Photo-generated hydroxyl radicals contribute to the formation of halogen radicals leading to ozone depletion on and within polar stratospheric clouds surface

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&#176;N, 86.42&#176;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 NO2 during spring, as well as enhanced reactive halogen species (OClO and BrO). Complementary measurements of HCl and ClONO2 (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 HNO3 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.

Download Full-text

The wrong kind of snow: Polar stratospheric clouds and ozone depletion

Journal of Aerosol Science ◽

10.1016/s0021-8502(97)86848-6 ◽

1997 ◽

Vol 28 (2) ◽

pp. 337

Author(s):

A.R. MacKenzie ◽

N. Nikiforakis ◽

J. Sessler

Keyword(s):

Ozone Depletion ◽

Polar Stratospheric Clouds ◽

Stratospheric Clouds

Download Full-text

Nucleation of nitric acid hydrates in Polar Stratospheric Clouds by meteoric material

10.5194/acp-2017-816 ◽

2017 ◽

Cited By ~ 1

Author(s):

Alexander D. James ◽

James S. A. Brooke ◽

Thomas P. Mangan ◽

Thomas F. Whale ◽

John M. C. Plane ◽

...

Keyword(s):

Nitric Acid ◽

Heterogeneous Nucleation ◽

Ozone Depletion ◽

Mode Of Action ◽

Polar Stratospheric Clouds ◽

Water Ice ◽

Meteoric Smoke ◽

Polar Stratosphere ◽

Stratospheric Clouds ◽

Meteoric Material

Abstract. Heterogeneous nucleation of crystalline nitric acid hydrates in Polar Stratospheric Clouds (PSCs) enhances ozone depletion. However, the identity and mode of action of the particles responsible for nucleation remains unknown. It has been suggested that meteoric material may trigger nucleation of nitric acid trihydrate (NAT), but this has never been directly demonstrated in the laboratory. Meteoric material is present in two forms in the stratosphere, smoke which results from the ablation and re-condensation of vapours, and fragments which result from the disruption of meteoroids entering the atmosphere. Here we show that analogues of both materials have a capacity to nucleate nitric acid hydrates. In combination with estimates from a global model of the amount of meteoric smoke and fragments in the polar stratosphere we show that meteoric material probably accounts for NAT observations in early season polar stratospheric clouds in the absence of water ice.

Download Full-text

Stratospheric Aerosols, Polar Stratospheric Clouds, and Polar Ozone Depletion After the Mount Calbuco Eruption in 2015

Journal of Geophysical Research Atmospheres ◽

10.1029/2018jd028974 ◽

2018 ◽

Vol 123 (21) ◽

pp. 12,308-12,331 ◽

Cited By ~ 5

Author(s):

Yunqian Zhu ◽

Owen Brian Toon ◽

Douglas Kinnison ◽

V. Lynn Harvey ◽

Michael J. Mills ◽

...

Keyword(s):

Ozone Depletion ◽

Polar Stratospheric Clouds ◽

Stratospheric Clouds ◽

Polar Ozone ◽

Stratospheric Aerosols

Download Full-text

Nucleation of nitric acid hydrates in polar stratospheric clouds by meteoric material

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-4519-2018 ◽

2018 ◽

Vol 18 (7) ◽

pp. 4519-4531 ◽

Cited By ~ 3

Author(s):

Alexander D. James ◽

James S. A. Brooke ◽

Thomas P. Mangan ◽

Thomas F. Whale ◽

John M. C. Plane ◽

...

Keyword(s):

Nitric Acid ◽

Heterogeneous Nucleation ◽

Ozone Depletion ◽

Mode Of Action ◽

Polar Stratospheric Clouds ◽

Water Ice ◽

Meteoric Smoke ◽

Polar Stratosphere ◽

Stratospheric Clouds ◽

Meteoric Material

Abstract. Heterogeneous nucleation of crystalline nitric acid hydrates in polar stratospheric clouds (PSCs) enhances ozone depletion. However, the identity and mode of action of the particles responsible for nucleation remains unknown. It has been suggested that meteoric material may trigger nucleation of nitric acid trihydrate (NAT, or other nitric acid phases), but this has never been quantitatively demonstrated in the laboratory. Meteoric material is present in two forms in the stratosphere: smoke that results from the ablation and re-condensation of vapours, and fragments that result from the break-up of meteoroids entering the atmosphere. Here we show that analogues of both materials have a capacity to nucleate nitric acid hydrates. In combination with estimates from a global model of the amount of meteoric smoke and fragments in the polar stratosphere we show that meteoric material probably accounts for NAT observations in early season polar stratospheric clouds in the absence of water ice.

Download Full-text

Polar Stratospheric Clouds: Satellite Observations, Processes, and Role in Ozone Depletion

10.5194/egusphere-egu21-6643 ◽

2021 ◽

Author(s):

Ines Tritscher ◽

Michael C. Pitts ◽

Lamont R. Poole ◽

Thomas Peter ◽

Keyword(s):

Ozone Depletion ◽

Stratospheric Ozone ◽

Michelson Interferometer ◽

Orthogonal Polarization ◽

Polar Stratospheric Clouds ◽

Spatial And Temporal Distributions ◽

Stratospheric Clouds ◽

Polar Ozone ◽

Made In

The important role of polar stratospheric clouds (PSCs) in stratospheric ozone depletion during winter and spring at high latitudes has been known since the 1980s. However, contemporary observations by the spaceborne instruments MIPAS (Michelson Interferometer for Passive Atmospheric Sounding), MLS (Microwave Limb Sounder), and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) have brought about a comprehensive and clearer understanding of PSC spatial and temporal distributions, their conditions of existence, and the processes through which they impact polar ozone. Within the SPARC (Stratosphere-troposphere Processes And their Role in Climate) PSC initiative (PSCi), those datasets have been synthesized and discussed in depth with the result of a new vortex-wide climatology of PSC occurrence and composition. We will present our results within this vPICO together with a review of the significant progress that has been made in our understanding of PSC nucleation, related dynamical processes, and heterogeneous chlorine activation. Moreover, we have compiled different techniques for parameterizing PSCs and we will show their effects in global models.

Download Full-text

New Insights into Polar Stratospheric Clouds

Eos ◽

10.1029/2021eo215001 ◽

2021 ◽

Vol 102 ◽

Author(s):

Lamont R.

Keyword(s):

Ozone Depletion ◽

Satellite Observations ◽

Polar Stratospheric Clouds ◽

Stratospheric Clouds

New satellite observations of polar stratospheric clouds have advanced our understanding of how, when, and where they form, their composition, and their role in ozone depletion.

Download Full-text