scholarly journals Modeling Volcanic Debris Clouds

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Sarah Derouin
Keyword(s):  
Lower Stratosphere ◽  
Volcanic Cloud ◽  
Volcanic Debris ◽  
Middle Stratosphere

How does a large volcanic cloud get into the stratosphere? Scientists model how volcanic debris injected into the lower stratosphere can be lofted high into the middle stratosphere.

Organic and inorganic bromine measurements around the extratropical tropopause and lowermost stratosphere (Ex-LMS): Insights into transport pathways and total bromine 

2021 ◽  
Author(s):  
Meike Rotermund ◽  
Vera Bense ◽  
Martyn Chipperfield ◽  
Andreas Engel ◽  
Jens-Uwe Grooß ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Lower Stratosphere ◽  
Boreal Summer ◽  
Transport Modelling ◽  
Transport Pathways ◽  
Air Mass ◽  
Model Simulations ◽  
Extratropical Tropopause ◽  
Background Air ◽  
Middle Stratosphere

<p>We report on measurements of total bromine (Br<sup>tot</sup>) in the upper troposphere and lower stratosphere (UTLS) taken from the German High Altitude and LOng range research aircraft (HALO) over the North Atlantic, Norwegian Sea and north-western Europe in September/ October 2017 during the WISE (Wave-driven ISentropic Exchange) research campaign. Br<sup>tot</sup> is calculated from measured total organic bromine (Br<sup>org</sup>) (i.e., the sum of bromine contained in CH<sub>3</sub>Br, the halons and the major very short-lived brominated substances) added to inorganic bromine (Br<sub>y</sub><sup>inorg</sup>), evaluated from measured BrO and photochemical modelling. Combining these data, the weighted mean [Br<sup>tot</sup>] is 19.2 ± 1.2 ppt in the extratropical lower stratosphere (Ex-LS) of the northern hemisphere. The inferred average Br<sup>tot</sup> for the Ex-LS is slightly smaller than expected for the middle stratosphere in 2016 (~19.6 ppt (ranging from 19-20 ppt) as reported by the WMO/UNEP Assessment (2018)). However, it reflects the expected variability in Br<sup>tot</sup> in the Ex-LS due to influxes of shorter lived brominated source and product gases from different regions of entry. A closer look into Br<sup>org</sup> and Br<sub>y</sub><sup>inorg</sup> as well as simultaneously measured transport tracers (CO, N<sub>2</sub>O, ...) and an air mass lag-time tracer (SF<sub>6</sub>), suggests that a filament of air with elevated Br<sup>tot</sup> protruded into the extratropical lowermost stratosphere (Ex-LMS) from 350-385 K and between equivalent latitudes of 55-80˚N (high bromine filament – HBrF). Lagrangian transport modelling shows the multi-pathway contributions to Ex-LMS bromine. According to CLaMS air mass origin simulations, contributions to the HBrF consist of predominantly isentropic transport from the tropical troposphere (also with elevated [Br<sup>tot</sup>] = 21.6 ± 0.7 ppt) as well as a smaller contribution from an exchange across the extratropical tropopause which are mixed into the stratospheric background air. In contrast, the surrounding LS above and below the HBrF has less tropical tropospheric air, but instead additional stratospheric background air. Of the tropical tropospheric air in the HBrF, the majority is from the outflow of the Asian monsoon anticyclone and the adjacent tropical regions, which greatly influences concentrations of trace gases transported into the Ex-LMS in boreal summer and fall. The resulting increase of Br<sup>tot</sup> in the Ex-LMS and its consequences for ozone is investigated through the TOMCAT/SLIMCAT model simulations. However, more extensive monitoring of total stratospheric bromine in more aged air (i.e., in the middle stratosphere) as well as globally and seasonally is required in addition to model simulations to fully understand its impact on Ex-LMS ozone and the radiative forcing of climate.</p>

scholarly journals Decadal solar effects on temperature and ozone in the tropical stratosphere

2006 ◽  
Vol 24 (8) ◽  
pp. 2091-2103 ◽  
Author(s):  
S. Fadnavis ◽  
G. Beig
Keyword(s):  
Lower Stratosphere ◽  
Middle Atmosphere ◽  
Stratospheric Aerosol ◽  
Radiation Budget ◽  
Atmospheric Research ◽  
The Earth ◽  
Earth Radiation Budget ◽  
Earth Radiation ◽  
Good Agreement ◽  
Middle Stratosphere

Abstract. To investigate the effects of decadal solar variability on ozone and temperature in the tropical stratosphere, along with interconnections to other features of the middle atmosphere, simultaneous data obtained from the Halogen Occultation Experiment (HALOE) aboard the Upper Atmospheric Research Satellite (UARS) and the Stratospheric Aerosol and Gas Experiment II (SAGE II) aboard the Earth Radiation Budget Satellite (ERBS) during the period 1992–2004 have been analyzed using a multifunctional regression model. In general, responses of solar signal on temperature and ozone profiles show good agreement for HALOE and SAGE~II measurements. The inferred annual-mean solar effect on temperature is found to be positive in the lower stratosphere (max 1.2±0.5 K / 100 sfu) and near stratopause, while negative in the middle stratosphere. The inferred solar effect on ozone is found to be significant in most of the stratosphere (2±1.1–4±1.6% / 100 sfu). These observed results are in reasonable agreement with model simulations. Solar signals in ozone and temperature are in phase in the lower stratosphere and they are out of phase in the upper stratosphere. These inferred solar effects on ozone and temperature are found to vary dramatically during some months, at least in some altitude regions. Solar effects on temperature are found to be negative from August to March between 9 mb–3 mb pressure levels while solar effects on ozone are maximum during January–March near 10 mb in the Northern Hemisphere and 5 mb–7 mb in the Southern Hemisphere.

scholarly journals Vertical distributions of N<sub>2</sub>O isotopocules in the equatorial stratosphere

2018 ◽  
Vol 18 (2) ◽  
pp. 833-844 ◽  
Author(s):  
Sakae Toyoda ◽  
Naohiro Yoshida ◽  
Shinji Morimoto ◽  
Shuji Aoki ◽  
Takakiyo Nakazawa ◽  
...  
Keyword(s):  
High Latitude ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Mixing Ratio ◽  
Residual Circulation ◽  
Chemical Transport Model ◽  
Eastern Equatorial Pacific ◽  
Middle Stratosphere

Abstract. Vertical profiles of nitrous oxide (N2O) and its isotopocules, isotopically substituted molecules, were obtained over the Equator at altitudes of 16–30 km. Whole air samples were collected using newly developed balloon-borne compact cryogenic samplers over the eastern equatorial Pacific in 2012 and Biak Island, Indonesia, in 2015. They were examined in the laboratory using gas chromatography and mass spectrometry. The mixing ratio and isotopocule ratios of N2O in the equatorial stratosphere showed a weaker vertical gradient than the previously reported profiles in the subtropical and mid-latitude and high-latitude stratosphere. From the relation between the mixing ratio and isotopocule ratios, further distinct characteristics were found over the Equator: (1) observed isotopocule fractionations (ε values) in the middle stratosphere (25–30 km or [N2O] < ca. 260 nmol mol−1) are almost equal to ε values reported from broadband photolysis experiments conducted in the laboratory; (2) ε values in the lower stratosphere (< ca. 25 km or [N2O] > ca. 260 nmol mol−1) are about half of the experimentally obtained values, being slightly larger than those observed in the mid-latitude and high-latitude lower stratosphere ([N2O] > ca. 170 nmol mol−1). These results from the deep tropics suggest the following. (i) The timescale for quasi-horizontal mixing between tropical and mid-latitude air in the tropical middle stratosphere is sufficiently slow relative to the tropical upwelling rate that isotope fractionation approaches the Rayleigh limit for N2O photolysis. (ii) The air in the tropical lower stratosphere is exchanged with extratropical air on a timescale that is shorter than that of photochemical decomposition of N2O. Previously observed ε values, which are invariably smaller than those of photolysis, can be explained qualitatively using a three-dimensional chemical transport model and using a simple model that assumes mixing of “aged” tropical air and extratropical air during residual circulation. Results show that isotopocule ratios are useful to examine the stratospheric transport scheme deduced from tracer–tracer relations.

scholarly journals Validation of version-4.61 methane and nitrous oxide observed by MIPAS

2009 ◽  
Vol 9 (2) ◽  
pp. 413-442 ◽  
Author(s):  
S. Payan ◽  
C. Camy-Peyret ◽  
H. Oelhaf ◽  
G. Wetzel ◽  
G. Maucher ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Positive Bias ◽  
Full Resolution ◽  
Processing Facility ◽  
Satellite Sensors ◽  
Ch4 And N2o ◽  
The Individual ◽  
Instrument Processing ◽  
Internal Error ◽  
Middle Stratosphere

Abstract. The ENVISAT validation programme for the atmospheric instruments MIPAS, SCIAMACHY and GOMOS is based on a number of balloon-borne, aircraft, satellite and ground-based correlative measurements. In particular the activities of validation scientists were coordinated by ESA within the ENVISAT Stratospheric Aircraft and Balloon Campaign or ESABC. As part of a series of similar papers on other species [this issue] and in parallel to the contribution of the individual validation teams, the present paper provides a synthesis of comparisons performed between MIPAS CH4 and N2O profiles produced by the current ESA operational software (Instrument Processing Facility version 4.61 or IPF v4.61, full resolution MIPAS data covering the period 9 July 2002 to 26 March 2004) and correlative measurements obtained from balloon and aircraft experiments as well as from satellite sensors or from ground-based instruments. In the middle stratosphere, no significant bias is observed between MIPAS and correlative measurements, and MIPAS is providing a very consistent and global picture of the distribution of CH4 and N2O in this region. In average, the MIPAS CH4 values show a small positive bias in the lower stratosphere of about 5%. A similar situation is observed for N2O with a positive bias of 4%. In the lower stratosphere/upper troposphere (UT/LS) the individual used MIPAS data version 4.61 still exhibits some unphysical oscillations in individual CH4 and N2O profiles caused by the processing algorithm (with almost no regularization). Taking these problems into account, the MIPAS CH4 and N2O profiles are behaving as expected from the internal error estimation of IPF v4.61 and the estimated errors of the correlative measurements.

scholarly journals Direct inversion of circulation from tracer measurements – Part 2: Sensitivity studies and model recovery tests

2020 ◽  
Author(s):  
Thomas von Clarmann ◽  
Udo Grabowski
Keyword(s):  
Lower Stratosphere ◽  
Velocity Fields ◽  
Trace Gas ◽  
Meridional Transport ◽  
Upper Troposphere ◽  
Direct Inversion ◽  
Circulation Patterns ◽  
Sensitivity Studies ◽  
Reference Fields ◽  
Middle Stratosphere

Abstract. The direct inversion of the 2D continuity equation allows to infer the effective meridional transport of trace gases in the middle stratosphere. This methods exploits the information both given by the displacement of patterns in measured trace gas distributions and by the approximate balance between sinks and horizontal as well as vertical advection. Model recovery tests have shown that with the current setup of the algorithm, this method reliably reproduces the circulation patterns in the entire analysis domain from 6 to 66 km altitude. Due to the regularization of the inversion, velocities above about 30 km are more likely under- than overestimated. This is explained by the fact that the measured trace gas distributions at higher altitudes generally contain less information and that the regularization of the inversion pushes results towards zero. Weaker regularization would in some cases allow a more accurate recovery of the velocity fields. However, there is a price to pay in that the risk of convergence failure increases. No instance was found where the algorithm generated artificial patterns not present in the reference fields. Most information on effective velocities above 50 km is included in measurements of CH4, CO, H2O, and N2O, while CFC-11, HCFC-22, and CFC-12 constrain the inversion most efficiently in the middle stratosphere. H2O is a particularly important tracer in the upper troposphere/lower stratosphere. SF6 and CCl4 contain generally less information but still contribute to the reduction of the estimated uncertainties.

scholarly journals How does a Pinatubo‐size Volcanic Cloud Reach the Middle Stratosphere?

2021 ◽  
Author(s):  
Georgiy Stenchikov ◽  
Alexander Ukhov ◽  
Sergey Osipov ◽  
Ravan Ahmadov ◽  
Georg Grell ◽  
...  
Keyword(s):  
Volcanic Cloud ◽  
Middle Stratosphere

scholarly journals Direct inversion of circulation from tracer measurements – Part 2: Sensitivity studies and model recovery tests

2021 ◽  
Vol 21 (4) ◽  
pp. 2509-2526
Author(s):  
Thomas von Clarmann ◽  
Udo Grabowski
Keyword(s):  
Lower Stratosphere ◽  
Velocity Fields ◽  
Trace Gas ◽  
Meridional Transport ◽  
Upper Troposphere ◽  
Direct Inversion ◽  
Circulation Patterns ◽  
Sensitivity Studies ◽  
Reference Fields ◽  
Middle Stratosphere

Abstract. The direct inversion of the 2D continuity equation allows for the inference of the effective meridional transport of trace gases in the middle stratosphere. This method exploits the information given by both the displacement of patterns in measured trace gas distributions and the approximate balance between sinks and horizontal as well as vertical advection. Model recovery tests show that with the current setup of the algorithm, this method reliably reproduces the circulation patterns in the entire analysis domain from 6 to 66 km altitude. Due to the regularization of the inversion, velocities above about 30 km are more likely under- than overestimated. This is explained by the fact that the measured trace gas distributions at higher altitudes generally contain less information and that the regularization of the inversion pushes results towards 0. Weaker regularization would in some cases allow a more accurate recovery of the velocity fields, but there is a price to pay in that the risk of convergence failure increases. No instance was found where the algorithm generated artificial patterns not present in the reference fields. Most information on effective velocities above 50 km is included in measurements of CH4, CO, H2O, and N2O, while CFC-11, HCFC-22, and CFC-12 constrain the inversion most efficiently in the middle stratosphere. H2O is a particularly important tracer in the upper troposphere or lower stratosphere. SF6 and CCl4 generally contain less information but still contribute to the reduction in the estimated uncertainties. With these tests, the reliability of the method has been established.

scholarly journals Comparison of the inversion algorithms applied to the ozone vertical profile retrieval from SCIAMACHY limb measurements

2007 ◽  
Vol 7 (18) ◽  
pp. 4763-4779 ◽  
Author(s):  
A. Rozanov ◽  
K.-U. Eichmann ◽  
C. von Savigny ◽  
H. Bovensmann ◽  
J. P. Burrows ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
European Space Agency ◽  
Air Masses ◽  
Upper Troposphere ◽  
Space Agency ◽  
Lidar Measurements ◽  
Retrieval Problem ◽  
Level 1 ◽  
Ground Based Lidar ◽  
Middle Stratosphere

Abstract. This paper is devoted to an intercomparison of ozone vertical profiles retrieved from the measurements of scattered solar radiation performed by the SCIAMACHY instrument in the limb viewing geometry. Three different inversion algorithms including the prototype of the operational Level 1 to 2 processor to be operated by the European Space Agency are considered. Unlike usual validation studies, this comparison removes the uncertainties arising when comparing measurements made by different instruments probing slightly different air masses and focuses on the uncertainties specific to the modeling-retrieval problem only. The intercomparison was performed for 5 selected orbits of SCIAMACHY showing a good overall agreement of the results in the middle stratosphere, whereas considerable discrepancies were identified in the lower stratosphere and upper troposphere altitude region. Additionally, comparisons with ground-based lidar measurements are shown for selected profiles demonstrating an overall correctness of the retrievals.

scholarly journals Satellite observations and modeling of transport in the upper troposphere through the lower mesosphere during the 2006 major stratospheric sudden warming

2009 ◽  
Vol 9 (14) ◽  
pp. 4775-4795 ◽  
Author(s):  
G. L. Manney ◽  
R. S. Harwood ◽  
I. A. MacKenzie ◽  
K. Minschwaner ◽  
D. R. Allen ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Polar Vortex ◽  
Trace Gas ◽  
Transport Barrier ◽  
Stratospheric Sudden Warming ◽  
Upper Troposphere ◽  
Comprehensive Picture ◽  
Middle Stratosphere

Abstract. An unusually strong and prolonged stratospheric sudden warming (SSW) in January 2006 was the first major SSW for which globally distributed long-lived trace gas data are available covering the upper troposphere through the lower mesosphere. We use Aura Microwave Limb Sounder (MLS), Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) data, the SLIMCAT Chemistry Transport Model (CTM), and assimilated meteorological analyses to provide a comprehensive picture of transport during this event. The upper tropospheric ridge that triggered the SSW was associated with an elevated tropopause and layering in trace gas profiles in conjunction with stratospheric and tropospheric intrusions. Anomalous poleward transport (with corresponding quasi-isentropic troposphere-to-stratosphere exchange at the lowest levels studied) in the region over the ridge extended well into the lower stratosphere. In the middle and upper stratosphere, the breakdown of the polar vortex transport barrier was seen in a signature of rapid, widespread mixing in trace gases, including CO, H2O, CH4 and N2O. The vortex broke down slightly later and more slowly in the lower than in the middle stratosphere. In the middle and lower stratosphere, small remnants with trace gas values characteristic of the pre-SSW vortex lingered through the weak and slow recovery of the vortex. The upper stratospheric vortex quickly reformed, and, as enhanced diabatic descent set in, CO descended into this strong vortex, echoing the fall vortex development. Trace gas evolution in the SLIMCAT CTM agrees well with that in the satellite trace gas data from the upper troposphere through the middle stratosphere. In the upper stratosphere and lower mesosphere, the SLIMCAT simulation does not capture the strong descent of mesospheric CO and H2O values into the reformed vortex; this poor CTM performance in the upper stratosphere and lower mesosphere results primarily from biases in the diabatic descent in assimilated analyses.

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