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Recent Trends in Stratospheric Chlorine From Very Short-Lived Substances

Hossaini, Ryan; Atlas, Elliot; Dhomse, Sandip S.; Chipperfield, Martyn P.; Bernath, Peter F.; Fernando, Anton M.; Mühle, Jens; Leeson, Amber A.; Montzka, Stephen A.; Feng, Wuhu; Harrison, Jeremy J.; Krummel, Paul; Vollmer, Martin K.; Reimann, Stefan; O'Doherty, Simon; Young, Dickon; Maione, Michela; Arduini, Jgor; Lunder, Chris Rene

Very short‐lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2‐dichloroethane (C2H4Cl2), are a stratospheric chlorine source and therefore contribute to ozone depletion. We quantify stratospheric chlorine trends from these VSLS (VSLCltot) using a chemical transport model and atmospheric measurements, including novel high‐altitude aircraft data from the NASA VIRGAS (2015) and POSIDON (2016) missions. We estimate VSLCltot increased from 69 (±14) parts per trillion (ppt) Cl in 2000 to 111 (±22) ppt Cl in 2017, with >80% delivered to the stratosphere through source gas injection, and the remainder from product gases. The modeled evolution of chlorine source gas injection agrees well with historical aircraft data, which corroborate reported surface CH2Cl2 increases since the mid‐2000s. The relative contribution of VSLS to total stratospheric chlorine increased from ~2% in 2000 to ~3.4% in 2017, reflecting both VSLS growth and decreases in long‐lived halocarbons. We derive a mean VSLCltot growth rate of 3.8 (±0.3) ppt Cl/year between 2004 and 2017, though year‐to‐year growth rates are variable and were small or negative in the period 2015–2017. Whether this is a transient effect, or longer‐term stabilization, requires monitoring. In the upper stratosphere, the modeled rate of HCl decline (2004–2017) is −5.2% per decade with VSLS included, in good agreement to ACE satellite data (−4.8% per decade), and 15% slower than a model simulation without VSLS. Thus, VSLS have offset a portion of stratospheric chlorine reductions since the mid‐2000s.

2019

SuperDARN observations of semidiurnal tidal variability in the MLT and the response to sudden stratospheric warming events

Hibbins, Robert; Espy, Patrick Joseph; Orsolini, Yvan; Limpasuvan, Varavut; Barnes, Robin J.

Using meteor wind data from the Super Dual Auroral Radar Network (SuperDARN) in the Northern Hemisphere, we (1) demonstrate that the migrating (Sun‐synchronous) tides can be separated from the nonmigrating components in the mesosphere and lower thermosphere (MLT) region and (2) use this to determine the response of the different components of the semidiurnal tide (SDT) to sudden stratospheric warming (SSW) conditions. The radars span a limited range of latitudes around 60°N and are located over nearly 180° of longitude. The migrating tide is extracted from the nonmigrating components observed in the meridional wind recorded from meteor ablation drift velocities around 95‐km altitude, and a 20‐year climatology of the different components is presented. The well‐documented late summer and wintertime maxima in the semidiurnal winds are shown to be due primarily to the migrating SDT, whereas during late autumn and spring the nonmigrating components are at least as strong as the migrating SDT. The robust behavior of the SDT components during SSWs is then examined by compositing 13 SSW events associated with an elevated stratopause recorded between 1995 and 2013. The migrating SDT is seen to reduce in amplitude immediately after SSW onset and then return anomalously strongly around 10–17 days after the SSW onset. We conclude that changes in the underlying wind direction play a role in modulating the tidal amplitude during the evolution of SSWs and that the enhancement in the midlatitude migrating SDT (previously reported in modeling studies) is observed in the MLT at least up to 60°N.

2019

New insights in sources of the sub-micrometre aerosol at Mt. Zeppelin observatory (Spitsbergen) in the year 2015

Karl, Matthias; Leck, Caroline; Rad, Farshid Mashayekhy; Bäcklund, Are; Lopez-Aparicio, Susana; Heintzenberg, Jost

In order to evaluate the potential impact of the Arctic anthropogenic emission sources it is essential to understand better the natural aerosol sources of the inner Arctic and the atmospheric processing of the aerosols during their transport in the Arctic atmosphere. A 1-year time series of chemically specific measurements of the sub-micrometre aerosol during 2015 has been taken at the Mt. Zeppelin observatory in the European Arctic. A source apportionment study combined measured molecular tracers as source markers, positive matrix factorization, analysis of the potential source distribution and auxiliary information from satellite data and ground-based observations. The annual average sub-micrometre mass was apportioned to regional background secondary sulphate (56%), sea spray (17%), biomass burning (15%), secondary nitrate (5.8%), secondary marine biogenic (4.5%), mixed combustion (1.6%), and two types of marine gel sources (together 0.7%). Secondary nitrate aerosol mainly contributed towards the end of summer and during autumn. During spring and summer, the secondary marine biogenic factor reached a contribution of up to 50% in some samples. The most likely origin of the mixed combustion source is due to oil and gas extraction activities in Eastern Siberia. The two marine polymer gel sources predominantly occurred in autumn and winter. The small contribution of the marine gel sources at Mt. Zeppelin observatory in summer as opposed to regions closer to the North Pole is attributed to differences in ocean biology, vertical distribution of phytoplankton, and the earlier start of the summer season.

2019

Recent developments in screening and monitoring of airborne contaminants of emerging concern

Schlabach, Martin; Aas, Wenche; Bohlin-Nizzetto, Pernilla; Tørseth, Kjetil

2019

Results from EMEP/COLOSSAL/ACRTIS intensive measurement campaign

Platt, Stephen Matthew; Yttri, Karl Espen; Aas, Wenche

2019

Semidiurnal Tidal Perturbations During SSW in SuperDARN and WACCM

Limpasuvan, Varavut; Orsolini, Yvan; Espy, Patrick Joseph; Hibbins, Robert

2019

Evaluation of Snow Depth and Snow Cover over the Tibetan Plateau in Global Reanalyses Using In-situ and Satellite Remote Sensing Observations

Orsolini, Yvan; Wegmann, M.; Dutra, Emanuel; Liu, Boqi; Balsamo, Gianpaolo; Yang, Kun; Rosnay, Patricia de; Zhu, Congwen; Wang, Wenli; Senan, Retish

2019

Impact of medium-energy electron precipitation on ozone and middle atmosphere dynamics in WACCM simulations

Guttu, Sigmund; Orsolini, Yvan; Stordal, Frode; Limpasuvan, Varavut; Marsh, D.

2019

PFAS in ambient air - the way to ISO accredited method - Europe

Rostkowski, Pawel; Yeung, Leo; Nikiforov, Vladimir; Yamashita, Nobuyoshi

2019

Evaluation of Snow Cover and Depth over the Tibetan Plateau in Global Reanalyses Using In-situ and Satellite Remote Sensing Observations

Orsolini, Yvan; Wegmann, Martin; Dutra, E.; Rosnay, P. de; Balsamo, G.; Liu, B.; Senan, R.; Wang, W.; Yang, K.; Zhu, C.

2019

Impact of snow cover data assimilation over the Tibetan Plateau on medium range Numerical weather prediction

Rosnay, P. de; Balsamo, G.; Orsolini, Yvan; Dutra, E.; Liu, B.; Senan, R.; Wang, W.; Wegmann, Martin; Yang, K.; Zhu, C.

2019

Toxic effects and characterization of gunshot fumes from different ammunitions for small arms.

Mariussen, Espen; Fjellbø, Lise Marie; Frømyr, Tomas Roll; Johnsen, Ida Vaa; Voie, Øyvind Albert

2019

EVDC for TCCON

Fjæraa, Ann Mari

2019

Turbulent dispersion observed during the COMTESSA artificial release experiments

Dinger, Anna Solvejg; Stebel, Kerstin; Cassiani, Massimo; Ardeshiri, Hamidreza; Bernardo, Cirilo; Kylling, Arve; Park, Soon-Young; Pisso, Ignacio; Schmidbauer, Norbert; Stohl, Andreas

2019

Effects of grid resolution on Large eddy simulation of plume dispersion in a neutral boundary layer

Ardeshiri, Hamidreza; Park, Soon-Young; Cassiani, Massimo; Stohl, Andreas; Stebel, Kerstin; Pisso, Ignacio; Dinger, Anna Solvejg

2019

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