scholarly journals Derivation of Antarctic stratospheric sulfuric acid profiles and nucleation modeling of the polar stratospheric CN layer

2016 ◽  
Author(s):  
Steffen Münch ◽  
Joachim Curtius
Keyword(s):  
Sulfuric Acid ◽  
Polar Vortex ◽  
Recent Analysis ◽  
Model Calculations ◽  
Sulfuric Acid Production ◽  
Mixing Ratios ◽  
Nucleation Model ◽  
Order Of Magnitude ◽  
The Antarctic

Abstract. Recent analysis of long-term balloon-borne measurements of Antarctic stratospheric condensation nuclei (CN) and temperature combined with global model calculations showed the wide extent of a mid stratospheric layer of new particles. Here the nucleation model SAWNUC is used to derive Antarctic stratospheric gaseous sulfuric acid profiles and to investigate the nucleation process of this CN layer. The sulfuric acid profiles were derived for an altitude range of 18–32 km between July and October by simulating air parcel trajectories that descend inside the polar vortex and calculating the sulfuric acid amount that reproduces the observations. The derived sulfuric acid concentrations (volume mixing ratios) are of the order of magnitude of 104 cm−3 (10−14) in July. In the following months the concentrations increase to about 107 cm−3 (10−11) in October. They depend strongly on the temperature because a given temperature leaves only a small sulfuric acid range to reproduce the observed magnitude of CN. Ion-induced nucleation occurs. However, while it dominates nucleation at higher temperatures it has no significant influence on the nucleation rates at lower temperatures. Preexisting particles significantly reduce nucleation at sulfuric acid mixing ratios below 1 ppt. First estimates of sulfuric acid production rates range from 0.5 to about 500 molecules cm−3 s−1. A production mechanism for gaseous sulfuric acid during the Antarctic winter seems to be necessary to fully explain the observations. The derived sulfuric acid profiles compare well with mid-latitude and Arctic sulfuric acid concentrations.

scholarly journals Nucleation modeling of the Antarctic stratospheric CN layer and derivation of sulfuric acid profiles

2017 ◽  
Vol 17 (12) ◽  
pp. 7581-7591 ◽  
Author(s):  
Steffen Münch ◽  
Joachim Curtius
Keyword(s):  
Sulfuric Acid ◽  
Nucleation And Growth ◽  
Recent Analysis ◽  
Layer Formation ◽  
Upper Limits ◽  
Nucleation Model ◽  
Charged Clusters ◽  
Order Of Magnitude ◽  
The Antarctic

Abstract. Recent analysis of long-term balloon-borne measurements of Antarctic stratospheric condensation nuclei (CN) between July and October showed the formation of a volatile CN layer at 21–27 km altitude in a background of existing particles. We use the nucleation model SAWNUC to simulate these CN in subsiding air parcels and study their nucleation and coagulation characteristics. Our simulations confirm recent analysis that the development of the CN layer can be explained with neutral sulfuric acid–water nucleation and we show that outside the CN layer the measured CN concentrations are well reproduced just considering coagulation and the subsidence of the air parcels. While ion-induced nucleation is expected as the dominating formation process at higher temperatures, it does not play a significant role during the CN layer formation as the charged clusters recombine too fast. Further, we derive sulfuric acid concentrations for the CN layer formation. Our concentrations are about 1 order of magnitude higher than previously presented concentrations as our simulations consider that nucleated clusters have to grow to CN size and can coagulate with preexisting particles. Finally, we calculate threshold sulfuric acid profiles that show which concentration of sulfuric acid is necessary for nucleation and growth to observable size. These threshold profiles should represent upper limits of the actual sulfuric acid outside the CN layer. According to our profiles, sulfuric acid concentrations seem to be below midlatitude average during Antarctic winter but above midlatitude average for the CN layer formation.

scholarly journals A multi-wavelength classification method for polar stratospheric cloud types using infrared limb spectra

2016 ◽  
Vol 9 (8) ◽  
pp. 3619-3639 ◽  
Author(s):  
Reinhold Spang ◽  
Lars Hoffmann ◽  
Michael Höpfner ◽  
Sabine Griessbach ◽  
Rolf Müller ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Michelson Interferometer ◽  
Polar Vortex ◽  
Bayesian Classifier ◽  
Solid Particles ◽  
Detection Sensitivity ◽  
Ratio Method ◽  
Transfer Model ◽  
Model Calculations ◽  
The Antarctic

Abstract. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on board the ESA Envisat satellite operated from July 2002 until April 2012. The infrared limb emission measurements represent a unique dataset of daytime and night-time observations of polar stratospheric clouds (PSCs) up to both poles. Cloud detection sensitivity is comparable to space-borne lidars, and it is possible to classify different cloud types from the spectral measurements in different atmospheric windows regions. Here we present a new infrared PSC classification scheme based on the combination of a well-established two-colour ratio method and multiple 2-D brightness temperature difference probability density functions. The method is a simple probabilistic classifier based on Bayes' theorem with a strong independence assumption. The method has been tested in conjunction with a database of radiative transfer model calculations of realistic PSC particle size distributions, geometries, and composition. The Bayesian classifier distinguishes between solid particles of ice and nitric acid trihydrate (NAT), as well as liquid droplets of super-cooled ternary solution (STS). The classification results are compared to coincident measurements from the space-borne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument over the temporal overlap of both satellite missions (June 2006–March 2012). Both datasets show a good agreement for the specific PSC classes, although the viewing geometries and the vertical and horizontal resolution are quite different. Discrepancies are observed between the CALIOP and the MIPAS ice class. The Bayesian classifier for MIPAS identifies substantially more ice clouds in the Southern Hemisphere polar vortex than CALIOP. This disagreement is attributed in part to the difference in the sensitivity on mixed-type clouds. Ice seems to dominate the spectral behaviour in the limb infrared spectra and may cause an overestimation in ice occurrence compared to the real fraction of ice within the PSC area in the polar vortex. The entire MIPAS measurement period was processed with the new classification approach. Examples like the detection of the Antarctic NAT belt during early winter, and its possible link to mountain wave events over the Antarctic Peninsula, which are observed by the Atmospheric Infrared Sounder (AIRS) instrument, highlight the importance of a climatology of 9 Southern Hemisphere and 10 Northern Hemisphere winters in total. The new dataset is valuable both for detailed process studies, and for comparisons with and improvements of the PSC parameterizations used in chemistry transport and climate models.

Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulfate soils

1996 ◽  
Vol 47 (5) ◽  
pp. 669 ◽  
Author(s):  
J Sammut ◽  
I White ◽  
MD Melville
Keyword(s):  
Sulfuric Acid ◽  
Management Options ◽  
Short Pulses ◽  
Sulfuric Acid Production ◽  
South Wales ◽  
Eastern Australia ◽  
Tidal Reach ◽  
Sulfate Soils ◽  
Floodplain Sediments

Episodic acidification (pH <5) of estuarine tributaries caused by the oxidation of sulfidic floodplain sediments is widespread in eastern Australia. Drainage and flood mitigation works promote oxidation and the export of sulfuric acid and dissolved aluminium and iron into streams. This paper examines the acidification of a tidal reach on the Richmond River, New South Wales. Acid discharge is controlled by the floodplain water balance, drainage of shallow acid groundwater, and tidal floodgate operation. Floodgates store acid waters for more than six months. Acid discharges ranged from short pulses during light rains to ~950 t of sulfuric acid in a major flood that acidified the reach for over seven weeks. Extensive iron flocs accompanied acidification and coated the benthos. The chemistry of the reach reflected mixing of acid groundwater with upland waters and showed pH-dependent enhancement or depletion of species relative to chloride. Concentrations of monomeric aluminium were over 300 times larger than local (ANZECC) guidelines and 90 km of the river were acidified after floods. The estimated rate of sulfuric acid production from the floodplain is ~300 kg ha-1 year-1 and discharge may occur for over 1000 years. Management options are considered; however, the long-term consequences of acidification of tidal reaches are unknown.

scholarly journals Spatio-temporal variations of NO<sub>y</sub> species in the northern latitudes stratosphere measured with the balloon-borne MIPAS instrument

2009 ◽  
Vol 9 (4) ◽  
pp. 1151-1163 ◽  
Author(s):  
A. Wiegele ◽  
A. Kleinert ◽  
H. Oelhaf ◽  
R. Ruhnke ◽  
G. Wetzel ◽  
...  
Keyword(s):  
Continuous Measurement ◽  
Temporal Distribution ◽  
Polar Vortex ◽  
Temporal Variations ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Northern Latitudes ◽  
Photolysis Rates ◽  
Spatio Temporal ◽  
Good Agreement

Abstract. This paper presents the spatio-temporal distribution of NOy species at altitudes between 14 and 31 km as measured with the MIPAS-B instrument on the morning of 21 March 2003 in northern Scandinavia. At lower altitudes (below about 22 km), temperature variations, the distribution of ClONO2, and the tracer N2O reveal the dynamics through the edge of the late arctic polar vortex. At higher altitudes, continuous measurement before, during, and after sunrise provides information about photochemistry illustrating the evolution of the photochemically active gases NO2 and N2O5 around sunrise. The measured temporal evolution of NO2 and N2O5 is compared to box modelling that is run along backward calculated trajectories. While the comparison of measured and modelled N2O5 reveals significant differences, there is a good agreement between the model and observations for NO2 in terms of volume mixing ratios but the simulated decrease shortly after sunrise is underestimated compared to the measurements. The differences are attributed to the photolysis rates used in the box model calculations.

scholarly journals A multi-wavelength classification method for polar stratospheric cloud types using infrared limb spectra

2016 ◽  
Author(s):  
R. Spang ◽  
L. Hoffmann ◽  
M. Höpfner ◽  
S. Griessbach ◽  
R. Müller ◽  
...  
Keyword(s):  
Climate Models ◽  
Polar Vortex ◽  
Bayesian Classifier ◽  
Solid Particles ◽  
Detection Sensitivity ◽  
Radiative Transfer Model ◽  
Ratio Method ◽  
Transfer Model ◽  
Model Calculations ◽  
The Antarctic

Abstract. The MIPAS instrument onboard the ESA Envisat satellite operated from July 2002 until April 2012. The infrared limb emission measurements represent a unique dataset of day and night observations of polar stratospheric clouds (PSCs) up to both poles. Cloud detection sensitivity is comparable to spaceborne lidars, and it is possible to classify different cloud types from the spectral measurements in different atmospheric windows regions. Here we present a new PSC classification scheme based on the combination of a well-established two-colour ratio method and multiple 2D brightness temperature difference probability density functions. The method is a simple probabilistic classifier based on Bayes' theorem with a strong independence assumption. The method has been tested in conjunction with a database of radiative transfer model calculations of realistic PSC particle size distributions, geometries, and composition. The Bayesian classifier distinguishes between solid particles of ice and nitric acid trihydrate (NAT), as well as liquid droplets of super-cooled ternary solution (STS). The classification results are compared to coincident measurements from the space borne lidar CALIOP instrument over the temporal overlap of both satellite missions (June 2006 to March 2012). Both datasets show a good agreement for the specific PSC classes, although the viewing geometries, vertical and horizontal resolution are quite different. Discrepancies are observed for the MIPAS ice class. The Bayesian classifier for MIPAS identifies substantially more ice clouds in the southern hemisphere polar vortex than CALIOP. This disagreement is attributed in parts to the difference in the sensitivity on mixed-type clouds. Ice seems to dominate the spectral behaviour in the limb infrared spectra and may cause an overestimation in ice occurrence compared to the real fraction of ice within the PSC area in the polar vortex. The entire MIPAS measurement period was processed with the new classification approach. Examples like the detection of the Antarctic NAT belt during early winter, and its possible link to mountain wave events over the Antarctic Peninsula, which are observed by the AIRS instrument, are highlighting the importance of a climatology of in total 9 southern and 10 northern hemisphere winters. The new dataset is valuable both for detailed process studies, and for comparisons with and improvements of the PSC parameterisations used in chemistry transport and climate models.

Comparison of northern hemispheric and southern hemispheric Mean Age derived from in situ tracer measurements during POLSTRACC and SouthTRAC

2021 ◽  
Author(s):  
Thomas Wagenhäuser ◽  
Markus Jesswein ◽  
Timo Keber ◽  
Tanja Schuck ◽  
Andreas Engel
Keyword(s):  
Southern Hemisphere ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Transport Processes ◽  
Trace Gas ◽  
Model Calculations ◽  
Mixing Ratios ◽  
The Mean ◽  
Gas Measurements

&lt;p&gt;The mean age of air is a powerful diagnostic tool to investigate stratospheric transport processes. It can be derived from suitable trace gas measurements and from model calculations. In contrast to the Northern Hemisphere (NH), data coverage of in situ measurements of such trace gases in the Southern Hemisphere (SH) is sparse. Due to its tropospheric trend and its very long atmospheric lifetime, SF&lt;sub&gt;6 &lt;/sub&gt;is such a suitable trace gas. SF&lt;sub&gt;6&lt;/sub&gt; mixing ratios were measured with an airborne in situ GC-ECD system during several HALO aircraft campaigns, including locations in the SH polar vortex.&lt;/p&gt;&lt;p&gt;Here we present the mean age derived from in situ SF&lt;sub&gt;6&lt;/sub&gt; measurements during the POLSTRACC campaign (Polar Stratosphere in a Changing Climate) in NH winter/spring 2015/2016 and during the SouthTRAC campaign (Transport and Composition of the Southern Hemisphere UTLS) in SH winter/spring 2019. Mean age values over 4 years were observed in both polar vortices. On average, higher mean age values were observed at lower levels of potential temperature during SouthTRAC 2019 than during POLSTRACC 2015/2016. The findings will be discussed in context of the Brewer-Dobson circulation.&lt;/p&gt;

scholarly journals H<sub>2</sub>SO<sub>4</sub> and particle production in a photolytic flow reactor: chemical modeling, cluster thermodynamics and contamination issues

2019 ◽  
Vol 19 (14) ◽  
pp. 8999-9015 ◽  
Author(s):  
David R. Hanson ◽  
Hussein Abdullahi ◽  
Seakh Menheer ◽  
Joaquin Vences ◽  
Michael R. Alves ◽  
...  
Keyword(s):  
Water Vapor ◽  
Sulfuric Acid ◽  
Particle Production ◽  
Flow Reactor ◽  
Particle Formation ◽  
Particle Number Density ◽  
Single Digit ◽  
Chemical Modeling ◽  
Sulfuric Acid Production ◽  
Mixing Ratios

Abstract. Size distributions of particles formed from sulfuric acid (H2SO4) and water vapor in a photolytic flow reactor (PhoFR) were measured with a nanoparticle mobility sizing system. Experiments with added ammonia and dimethylamine were also performed. H2SO4(g) was synthesized from HONO, sulfur dioxide and water vapor, initiating OH oxidation by HONO photolysis. Experiments were performed at 296 K over a range of sulfuric acid production levels and for 16 % to 82 % relative humidity. Measured distributions generally had a large-particle mode that was roughly lognormal; mean diameters ranged from 3 to 12 nm and widths (lnσ) were ∼0.3. Particle formation conditions were stable over many months. Addition of single-digit pmol mol−1 mixing ratios of dimethylamine led to very large increases in particle number density. Particles produced with ammonia, even at 2000 pmol mol−1, showed that NH3 is a much less effective nucleator than dimethylamine. A two-dimensional simulation of particle formation in PhoFR is also presented that starts with gas-phase photolytic production of H2SO4, followed by kinetic formation of molecular clusters and their decomposition, which is determined by their thermodynamics. Comparisons with model predictions of the experimental result's dependency on HONO and water vapor concentrations yield phenomenological cluster thermodynamics and help delineate the effects of potential contaminants. The added-base simulations and experimental results provide support for previously published dimethylamine–H2SO4 cluster thermodynamics and provide a phenomenological set of ammonia–sulfuric acid thermodynamics.

scholarly journals The Antarctic ozone hole during 2014

2019 ◽  
Vol 69 (1) ◽  
pp. 1
Author(s):  
Paul B. Krummel ◽  
Andrew R. Klekociuk ◽  
Matthew B. Tully ◽  
H. Peter Gies ◽  
Simon P. Alexander ◽  
...  
Keyword(s):  
Polar Vortex ◽  
Ultra Violet ◽  
Ozone Hole ◽  
Ultra Violet Radiation ◽  
Hole Making ◽  
Antarctic Ozone ◽  
The Antarctic ◽  
Violet Radiation ◽  
Antarctic Ozone Hole

We review the 2014 Antarctic ozone hole, making use of a variety of ground-based and space-based measurements of ozone and ultra-violet radiation, supplemented by meteorological reanalyses. Although the polar vortex was relatively stable in 2014 and persisted some weeks longer into November than was the case in 2012 or 2013, the vortex temperature was close to the long-term mean in September and October with modest warming events occurring in both months, preventing severe depletion from taking place. Of the seven metrics reported here, all were close to their respective median values of the 1979–2014 record, being ranked between 16th and 21st of the 35 years for which adequate satellite observations exist.

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 Near‐Complete Local Reduction of Arctic Stratospheric Ozone by Severe Chemical Loss in Spring 2020

2021 ◽  
Author(s):  
Ingo Wohltmann ◽  
Peter von der Gathen ◽  
Ralph Lehmann ◽  
Marion Maturilli ◽  
Holger Deckelmann ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Polar Vortex ◽  
Ozone Loss ◽  
Mixing Ratios ◽  
Local Reduction ◽  
Slow Decline ◽  
Antarctic Ozone ◽  
Ozone Depleting Substances ◽  
Individual Profiles ◽  
The Antarctic

&lt;p&gt;In the Antarctic ozone hole, ozone mixing ratios have been decreasing to extremely low values of 0.01&amp;#8211;0.1 ppm in nearly all spring seasons since the late 1980s, corresponding to 95&amp;#8211;99% local chemical loss. In contrast, Arctic ozone loss has been much more limited and mixing ratios have never before fallen below 0.5 ppm. In Arctic spring 2020, however, ozonesonde measurements in the most depleted parts of the polar vortex show a highly depleted layer, with ozone loss averaged over sondes peaking at 93% at 18 km. Typical minimum mixing ratios of 0.2 ppm were observed, with individual profiles showing values as low as 0.13 ppm (96% loss). The reason for the unprecedented chemical loss was an unusually strong, long-lasting, and cold polar vortex, showing that for individual winters the effect of the slow decline of ozone-depleting substances on ozone depletion may be counteracted by low temperatures.&lt;/p&gt;

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