Volcanic aerosol and polar stratospheric clouds in the winter 1992/93 North Polar vortex

1994 ◽  
Vol 21 (1) ◽  
pp. 61-64 ◽  
Author(s):  
James M. Rosen ◽  
N. T. Kjome ◽  
H. Fast ◽  
N. Larsen
Keyword(s):  
Polar Vortex ◽  
Volcanic Aerosol ◽  
Polar Stratospheric Clouds ◽  
North Polar ◽  
North Polar Vortex ◽  
Stratospheric Clouds

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

<p>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°N, 86.42°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<sub>2</sub> during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO<sub>2</sub> (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<sub>3</sub> 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.</p>

A 3D simulation of the early winter distribution of reactive chlorine in the north polar vortex

1993 ◽  
Vol 20 (12) ◽  
pp. 1271-1274 ◽  
Author(s):  
A. Douglass ◽  
R. Rood ◽  
J. Waters ◽  
L. Froidevaux ◽  
W. Read ◽  
...  
Keyword(s):  
Polar Vortex ◽  
3D Simulation ◽  
Early Winter ◽  
The North ◽  
Winter Distribution ◽  
North Polar ◽  
North Polar Vortex

A three-dimensional model comparison of PSC processing during the Arctic winters of 1991/1992 and 1992/1993

1994 ◽  
Vol 12 (4) ◽  
pp. 342-354 ◽  
Author(s):  
M. P. Chipperfield
Keyword(s):  
Model Comparison ◽  
Transport Model ◽  
Three Dimensional ◽  
Polar Vortex ◽  
The Arctic ◽  
Three Dimensional Model ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Stratospheric Clouds ◽  
Compare And Contrast

Abstract. A three-dimensional transport model has been used to compare and contrast the extent of processing by polar stratospheric clouds during the northern hemisphere winters of 1991/1992 and 1992/1993. The model has also been used to compare the potential for ozone loss between these two winters. The TOMCAT off-line model is forced using meteorological analyses from the ECMWF. During winter 1992/1993 polar stratospheric clouds (PSCs) in the model persisted into late February/early March, which is much later than in 1991/1992. This persistence of PSCs should have resulted in much more ozone loss in the later winter. Interestingly, however, the extent of PSC processing and ozone loss was greater in January 1992 than January 1993. In January 1992 PSCs occurred at the edge of a distorted polar vortex whilst in January 1993 the PSCs were located at the centre of a much more zonally symmetrical vortex. In March 1993, distortions of the vortex led to the tearing off of vortex air and its mixing into midlatitudes.

Has the stratospheric HCl in the Northern Hemisphere been increasing since 2005

2020 ◽  
Author(s):  
Yuanyuan Han ◽  
Wenshou Tian ◽  
Fei Xie
Keyword(s):  
Northern Hemisphere ◽  
Linear Trend ◽  
Polar Vortex ◽  
Joint Effect ◽  
Residual Circulation ◽  
Quasi Biennial Oscillation ◽  
Middle Latitudes ◽  
North Polar ◽  
North Polar Vortex ◽  
Biennial Oscillation

<p>Stratospheric hydrogen chloride (HCl) is the main stratospheric reservoir of chlorine, deriving from the decomposition of chlorine-containing source gases. Its trend has been used as a metrics of ozone depletion or recovery. Using the latest satellite observations, the authors find that a significant increase of Northern Hemisphere stratospheric HCl during 2010–2011 can mislead trends of HCl in recent decades. Agree with previous studies, HCl increased from 2005 to 2011; while when removing the large increase of stratospheric HCl during 2010–2011, the increasing linear trend from 2005 to 2011 becomes weak and insignificant, in addition, the linear trend of Northern Hemisphere stratospheric HCl from 2005 to 2016 also shows weak and insignificant. The significant increase of HCl during 2010–2011 is attributed to a super strong north polar vortex and a reduced residual circulation during 2010–2011, which slowed down the transport of HCl from the low–mid latitudes to the high latitudes, leading to accumulation of HCl in the middle latitudes of the stratosphere during 2010–2011. Further analysis suggests that the strong polar vortex and the reduced residual circulation were caused by the joint effect of a La Niña event and the west phase of the quasi-biennial oscillation.</p>

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 Simultaneous occurrence of polar stratospheric clouds and upper-tropospheric clouds caused by blocking anticyclones

2012 ◽  
Vol 12 (8) ◽  
pp. 20007-20032
Author(s):  
M. Kohma ◽  
K. Sato
Keyword(s):  
Polar Vortex ◽  
Simultaneous Occurrence ◽  
Polar Stratospheric Clouds ◽  
Stratospheric Polar Vortex ◽  
Height Range ◽  
Blocking High ◽  
Ternary Solutions ◽  
Tall Structure ◽  
Stratospheric Clouds ◽  
Lidar Observations

Abstract. This study statistically examines the simultaneous appearance of polar stratospheric clouds (PSCs) and upper tropospheric clouds (UCs) using satellite lidar observations for five austral winters of 2007–2011. The time series of PSC occurrence in the height range of 15–25 km are significantly correlated with those of UC in 9–11 km. The UCs observed simultaneously with PSCs reported in previous case studies are possibly located around and slightly above the tropopause (~7–8 km) rather than in the troposphere. It is shown that the simultaneous occurrence of PSCs and UCs is frequently associated with blocking highs having large horizontal scales (several thousand kilometers) and tall structure (up to a~height of ~15 km). The longitudinal variation of blocking high frequency accords well with that of the simultaneous occurrence frequency of PSCs and UCs. This coincidence is clearer when the analysis is limited to the latitudinal regions inside the stratospheric polar vortex. This fact suggests that the blocking highs provide a~preferable condition for the simultaneous occurrence of PSCs and UCs. Moreover, PSC compositions are investigated as a~function of relative-longitude of the anticyclones including blocking highs. It is seen that relatively high proportions of STS (super-cooled ternary solutions), Ice, and Mix2 (mixture of nitric acid trihydrate and STS) types are distributed to windward of, around, and to leeward of the anticyclones in the westerly background flows, respectively.

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