CCl&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt; distribution derived from MIPAS ESA v7 data: intercomparisons, trend, and lifetime estimation

Valeri, Massimo; Barbara, Flavio; Boone, C. D.; Ceccherini, Simone; Gai, Marco; Maucher, G.; Raspollini, Piera; Ridolfi, Marco; Sgheri, Luca; Wetzel, G.; Zoppetti, Nicola

doi:10.5194/acp-17-10143-2017

Cited by 14 publications

(19 citation statements)

References 52 publications

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“…3, a model VMR(t) is adapted, with the least squares approach, to the time series of the monthly COCl 2 averages. As explained in Valeri et al (2017), the model includes two different offsets for the two mission phases (FR and OR), a common linear term (the trend we are interested in), QBO-and solar flux-related terms and the characteristic atmospheric periodicities of 24, 18, 12, 9, 8, 6, 4, 3 months. Note that the residuals oscillate around zero, except in the first half of 2005 (between 24 th and 36 th month), which corresponds to the transition period between FR and OR mission phases.…”

Section: Phosgene Trendsmentioning

confidence: 99%

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Pettinari

Barbara

Ceccherini

et al. 2021

Preprint

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Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) measured the middle-infrared limb emission spectrum of the atmosphere from 2002 to 2012 on board ENVISAT, a polar-orbiting satellite. Recently, the European Space Agency (ESA) completed the ﬁnal reprocessing of MIPAS measurements, using Version 8 of the Level 1 and Level 2 processors, which include more accurate models, processing strategies and auxiliary data. The list of retrieved gases has been extended, it now includes a number of new species with weak emission features in the MIPAS spectral range. The new retrieved trace species include carbonyl chloride (COCl2), also called phosgene. Due to its toxicity, its use has been reduced over the years, however it is still used by chemical industries for sevaeral applications. Besides its direct injection in the troposphere, stratospheric phosgene is mainly produced from the photolysis of CCl4, a molecule present in the atmosphere because of human activity. Since phosgene has a long stratospheric lifetime, it must be carefully monitored as it is involved in the ozone destruction cycles, especially over the winter polar regions. In this paper we exploit the ESA MIPAS Version 8 data in order to discuss the phosgene distribution, variability and trends in the middle and lower stratosphere and in the upper troposphere. The zonal averages show that phosgene volume mixing ratio is larger in the stratosphere, with a peak of 40 pptv between 50 and 30 hPa at equatorial latitudes, while at middle and polar latitudes it varies from 10 to 25 pptv. A moderate seasonal variability is observed in polar regions, mostly between 80 and 50 hPa. The comparison of MIPAS/ENVISAT COCl2 v.8 proﬁles with the ones retrieved from MIPAS/balloon and ACE-FTS measurements highlights a negative bias of about 2 pptv, mainly in polar and mid-latitude regions. Part of this bias is attributed to the fact that the ESA Level 2 v.8 processor uses an updated spectroscopic database. For the trend computation, a ﬁxed pressure grid is used to interpolate the phosgene proﬁles and, for each pressure level, VMR monthly averages are computed in pre-deﬁned 10°-wide latitude bins. Then, for each latitudinal bin and pressure level, a regression model has been ﬁtted to the resulting time-series in order to derive the atmospheric trends. We ﬁnd that the phosgene trends are different in the two hemispheres. The analysis shows that the stratosphere of the Northern Hemisphere is characterised by a negative trend, of about −7 pptv/decade, while in the Southern Hemisphere phosgene mixing ratios increase with a rate of the order of +4 pptv/decade. In the upper troposphere a positive trend is found in both hemispheres.

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Section: Phosgene Trendsmentioning

confidence: 99%

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Pettinari

Barbara

Ceccherini

et al. 2021

Preprint

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“…This is the MIPAS-ESA V7R NOM dataset. The MI-PAS V7 retrievals differ from the MIPAS V5 retrievals in that they use the level-1b radiances version 7 for which a timedependent nonlinearity correction scheme has been adopted to account for the change in nonlinearities over the course of the mission due to the aging of the detectors (Valeri et al, 2017). This correction introduces an altitude-dependent temporal change in the MIPAS retrievals.…”

Section: Relative Instrumental Driftsmentioning

confidence: 99%

The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements

et al. 2017

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Abstract. As part of the second SPARC (Stratospheretroposphere Processes And their Role in Climate) water vapor assessment (WAVAS-II), we present measurements taken from or coincident with seven sites from which ground-based microwave instruments measure water vapor in the middle atmosphere. Six of the ground-based instruments are part of the Network for the Detection of Atmospheric Composition Change (NDACC) and provide datasets that can be used for drift and trend assessment. We compare measurements from these ground-based instruments with satellite datasets that have provided retrievals of water vapor in the lower mesosphere over extended periods since 1996.We first compare biases between the satellite and groundbased instruments from the upper stratosphere to the upper mesosphere. We then show a number of time series comparisons at 0.46 hPa, a level that is sensitive to changes in H 2 O and CH 4 entering the stratosphere but, because almost all CH 4 has been oxidized, is relatively insensitive to dynamical variations. Interannual variations and drifts are investigated with respect to both the Aura Microwave Limb Sounder (MLS; from 2004 onwards) and each instrument's climatological mean. We find that the variation in the interannual difference in the mean H 2 O measured by any two instruments is typically ∼ 1%. Most of the datasets start in or after 2004 and show annual increases in H 2 O of 0-1 % yr −1 . In particular, MLS shows a trend of between 0.5 % yr −1 and 0.7 % yr −1 at the comparison sites. However, the two longest measurement datasets used here, with measurements back to 1996, show much smaller trends of +0.1 % yr −1 (at Mauna Loa, Hawaii) and −0.1 % yr −1 (at Lauder, New Zealand).

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“…These values justify the need for studying its potential interference in benzene measurements. It should also be noted that the global average lifetime of TCM reported in the recent literature is 44 years (36-58) (Ko et al, 2013;Valeri et al, 2017), so its effects, such as the one indicated here, will be manifested during the next decades.…”

Section: Introductionmentioning

confidence: 67%

“…In this sense, 9500 Mt of TCM were estimated to be emitted in 192 countries in 2007 (Penny et al, 2010). However, since the entry into force of the Montreal Protocol, there has been a progressive decrease in the environmental presence of TCM, with a decrease in (Valeri et al, 2017). In 2005, the Agency for Toxic Substances and Disease Registry (ATSDR, 2005) determined a global average concentration of 0.7 µg Nm −3 with peaks in urban areas of 1.4 to 4.5 µg Nm −3 , whereas 45 µg Nm −3 was detected in the vicinity of landfills (Brosas-Montecastro, 2008).…”

Section: Introductionmentioning

confidence: 99%

The interference of tetrachloromethane in the measurement of benzene in the air by a gas chromatography–photoionisation detector (GC-PID)

et al. 2019

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The European Union requires that benzene in the air is continuously measured due to its toxicity and widespread presence in the population nuclei, mainly motivated by vehicle emissions. The reference measuring technique is gas chromatography (GC). Automatic chromatographs used in monitoring stations must verify the operating conditions established in Standard EN 14662 part 3, which includes a type approval section with a number of tests that analysers must pass. Among these tests, the potential interference of a number of compounds is evaluated. The 2005 version of the mentioned standard requires the evaluation of the potential interference of tetrachloromethane (TCM). The 2015 version eliminates TCM as a potential interferent. Although most consumer uses of TCM have been banned, recent studies have measured significant concentrations of TCM in the air. In this paper, the potential interference of TCM in benzene measurements obtained with gas chromatography coupled to a photoionisation detector (GC-PID) has been investigated. Our study shows that the simultaneous presence of benzene and TCM causes a significant decrease in benzene readings. For TCM concentrations of 0.7 µg m −3 (typical of urban areas) and 4.5 µg m −3 (detected in the vicinity of landfills), the relative errors in benzene measurements were 34 % and 70 %, respectively, which are far too high compared to the maximum overall uncertainty allowed for benzene measurements (25 %). Possible mechanisms to qualitatively and quantitatively explain the behaviour of the PID when measuring benzene with and without TCM have been proposed.

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CCl<sub>4</sub> distribution derived from MIPAS ESA v7 data: intercomparisons, trend, and lifetime estimation

Cited by 14 publications

References 52 publications

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

Phosgene distribution derived from MIPAS ESA v8 data: intercomparisons and trends

The SPARC water vapor assessment II: intercomparison of satellite and ground-based microwave measurements

The interference of tetrachloromethane in the measurement of benzene in the air by a gas chromatography–photoionisation detector (GC-PID)

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