Improved FTIR retrieval strategy for HCFC-22 (CHClF2), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch

Prignon, Maxime; Chabrillat, Simon; Minganti, Daniele; O’Doherty, Simon; Servais, Christian; Stiller, G. P.; Toon, G. C.; Vollmer, Martin K.; Mahieu, Emmanuel

doi:10.5194/acp-2019-73

Cited by 11 publications

(23 citation statements)

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“…Here, we use the same CTM as for the kinematic AoA study, i.e., the Belgian Assimilation System of Chemical Ob-sErvation (BASCOE) CTM. Observations of another longlived stratospheric tracer, HCFC-22, were recently interpreted with WACCM and BASCOE CTM simulations, showing the interest of this model intercomparison (Prignon et al, 2019). In order to contribute further to the S-RIP BDC activity, four different dynamical reanalyses are used here to drive the BASCOE CTM simulations, compute the N 2 O TEM budget and compare its components with the results derived from WACCM, namely the European Centre for Medium-Range Weather Forecasts Interim reanalysis (ERA-Interim; Dee et al, 2011), the Japanese 55-year Reanalysis (JRA-55; Kobayashi et al, 2015), and the Modern-Era Retrospective analysis for Research and Applications version 1 (MERRA; Rienecker et al, 2011) and version 2 (MERRA-2; Gelaro et al, 2017).…”

Section: Introductionmentioning

confidence: 93%

“…The BASCOE data assimilation system (Errera et al, 2019) is built on a chemistry transport model, which consists in a kinematic transport module with the FFSL advection scheme (Lin and Rood, 1996) and an explicit solver for stratospheric chemistry, comprising 65 species and 243 reactions (Prignon et al, 2019). Chabrillat et al (2018) explain in detail the preprocessing procedure that allows the BASCOE CTM to be driven by arbitrary reanalysis datasets as well as the setup of model transport.…”

Section: Bascoe Ctmmentioning

confidence: 99%

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Climatological impact of the Brewer–Dobson circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

et al. 2020

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Abstract. The Brewer–Dobson circulation (BDC) is a stratospheric circulation characterized by upwelling of tropospheric air in the tropics, poleward flow in the stratosphere, and downwelling at mid and high latitudes, with important implications for chemical tracer distributions, stratospheric heat and momentum budgets, and mass exchange with the troposphere. As the photochemical losses of nitrous oxide (N2O) are well known, model differences in its rate of change are due to transport processes that can be separated into the mean residual advection and the isentropic mixing terms in the transformed Eulerian mean (TEM) framework. Here, the climatological impact of the stratospheric BDC on the long-lived tracer N2O is evaluated through a comparison of its TEM budget in the Whole Atmosphere Community Climate Model (WACCM), in a chemical reanalysis of the Aura Microwave Limb Sounder version 2 (BRAM2) and in a chemistry transport model (CTM) driven by four modern reanalyses: the European Centre for Medium-Range Weather Forecasts Interim reanalysis (ERA-Interim; Dee et al., 2011), the Japanese 55-year Reanalysis (JRA-55; Kobayashi et al., 2015), and the Modern-Era Retrospective analysis for Research and Applications version 1 (MERRA; Rienecker et al., 2011) and version 2 (MERRA-2; Gelaro et al., 2017). The effects of stratospheric transport on the N2O rate of change, as depicted in this study, have not been compared before across this variety of datasets and have never been investigated in a modern chemical reanalysis. We focus on the seasonal means and climatological annual cycles of the two main contributions to the N2O TEM budget: the vertical residual advection and the horizontal mixing terms. The N2O mixing ratio in the CTM experiments has a spread of approximately ∼20 % in the middle stratosphere, reflecting the large diversity in the mean age of air obtained with the same CTM experiments in a previous study. In all datasets, the TEM budget is closed well; the agreement between the vertical advection terms is qualitatively very good in the Northern Hemisphere, and it is good in the Southern Hemisphere except above the Antarctic region. The datasets do not agree as well with respect to the horizontal mixing term, especially in the Northern Hemisphere where horizontal mixing has a smaller contribution in WACCM than in the reanalyses. WACCM is investigated through three model realizations and a sensitivity test using the previous version of the gravity wave parameterization. The internal variability of the horizontal mixing in WACCM is large in the polar regions and is comparable to the differences between the dynamical reanalyses. The sensitivity test has a relatively small impact on the horizontal mixing term, but it significantly changes the vertical advection term and produces a less realistic N2O annual cycle above the Antarctic. In this region, all reanalyses show a large wintertime N2O decrease, which is mainly due to horizontal mixing. This is not seen with WACCM, where the horizontal mixing term barely contributes to the TEM budget. While we must use caution in the interpretation of the differences in this region (where the reanalyses show large residuals of the TEM budget), they could be due to the fact that the polar jet is stronger and is not tilted equatorward in WACCM compared with the reanalyses. We also compare the interannual variability in the horizontal mixing and the vertical advection terms between the different datasets. As expected, the horizontal mixing term presents a large variability during austral fall and boreal winter in the polar regions. In the tropics, the interannual variability of the vertical advection term is much smaller in WACCM and JRA-55 than in the other experiments. The large residual in the reanalyses and the disagreement between WACCM and the reanalyses in the Antarctic region highlight the need for further investigations on the modeling of transport in this region of the stratosphere.

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Section: Introductionmentioning

confidence: 93%

Section: Bascoe Ctmmentioning

confidence: 99%

Climatological impact of the Brewer–Dobson circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

et al. 2020

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show abstract

“…The BASCOE data assimilation system (Errera et al, 2019) is built on a Chemistry-Transport Model which consists in a kinematic transport module with the FFSL advection scheme (Lin and Rood, 1996) and an explicit solver for stratospheric chemistry, comprising 65 species and 243 reactions (Prignon et al, 2019). The transport module requires on input only the surface pressure and horizontal wind fields from reanalyses, as it relies on mass continuity to derive vertical mass fluxes.…”

Section: Bascoe Ctmmentioning

confidence: 99%

Climatological impact of the Brewer–Dobson Circulation on the N2O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Minganti¹,

Chabrillat²,

Christophe³

et al. 2020

Preprint

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Abstract. The Brewer&#8211;Dobson Circulation (BDC) transports chemical tracers from the well-mixed tropical troposphere to the polar stratosphere, with many important implications for climate, chemistry, ozone distribution and recovery. Since the photochemical losses of nitrous oxide (N2O) are well-known, model differences in its rate of change are due to transport processes that can be separated in the mean residual advection and the isentropic mixing terms in the Transformed Eulerian Mean (TEM) framework. Here the climatological impact of the stratospheric BDC on the long-lived tracer N2O is evaluated through a comparison of its TEM budget in the Whole Atmosphere Community Climate Model (WACCM), a chemical reanalysis of the Aura Microwave Limb Sounder version 2 (BRAM2) and in a Chemistry-Transport Model (CTM) driven by four modern reanalyses (ERA-Interim, JRA-55, MERRA and MERRA2). The effects of stratospheric transport on the N2O rate of change, as depicted in this study, have not been compared across this variety of datasets and never investigated in a chemical reanalysis. We focus on the seasonal means and climatological annual cycles of the two main contributions to the N2O TEM budget: the vertical residual advection and the horizontal mixing terms. The N2O mixing ratio in the CTM experiments has a spread of approximately ~&#8201;20&#8201;% in the middle stratosphere, reflecting the large diversity in the mean Age of Air obtained with the same experiments. In all datasets the TEM budget is well-closed and the agreement between the vertical advection terms is qualitatively very good in the Northern Hemisphere, and good in the Southern Hemisphere except above the Antarctic region. The datasets do not agree as well with respect to the horizontal mixing term, especially in the Northern Hemisphere where horizontal mixing has a smaller contribution in WACCM than in the reanalyses. WACCM is investigated through three model realizations and a sensitivity test where gravity waves are forced differently in the Southern Hemisphere. The internal variability of the horizontal mixing in WACCM is large in the polar regions, and comparable to the differences between the dynamical reanalyses. The sensitivity test has a relatively small impact on the horizontal mixing term, but significantly changes the vertical advection term and produces a less realistic N2O annual cycle above the Antarctic. In this region, all reanalyses show a large wintertime N2O decrease, which is mainly due to horizontal mixing. This is not seen with WACCM, where the horizontal mixing term barely contributes to the TEM budget. While we must use caution in the interpretation of the differences in this region, where the reanalyses show large residuals of the TEM budget, they could be due to the fact that the polar jet is stronger and not tilted equatorward in WACCM compared with the reanalyses. We also compare the inter-annual variability in the horizontal mixing and the vertical advection terms. As expected, the horizontal mixing term presents a large variability during austral fall and boreal winter in the polar regions. In the Tropics, the inter-annual variability of the vertical advection term is much smaller in WACCM and JRA-55 than in the other experiments. The large residual in the reanalyses and the disagreement between WACCM and the reanalyses in the Antarctic region highlight the need for further investigations on the modeling of transport in this region of the stratosphere.

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“…Notholt, 1994;Zander et al, 2005;Mahieu et al, 2010), although they started to be used more actively in the last decade (e.g. Mahieu et al, 2013Mahieu et al, , 2017Zhou et al, 2016;Prignon et al, 2019). Within the NDACC network (http://www.ndsc.ncep.noaa.gov), regular FTIR measurements provide the information on the TCs of a number of atmospheric trace gases, including freons, with a large spatial coverage (at 19 out of 77 network stations located at latitudes between 78°S to 80°N).…”

mentioning

confidence: 99%

“…(2016) showed the results of CFC-11, CFC-12, and HCFC-22 measurements at two NDACC sites on Réunion Island for the period of 2004-2016, including the trend estimates and the comparison with the satellite data. Prignon et al (2019) proposed a technique for estimating the TCs of HCFC-22 at the Jungfraujoch mountain station and corresponding time series of TCs for 1999-2018 along with the trend analysis for various time periods.…”

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confidence: 99%

Measurements of CFC-11, CFC-12, and HCFC-22 total columns in the atmosphere at the St. Petersburg site in 2009–2019

Polyakov¹,

Poberovsky²,

Makarova³

et al. 2020

Preprint

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Abstract. The retrieval strategies for deriving the atmospheric total columns (TCs) of CFC-11 (CCl3F), CFC-12 (CCl2F2), and HCFC-22 (CHClF2) from ground–based measurements of IR solar radiation have been improved. We demonstrate the advantage of using the Tikhonov-Phillips regularization approach for solving the inverse problem of the retrieval of these gases and give the optimized values of regularization parameters. The estimates of relative systematic and random errors amount to 7.61 % and 3.08 %, 2.24 % and 2.40 %, 5.75 % and 3.70 %, for CFC-11, CFC-12, and HCFC-22, respectively. We analyze the time series of the TCs and mean molar fractions (MMFs) of CFC-11, CFC-12, and HCFC-22 measured at the NDACC site St. Petersburg located near Saint Petersburg, Russia for the period of 2009–2019. Mean values of the MMFs for CFC-11, CFC-12, and HCFC-22 total 225, 493, and 238 pptv, respectively. Estimates of the MMFs trends for CFC-11, CFC-12, and HCFC-22 account for −0.40 ± 0.07 %/yr, -0.49 ±0.05 %/yr, and 2.12±0.13 %/yr, respectively. We have compared the mean values, trends and seasonal variability of CFC-11, CFC-12, and HCFC-22 MMFs measured at the St. Petersburg site in 2009–2019 to that of 1) near–ground volume mixing ratios (VMRs) measured at the observational site Mace Head, Ireland (GVMR); 2) the mean in the 8–12 km layer VMRs measured by ACE–FTS and averaged over 55–65° N latitudes (SVMR); and the MMFs of the Whole Atmosphere Community Climate Model for the St. Petersburg site (WMMF). The means of the MMFs are less than that of the GVMR for CFC-11 by 9 pptv (3.8 %), for CFC-12 by 24 pptv (4.6 %); for HCFC-22, the mean MMFs does not differ significantly from the mean GVMR. The absolute value of the trend estimates of the MMFs is less than that of the GVMR for CFC-11 (−0.40 vs −0.53 %/yr) and CFC-12 (−0.49 vs −0.59 %yr); the trend estimate of the HCFC-22 MMFs does not differ significantly from that of the GVMR. The seasonal variability of the GVMR for all three gases is much lower than the MMFs variability. The means of the MMFs are less than that of the SVMR for CFC-11 by 10 pptv (4.3 %), for CFC-12 by 33 pptv (6.3 %), and for HCFC-22 by 2 pptv (0.8 %). The absolute value of the trend estimates of the MMFs is less than that of the SVMR for CFC-11 (−0.40 vs −0.63 %/yr) and CFC-12 (−0.49 vs −0.58 %/yr); the trend estimate of the HCFC-22 MMFs does not differ significantly from that of the SVMR. The MMF and SVMR values show nearly the same qualitative and quantitative seasonal variability for all three gases. The means of the MMFs are greater than that of the WMMF for CFC-11 by 22 pptv (10 %), for CFC-12 by 15 pptv (3.1 %), and for HCFC-22 by 23 pptv (10 %). The absolute value of the trend estimates of the MMFs is less than that of the WMMF for CFC-11 (−0.40 vs −1.68 %/yr), CFC-12 (−0.49 vs −0.84 %/yr), and HCFC-22 (2.12 %/yr vs 3.40 %/yr). The MMFs and WMMF values show nearly the same qualitative and quantitative seasonal variability for CFC-11 and CFC-12, whereas the seasonal variability of the WMMF for HCFC-22 is essentially less than that of the MMFs. In general, the comparison of the MMFs with the independent data shows a good agreement of their means within the systematic error of considered measurements. The observed trends over the St. Petersburg site demonstrate the smaller decrease rates for CFC-11 and CFC-12 TCs than that of the independent data, and the same decrease rate for HCFC-22. The suggested retrieval strategies can be used for analysis of the IR solar spectra measurements using Bruker FS125HR spectrometers, e.g. at other IRWG sites of the NDACC observational network.

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Improved FTIR retrieval strategy for HCFC-22 (CHClF2), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch

Cited by 11 publications

References 50 publications

Climatological impact of the Brewer–Dobson circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson Circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Measurements of CFC-11, CFC-12, and HCFC-22 total columns in the atmosphere at the St. Petersburg site in 2009–2019

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Improved FTIR retrieval strategy for HCFC-22 (CHClF2), comparisons with in situ and satellite datasets with the support of models, and determination of its long-term trend above Jungfraujoch

Cited by 11 publications

References 50 publications

Climatological impact of the Brewer–Dobson circulation on the N&lt;sub&gt;2&lt;/sub&gt;O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson circulation on the N&lt;sub&gt;2&lt;/sub&gt;O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson Circulation on the N&lt;sub&gt;2&lt;/sub&gt;O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Measurements of CFC-11, CFC-12, and HCFC-22 total columns in the atmosphere at the St. Petersburg site in 2009–2019

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Climatological impact of the Brewer–Dobson circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses

Climatological impact of the Brewer–Dobson Circulation on the N<sub>2</sub>O budget in WACCM, a chemical reanalysis and a CTM driven by four dynamical reanalyses