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C. H. Jackman,
D. R. Marsh,
F. M. Vitt,
R. G. Roble,
C. E. Randall,
P. F. Bernath,
B. Funke,
M. López-Puertas,
S. Versick,
G. P. Stiller,
A. J. Tylka, E. L. Fleming
Atmos. Chem. Phys. 01/2011; 11:6153-6166.
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[show abstract]
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ABSTRACT: Hypothetical reductions in future emissions of ozone-depleting substances (ODSs), including N2O, are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact that regulations already in force have had. If all anthropogenic ODS emissions were halted beginning in 2011, ozone is calculated to be higher by about 1–2{%} during the period 2030–2100 compared to a case of no additional ODS restrictions. Radiative forcing by 2100 would be about 0.23 W/m2 lower due to the elimination of N2O emissions and about 0.005 W/m2 lower due to destruction of the chlorofluorocarbon (CFC) bank. The ability of EESC to be a suitable metric for total ozone is also quantified. Responding to the recent suggestion that N2O should be considered an ODS, we provide an approach to incorporate N2O into the EESC formulation.
Atmospheric Chemistry and Physics Discussions. 01/2010;
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[show abstract]
[hide abstract]
ABSTRACT: Absorption cross sections of nitrous oxide (N<sub>2</sub>O) and carbon tetrachloride (CCl<sub>4</sub>) are reported at five atomic UV lines (184.95, 202.548, 206.200, 213.857, and 228.8 nm) at temperatures in the range 210–350 K. In addition, UV absorption spectra of CCl<sub>4</sub> are reported between 200–235 nm as a function of temperature (225–350 K). The results from this work are critically compared with results from earlier studies. For N<sub>2</sub>O, the present results are in good agreement with the current JPL recommendation enabling a reduction in the estimated uncertainty in the N<sub>2</sub>O atmospheric photolysis rate. For CCl<sub>4</sub>, the present cross section results are systematically greater than the current recommendation at the reduced temperatures most relevant to stratospheric photolysis. The new cross sections result in a 5–7% increase in the modeled CCl<sub>4</sub> photolysis loss, and a slight decrease in the stratospheric lifetime, from 51 to 50 years, for present day conditions. The corresponding changes in modeled inorganic chlorine and ozone in the stratosphere are quite small. A CCl<sub>4</sub> cross section parameterization for use in atmospheric model calculations is presented.
Atmospheric Chemistry and Physics Discussions. 01/2010;
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C. H. Jackman,
B. Funke,
M. Lopez-Puertas,
S. Versik,
G. P. Stiller,
A. J. Tylka,
D. R. Marsh,
F. M. Vitt,
R. R. Garcia,
C. E. Randall, E. L. Fleming
[show abstract]
[hide abstract]
ABSTRACT: Solar eruptions in early 2005 led to a substantial barrage of charged
particles on the Earth’s atmosphere in a few separate events
during the January 16-21 period. Significant production of OH [Verronen
et al. 2006] and destruction of ozone [Verronen et al. 2006; Seppala et
al. 2006] have been documented due to the enhanced solar proton flux in
January 2005. These solar proton events (SPEs) also led to the
production of NOx (NO, NO2), when the protons and associated secondary
electrons dissociated molecular nitrogen (N2). Our simulations with the
Whole Atmosphere Community Climate Model (WACCM) show that mesospheric
NOx is enhanced in both the polar Southern (greater than 10 ppbv) and
Northern (greater than 40 ppbv) Hemispheres. Envisat MIPAS measurements
of nighttime NO2 for the Northern Hemisphere are in reasonable agreement
with these predictions. Such enhancements are considerable for the
mesosphere and led to increases in Northern Hemisphere polar upper
stratospheric odd nitrogen (NOy) greater than 20% in February and March
2005. The largest ground level enhancement (GLE) of solar cycle 23
occurred on January 20, 2005 with a neutron monitor increase of about
270% [Gopalswamy et al. 2005]. Using results from a recent analysis of
the proton spectrum derived from neutron-monitor data [Tylka &
Dietrich 2009], we found that protons of energies 300 to 20,000 MeV, not
normally included in our computations, led to enhanced stratospheric NOy
of less than 1% as a result of this GLE. Thus, the primary impact of the
January 2005 solar events on the middle atmosphere was through protons
with energies less than 300 MeV. This presentation will show both short-
and longer-term changes due to the January 2005 solar protons.
Gopalswamy, N., et al., Coronal mass ejections and ground level
enhancements, 29th International Cosmic Ray Conference Pune, 1, 169-173,
2005. Seppala, A., et al., Destruction of the tertiary ozone maximum
during a solar proton event, Geophys. Res. Lett., 33, L07804,
doi:10.1029/2005GL025571, 2006. Tylka, A.J. & W.F. Dietrich, A new
and comprehensive analysis of proton spectra in ground-level enhanced
(GLE) solar particle events, 31st International Cosmic Ray Conference
Lodz, paper 0273, 2009. Verronen, P. T., et al., Production of odd
hydrogen in the mesosphere during the January 2005 solar proton event,
Geophys Res. Lett., 33, L24811, doi:10.1029/2006GL028115, 2006.
AGU Fall Meeting Abstracts. 11/2009; -1:1245.
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P. A. Newman,
L. D. Oman,
A. R. Douglass, E. L. Fleming,
S. M. Frith,
M. M. Hurwitz,
S. R. Kawa,
C. H. Jackman,
N. A. Krotkov,
E. R. Nash,
J. E. Nielsen,
Pawson S,
R. S. Stolarski,
G. J. M. Velders
[show abstract]
[hide abstract]
ABSTRACT: Ozone depletion by chlorofluorocarbons (CFCs) was first proposed by Molina and Rowland in their 1974 Nature paper. Since that time, the scientific connection between ozone losses and CFCs and other ozone depleting substances (ODSs) has been firmly established with laboratory measurements, atmospheric observations, and modeling studies. This science research led to the implementation of international agreements that largely stopped the production of ODSs. In this study we use a fully-coupled radiation-chemical-dynamical model to simulate a future world where ODSs were never regulated and ODS production grew at an annual rate of 3%. In this "world avoided" simulation, 17% of the globally-averaged column ozone is destroyed by 2020, and 67% is destroyed by 2065 in comparison to 1980. Large ozone depletions in the polar region become year-round rather than just seasonal as is currently observed in the Antarctic ozone hole. Very large temperature decreases are observed in response to circulation changes and decreased shortwave radiation absorption by ozone. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058 as a result of heterogeneous chemical processes (as currently observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical upwelling. In response to ozone changes, ultraviolet radiation increases, more than doubling the erythemal radiation in the northern summer midlatitudes by 2060.
Atmospheric Chemistry and Physics. 01/2009;
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C. H. Jackman,
D. R. Marsh,
F. M. Vitt,
R. R. Garcia, E. L. Fleming,
G. J. Labow,
C. E. Randall,
López-Puertas M,
Funke B,
T. von Clarmann,
G. P. Stiller
[show abstract]
[hide abstract]
ABSTRACT: Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short- and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003) as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NOx (NO+NO2) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO3, N2O5, ClONO2, HOCl, and ClO were indirectly caused by the very large SPEs in October–November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO3 and ClONO2 enhancements being smaller than measured and N2O5 enhancements being larger than measured. The HOCl enhancements were fairly similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric and lower mesospheric NOx increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in several weeks past the SPE. The WACCM3 simulations confirmed the SH HALOE observations of enhanced NOx in September 2000 as a result of the July 2000 SPE and the NH SAGE II observations of enhanced NO2 in March 1990 as a result of the October 1989 SPEs.
Atmospheric Chemistry and Physics. 01/2008;
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[show abstract]
[hide abstract]
ABSTRACT: Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and odd-nitrogen in the polar cap regions (>60° geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period 1963–2005. The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months to years after the events. We present the short- and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972; October 1989; July 2000; and October–November 2003) as computed by WACCM3 and observed by satellite instruments. The polar effects can be summarized as follows: 1) Mesospheric NOx (NO+NO2) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs; 2) upper stratospheric and lower mesospheric NOx increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in a few weeks; 3) mid- to upper stratospheric ozone decreased over 20%; and 4) enhancements of HNO3, HOCl, ClO, ClONO2, and N2O5 were indirectly caused by the very large SPEs, although the model results suggest impacts at higher altitudes than indicated by the measurements for the October–November 2003 SPE period.
Atmospheric Chemistry and Physics Discussions. 01/2007;
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[show abstract]
[hide abstract]
ABSTRACT: Some solar eruptions lead to solar proton events (SPEs) at the Earth, which typically last a few days. High energy solar protons
associated with SPEs precipitate on the Earth’s atmosphere and cause increases in odd hydrogen (HOx) and odd nitrogen (NOy) in the polar cap regions (>60° geomagnetic). The enhanced HOx leads to short-lived ozone depletion (~days) due to the short lifetime of HOx constituents. The enhanced NOy leads to long-lived ozone changes because of the long lifetime of the NOy family in the stratosphere and lower mesosphere. Very large SPEs occurred in 1972, 1989, 2000, 2001, and 2003 and were predicted
to cause maximum total ozone depletions of 1–3%, which lasted for several months to years past the events. A long-term data
set of solar proton fluxes used in these computations has been compiled for the time period 1963–2005. Several satellites,
including the NASA Interplanetary Monitoring Platforms (1963–1993) and the NOAA Geostationary Operational Environmental Satellites
(1994–2005), have been used to compile this data set.
12/2006: pages 333-345;
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ABSTRACT: Solar cycle 23 was extremely active with seven of the largest twelve solar proton events (SPEs) in the past forty years recorded.
These events caused significant polar middle atmospheric changes that were observed by a number of satellites. The highly
energetic protons produced ionizations, excitations, dissociations, and dissociative ionizations of the background constituents
in the polar cap regions (>60 degrees geomagnetic latitude), which led to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, BrONO2, ClONO2). The HOx increases led to short-lived ozone decreases in the polar mesosphere and upper stratosphere due to the short lifetimes of
the HOx constituents. Polar middle mesospheric ozone decreases greater than 50% were observed and computed to last for hours to days
due to the enhanced HOx. The NOy increases led to long-lived polar stratospheric ozone changes because of the long lifetime of the NOy family in this region. Upper stratospheric ozone decreases of >10% were computed to last for several months past the solar
events in the winter polar regions because of the enhanced NOy.
12/2006: pages 381-391;
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[show abstract]
[hide abstract]
ABSTRACT: The huge coronal mass ejection (CME) on October 28,2003 caused an extremely large solar proton event (SPE) at the Earth, which impacted the middle atmospheric polar cap regions. The highly energetic protons produce ionizations, excitations, dissociations, and dissociative ionizations of the background constituents, which lead to the production of HOx (H, OH, HO2) and NOy (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, BrONO2). The total production of middle atmospheric NOy molecules by individual SPEs can be used to compare their sizes. Using this scale, the extremely large October 2003 SPE was the fourth largest in the past 40 years and the second largest of solar cycle 23. Only the October 1989, August 1972, and July 2000 SPEs were larger. The Goddard Space Flight Center (GSFC) Two-dimensional (2D) Model was used in computing the influence of this gigantic SPE. The NOy amount was increased by over two orders of magnitude in the mesosphere in both the GSFC 2D Model computations and Upper Atmosphere Research Satellite (UARS) Halogen Occultation Experiment (HALOE) measurements as a result of this noteworthy SPE. The model also calculated polar middle mesospheric ozone decreases of over 70% during the SPE. Other atmospheric impacts from both model predictions and measurements as a result of this major SPE will be discussed in this paper.
02/2004;
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[show abstract]
[hide abstract]
ABSTRACT: As a result of photochemistry, some relationship between the stratospheric age of air or mean age and the amount of tracer contained within an air sample is expected. The existence of such a relationship allows inferences about transport history to be made from observations of chemical tracers. This paper lays down the conceptual foundations for the relationship between age and tracer amount for long-lived tracers, developed within a Lagrangian framework. Although the photochemical loss depends not only on the age of the parcel but also on its path, we show that under the "average path approximation" that the path variations are less important than parcel age. The average path approximation then allows us to develop a formal relationship between the age spectrum and the tracer distribution. Using this relationship, tracer-tracer correlations can be interpreted as the result of mixing which connects parts of the "single-path photochemistry curve," a universal path-independent curve that describes the photochemical loss in terms of the total photon exposure. This geometric interpretation of mixing gives rise to constraints on trace gas correlation curves as can be seen in the atmospheric trace molecule spectroscopy observations.
Journal of Geophysical Research 01/2000; 105(20):1537-1552. · 3.02 Impact Factor
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M. Y. Danilin,
D. W. Fahey,
U. Schumann,
M. J. Prather,
J. E. Penner,
M. K. W. Ko,
D. K. Weisenstein,
C. H. Jackman,
G. Pitari,
I. Koehler,
R. Sausen,
C. J. Weaver,
A. R. Douglass,
P. S. Connell,
D. E. Kinnison,
F.J. Dentener, E. L. Fleming,
T. K. Berntsen,
I. S. A. Isaksen
[show abstract]
[hide abstract]
ABSTRACT: An upper limit for aircraft-produced perturbations to aerosols and gaseous exhaust products in the upper troposphere and lower stratosphere (UT/LS) is derived using the 1992 aviation fuel tracer simulation performed by eleven global atmospheric models. Key findings are that subsonic aircraft emissions: (1) have not been responsible for the observed water vapor trends at 40degN; (2) could be a significant source of soot mass near 12 km, but not at 20 km; (3) might cause a noticeable increase in the background sulfate aerosol surface area and number densities (but not mass density) near the northern mid-latitude tropopause; and (4) could provide a global, annual mean top of the atmosphere radiative forcing up to +0.006 W/sq m and -0.013 W/sq m due to emitted soot and sulfur, respectively.
12/1998;
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[show abstract]
[hide abstract]
ABSTRACT: Volume mixing ratio profiles of fluorine source gases (CF2C12, CFC13, CF2C1CFC12, CHF2C1, CF4, and SF6) and reservoir gases (COF2 and HF) have been derived from a series of high-resolution infrared solar spectra recorded by the Jet Propulsion Laboratory MklV interferometer during a September 1993 balloon flight from Fort Sumner, New Mexico (34øN, 104øW). The total fluorine budget over the 5-to 38-km altitude range has been evaluated by adding these individual measured profiles to modeled predictions for the unmeasured gas COFC1 (considered to be at most 6% of the total fluorine budget). The results indicate a steady decrease of total fluorine, with increasing altitude, from a tropospheric value of about 1.82 parts per billion by volume f'-'- • "' • .4 t • , • ,ov • to I 8 ppbv at 38 km. The latter value, made up entirely of the reservoir species, is commensurate with tropospheric concentrations of fluorine reported in the late 1980s and with time-dependent two-dimensional model predictions (1.45 ppbv). Therefore the "age" of the stratospheric air mass estimated from the MklV fluorine budget is 4-5 years, in agreement with model simulations (--6 years) and recent ATMOS measurements.
Journal of Geophysical Research 01/1996; 101:9045-9054. · 3.02 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: Measurements of stratospheric hydrofluoric acid (HF) have been made by the JPL MkIV interferometer during high-altitude balloon flights. Infrared solar absorption spectra were acquired near 35 deg N at altitudes between local tropopause and 38 km. Volume mixing ratio profiles of HF derived from 4 flights (1990-93), in conjunction with simultaneously observed N2O profiles, indicate an average rate of HF increase of (5.5 +/- 0.3)% per year, in agreement with time-dependent, two-dimensional model simulations (6% per year) and ATMOS measurements.
05/1995;
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[show abstract]
[hide abstract]
ABSTRACT: 1] Projections of the recovery of the ozone layer are made with global atmospheric models using a specified time series of mixing ratios of ozone depleting substances (ODSs) at the lower boundary. This time series is calculated using atmospheric mixing ratio observations, emission rates, and an estimate for the atmospheric lifetime. ODS destruction and simulated atmospheric-lifetime vary among models because they depend on the simulated stratospheric transport and mixing. We investigate the balance between the annual change in ODS burden, its atmospheric loss, and the annual ODS input to the atmosphere using several models. Some models produce realistic distributions for the mean age of air and some do not. Back trajectory calculations relate the fractional release (one minus the amount of ODS at a location relative to its stratospheric entry value) to the mean age through the age spectrum, showing that, for the individual spectrum elements, the maximum altitude and loss increase with age. Models with faster circulations produce ''young'' distributions for the age of air and fail to reproduce the observed relationship between the mean age of air and the fractional release. Models with realistic mean age of air reproduce the observed relationship. These models yield a lifetime for CFCl 3 of $56 years, longer than the 45 year lifetime currently used to project future mixing ratios. Use of flux boundary conditions in assessment models would have several advantages, including consistency between the ODS evolution and simulated loss even if the simulated residual circulation changes due to climate change. (2008), Relationship of loss, mean age of air and the distribution of CFCs to stratospheric circulation and implications for atmospheric lifetimes, J. Geophys. Res., 113, D14309, doi:10.1029/2007JD009575.
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S.B. Andersen,
E.C Weatherhead,
A. Stevermer,
J. Austin,
C. Brühl, E.L. Fleming,
J. de Grandpré,
Volker Grewe,
I. Isaksen,
G. Pitari,
R.W. Portmann,
B. Rognerud,
J.E. Rosenfield,
S Smyshlyaev,
T. Nagashima,
G.J.M. Velders,
D.K. Weisenstein,
J. Xia
[show abstract]
[hide abstract]
ABSTRACT: We present a comparison of trends in total column ozone from 10 two-dimensional and 4 three-dimensional models and solar backscatter ultraviolet–2 (SBUV/2) satellite observations from the period 1979–2003. Trends for the past (1979–2000), the recent 7 years (1996–2003), and the future (2000–2050) are compared. We have analyzed the data using both simple linear trends and linear trends derived with a hockey stick method including a turnaround point in 1996. If the last 7 years, 1996–2003, are analyzed in isolation, the SBUV/2 observations show no increase in ozone, and most of the models predict continued depletion, although at a lesser rate. In sharp contrast to this, the recent data show positive trends for the Northern and the Southern Hemispheres if the hockey stick method with a turnaround point in 1996 is employed for the models and observations. The analysis shows that the observed positive trends in both hemispheres in the recent 7-year period are much larger than what is predicted by the models. The trends derived with the hockey stick method are very dependent on the values just before the turnaround point. The analysis of the recent data therefore depends greatly on these years being representative of the overall trend. Most models underestimate the past trends at middle and high latitudes. This is particularly pronounced in the Northern Hemisphere. Quantitatively, there is much disagreement among the models concerning future trends. However, the models agree that future trends are expected to be positive and less than half the magnitude of the past downward trends. Examination of the model projections shows that there is virtually no correlation between the past and future trends from the individual models.
Journal of Geophysical Research. 111(2006-04):D02303.
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M.Y. Danilin,
D.W. Fahey,
U. Schumann,
M.J. Prather,
J.E. Penner,
M.K.W. Ko,
D.K. Weisenstein,
C.H. Jackman,
G. Pitari,
I. Köhler, [......],
C.J. Weaver,
A.R. Douglass,
P.S. Connell,
D.E. Kinnison,
F.J. Dentener, E.L. Fleming,
T.K. Berntsen,
I.S.A. Isaksen,
J.M. Haywood,
B. Kärcher
[show abstract]
[hide abstract]
ABSTRACT: An upper limit for aircraft-produced perturbations to aerosols and gaseous exhaust products in the upper troposphere and lower stratosphere (UT/LS) is derived using the 1992 aviation fuel tracer simulation performed by eleven global atmospheric models. Key findings are that subsonic aircraft emissions: 1) have not be responsible for the observed water vapor trends at 40°N; 2) could be a significant source of soot mass near 12 km, but not at 20 km, 3) might cause a noticeable increase in the background sulfate aerosol surface area and number densities (but not mass density) near the northern mid-latitude tropopause, and 4) could provide a global, annual mean top of the atmosphere radiative forcing up to +0.006 W/m² and −0.013 W/m² due to emitted soot and sulfur, respectively.
Geophysical Research Letters. 25(1998):3947-3950.
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M. Y. Danilin,
D. W. Fahey,
U. Schumann,
M. Prather,
J. Penner,
M. K. W. Ko,
D. K. Weisenstein,
C. H. Jackman,
G. Pitari,
I. Kohler, [......],
C. J. Weaver,
A. R. Douglass,
P.S. Conell,
D. E. Kinnison,
F.J. Dentener, E. L. Fleming,
T. K. Berntsen,
I. S. A. Isaksen,
J.M. Haywood,
B. Kärcher
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S. B. Andersen,
E. C. Weatherhead,
J. Austin,
C. Brühl, E. L. Fleming,
J. de Grandpre,
V. Grewe,
I. Isaksen,
G. Pitari,
R. W. Portmann,
B. Rognerud,
J. E. Rosenfield,
D. Shindell,
S. Smyshlayev,
T. Nagashime,
G. J. M. Velders,
D. K. Weisenstein,
J. Xia
Zerefos, C.: Ozone. Proceedings of the XX Quadrennial Ozone Symposium, Kos 1-8 June 2004, Greece, Vol. I, 155-156 (2004).
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S. B. Andersen,
E. C. Weatherhead,
A. Stevermer,
J. Austin,
C. Brühl, E. L. Fleming,
J. de Grandpré,
V. Grewe,
I. Isaksen,
G. Pitari,
R. W. Portmann,
B. Rognerud,
J. E. Rosenfield,
S. Smyshlyaev,
T Nagashima,
G. J. M. Velders,
D. K. Weisenstein,
J. Xia
Journal of Geophysical Research-Atmospheres, v.111 (2006).
