are not standard products for many of these FTIRs, and as such, the initial stage of this study is to develop the retrieval of each species. Harmonization of retrieval parameters between the sites is an important step in this process. The development of these retrievals and preliminary results will be presented. Additionally, a new method for the validation of ACE-FTS measurements will be discussed. [less ▲]

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See detailMeasurements of HCFC-22 and validation update
Kolonjari, F.; Walker, K.A.; Mahieu, Emmanuel ULg et al

Scientific conference (2012, May 24)

This talk reports about global HCFC-22 measurements derived from ACE-FTS occultation observations recorded from 2004 onwards. It further provides information on the validation of ACE-FTS products for CFC ... [more ▼]

This talk reports about global HCFC-22 measurements derived from ACE-FTS occultation observations recorded from 2004 onwards. It further provides information on the validation of ACE-FTS products for CFC-11, -12 and HCFC-22 with ground-based FTIR instruments operated at four sites: Eureka, Poker Flat, Toronto and Jungfraujoch. [less ▲]

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See detailComparisons of long-term stratospheric nitric acid and hydrogen fluoride variations using satellite and ground-based measurements
Froidevaux, L.; Anderson, J.; Hannigan, J. et al

Conference (2011, November 09)

We investigate the long-term variations of stratospheric nitric acid (HNO3) and hydrogen fluoride (HF), based on several satellite and ground-based measurement records. We use results from the Upper ... [more ▼]

We investigate the long-term variations of stratospheric nitric acid (HNO3) and hydrogen fluoride (HF), based on several satellite and ground-based measurement records. We use results from the Upper Atmosphere Research Satellite (launched in late 1991 and decommissioned in late 2005), the Aura satellite (launched in summer 1991, with on-going measurements), and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) (from 2004 to present), in conjunction with several long-term ground-based datasets from the Network for the Detection of Atmosphere Composition Change (NDACC). In particular, we investigate the time series of HNO3 and HF, using NDACC column data for validation. We focus here on a few NDACC sites with long-term and frequent measurements, namely the Jungfraujoch (45N, 8E), Lauder (45S, 170E), and Mauna Loa (20N, 204E) sites, where ground-based Fourier Transform Infrared (FTIR) measurements have covered both the UARS and Aura time periods (1991 to present). For HNO3, we investigate whether there are indications of a systematic offset between the measurements by the Microwave Limb Sounder (MLS) instruments aboard both UARS and Aura. For hydrogen fluoride, the HALogen Occultation Experiment's HF time series are connected to the ACE-FTS dataset, and we analyze the correlation of this time series with the ground-based datasets. In addition, model runs from the Whole Atmosphere Community Climate Model (WACCM) and the TOMCAT/SLIMCAT model are used as part of the long-term time series intercomparisons. We note that there is a significant time gap in the HNO3 time series from the satellite measurements used here. The long-term satellite datasets studied here include zonal average Earth Science Data Records (ESDRs) being produced under the Global Ozone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) project, part of the NASA Making Earth Science data records for Use in Research Environments (MEaSUREs) program. We also analyze coincident-type measurements, for the comparisons between satellite and ground-based observations. [less ▲]

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See detailTime series of 12CO and 13CO at northern mid-latitudes: Determination of Partial Column and δ13C seasonal and interannual variations
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Rinsland, C. P. et al

in Geophysical Research Abstracts (2009, April), 11(EGU2009-10017-1),

Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of ... [more ▼]

Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of methane and nonmethane hydrocarbons complete the emissions budget. Large uncertainties still affect the relative contributions of the identified anthropogenic and natural sources. Destruction by the hydroxyl radical (OH) is the main removal process for CO in both the troposphere and the stratosphere. The resulting average tropospheric lifetime of CO varies from several weeks to a few months. Two approaches have been developed and optimized to independently retrieve abundances of 12CO and 13CO from high-resolution ground-based infrared solar spectra, using sets of carefully selected lines and the SFIT-2 (v3.91) algorithm which implements the optimal estimation method. The corresponding products will be described and characterized in terms of error budget and information content. These strategies have allowed us to produce partial column time series of 12CO and 13CO, using spectra recorded on a regular basis at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580 m asl, Swiss Alps), a site of the Network for the Detection of Atmospheric Composition Change (NDACC). The seasonal and interannual changes observed in the 12CO,13CO and δ13C (13C/12C) data sets will be presented and discussed. Complementary zonal mean time series derived from occultation measurements collected by the ACE-FTS instrument onboard the Canadian SCISAT-1 platform since 2004 will also be included and analyzed, focusing on the upper troposphere-lower stratosphere region of the atmosphere. Finally, we will use GEOS-Chem 3-D chemistry transport model results to help in the interpretation of the short and long-term variations characterizing the ground-based and satellite data sets, focusing on the factors influencing the partitioning between the two CO isotopologues. [less ▲]

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See detailRetrievals of C2H2 from high-resolution FTIR solar spectra recorded at the Jungfraujoch station (46.5ºN) and comparison with ACE-FTS observations
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Bernath, P. F. et al

in Geophysical Research Abstracts (2008), 10

Acetylene (C2H2) is among the nonmethane hydrocarbons (NMHCs) accessible to infrared remote sensing technique. As a product of combustion and biomass burning, it is emitted at the Earth’s surface and ... [more ▼]

Acetylene (C2H2) is among the nonmethane hydrocarbons (NMHCs) accessible to infrared remote sensing technique. As a product of combustion and biomass burning, it is emitted at the Earth’s surface and further transported and mixed into the troposphere. Destruction by OH is the main removal process. The average tropospheric lifetime of C2H2 is estimated at about 1 month on the global scale; at mid-latitudes, it varies between 20 days in summer to 160 days in winter. This compound is appropriate to study tropospheric pollution and transport, and is often used in conjunction with other tracers of fires. C2H2 presents exploitable infrared absorption features near 3 and 15 μm, where weak isolated lines of the nu5 and the nu2 + nu4 + nu5 bands are found, respectively. Several of these lines can be used to retrieve abundances of C2H2 from high-resolution groundbased infrared solar spectra. Typical observations recorded at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580m asl, Swiss Alps) by the NDACC (Network for the Detection of Atmospheric Composition Change)-affiliated Bruker instrument have been fitted with the OEM-SFIT-2 (v3.91) algorithm. Various approaches and combination of lines have been tested, seeking for the optimum inversion strategy. The HITRAN-2004 spectroscopic line parameters including the August 2006 updates for water vapor have been adopted in the retrievals. These approaches will be presented and critically compared, with the help of error budget and information content analyses, taking into account the impact of major interferences such as water vapor. The time series of C2H2 tropospheric column abundances above Jungfraujoch will also be presented, including determination of its long-term trend and strong seasonal cycle. The ground-based results will further be compared with zonal mean observations performed by the ACE-FTS space-based instrument since early 2004. [less ▲]

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See detailRetrievals of HCN from high-resolution FTIR solar spectra recorded at the Jungfraujoch station
Mahieu, Emmanuel ULg; Duchatelet, Pierre ULg; Demoulin, Philippe ULg et al

in Geophysical Research Abstracts (2007, April)

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the ... [more ▼]

Recent investigations have resulted in the revision of the lifetime of hydrogen cyanide (HCN) from 2.5 years to 2-5 months, more in line with its important and well documented variability in the troposphere. The main HCN source is believed to be biomass burning, making this species a useful tracer of fires, e.g. the widespread and intense 2004 boreal fires. Oxidation by the OH radical is among the identified sinks, while uptake by oceans has been hypothesized as the dominant sink. As shown by previous investigations, several lines from the nu3 fundamental HCN band at 3 μm can be used to retrieve information on vertical distribution of hydrogen cyanide from high-resolution FTIR solar absorption spectra. The major interfering gas in this region is water vapor. A series of typical observations recorded at the Jungfraujoch station (46.5ºN, 8.0ºE, 3580m asl, Swiss Alps) by the NDACC (Network for the Detection of Atmospheric Composition Change)-affiliated Bruker instrument have been fitted using various approaches to determine the optimum strategy to be used for HCN retrievals at that site, even under very wet conditions. The selected approach is made of 7 windows encompassing 5 HCN lines. The a priori information (HCN vertical distribution and covariance matrix) is based on ACE-FTS measurements performed over northern midlatitudes. The HITRAN-2004 spectroscopic line parameters including the August 2006 updates for water vapor have been adopted in the retrievals performed with the OEM-SFIT-2 (v3.91) algorithm. This contribution will give a full description of the adopted retrieval approach, including error budget and information content analysis. Tropospheric column time series of HCN from 1994 onwards will also be presented and discussed. [less ▲]

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See detailOptimisation of retrieval strategies using Jungfraujoch high-resolution FTIR observations for long-term trend studies and satellite validation.
Mahieu, Emmanuel ULg; Servais, Christian ULg; Duchatelet, Pierre ULg et al

in Burrows, J.; Borrell, P. (Eds.) Observing Tropospheric Trace Constituents from Space. (2007)

Detailed reference viewed: 4 (2 ULg)