C6H6 condensation on Titan’s stratospheric aerosols: An integrated laboratory, modeling and experimental approach

2019 ◽  
Vol 15 (S350) ◽  
pp. 189-192
Author(s):  
David Dubois ◽  
Ella Sciamma-O’Brien ◽  
Laura T. Iraci ◽  
Erika Barth ◽  
Farid Salama ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Experimental Approach ◽  
Polar Regions ◽  
Spectral Features ◽  
South Pole ◽  
Laboratory Modeling ◽  
Spectral Signatures ◽  
Cassini Mission ◽  
Stratospheric Clouds ◽  
Observational Effort

AbstractSaturn’s moon Titan was explored by the Cassini mission for nearly 13 years. Important discoveries made during the Cassini mission include the observations of stratospheric clouds in Titan’s cold polar regions in which spectral features or organic molecules were detected in the infrared (<100 μm). In particular, benzene (C6H6) ice spectral signatures were recently detected at unexpectedly high altitudes over the South Pole. The combined experimental, modeling and observational effort presented here has been devised and executed in order to interpret these high altitude benzene observations. Our multi-disciplinary approach aims to understand and characterize the microphysics of benzene clouds in Titan’s South Pole.

scholarly journals Lidar observations of polar stratospheric clouds at the South Pole: 2. Stratospheric perturbed conditions, 1992 and 1993

1997 ◽  
Vol 102 (D11) ◽  
pp. 12945-12955 ◽  
Author(s):  
Marco Cacciani ◽  
Paola Colagrande ◽  
Alcide di Sarra ◽  
Daniele Fuà ◽  
Paolo Di Girolamo ◽  
...  
Keyword(s):  
South Pole ◽  
The South ◽  
Polar Stratospheric Clouds ◽  
Stratospheric Clouds ◽  
Lidar Observations

Evolution of Titan’s stratosphere with Cassini/CIRS

2021 ◽  
Author(s):  
Athena Coustenis ◽  
Donald Jennings ◽  
Richard Achterberg ◽  
Panayotis Lavvas ◽  
Conor Nixon ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Species ◽  
Far Infrared ◽  
Organic Content ◽  
Large Temperature ◽  
Neutral Atmosphere ◽  
South Pole ◽  
The South ◽  
The North ◽  
Cassini Mission

&lt;p&gt;Titan is a unique body in the solar system in particular because of its earth-like surface features, its putative undersurface liquid water ocean and its large organic content in the atmosphere and on the surface . These chemical species evolve with season, as Titan follows Saturn in its orbit around the Sun with an inclination of about 27&amp;#176;. We performed an analysis of spectra acquired by Cassini/CIRS at high resolution covering the range from 10 to 1500 cm&lt;sup&gt;-1&lt;/sup&gt; since the beginning and until the last flyby of Titan in 2017 and describe the temperature and composition variations ([1-3]. By applying our radiative transfer code (ARTT) to the high-resolution CIRS spectra we study the stratospheric evolution over almost two Titan seasons [1,2]. CIRS nadir and limb spectral together show variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE) and also during one Titan year.&lt;/p&gt;&lt;p&gt;Since the 2010 equinox we have thus reported on monitoring of Titan&amp;#8217;s stratosphere near the poles and in particular on the observed strong temperature decrease and compositional enhancement above Titan&amp;#8217;s southern polar latitudes since 2012 and until 2014 of several trace species, such as complex hydrocarbons and nitriles, which were previously observed only at high northern latitudes. This effect followed the transition of Titan&amp;#8217;s seasons from northern winter in 2002 to northern summer in 2017, while at that latter time the southern hemisphere was entering winter.&lt;/p&gt;&lt;p&gt;Our data show a continued decrease of the abundances which we first reported to have started in 2015. The 2017 data we have acquired and analyzed here are important because they are the only ones recorded since 2014 close to the south pole in the far-infrared nadir mode at high resolution. A large temperature increase in the southern polar stratosphere (by 10-50 K in the 0.5 mbar-0.05 mbar pressure range) is found and a change in the temperature profile&amp;#8217;s shape. The 2017 observations also show a related significant decrease in most of the abundances which must have started sometime between 2014 and 2017 [3]. In our work, we show that the equatorial latitudes remain rather constant throughout the Cassini mission.&lt;/p&gt;&lt;p&gt;We have thus shown that the south pole of Titan is now losing its strong enhancement, while the north pole also slowly continues its decrease in gaseous opacities. It would have been interesting to see when this might happen, but the Cassini mission ended in September 2017. Perhaps future ground-based measurements and the Dragonfly mission can pursue this investigation and monitor Titan&amp;#8217;s atmosphere to characterize the seasonal events. Our results set constraints on GCM and photochemical models.&lt;/p&gt;&lt;p&gt;References:&lt;/p&gt;&lt;p&gt;&amp;#160;[1] Coustenis et al., 2016, Icarus 270, 409-420; [2] Coustenis et al., 2018, Astroph. J., Lett., 854, no2; [3] Coustenis et al., 2020. Titan&amp;#8217;s neutral atmosphere seasonal variations up to the end of the Cassini mission. Icarus 344, 113413. https://doi.org/10.1016/j.icarus.2019.113413.&lt;/p&gt;

The Infrared Spectral Signatures of Disease: Extracting the Distinguishing Spectral Features between Normal and Diseased States

2009 ◽  
Vol 63 (11) ◽  
pp. 307A-318A ◽  
Author(s):  
Max Diem ◽  
Kostas Papamarkakis ◽  
Jennifer Schubert ◽  
Benjamin Bird ◽  
Melissa J. Romeo ◽  
...  
Keyword(s):  
Spectral Features ◽  
Spectral Signatures ◽  
Infrared Spectral

Stratospheric clouds at south pole during 1988 1. Results of lidar observations and their relationship to temperature

1992 ◽  
Vol 97 (D5) ◽  
pp. 5939 ◽  
Author(s):  
Giorgio Fiocco ◽  
Marco Cacciani ◽  
Paolo Di Girolamo ◽  
Daniele Fuà ◽  
John Deluisi
Keyword(s):  
South Pole ◽  
Stratospheric Clouds ◽  
Lidar Observations

10 years of Polar Stratospheric Clouds lidar measurements at the French antarctic station Dumont d’Urville

2020 ◽  
Author(s):  
Florent Tencé ◽  
Julien Jumelet ◽  
Alain Sarkissian ◽  
Slimane Bekki ◽  
Philippe Keckhut
Keyword(s):  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Polar Regions ◽  
Primary Role ◽  
Atmospheric Conditions ◽  
Polar Stratospheric Clouds ◽  
Ice Clouds ◽  
Yearly Average ◽  
Lidar Measurements ◽  
Stratospheric Clouds

&lt;p&gt;&lt;span&gt;Polar Stratospheric Clouds (PSCs) play a primary role in polar stratospheric ozone depletion processes. &lt;/span&gt;&lt;span&gt;Aside from recent improvements in both spaceborne PSCs monitoring as well as investigations on PSCs microphysics and modeling, there are still uncertainties associated to solid particle formation and their denitrification potential. In that regard, groundbased instruments deliver detailed and valuable measurements that complement the global spaceborne coverage.&lt;/span&gt;&lt;/p&gt;&lt;p&gt;Operated since 1989 at the French antarctic station Dumont d&amp;#8217;Urville (DDU) in the frame of the international Network for the Detection of Atmospheric Composition Change (NDACC), the Rayleigh/Mie/Raman lidar provides over the years a solid dataset to feed both process and classification studies, by monitoring cloud and aerosol occurrences in the upper troposphere and lower stratosphere. Located on antarctic shore (66&amp;#176;S - 140&amp;#176;E), the station has a privileged access to polar vortex dynamics. Measurements are weather-dependent with a yearly average of 130 nights of monitoring. Expected PSC formation temperatures are used to evaluate the whole PSC season occurrences.&lt;/p&gt;&lt;p&gt;We hereby present a consolidated dataset from 10 years of lidar measurements using the 532nm backscatter ratio, the aerosol depolarisation and local atmospheric conditions to help in building an aerosol/cloud classification. Using the different PSC classes and associated optical properties thresholds established in the recent PSC CALIOP classification, we build a picture of the 2007-2019 events, from march to october.&lt;/p&gt;&lt;p&gt;Overall, the DDU PSC pattern is very consistent with expected typical temperature controlled microphysical calculations. Outside of background sulfate aerosols and anomalies related to volcanic activity (like in 2015), Supercooled Ternary Solution (STS) particles are the most observed particle type, closely followed by Nitric Acid Trihydrate (NAT). ICE clouds are less but regularly observed. ICE clouds also have to be cleary separated from cirrus clouds, raising the issue of accurate dynamics tropopause calculations.&lt;/p&gt;&lt;p&gt;&lt;span&gt;Validation of the spaceborne measurements as well as multiple signatures of volcanic or even biomass originated aerosol plumes strengthens the need for groundbased monitoring &lt;/span&gt;&lt;span&gt;especially in polar regions where instrumental facilities remain sparse.&lt;/span&gt;&lt;/p&gt;

scholarly journals Spatio-temporal variations of nitric acid total columns from 9 years of IASI measurements – a driver study

2018 ◽  
Vol 18 (7) ◽  
pp. 4403-4423 ◽  
Author(s):  
Gaétane Ronsmans ◽  
Catherine Wespes ◽  
Daniel Hurtmans ◽  
Cathy Clerbaux ◽  
Pierre-François Coheur
Keyword(s):  
Time Series ◽  
Temporal Variations ◽  
Major Influence ◽  
P Value ◽  
Spatial And Temporal Variability ◽  
Good Representation ◽  
Polar Regions ◽  
Polar Stratospheric Clouds ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Clouds

Abstract. This study aims to understand the spatial and temporal variability of HNO3 total columns in terms of explanatory variables. To achieve this, multiple linear regressions are used to fit satellite-derived time series of HNO3 daily averaged total columns. First, an analysis of the IASI 9-year time series (2008–2016) is conducted based on various equivalent latitude bands. The strong and systematic denitrification of the southern polar stratosphere is observed very clearly. It is also possible to distinguish, within the polar vortex, three regions which are differently affected by the denitrification. Three exceptional denitrification episodes in 2011, 2014 and 2016 are also observed in the Northern Hemisphere, due to unusually low arctic temperatures. The time series are then fitted by multivariate regressions to identify what variables are responsible for HNO3 variability in global distributions and time series, and to quantify their respective influence. Out of an ensemble of proxies (annual cycle, solar flux, quasi-biennial oscillation, multivariate ENSO index, Arctic and Antarctic oscillations and volume of polar stratospheric clouds), only the those defined as significant (p value < 0.05) by a selection algorithm are retained for each equivalent latitude band. Overall, the regression gives a good representation of HNO3 variability, with especially good results at high latitudes (60–80 % of the observed variability explained by the model). The regressions show the dominance of annual variability in all latitudinal bands, which is related to specific chemistry and dynamics depending on the latitudes. We find that the polar stratospheric clouds (PSCs) also have a major influence in the polar regions, and that their inclusion in the model improves the correlation coefficients and the residuals. However, there is still a relatively large portion of HNO3 variability that remains unexplained by the model, especially in the intertropical regions, where factors not included in the regression model (such as vegetation fires or lightning) may be at play.

Satellite-borne measurements of middle-atmosphere composition

1987 ◽  
Vol 323 (1575) ◽  
pp. 545-565 ◽  
Keyword(s):  
Satellite Data ◽  
Middle Atmosphere ◽  
Transport Processes ◽  
Polar Regions ◽  
Polar Night ◽  
Data Set ◽  
The North ◽  
Heterogeneous Processes ◽  
Stratospheric Clouds ◽  
Odd Nitrogen

A number of satellite experiments have been launched in recent years with the goal of providing fundamental data needed for analysis of photochemistry, radiation, dynamics, and transport processes. Collectively, these experiments have accumulated information on the vertical and horizontal distributions of a host of minor constituents in the middle atmosphere. The combined satellite data set includes new global measurements of O 3 , NO 2 , N 2 O , HNO 3 , CH 4 , H 2 O, and aerosols, and more-limited data on CO, N 2 O 5 , CIONO 2 , HNO 4 , COF 2 , and CH 3 CI. These data have provided descriptions of (1) the geographic extent and year-to-year change in the recently discovered Antarctic ozone hole; (2) interannual variability in N 2 O and CH 4 ; (3) the winter high latitude NO 2 ‘cliff’; (4) exchange of NO 2 from the mesosphere to the stratosphere during polar night; (5) a lower limit total odd nitrogen distribution that displays a maximum that exceeds model calculated values; (6) variations in the newly discovered polar stratospheric clouds (PSCS) seen in the north and south polar regions; and (7) details of latitudinal and temporal aerosol variability. The existing satellite data set is deficient in certain key measurements including OH, HO2 , H 2 O 2 , polar night N 2 O 5 , radiatively important aerosol properties, and simultaneous measurements of aerosols and gases involved in heterogeneous processes.

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