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1. The covariation of Northern Hemisphere summertime CO2 with surface temperature in boreal regions

Author

Wunch, D., Wennberg, P. O, Messerschmidt, J., Parazoo, N. C, Toon, G. C, Deutscher, N. M, Keppel-Aleks, G., Roehl, C. M, Randerson, J. T, Warneke, T., and Notholt, J.

Subjects
annual variation, atmospheric transport, biosphere, carbon dioxide, Northern Hemisphere, summer, surface temperature
Abstract

We observe significant interannual variability in the strength of the seasonal cycle drawdown in northern midlatitudes from measurements of CO2 made by the Total Carbon Column Observing Network (TCCON) and the Greenhouse Gases Observing Satellite (GOSAT). This variability correlates with surface temperature in the boreal regions. Using TCCON measurements, we find that the slope of the relationship between the XCO2 seasonal cycle minima and boreal surface temperature is 1.2 ± 0.7 ppm K−1. Assimilations from CarbonTracker 2011 and CO2 simulations using the Simple Biosphere exchange Model (SiB) transported by GEOS-Chem underestimate this covariation. Both atmospheric transport and biospheric activity contribute to the observed covariation.

Published
2013

2. Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide

Author

Mu, M., Randerson, J. T, van der Werf, G. R, Giglio, L., Kasibhatla, P., Morton, D., Collatz, G. J, DeFries, R. S, Hyer, E. J, Prins, E. M, Griffith, D. W. T, Wunch, D., Toon, G. C, Sherlock, V., and Wennberg, P. O

Subjects
Active fires, Aerosol variability, Aqua satellites, Atmospheric model, Atmospheric model simulations, Atmospheric trace gas, Biomass-burning, Boreal ecosystems, Burned areas, Diurnal cycle, Fire behavior, Fire emissions, Fire radiative power, Future directions, Geostationary operational environmental satellites, Global fire, High resolution, High temporal resolution, Measurements of pollution in the tropospheres, Moderate resolution imaging spectroradiometer, Multiple satellites, Natural emissions, Temporal variability, Time step, Time-scales, Topdown, Total carbon, Atmospheric aerosols, Atmospherics, Carbon monoxide, Computer simulation, Ecosystems, Estimation, Gas emissions, Geostationary satellites, Radiometers, Satellite imagery, Time series, Uncertainty analysis, Fires, agricultural land, algorithm, Aqua (satellite), atmospheric modeling, biomass burning, carbon monoxide, database, emission inventory, GOES, grassland, MODIS, satellite sensor, savanna, temporal variation, Terra (satellite), time series, top-down approach, trace gas, troposphere, uncertainty analysis, wildfire
Abstract

Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We disaggregated monthly GFED3 emissions during 2003–2009 to a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) active fire observations. Daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of burning in savannas. These patterns were consistent with earlier field and modeling work characterizing fire behavior dynamics in different ecosystems. On diurnal timescales, our analysis of the GOES WF_ABBA active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top-down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates.

Published
2011

4. Precision requirements for space-based X CO 2 data

Author

Miller, C. E, Crisp, D., DeCola, P. L, Olsen, S. C, Randerson, J. T, Michalak, A. M, Alkhaled, A., Rayner, P., Jacob, D. J, Suntharalingam, P., Jones, D. B. A, Denning, A. S, Nicholls, M. E, Doney, S. C, Pawson, S., Boesch, H., Connor, B. J, Fung, I. Y, O'Brien, D., Salawitch, R. J, Sander, S. P, Sen, B., Tans, P., Toon, G. C, Wennberg, P. O, Wofsy, S. C, Yung, Y. L, and Law, R. M

Subjects
atmospheric composition, carbon dioxide, mathematical models, uncertainty analysis, assessment method, carbon dioxide, carbon flux, precision, sampling, simulation, spatiotemporal analysis
Abstract

Precision requirements are determined for space-based column-averaged CO2 dry air mole fraction data. These requirements result from an assessment of spatial and temporal gradients in the relationship between precision and surface CO2 flux uncertainties inferred from inversions of the data, and the effects of biases on the fidelity of CO2 flux inversions. Observational system simulation experiments and synthesis inversion modeling demonstrate that the Orbiting Carbon Observatory mission design and sampling strategy provide the means to achieve these data precision requirements.

Published
2007

5. The HITRAN2020 molecular spectroscopic database

Author

Gordon, I. E., Rothman, L. S., Hargreaves, R. J., Hashemi, R., Karlovets, E., V, Skinner, F. M., Conway, E. K., Hill, C., Kochanov, R., V, Tan, Y., Wcislo, P., Finenko, A. A., Nelson, K., Bernath, P. F., Birk, M., Boudon, V, Campargue, A., Chance, K., V, Coustenis, A., Drouin, B. J., Flaud, J-M, Gamache, R. R., Hodges, J. T., Jacquemart, D., Mlawer, E. J., Nikitin, A., V, Perevalov, V., I, Rotger, M., Tennyson, J., Toon, G. C., Tran, H., Tyuterev, V. G., Adkins, E. M., Baker, A., Barbe, A., Cane, E., Csaszar, A. G., Dudaryonok, A., Egorov, O., Fleisher, A. J., Fleurbaey, H., Foltynowicz, A., Furtenbacher, T., Harrison, J. J., Hartmann, J-M, Horneman, V-M, Huang, X., Karman, T., Karns, J., Kassi, S., Kleiner, I, Kofman, V, Kwabia-Tchana, F., Lavrentieva, N. N., Lee, T. J., Long, D. A., Lukashevskaya, A. A., Lyulin, O. M., Makhnev, V. Yu, Matt, W., Massie, S. T., Melosso, M., Mikhailenko, S. N., Mondelain, D., Mueller, H. S. P., Naumenko, O., V, Perrin, A., Polyansky, O. L., Raddaoui, E., Raston, P. L., Reed, Z. D., Rey, M., Richard, C., Tobias, R., Sadiek, I, Schwenke, D. W., Starikova, E., Sung, K., Tamassia, F., Tashkun, S. A., Vander Auwera, J., Vasilenko, I. A., Vigasin, A. A., Villanueva, G. L., Vispoel, B., Wagner, G., Yachmenev, A., Yurchenko, S. N., Gordon, I. E., Rothman, L. S., Hargreaves, R. J., Hashemi, R., Karlovets, E., V, Skinner, F. M., Conway, E. K., Hill, C., Kochanov, R., V, Tan, Y., Wcislo, P., Finenko, A. A., Nelson, K., Bernath, P. F., Birk, M., Boudon, V, Campargue, A., Chance, K., V, Coustenis, A., Drouin, B. J., Flaud, J-M, Gamache, R. R., Hodges, J. T., Jacquemart, D., Mlawer, E. J., Nikitin, A., V, Perevalov, V., I, Rotger, M., Tennyson, J., Toon, G. C., Tran, H., Tyuterev, V. G., Adkins, E. M., Baker, A., Barbe, A., Cane, E., Csaszar, A. G., Dudaryonok, A., Egorov, O., Fleisher, A. J., Fleurbaey, H., Foltynowicz, A., Furtenbacher, T., Harrison, J. J., Hartmann, J-M, Horneman, V-M, Huang, X., Karman, T., Karns, J., Kassi, S., Kleiner, I, Kofman, V, Kwabia-Tchana, F., Lavrentieva, N. N., Lee, T. J., Long, D. A., Lukashevskaya, A. A., Lyulin, O. M., Makhnev, V. Yu, Matt, W., Massie, S. T., Melosso, M., Mikhailenko, S. N., Mondelain, D., Mueller, H. S. P., Naumenko, O., V, Perrin, A., Polyansky, O. L., Raddaoui, E., Raston, P. L., Reed, Z. D., Rey, M., Richard, C., Tobias, R., Sadiek, I, Schwenke, D. W., Starikova, E., Sung, K., Tamassia, F., Tashkun, S. A., Vander Auwera, J., Vasilenko, I. A., Vigasin, A. A., Villanueva, G. L., Vispoel, B., Wagner, G., Yachmenev, A., and Yurchenko, S. N.

Abstract

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITR

Published
2022

6. The HITRAN2020 molecular spectroscopic database

Author

Gordon, I. E. (I. E.), Rothman, L. S. (L. S.), Hargreaves, R. J. (R. J.), Hashemi, R. (R.), Karlovets, E. V. (E., V), Skinner, F. M. (F. M.), Conway, E. K. (E. K.), Hill, C. (C.), Kochanov, R. V. (R., V), Tan, Y. (Y.), Wcislo, P. (P.), Finenko, A. A. (A. A.), Nelson, K. (K.), Bernath, P. F. (P. F.), Birk, M. (M.), Boudon, V. (V), Campargue, A. (A.), Chance, K. V. (K., V), Coustenis, A. (A.), Drouin, B. J. (B. J.), Flaud, J.-M. (J-M), Gamache, R. R. (R. R.), Hodges, J. T. (J. T.), Jacquemart, D. (D.), Mlawer, E. J. (E. J.), Nikitin, A. V. (A., V), Perevalov, V. I. (V., I), Rotger, M. (M.), Tennyson, J. (J.), Toon, G. C. (G. C.), Tran, H. (H.), Tyuterev, V. G. (V. G.), Adkins, E. M. (E. M.), Baker, A. (A.), Barbe, A. (A.), Cane, E. (E.), Csaszar, A. G. (A. G.), Dudaryonok, A. (A.), Egorov, O. (O.), Fleisher, A. J. (A. J.), Fleurbaey, H. (H.), Foltynowicz, A. (A.), Furtenbacher, T. (T.), Harrison, J. J. (J. J.), Hartmann, J.-M. (J-M), Horneman, V.-M. (V-M), Huang, X. (X.), Karman, T. (T.), Karns, J. (J.), Kassi, S. (S.), Kleiner, I. (I), Kofman, V. (V), Kwabia-Tchana, F. (F.), Lavrentieva, N. N. (N. N.), Lee, T. J. (T. J.), Long, D. A. (D. A.), Lukashevskaya, A. A. (A. A.), Lyulin, O. M. (O. M.), Makhnev, V. Y. (V. Yu), Matt, W. (W.), Massie, S. T. (S. T.), Melosso, M. (M.), Mikhailenko, S. N. (S. N.), Mondelain, D. (D.), Mueller, H. S. (H. S. P.), Naumenko, O. V. (O., V), Perrin, A. (A.), Polyansky, O. L. (O. L.), Raddaoui, E. (E.), Raston, P. L. (P. L.), Reed, Z. D. (Z. D.), Rey, M. (M.), Richard, C. (C.), Tobias, R. (R.), Sadiek, I. (I), Schwenke, D. W. (D. W.), Starikova, E. (E.), Sung, K. (K.), Tamassia, F. (F.), Tashkun, S. A. (S. A.), Vander Auwera, J. (J.), Vasilenko, I. A. (I. A.), Vigasin, A. A. (A. A.), Villanueva, G. L. (G. L.), Vispoel, B. (B.), Wagner, G. (G.), Yachmenev, A. (A.), Yurchenko, S. N. (S. N.), Gordon, I. E. (I. E.), Rothman, L. S. (L. S.), Hargreaves, R. J. (R. J.), Hashemi, R. (R.), Karlovets, E. V. (E., V), Skinner, F. M. (F. M.), Conway, E. K. (E. K.), Hill, C. (C.), Kochanov, R. V. (R., V), Tan, Y. (Y.), Wcislo, P. (P.), Finenko, A. A. (A. A.), Nelson, K. (K.), Bernath, P. F. (P. F.), Birk, M. (M.), Boudon, V. (V), Campargue, A. (A.), Chance, K. V. (K., V), Coustenis, A. (A.), Drouin, B. J. (B. J.), Flaud, J.-M. (J-M), Gamache, R. R. (R. R.), Hodges, J. T. (J. T.), Jacquemart, D. (D.), Mlawer, E. J. (E. J.), Nikitin, A. V. (A., V), Perevalov, V. I. (V., I), Rotger, M. (M.), Tennyson, J. (J.), Toon, G. C. (G. C.), Tran, H. (H.), Tyuterev, V. G. (V. G.), Adkins, E. M. (E. M.), Baker, A. (A.), Barbe, A. (A.), Cane, E. (E.), Csaszar, A. G. (A. G.), Dudaryonok, A. (A.), Egorov, O. (O.), Fleisher, A. J. (A. J.), Fleurbaey, H. (H.), Foltynowicz, A. (A.), Furtenbacher, T. (T.), Harrison, J. J. (J. J.), Hartmann, J.-M. (J-M), Horneman, V.-M. (V-M), Huang, X. (X.), Karman, T. (T.), Karns, J. (J.), Kassi, S. (S.), Kleiner, I. (I), Kofman, V. (V), Kwabia-Tchana, F. (F.), Lavrentieva, N. N. (N. N.), Lee, T. J. (T. J.), Long, D. A. (D. A.), Lukashevskaya, A. A. (A. A.), Lyulin, O. M. (O. M.), Makhnev, V. Y. (V. Yu), Matt, W. (W.), Massie, S. T. (S. T.), Melosso, M. (M.), Mikhailenko, S. N. (S. N.), Mondelain, D. (D.), Mueller, H. S. (H. S. P.), Naumenko, O. V. (O., V), Perrin, A. (A.), Polyansky, O. L. (O. L.), Raddaoui, E. (E.), Raston, P. L. (P. L.), Reed, Z. D. (Z. D.), Rey, M. (M.), Richard, C. (C.), Tobias, R. (R.), Sadiek, I. (I), Schwenke, D. W. (D. W.), Starikova, E. (E.), Sung, K. (K.), Tamassia, F. (F.), Tashkun, S. A. (S. A.), Vander Auwera, J. (J.), Vasilenko, I. A. (I. A.), Vigasin, A. A. (A. A.), Villanueva, G. L. (G. L.), Vispoel, B. (B.), Wagner, G. (G.), Yachmenev, A. (A.), and Yurchenko, S. N. (S. N.)

Abstract

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH₃F, GeH₄, CS₂, CH₃I and NF₃. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and

Published
2022

9. The 5.8 µm absorption bands for nitric acid (H 14 N 16 O 3 ): line positions and intensities for the ν 2 band at 1709.567 cm −1 and for its first associated hot bands (ν 2 +ν 9 −ν 9 , ν 2 +ν 7 −ν 7 , ν 2 +ν 6 −ν 6 )

Author

Perrin, A., Manceron, L., Armante, R., Kwabia-Tchana, F., Roy, P., Doizi, D., Toon, G. C., Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Service d'Etudes du Comportement des Radionucléides (SECR), Département de Physico-Chimie (DPC), CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire) (CEA-DES (ex-DEN)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and ANR-19-CE29-0013,QUASARS,Spectroscopie quantitative pour la télédétection atmosphérique : des mesures simultanées IR/THz à la télédétection satellitaire(2019)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]
Abstract

International audience; This paper is the second of two back-to-back works, whose goal was to generate a more accurate linelist for the 5.8 µm absorption band of HNO3. Here, we report improved line positions and intensities in the ν2 cold band which is the main band in this region. For this, we recorded four high-resolution Fourier transform spectra for the ν2 band, centered at 1709.567 cm−1, under different experimental conditions. Using these spectra, a new extended line position analysis was performed for the ν2 band, leading to more accurate line positions. In parallel, individual line intensities were measured. It appears that, although the ν2 band is mainly of B-type, it also possesses a (very) weak A-type component that cannot be ignored. Overall, the line intensities in this new database are about 8% weaker than those quoted presently in the HITRAN (https://hitran.org/) or GEISA (https://geisa.aeris-data.fr/) databases. Our final linelist for HNO3 at 5.8 µm is provided as a supplement to this paper. It includes lines from the ν2 band together with those of the ν2+ν9−ν9, ν2+ν6−ν6, and ν2+ν7−ν7 associated hot bands that were generated during the first part of this study, described in the companion paper.

Published
2021
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10. Validation of MIPAS IMK-IAA Temperature, Water Vapor, and Ozone Profiles with MOHAVE-2009 Campaign Measurements

Author

Stiller, Gabrielle, Kiefer, M, Eckert, E, von Clarmann, T, Kellmann, S, Garcia-Comas, M, Funke, B, Leblanc, T, Fetzer, E, Froidevaux, L, Gomez, M, Hall, E, Hurst, D, Jordan, A, Kampfer, N, Lambert, A, McDermid, I. S, McGee, T, Miloshevich, L, Nedoluha, G, Read, W, Schneider, M, Schwartz, M, Straub, C, Toon, G, Twigg, L. W, Walker, K, and Whiteman, D. N

Subjects
Earth Resources And Remote Sensing, Meteorology And Climatology
Abstract

MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofısica de Andalucıa (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infrared (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further significant biases have been detected. Cross-comparison to co-located observations of other satellite instruments (Aura/MLS, ACE-FTS, AIRS) is provided as well.

Published
2012
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12. Daily and Hourly Variability in Global Fire Emissions and Consequences for Atmospheric Model Predictions of Carbon Monoxide

Author

Mu, M, Randerson, J. T, van der Werf, G. R, Giglio, L, Kasibhatla, P, Morton, D, Collatz, G. J, DeFries, R. S, Hyer, E. J, Prins, E. M, Griffith, D. W. T, Wunch, D, Toon, G. C, Sherlock, V, and Wennberg, P. O

Subjects
Environment Pollution
Abstract

Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We distributed monthly GFED3 emissions during 2003-2009 on a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) active fire observations. We found that patterns of daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of bunting in savannas. On diurnal timescales, our analysis of the GOES active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top-down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates.

Published
2011

13. An Introduction to the Mars Atmospheric Trace Molecule Occultation Spectrometer (MATMOS)

Author

Wennberg, P. O, Hipkin, V. J, Drummond, J. R, Toon, G. C, Allen, M, Blavier, J.-F, Brown, L. R, Kleinbohl, A, Abbatt, J. P. D, Lollar, B. Sherwood, Strong, K, Walker, K. A, Bernath, P .F, Clancy, R. T, Cloutis, E. A, DesMarais, D. J, Eiler, J. M, Yung, Y. L, Encrenaz, T, and McConnell, J. C

Subjects
Lunar And Planetary Science And Exploration
Published
2011

14. Validation of Aura Microwave Limb Sounder HCl Measurements

Author

Froidevaux, L, Jiang, Y. B, Lambert, A, Livesey, N. J, Read, W. G, Waters, J. W, Fuller, R. A, Marcy, T. P, Popp, P. J, Gao, R. S, Fahey, D. W, Jucks, K. W, Stachnik, R. A, Toon, G. C, Christensen, L. E, Webster, C. R, Bernath, P. F, Boone, C. D, Walker, K. A, Pumphrey, H. C, Harwood, R. S, Manney, G. L, Schwartz, M. J, Daffer, W. H, and Drouin, B. J

Subjects
Space Sciences (General)
Abstract

The Earth Observing System (EOS) Microwave Limb Sounder (MLS) aboard the Aura satellite has provided daily global HCl profiles since August 2004. We provide a characterization of the resolution, random and systematic uncertainties, and known issues for the version 2.2 MLS HCl data. The MLS sampling allows for comparisons with many (~1500 to more than 3000) closely matched profiles from the Halogen Occultation Experiment (HALOE) and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). These data sets provide HCl latitudinal distributions that are, overall, very similar to those from (coincident) MLS profiles, although there are some discrepancies in the upper stratosphere between the MLS and HALOE gradients. As found in previous work, MLS and ACE HCl profiles agree very well (within approximately 5%, on average), but the MLS HCl abundances are generally larger (by 10-20%) than HALOE HCl. The bias versus HALOE is unlikely to arise mostly from MLS, as a similar systematic bias (of order 15%) is not observed between average MLS and balloon-borne measurements of HCl, obtained over Fort Sumner, New Mexico, in 2004 and 2005. At the largest pressure (147 hPa) for MLS HCl, a high bias (approximately 0.2 ppbv) is apparent in analyses of low to midlatitude data versus in situ aircraft chemical ionization mass spectrometry (CIMS) HCl measurements from the Aura Validation Experiment (AVE) campaigns in 2004, 2005, and 2006; this bias is also observed in comparisons of MLS and aircraftHCl/O3 correlations. Good agreement between MLS and CIMS HCl is obtained at 100 to 68 hPa. The recommended pressure range for MLS HCl is from 100 to 0.15 hPa.

Published
2008
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15. Validation of the Aura Microwave Limb Sounder middle atmosphere water vapor and nitrous oxide measurements

Author

Atlas, E, Elkins, J. W, Murtagh, D, Urban, J, Walker, K. A, Boone, C. D, Bernath, P. F, Stachnik, R. A, Toon, G. C, Jucks, K. W, Waters, J. W, Wagner, P. A, Thurstans, R. P, Stek, P. C, Snyder, W. V, Perun, V. S, Pickett, H. M, Knosp, B. W, Jarnot, R. F, Fuller, R. A, Drouin, B. J, Daffer, W. H, Cuddy, D. T, Cofield, R. E, Nedoluha, G. E, Jimenez, C, Pumphrey, H. C, Schwartz, M. J, Wu, D. L, Froidevaux, L, Manney, G. L, Santee, M. L, Livesey, N. J, Read, W. G, and Lambert, A

Abstract

The quality of the version 2.2 (v2.2) middle atmosphere water vapor and nitrous oxide measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System (EOS) Aura satellite is assessed. The impacts of the various sources of systematic error are estimated by a comprehensive set of retrieval simulations. Comparisons with correlative data sets from ground-based, balloon and satellite platforms operating in the UV/visible, infrared and microwave regions of the spectrum are performed. Precision estimates are also validated, and recommendations are given on the data usage. The v2.2 H2O data have been improved over v1.5 by providing higher vertical resolution in the lower stratosphere and better precision above the stratopause. The single-profile precision is ~0.2–0.3 ppmv (4–9%), and the vertical resolution is ~3–4 km in the stratosphere. The precision and vertical resolution become worse with increasing height above the stratopause. Over the pressure range 0.1–0.01 hPa the precision degrades from 0.4 to 1.1 ppmv (6–34%), and the vertical resolution degrades to ~12–16 km. The accuracy is estimated to be 0.2–0.5 ppmv (4–11%) for the pressure range 68–0.01 hPa. The scientifically useful range of the H2O data is from 316 to 0.002 hPa, although only the 82–0.002 hPa pressure range is validated here. Substantial improvement has been achieved in the v2.2 N2O data over v1.5 by reducing a significant low bias in the stratosphere and eliminating unrealistically high biased mixing ratios in the polar regions. The single-profile precision is ~13–25 ppbv (7–38%), the vertical resolution is ~4–6 km and the accuracy is estimated to be 3–70 ppbv (9–25%) for the pressure range 100–4.6 hPa. The scientifically useful range of the N2O data is from 100 to 1 hPa.

Published
2007

16. Validation of the Aura Microwave Limb Sounder middle atmosphere water vapor and nitrous oxide measurements

Author

Lambert, A, Read, W. G, Livesey, N. J, Santee, M. L, Manney, G. L, Froidevaux, L, Wu, D. L, Schwartz, M. J, Pumphrey, H. C, Jimenez, C, Nedoluha, G. E, Cofield, R. E, Cuddy, D. T, Daffer, W. H, Drouin, B. J, Fuller, R. A, Jarnot, R. F, Knosp, B. W, Pickett, H. M, Perun, V. S, Snyder, W. V, Stek, P. C, Thurstans, R. P, Wagner, P. A, Waters, J. W, Jucks, K. W, Toon, G. C, Stachnik, R. A, Bernath, P. F, Boone, C. D, Walker, K. A, Urban, J, Murtagh, D, Elkins, J. W, and Atlas, E

Published
2007

17. Observed and Modeled HOCl Profiles in the Midlatitude Stratosphere: Implication for Ozone Loss

Author

Kovalenko, L. J, Jucks, K. W, Salawitch, R. J, Toon, G. C, Blavier, J. F, Johnson, D. G, Kleinbohl, A, Livesey, N. J, Margitan, J. J, Pickett, H. M, Santee, M. L, Sen, B, Stachnik, R. A, and Waters, J. W

Subjects
Meteorology And Climatology
Abstract

Vertical profiles of stratospheric HOCl calculated with a diurnal steady-state photochemical model that uses currently recommended reaction rates and photolysis cross sections underestimate observed profiles of HOCl obtained by two balloon-borne instruments, FIRS-2 (a far-infrared emission spectrometer) and MkIV (a mid-infrared, solar absorption spectrometer). Considerable uncertainty (a factor of two) persists in laboratory measurements of the rate constant (k(sub 1)) for the reaction ClO + HO2 yields HOCl + O2. Agreement between modeled and measured HOCl can be attained using a value of k(sub 1) from Stimpfle et al. (1979) that is about a factor-of-two faster than the currently recommended rate constant. Comparison of modeled and measured HOCl suggests that models using the currently recommended value for k(sub 1) may underestimate the role of the HOCl catalytic cycle for ozone depletion, important in the midlatitude lower stratosphere.

Published
2007
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18. Space-Based Near-Infrared CO2 Measurements: Testing the Orbiting Carbon Observatory Retrieval Algorithm and Validation Concept Using SCIAMACHY Observations over Park Falls, Wisconsin

Author

Bosch, H, Toon, G. C, Sen, B, Washenfelder, R. A, Wennberg, P. O, Buchwitz, M, deBeek, R, Burrows, J. P, Crisp, D, Christi, M, Connor, B. J, Natraj, V, and Yung, Y. L

Subjects
Space Sciences (General)
Abstract

Space-based measurements of reflected sunlight in the near-infrared (NIR) region promise to yield accurate and precise observations of the global distribution of atmospheric CO2. The Orbiting Carbon Observatory (OCO) is a future NASA mission, which will use this technique to measure the column-averaged dry air mole fraction of CO2 (XCO2) with the precision and accuracy needed to quantify CO2 sources and sinks on regional scales (approx.1000 x 1000 sq km and to characterize their variability on seasonal timescales. Here, we have used the OCO retrieval algorithm to retrieve XCO2 and surface pressure from space-based Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) measurements and from coincident ground-based Fourier transform spectrometer (FTS) measurements of the O2 A band at 0.76 mm and the 1.58 mm CO2 band for Park Falls,Wisconsin. Even after accounting for a systematic error in our representation of the O2 absorption cross sections, we still obtained a positive bias between SCIAMACHY and FTS XCO2 retrievals of approx.3.5%. Additionally, the retrieved surface pressures from SCIAMACHY systematically underestimate measurements of a calibrated pressure sensor at the FTS site. These findings lead us to speculate about inadequacies in the forward model of our retrieval algorithm. By assuming a 1% intensity offset in the O2 A band region for the SCIAMACHY XCO2 retrieval, we significantly improved the spectral fit and achieved better consistency between SCIAMACHY and FTS XCO2 retrievals. We compared the seasonal cycle of XCO2 at Park Falls from SCIAMACHY and FTS retrievals with calculations of the Model of Atmospheric Transport and Chemistry/Carnegie-Ames-Stanford Approach (MATCH/CASA) and found a good qualitative agreement but with MATCH/CASA underestimating the measured seasonal amplitude. Furthermore, since SCIAMACHY observations are similar in viewing geometry and spectral range to those of OCO, this study represents an important test of the OCO retrieval algorithm and validation concept using NIR spectra measured from space. Finally, we argue that significant improvements in precision and accuracy could be obtained from a dedicated CO2 instrument such as OCO, which has much higher spectral and spatial resolutions than SCIAMACHY. These measurements would then provide critical data for improving our understanding of the carbon cycle and carbon sources and sinks.

Published
2006
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20. Using SCIAMACHY and Ground-based FTS Measurements to Test the OCO X(sub CO2) Retrieval and Validation Approach

Author

Boesch, Hartmut, Toon, G, Sen, B, Li, Q. B, Salawitch, R, Miller, C, Crisp, D, Washenfelder, R, Wennberg, P, Natraj, V, Yung, Y, Buchwitz, M, Burrows, J, DeBeek, R, Connor, B, Christi, M, and Spurr, R

Subjects
Space Sciences (General)
Abstract

Global, space-based observations of atmospheric CO2 with precision, resolution, and coverage needed to monitor sources and sinks: a) Spectra of reflected/scattered sunlight in NIR CO2 and O2 bands used to estimate X(sub CO2) with large sensitivity to surface; b) A-train orbit (1:15 PM polar sun sync); c) 16 day repeat cycle samples seasonal cycle on semi-monthly intervals; and d) NASA ESSP (Earth Space System Pathfinder) scheduled for Sept 2008 launch; 2 yrs lifetime. Initial comparison of SCIAMACHY and FTS retrievals for Park Falls: a) Positive bias in X(sub CO2) of approx. 10 ppm; and b) Negative bias in surface pressure After correction of spectral artifacts in O2A band: a) Largely improved agreement between SCIAMACHY and FTS X(sub CO2) (without clear bias) and in surface pressure; and b) Standard deviation of SCIAMACHY X(sub CO2 approx. 6 ppm. Good qualitative agreement with GEOS-CHEM, with GEOS-CHEM underestimating seasonal cycle. OCO is a dedicated CO2 instrument and will achieve much higher accuracy and precision: a) much higher spectral resolution (by factor of 20); and b) smaller ground pixels (by factor of 600).

Published
2006

21. Ground-based Photon Path Measurements from Solar Absorption Spectra of the O2 A-band

Author

Yang, Z, Wennberg, P. O, Cageao, R. P, Pongetti, T. J, Toon, G. C, and Sander, S. P

Subjects
Solar Physics
Abstract

High-resolution solar absorption spectra obtained from Table Mountain Facility (TMF, 34.38degN, 117.68degW, 2286 m elevation) have been analyzed in the region of the O2 A-band. The photon paths of direct sunlight in clear sky cases are retrieved from the O2 absorption lines and compared with ray-tracing calculations based on the solar zenith angle and surface pressure. At a given zenith angle, the ratios of retrieved to geometrically derived photon paths are highly precise (approx.0.2%), but they vary as the zenith angle changes. This is because current models of the spectral lineshape in this band do not properly account for the significant absorption that exists far from the centers of saturated lines. For example, use of a Voigt function with Lorentzian far wings results in an error in the retrieved photon path of as much as 5%, highly correlated with solar zenith angle. Adopting a super-Lorentz function reduces, but does not completely eliminate this problem. New lab measurements of the lineshape are required to make further progress.

Published
2005
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22. Measured and modeled HOCl profiles in the mid-latitude stratosphere : implication for ozone loss

Author

Kovalenko, L. J, Salawitch, R. J, Blavier, J. -F, Sen, B, Toon, G. C, Jucks, K. W, Johnson, D. G, Stachnik, R. A, and Margitan, J. J

Abstract

The HOCl catalytic cycle is an efficient ozone loss mechanism in the lower mid-latitude stratosphere. We use a diurnal steady-state photochemical model to calculate profiles of HOCl for conditions encountered by a number of high-altitude balloon flights. To assess how well this model represents ozone loss by the HOCl cycle, we compare our calculations of HOCl and its precursors Cl0 and HO2 with measurements obtained by an FTIR solar absorption spectrometer (MkIV), a far-infrared emission spectrometer (FIRS-2), and a submillimetenvave limb sounder (SLS). We then evaluate these comparisons in light of a number of recent laboratory studies of the main formation mechanism of HOCl, the reaction of Cl0 + HO2. Those studies measured both the reaction rate constant and the quantum yield for a second product pathway, formation of HCl.

Published
2004

23. Measured HDO/H2O Ratios Across the Tropical Tropopause

Author

Kuang, Z, Toon, G. C, Wennberg, P. O, and Yung, Y. L

Subjects
Earth Resources And Remote Sensing
Abstract

We present the first simultaneous measurements of HDO and H2O in the tropical upper troposphere and lower stratosphere as derived from infrared solar absorption spectra acquired by the Atmospheric Trace Molecule Spectroscopy.

Published
2003

25. Atmospheric CO2 retrieved from ground-based solar spectra

Author

Yang, Z, Toon, G. C, Margolis, J. S, and Wennberg, P. O

Subjects
Earth Resources And Remote Sensing
Abstract

The column-averaged volume mixing ration of CO2 over Kitt Peak, Arizona, has been retrieved from high-resolution solar absorption spectra obtained with the fourier transform spectrometer on the McMath telescope.

Published
2002

27. Comparison of satellite ozone observations in coincident air masses in early November 1994

Author

Zawodny, J. M, Toon, G. C, Russell, J. M. III, Riese, M, Oberheide, J, Livesey, N. J, Irion, F. W, Gunson, M. R, Bevilacqua, R. M, Michelsen, H. A, and Manney, G. L

Abstract

Ozone observed by seven satellite instruments, the Atmospheric Trace Molecule Spectroscopy instrument (ATMOS), Stratospheric Aerosol and Gas Experiment (SAGE) II, Polar Ozone and Aerosol Measurement (POAM) II instrument, Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS), Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA), and Millimeter-wave Atmospheric Sounder (MAS), during early November 1994 is mapped in equivalent latitude/potential temperature (EqL/ theta )space to facilitate nearly global comparisons of measurements taken in similar air masses.

Published
2001

33. Total column CO2 measurements at Darwin, Australia – site description and calibration against in situ aircraft profiles

Author

Deutscher, N. M., Griffith, D. W. T., Bryant, G. W., Wennberg, P. O., Toon, G. C., Washenfelder, R. A., Keppel-Aleks, G., Wunch, D., Yavin, Y., Allen, N. T., Blavier, J.-F., Jiménez, R., Daube, B. C., Bright, A. V., Matross, D. M., Wofsy, S. C., and Park, S.

Subjects
lcsh:TA715-787, lcsh:Earthwork. Foundations, lcsh:TA170-171, lcsh:Environmental engineering
Abstract

An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO2 and O2 and other gases. Measured CO2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January–February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clear-sky low airmass relative precision of 0.1% is demonstrated in the CO2 and O2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS XCO2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.

Published
2018

38. Lamination and polar vortex development in fall from ATMOS long-lived trace gases observed during November 1994

Author

Roche, A, Gunson, M, Toon, G, Irion, F, Michelson, H, and Manney, G

Abstract

Long-lived trace-gas profiles observed by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument around the developing polar vortex (the protovortex) during early November 1994 show distinctive inversions (lamiane). High-resolution profiles calculated using a reverse trajectory (RT) model to produce the majority of these laminae, demonstrating that most of these features arise from advection by the large-scale winds.

Published
2000

39. Ground-Based Measurements of Stratospheric Composition from Mt. Barcroft, California

Author

Toon, G. C, Blavier, J.-F, and Sen, B

Subjects
Geophysics
Abstract

The MkIV is an FTIR spectrometer designed and built at JPL in the 1980's for remote sensing the composition of the Earth's atmosphere by solar absorption spectrometry. Optically, MkIV is very similar to the JPL ATMOS instrument, which flew three times on the Space Shuttle. Both use double-passed configurations with a KBr beamsplitter and compensator, in order to cover the mid-infrared. The main advantage of the MkIV is that it uses two detectors in parallel, a HgCdTe photoconductor for the long wavelengths and an InSb photodiode for the short wavelengths, allowing the entire 650 to 5650/cm region to be measured simultaneously. At a 10 kHz sampling rate, each 130 cm OPD interferogram takes 3 minutes to acquire. This paper describes how the MkIV instrument was adapted for remote operation from the Barcroft site, where the harsh winter conditions make access difficult. Some of the main technical challenges will be discussed including, (i) operation from solar panels and batteries, (ii) cooling the detectors with LN2, (iii) instrument control and monitoring over a cellular phone, and (iv) data storage, processing and analysis. Finally, MkIV spectra measured from Barcroft are compared with those measured from JPL to highlight the advantages of the higher altitude site.

Published
2000

42. Remotely Operating a Fourier Transform Spectrometer for Atmospheric Remote Sensing

Author

Blavier, J.-F, Toon, G. C, and Sen, B

Subjects
Geophysics
Abstract

This paper describes how the MkIV instrument was adapted for remote operation from the Barcroft site, where the harsh winter conditions make access difficult. Some of the main technical challenges will be discussed including, (i) operation from solar panels and batteries, (ii) cooling the detectors with LN2, (iii) instrument control and monitoring over a cellular phone, and (iv) data storage, processing and analysis. Finally, MkIV spectra measured from Barcroft and compared with those measured from JPL to highlight the advantages of the higher altitude site.

Published
2000

43. Simulating Observed Ozone Loss in the Northern Hemisphere Winter

Author

Kawa, S. R, Douglass, A. R, Lait, L. R, Considine, D. B, Anderson, J. G, Baumgardner, D, Elkins, J. W, Fahey, D. W, Richard, E. C, Jost, H, Rex, M, Toon, G. C, Webster, C. R, and Einaudi, Franco

Subjects
Environment Pollution
Abstract

Ozone amounts observed at high Northern latitudes in late winter and early spring have been relatively very low in four of the last six years. On the face of it, this decline appears similar to that observed in the Antarctic in the mid-1980s in spite of the fact that the abundance of stratospheric chlorine is currently steady or decreasing. In order to predict the extent to which this change represents a trend, and to understand what combination of factors produces the low ozone, we need to accurately simulate these observations with models. In this presentation, we focus on the winter of 1999-2000, which exhibited some of the lowest ozone ever recorded in the Northern hemisphere. It also contained the largest-ever assembled set of atmospheric measurements and modeling activities in the SAGE III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone (SOLVE/THESEO). We use SOLVE/THESEO observations in comparison with the Goddard 3-D global model of stratospheric chemistry and transport to explore the model's capability to simulate the evolution of ozone and other species through the winter. We will discuss advective transport and mixing, chlorine activation, and denitrification, which are key processes to accurately simulating wintertime ozone. Preliminary results show that, although the model tracer transport and chlorine activation compare relatively well with observations, the magnitude of observed ozone loss is difficult to achieve in the model. Calculated ozone loss is sensitive to denitrification, which presents a major challenge to parameterization in a global model. Simulation requirements and uncertainties will be evaluated.

Published
2000

44. An NOy Algorithm for Arctic Winter 2000

Author

Loewenstein, M, Jost, H, Greenblatt, J. B, Podolske, J. R, Gao, R. S, Popp, P. J, Toon, G. C, Webster, C. R, Herman, R. L, Hurst, D. F, and Hipskind, R. Stephen

Subjects
Environment Pollution
Abstract

NOy, total reactive nitrogen, and the long-lived tracer N2O, nitrous oxide, were measured by both in situ and remote sensing instruments during the Arctic winter 1999-2000 SAGE III Ozone Loss and Validation Experiment (SOLVE). The correlation function NOy:N2O observed before the winter Arctic vortex forms, which is known as NOy(sup), is an important reference relationship for conditions in the evolving vortex. NOy(sup) can, with suitable care, be used to quantify vortex denitrification by sedimentation of polar stratospheric cloud particles when NOy data is taken throughout the winter. Observed NOy values less than the reference value can be interpreted in terms of semi-permanent removal of active nitrogen by condensation and sedimentation processes. In this paper we present a segmented function representing NOy(sup) applicable over the full range of altitudes sampled during SOLVE. We also assess the range of application of this function and some of its limitations.

Published
2000

45. The Budget and Partitioning of Stratospheric Chlorine During the 1997 Arctic Summer

Author

Sen, B, Osterman, G. B, Salawitch, R. J, Toon, G. C, Marigitan, J. J, Blavier, J.-F, Chang, A. Y, May, R. D, Webster, C. R, and Stimpfle, R. M

Subjects
Geophysics
Abstract

Volume mixing ratio profiles of HCl, HOCl, ClNO3, CH3Cl, CFC-12, and CFC-11, CCl4, HCFC-22, and CFC-113 were measured simultaneously from 9 to 38 km by the Jet Propulsion Laboratory MkIV Fourier Transform Infrared solar absorption spectrometer during two balloon flights from Fairbanks, Alaska (64.8 N), on May 8 and July 8, 1997. The altitude variation of total organic chlorine (CCl(sub y)), total inorganic chlorine (Cl(sub y)), and the nearly constant value (3.7 +/- 0.2 ppbv) of their sum (Cl(sub TOT)) demonstrates that the stratospheric chlorine species available to react with O3 are supplied by the decomposition of organic chlorinated compounds whose abundances are well quantified. Measured profiles of HCl and ClNO3 agree well with profiles found by photochemical model (differences < 10% for altitudes below 35 km) constrained by various other constituents measured by MkIV. The production of HCl by ClO + OH plays a relatively small role in the partitioning of HCl and ClNO3 for the sampled air masses. However, better agreement with the measured profiles of HCl and ClNO3 is obtained when this source of HCl is included in the model. Both the measured and calculated [ClNO3]/[HCl] ratios exhibit the expected near linear variation with [O3](sup 2)/[CH4] over a broad range of altitudes. MkIV measurements of HCl, ClNO3, and CCl(sub y) agree well with ER-2 in situ observations of these quantities for directly comparable air masses. These results demonstrate good understanding of the budget of stratospheric chlorine and that the partitioning of inorganic chlorine is accurately described by photochemical models that employ JPL97 reaction rates and production of HCl from ClO + OH for the environmental conditions encountered: relatively warm temperatures, long periods of solar illumination, and relatively low aerosol surface areas.

Published
1999
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50. Comparison of MkIV Balloon and ER-2 Aircraft Measurements of Atmospheric Trace Gases

Author

Cohen, R, Voss, P, Bonne, G, Stimpfle, R, Bui, T, Flocke, F, Schauffler, S, Atlas, E, Oltmans, S, Hurst, D, Romashkin, P, Elkins, J, Proffitt, M, Del Negro, L, Gao, R, Fahey, D, May, R, Webster, C, Margitan, J, Sen, B, Blavier, J. F, and Toon, G

Abstract

On 8 May 1997 vertical profiles of over 30 different gases were measured remotely in solar occultation by the JPl MkIV Interferometer during a balloon flight launched from Fairbanks, Alaska.

Published
1999

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