Real refractive indices of infrared-characterized nitric-acid/ice films: Implications for optical measurements of polar stratospheric clouds

1994 ◽  
Vol 99 (D12) ◽  
pp. 25655 ◽  
Author(s):  
Ann M. Middlebrook ◽  
Brian S. Berland ◽  
Steven M. George ◽  
Margaret A. Tolbert ◽  
Owen B. Toon
Keyword(s):  
Nitric Acid ◽  
Optical Measurements ◽  
Refractive Indices ◽  
Polar Stratospheric Clouds ◽  
Ice Films ◽  
Stratospheric Clouds

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

2017 ◽  
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.

scholarly journals A closer look at Arctic ozone loss and polar stratospheric clouds

2010 ◽  
Vol 10 (17) ◽  
pp. 8499-8510 ◽  
Author(s):  
N. R. P. Harris ◽  
R. Lehmann ◽  
M. Rex ◽  
P. von der Gathen
Keyword(s):  
Nitric Acid ◽  
Climate Models ◽  
Empirical Relationship ◽  
Early Spring ◽  
Aerosol Formation ◽  
Polar Stratospheric Clouds ◽  
Ozone Loss ◽  
Relationship Analysis ◽  
Near Ultraviolet ◽  
Stratospheric Clouds

Abstract. The empirical relationship found between column-integrated Arctic ozone loss and the potential volume of polar stratospheric clouds inferred from meteorological analyses is recalculated in a self-consistent manner using the ERA Interim reanalyses. The relationship is found to hold at different altitudes as well as in the column. The use of a PSC formation threshold based on temperature dependent cold aerosol formation makes little difference to the original, empirical relationship. Analysis of the photochemistry leading to the ozone loss shows that activation is limited by the photolysis of nitric acid. This step produces nitrogen dioxide which is converted to chlorine nitrate which in turn reacts with hydrogen chloride on any polar stratospheric clouds to form active chlorine. The rate-limiting step is the photolysis of nitric acid: this occurs at the same rate every year and so the interannual variation in the ozone loss is caused by the extent and persistence of the polar stratospheric clouds. In early spring the ozone loss rate increases as the solar insolation increases the photolysis of the chlorine monoxide dimer in the near ultraviolet. However the length of the ozone loss period is determined by the photolysis of nitric acid which also occurs in the near ultraviolet. As a result of these compensating effects, the amount of the ozone loss is principally limited by the extent of original activation rather than its timing. In addition a number of factors, including the vertical changes in pressure and total inorganic chlorine as well as denitrification and renitrification, offset each other. As a result the extent of original activation is the most important factor influencing ozone loss. These results indicate that relatively simple parameterisations of Arctic ozone loss could be developed for use in coupled chemistry climate models.

Coexistence of metastable nitric acid dihydrates: A molecular level contribution to understanding the formation of polar stratospheric clouds crystals

2006 ◽  
Vol 426 (1-3) ◽  
pp. 20-25 ◽  
Author(s):  
Anas Al Natsheh ◽  
Alexey B. Nadykto ◽  
Kurt V. Mikkelsen ◽  
Fangqun Yu ◽  
Juhani Ruuskanen
Keyword(s):  
Nitric Acid ◽  
Molecular Level ◽  
Polar Stratospheric Clouds ◽  
Stratospheric Clouds

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

2018 ◽  
Vol 18 (7) ◽  
pp. 4519-4531 ◽  
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.

scholarly journals Nitric Acid Trihydrate (NAT) formation at low NAT supersaturation in Polar Stratospheric Clouds (PSCs)

2005 ◽  
Vol 5 (5) ◽  
pp. 1371-1380 ◽  
Author(s):  
C. Voigt ◽  
H. Schlager ◽  
B. P. Luo ◽  
A. Dörnbrack ◽  
A. Roiger ◽  
...  
Keyword(s):  
Nitric Acid ◽  
High Altitude ◽  
Equilibrium Temperature ◽  
In Situ Measurements ◽  
The Arctic ◽  
Polar Stratospheric Clouds ◽  
Research Aircraft ◽  
Stratospheric Clouds ◽  
Polar Ozone

Abstract. A PSC was detected on 6 February 2003 in the Arctic stratosphere by in-situ measurements onboard the high-altitude research aircraft Geophysica. Low number densities (~10-4cm-3) of small nitric acid (HNO3) containing particles (d<6µm) were observed at altitudes between 18 and 20km. Provided the temperatures remain below the NAT equilibrium temperature TNAT, these NAT particles have the potential to grow further and to remove HNO3 from the stratosphere, thereby enhancing polar ozone loss. Interestingly, the NAT particles formed in less than a day at temperatures just slightly below TNAT (T>TNAT-3.1K). This unique measurement of PSC formation at extremely low NAT saturation ratios (SNAT≤10) constrains current NAT nucleation theories. We suggest, that the NAT particles have formed heterogeneously, but for certain not on ice. Conversely, meteoritic particles may be favorable candidates for triggering NAT nucleation at the observed low number densities.

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