scholarly journals HOCl chemistry in the Antarctic Stratospheric Vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)

2009 ◽  
Vol 9 (5) ◽  
pp. 1817-1829 ◽  
Author(s):  
T. von Clarmann ◽  
N. Glatthor ◽  
R. Ruhnke ◽  
G. P. Stiller ◽  
O. Kirner ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Potential Temperature ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
Heterogeneous Chemistry ◽  
Polar Stratospheric Clouds ◽  
Mean Values ◽  
Mixing Ratios ◽  
Atmospheric Sounding ◽  
Stratospheric Clouds

Abstract. In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km (1000 K potential temperature), where HOCl abundances are ruled by gas phase chemistry and at around 18–24 km (475–625 K), which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. This is the altitude region where in midlatitudinal and tropic atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values) are observed. After deformation and displacement of the polar vortex in the course of a major warming, ClO-rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv), exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979) rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. The measurements were compared to a model run where no polar stratospheric clouds appeared during the observation period. The fact that HOCl still was produced in the model run suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO, lower ClONO2 and earlier loss of HOCl in the measurements are attributed to ongoing heterogeneous chemistry which is not reproduced by the model. On 11 October, polar vortex mean daytime mixing ratios were only 0.03 ppbv.

scholarly journals HOCl chemistry in the Antarctic stratospheric vortex 2002, as observed with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)

2008 ◽  
Vol 8 (6) ◽  
pp. 18967-18992
Author(s):  
T. von Clarmann ◽  
N. Glatthor ◽  
R. Ruhnke ◽  
G. P. Stiller ◽  
O. Kirner ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
Heterogeneous Chemistry ◽  
Polar Stratospheric Clouds ◽  
Mean Values ◽  
Mixing Ratios ◽  
Atmospheric Sounding ◽  
Antarctic Polar Vortex ◽  
Stratospheric Clouds

Abstract. In the 2002 Antarctic polar vortex enhanced HOCl mixing ratios were detected by the Michelson Interferometer for Passive Atmospheric Sounding both at altitudes of around 35 km, where HOCl abundances are ruled by gas phase chemistry and at around 24 km, which belongs to the altitude domain where heterogeneous chlorine chemistry is relevant. At altitudes of 33 to 40 km, where in midlatitudinal and tropical atmospheres peak HOCl mixing ratios significantly above 0.2 ppbv (in terms of daily mean values) are observed, polar vortex HOCl mixing ratios were found to be around 0.14 ppbv as long as the polar vortex was intact, centered at the pole, and thus received relatively little sunlight. After deformation and displacement of the polar vortex in the course of a major warming, ClO rich vortex air was more exposed to sunlight, where enhanced HOx abundances led to largely increased HOCl mixing ratios (up to 0.3 ppbv), exceeding typical midlatitudinal and tropical amounts significantly. The HOCl increase was preceded by an increase of ClO. Model runs could reproduce these measurements only when the Stimpfle et al. (1979) rate constant for the reaction ClO+HO2→HOCl+O2 was used but not with the current JPL recommendation. At an altitude of 24 km, HOCl mixing ratios of up to 0.15 ppbv were detected. This HOCl enhancement, which is already visible in 18 September data, is attributed to heterogeneous chemistry, which is in agreement with observations of polar stratospheric clouds. Comparison with a model run where no polar stratospheric clouds appeared during the observation period suggests that a significant part of HOCl was generated from ClO rather than directly via heterogeneous reaction. Excess ClO and HOCl in the measurements is attributed to ongoing heterogeneous chemistry which is not reproduced by the model. In the following days, a decay of HOCl abundances was observed and on 11 October, polar vortex mean daytime mixing ratios were only 0.03 ppbv.

scholarly journals Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B inside the January 2010 Arctic vortex

2012 ◽  
Vol 12 (14) ◽  
pp. 6581-6592 ◽  
Author(s):  
G. Wetzel ◽  
H. Oelhaf ◽  
O. Kirner ◽  
F. Friedl-Vallon ◽  
R. Ruhnke ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Michelson Interferometer ◽  
Emission Spectra ◽  
The Arctic ◽  
Polar Stratospheric Clouds ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Reservoir Species ◽  
Stratospheric Clouds

Abstract. The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx) from reservoir species. Stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change rapidly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to polar stratospheric clouds reducing the direct radiative flux from the sun. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (below 0.1 ppbv) of the chlorine reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are well reproduced by the model during night and noon. However, the onset of ClO production and NO2 loss around the terminator in the model is not consistent with the measurements. The MIPAS-B observations along with Tropospheric Ultraviolet-Visible (TUV) radiation model calculations suggest that polar stratospheric clouds lead to a delayed start followed by a faster increase of the photodissoziation of ClOOCl and NO2 near the morning terminator since stratospheric clouds alter the direct and the diffuse flux of solar radiation. These effects are not considered in the EMAC model simulations which assume a cloudless atmosphere.

scholarly journals Total depletion of ozone reached in the 2010–2011 Arctic winter as observed by MIPAS/ENVISAT using a 2-D tomographic approach

2011 ◽  
Vol 11 (12) ◽  
pp. 33191-33227
Author(s):  
E. Arnone ◽  
E. Castelli ◽  
E. Papandrea ◽  
M. Carlotti ◽  
B. M. Dinelli
Keyword(s):  
Potential Temperature ◽  
Michelson Interferometer ◽  
The Arctic ◽  
Late Winter ◽  
Infrared Measurements ◽  
Atmospheric Sounding ◽  
Depletion Rate ◽  
Horizontal Inhomogeneity ◽  
Stratospheric Clouds ◽  
The Antarctic

Abstract. We present observations of the 2010–2011 Arctic winter stratosphere from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT. Limb sounding infrared measurements were taken by MIPAS during the Northern polar winter and into the subsequent spring, giving a continuous vertically resolved view of the Arctic dynamics, chemistry and polar stratospheric clouds (PSCs). We adopted a 2-D tomographic retrieval approach to account for the strong horizontal inhomogeneity of the atmosphere present under vortex conditions, self-consistently comparing 2011 to the 2-D analysis of 2003–2010. Unlike most Arctic winters, 2011 was characterized by a strong stratospheric vortex lasting until early April. Lower stratospheric temperatures persistently remained below the threshold for PSC formation, extending the PSC season up to mid-March, resulting in significant chlorine activation leading to ozone destruction. Through inspection of MIPAS spectra, 84% of PSCs were identified as supercooled ternary solution (STS) or STS mixed with nitric acid trihydrate (NAT), 16% formed mostly by NAT particles, and only a few by ice. In the lower stratosphere at potential temperature 450 K, vortex average ozone showed a daily depletion rate reaching 100 ppbv day−1. In early April at 18 km altitude, 10% of vortex measurements displayed total depletion of ozone, and vortex average values dropped to 0.6 ppmv. This corresponds to a chemical loss from early winter greater than 80%. Ozone loss was accompanied by activation of ClO, associated depletion of its reservoir ClONO2, and significant denitrification, which further delayed the recovery of ozone in spring. Sporadic increases of NO2 associated with evaporation of sedimenting PSCs were also observed. Once the PSC season halted, ClO was reconverted into ClONO2. Compared to MIPAS observed 2003–2010 Arctic average values, the 2010–2011 vortex in late winter had 15 K lower temperatures, 40% lower HNO3 and 50% lower ozone, reaching the largest ozone depletion ever observed in the Arctic. The overall picture of this Arctic winter was remarkably closer to conditions typically found in the Antarctic vortex than ever observed before.

scholarly journals Diurnal variations of BrONO<sub>2</sub> observed by MIPAS-B at mid-latitudes and in the Arctic

2017 ◽  
Author(s):  
Gerald Wetzel ◽  
Hermann Oelhaf ◽  
Michael Höpfner ◽  
Felix Friedl-Vallon ◽  
Andreas Ebersoldt ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Michelson Interferometer ◽  
Diurnal Variations ◽  
The Arctic ◽  
Late Winter ◽  
Mixing Ratios ◽  
Reservoir Species ◽  
Atmospheric Sounding ◽  
Stratospheric Clouds

Abstract. The first stratospheric measurements of the diurnal variation of the inorganic bromine (Bry) reservoir species BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68°N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 21 parts per trillion by volume (pptv) were detected in the late winter 2011 in the absence of polar stratospheric clouds (PSCs). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 due to low available NO2 amounts (for the build-up of BrONO2), heterogeneous destruction of BrONO2 on PSC particles, and the gas-phase interaction of BrO (the source to form BrONO2) with ClO. A further balloon flight took place at mid-latitudes from Timmins (49°N, Canada) in September 2014. Mean BrONO2 mixing ratios of 22 pptv were observed after sunset in the altitude region between 21 and 29 km. Measurements are compared and discussed with the results of a multi-year simulation performed with the chemistry climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). The calculated temporal variation of BrONO2 is in principal agreement with the balloon-borne observations. Using the nighttime simulated ratio between BrONO2 and Bry, the amount of Bry observed by MIPAS-B was estimated to about 21–25 pptv in the lower stratosphere.

scholarly journals The MIPAS HOCl climatology

2011 ◽  
Vol 11 (7) ◽  
pp. 20793-20822
Author(s):  
T. von Clarmann ◽  
B. Funke ◽  
N. Glatthor ◽  
S. Kellmann ◽  
M. Kiefer ◽  
...  
Keyword(s):  
Michelson Interferometer ◽  
Polar Vortex ◽  
Solar Proton ◽  
Proton Event ◽  
Mixing Ratios ◽  
Atmospheric Sounding ◽  
Summer Hemisphere ◽  
Activation Conditions ◽  
The Antarctic ◽  
Winter Hemisphere

Abstract. Monthly zonal mean HOCl measurements by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) are presented for the episode from June 2002 to March 2004. Highest molar mixing ratios are found at pressure levels between 6 and 2 hPa, whereby largest mixing ratios occasionally exceed 200 ppt. The mixing ratio maximum is generally at lower altitudes in the summer hemisphere than in the winter hemisphere except for chlorine activation conditions in polar vortices, where enhanced HOCl abundances are also found in the lower stratosphere. During nighttime the maximum is found at higher altitudes than during daytime. Particularly low values are found in subpolar regions in the winter hemisphere, coinciding with the mixing barrier formed by the polar vortex boundary. The Antarctic polar winter HOCl distribution in 2002, the year of the split of the southern polar vortex, resembles northern polar winters rather than other southern polar winters. Increased HOCl amounts in response to the so-called Halloween solar proton event in autumn 2003 affect the representativeness of data recorded during this particular episode. Calculations with the EMAC model reproduce the structure of the measured HOCl distribution but predict approximately 40 % less HOCl except during polar night in the mid-stratosphere where calculated HOCl mixing ratios exceed observed ones.

scholarly journals Diurnal variations of BrONO<sub>2</sub> observed by MIPAS-B at midlatitudes and in the Arctic

2017 ◽  
Vol 17 (23) ◽  
pp. 14631-14643
Author(s):  
Gerald Wetzel ◽  
Hermann Oelhaf ◽  
Michael Höpfner ◽  
Felix Friedl-Vallon ◽  
Andreas Ebersoldt ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Climate Model ◽  
Michelson Interferometer ◽  
Diurnal Variations ◽  
The Arctic ◽  
Late Winter ◽  
Mixing Ratios ◽  
Reservoir Species ◽  
Atmospheric Sounding ◽  
Stratospheric Clouds

Abstract. The first stratospheric measurements of the diurnal variation in the inorganic bromine (Bry) reservoir species BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68° N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 21 pptv (parts per trillion by volume) were detected in late winter 2011 in the absence of polar stratospheric clouds (PSCs). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 due to low available NO2 amounts (for the build-up of BrONO2), the heterogeneous destruction of BrONO2 on PSC particles, and the gas-phase interaction of BrO (the source to form BrONO2) with ClO. A further balloon flight took place at midlatitudes from Timmins (49° N, Canada) in September 2014. Mean BrONO2 mixing ratios of 22 pptv were observed after sunset in the altitude region between 21 and 29 km. Measurements are compared and discussed with the results of a multi-year simulation performed with the chemistry climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). The calculated temporal variation in BrONO2 largely reproduces the balloon-borne observations. Using the nighttime simulated ratio between BrONO2 and Bry, the amount of Bry observed by MIPAS-B was estimated to be about 21–25 pptv in the lower stratosphere.

Record springtime stratospheric ozone depletion at 80°N in 2020

2021 ◽  
Author(s):  
Ramina Alwarda ◽  
Kristof Bognar ◽  
Kimberly Strong ◽  
Martyn Chipperfield ◽  
Sandip Dhomse ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Transport Model ◽  
Stratospheric Ozone ◽  
Polar Vortex ◽  
The Arctic ◽  
Optical Absorption Spectroscopy ◽  
Chemical Transport Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds

&lt;p&gt;The Arctic winter of 2019-2020 was characterized by an unusually persistent polar vortex and temperatures in the lower stratosphere that were consistently below the threshold for the formation of polar stratospheric clouds (PSCs). These conditions led to ozone loss that is comparable to the Antarctic ozone hole. Ground-based measurements from a suite of instruments at the Polar Environment Atmospheric Research Laboratory (PEARL) in Eureka, Canada (80.05&amp;#176;N, 86.42&amp;#176;W) were used to investigate chemical ozone depletion. The vortex was located above Eureka longer than in any previous year in the 20-year dataset and lidar measurements provided evidence of polar stratospheric clouds (PSCs) above Eureka. Additionally, UV-visible zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements showed record ozone loss in the 20-year dataset, evidence of denitrification along with the slowest increase of NO&lt;sub&gt;2&lt;/sub&gt; during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO&lt;sub&gt;2&lt;/sub&gt; (chlorine reservoir species) from a Fourier transform infrared (FTIR) spectrometer showed unusually low columns that were comparable to 2011, the previous year with significant chemical ozone depletion. Record low values of HNO&lt;sub&gt;3&lt;/sub&gt; in the FTIR dataset are in accordance with the evidence of PSCs and a denitrified atmosphere. Estimates of chemical ozone loss were derived using passive ozone from the SLIMCAT offline chemical transport model to account for dynamical contributions to the stratospheric ozone budget.&lt;/p&gt;

scholarly journals Regional stratospheric warmings in the Pacific-Western Canada (PWC) sector during winter 2004/2005: implications for temperatures, winds, chemical constituents and the characterization of the Polar vortex

2008 ◽  
Vol 26 (11) ◽  
pp. 3597-3622 ◽  
Author(s):  
A. H. Manson ◽  
C. E. Meek ◽  
T. Chshyolkova
Keyword(s):  
Chemical Constituents ◽  
Thermal Characteristics ◽  
Polar Vortex ◽  
Latitudinal Gradients ◽  
Western Canada ◽  
Heterogeneous Chemistry ◽  
High Latitudes ◽  
Eastern Canada ◽  
Mixing Ratios ◽  
The Pacific

Abstract. The vortex during winter 2004/2005 was interesting for several reasons. It has been described as "cold" stratospherically, with relatively strong westerly winds. Losses of ozone until the final warming in March were considerable, and comparable to the cold 1999–2000 winter. There were also modest warming events, indicated by peaks in 10 hPa zonal mean temperatures at high latitudes, near 1 January and 1 February. Events associated with a significant regional stratospheric warming in the Pacific-Western Canada (PWC) sector then began and peaked toward the end of February, providing strong longitudinal variations in dynamical characteristics (Chshyolkova et al., 2007; hereafter C07). The associated disturbed vortex of 25 February was displaced from the pole and either elongated (upper) or split into two cyclonic centres (lower). Observations from Microwave Limb Sounder (MLS) on Aura are used here to study the thermal characteristics of the stratosphere in the Canadian-US (253° E) and Scandinavian-Europe (16° E) sectors. Undisturbed high latitude stratopause (55 km) zonal mean temperatures during the mid-winter (December–February) reached 270 K, warmer than empirical-models such as CIRA-86, suggesting that seasonal polar warming due to dynamical influences affects the high altitude stratosphere as well as the mesosphere. There were also significant stratopause differences between Scandinavia and Canada during the warming events of 1 January and 1 February, with higher temperatures near 275 K at 16° E. During the 25 February "PWC" event a warming occurred at low and middle stratospheric heights (10–30 km: 220 K at 253° E) and the stratopause cooled; while over Scandinavia-Europe the stratosphere below ~30 km was relatively cold at 195 K and the stratopause became even warmer (>295 K) and lower (~45 km). The zonal winds followed the associated temperature gradients so that the vertical and latitudinal gradients of the winds differed strongly between Scandinavia-Europe and Canada-US. The data-archive of Aura-MLS was also used to produce height versus latitude contours of ozone and related constituents, using mixing ratios (r) for ClO, N2O and HCl, for the 16° E and 253° E sectors. The Q-diagnostic was used to display the positions of the cyclonic (polar) vortex, using data from the UK Meteorological Office (MetO) analyses. ClO/HCL maxima/minima occurred on 1 February in both sectors, consistent with loss of ozone by heterogeneous chemistry. Low N2O values at high latitudes indicated that both sectors were inside the polar vortex, Time-difference plots show greater reductions in O3 in the Canadian sector. For the 25 February PWC warming event, O3-rich air from lower latitudes continued to be excluded from Europe, while O3 penetrated to at least 82° N over the Canadian sector. The contours for ClO, N2O and HCl at 16° E are consistent with continued ozone loss within the vortex during the event. Finally the thermal and chemical changes at these 16° E and 253° E sectors are placed into a hemispheric context using polar-cylindrical plots, with the following results. Firstly, the mixing ratios of O3, ClO, HNO3, HCL and the temperatures from Aura-MLS were consistent with consensus views of heterogeneous chemistry. Secondly, and consistent with the polar plots of C07, the vortices and their edges were strongly distorted during the 1 January, 1 and 25 February warming events, with sinusoidal shapes consistent with stationary planetary waves of wave-numbers 1 and 2. Thirdly, the distributions of the chemicals followed the curvatures (cyclonic and anticyclonic) of the vortex edges with O3 losses occurring at the cold cyclonic locations. During February these were over Scandinavia-Western Europe and Central-Eastern Canada. Trajectory analysis was applied to the two February warming events. For the 1 February event, the rotation time for air parcels within the peanut-shaped vortex was 3–4 days; while the O3-rich low latitude air that entered the Pacific-Western Canada sector during the 25 February event, showed no signs of becoming trapped within the highly distorted but still strong remnant of the polar vortex.

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