Atmospheric Halos and the Search for Angle x

Tape, Walter; Moilanen, Jarmo

doi:10.1029/sp058

Cited by 35 publications

(25 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Nighttime cooling may then form small ice particles and pollution may also produce increased numbers of ice nuclei that could increase the number and decrease the size of ice particles as well as modify the chemical nature of their surface by presenting soluble impurities to the atmosphere. Suspended ice particles are ubiquitous in the atmosphere at high latitudes and are responsible for halos, ice pillars, and other well-known optical phenomena (Tape, 2006). The ubiquity of ice, both as suspended particles and in snowpack, may indicate that cold plumes are "self-scrubbing" of nitrogen oxides through an N 2 O 5 heterogeneous hydrolysis pathway that uses ice as the reactive surface.…”

Section: Discussionmentioning

confidence: 99%

The role of ice in N2O5 heterogeneous hydrolysis at high latitudes

2008

View full text Add to dashboard Cite

Abstract. We report evidence for ice catalyzing N 2 O 5 heterogeneous hydrolysis from a study conducted near Fairbanks, Alaska in November 2007. Mixing ratios of N 2 O 5 , NO, NO 2 , and ozone are reported and are used to determine steady state N 2 O 5 lifetimes. When air masses are subsaturated with respect to ice, the data show longer lifetimes (≈20 min) and elevated N 2 O 5 levels, while ice-saturated air masses show shorter lifetimes (≈6 min) and suppressed N 2 O 5 levels. We also report estimates of aerosol surface area densities that are on the order of 50 µm 2 /cm 3 , a surface area density that is insufficient to explain the rapid losses of N 2 O 5 observed in this study, reinforcing the importance of other reactive surfaces such as ice. Consideration of two possible responsible types of ice surfaces, the snowpack and suspended ice particles, indicates that both are reasonable as possible sinks for N 2 O 5 . Because ice-saturated conditions are ubiquitous in high latitudes, ice surfaces are likely to be a key loss of N 2 O 5 , leading to nitric acid production and loss of NO x in high latitude plumes.

show abstract

Section: Discussionmentioning

confidence: 99%

The role of ice in N2O5 heterogeneous hydrolysis at high latitudes

2008

View full text Add to dashboard Cite

show abstract

“…Formation of circumscribed halos, such as 221 and 461 halos, is caused by the interaction between sunlight and randomly oriented hexagonal ice crystals. As summarized in Tape and Moilanen [6], the first person who explained that circumscribed halos are due to ice crystals in the atmosphere was René Descartes in 1637, although he did not suggest the proper shape of ice crystals forming halos. In 1662, Christiaan Huygens proposed a shape of a transparent sphere with an opaque spherical core to explain the 221 halo.…”

Section: Introductionmentioning

confidence: 98%

Formation of atmospheric halos and applicability of geometric optics for calculating single-scattering properties of hexagonal ice crystals: Impacts of aspect ratio and ice crystal size

McFarquhar

2015

Journal of Quantitative Spectroscopy and Radiative Transfer

View full text Add to dashboard Cite

“…The early ray-tracing studies focused on the case of pristine hexagonal ice plates and columns that were solid ice particles with smooth faces (e.g., Takano and Jayaweera 1985;Takano and Liou 1989;Rockwitz 1989;Hess and Wiegner 1994). Such pristine particles are found in the Antarctic atmosphere (Tape 1994), but elsewhere more complex particles are common. Later, the single-scattering characteristics associated with complex habits, such as bullet rosettes, hollow columns, polycrystals, aggregates, and clusters (or aggregates) of bullet rosettes, were investigated using the ray-tracing technique (e.g., Macke 1993;Macke et al 1996b;Takano and Liou 1995;Iaquinta et al 1995;Yang and Liou 1998;Zhang et al 2004;Um and McFarquhar 2007).…”

Section: Introductionmentioning

confidence: 98%

Effect of Cavities on the Optical Properties of Bullet Rosettes: Implications for Active and Passive Remote Sensing of Ice Cloud Properties

Yang

Zhang

Kattawar

et al. 2008

Journal of Applied Meteorology and Climatology

View full text Add to dashboard Cite

Bullet rosette particles are common in ice clouds, and the bullets may often be hollow. Here the singlescattering properties of randomly oriented hollow bullet rosette ice particles are investigated. A bullet, which is an individual branch of a rosette, is defined as a hexagonal column attached to a hexagonal pyramidal tip. For this study, a hollow structure is included at the end of the columnar part of each bullet branch and the shape of the hollow structure is defined as a hexagonal pyramid. A hollow bullet rosette may have between 2 and 12 branches. An improved geometric optics method is used to solve for the scattering of light in the particle. The primary optical effect of incorporating a hollow end in each of the bullets is to decrease the magnitude of backscattering. In terms of the angular distribution of scattered energy, the hollow bullets increase the scattering phase function values within the forward scattering angle region from 1°to 20°but decrease the phase function values at side-and backscattering angles of 60°-180°. As a result, the presence of hollow bullets tends to increase the asymmetry factor. In addition to the scattering phase function, the other elements of the phase matrix are also discussed. The backscattering depolarization ratios for hollow and solid bullet rosettes are found to be very different. This may have an implication for active remote sensing of ice clouds, such as from polarimetric lidar measurements. In a comparison of solid and hollow bullet rosettes, the effect of the differences on the retrieval of both the ice cloud effective particle size and optical thickness is also discussed. It is found that the presence of hollow bullet rosettes acts to decrease the inferred effective particle size and to increase the optical thickness in comparison with the use of solid bullet rosettes.

show abstract

Atmospheric Halos and the Search for Angle x

Cited by 35 publications

References 37 publications

The role of ice in N<sub>2</sub>O<sub>5</sub> heterogeneous hydrolysis at high latitudes

The role of ice in N<sub>2</sub>O<sub>5</sub> heterogeneous hydrolysis at high latitudes

Formation of atmospheric halos and applicability of geometric optics for calculating single-scattering properties of hexagonal ice crystals: Impacts of aspect ratio and ice crystal size

Effect of Cavities on the Optical Properties of Bullet Rosettes: Implications for Active and Passive Remote Sensing of Ice Cloud Properties

Contact Info

Product

Resources

About

Atmospheric Halos and the Search for Angle x

Cited by 35 publications

References 37 publications

The role of ice in N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; heterogeneous hydrolysis at high latitudes

The role of ice in N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; heterogeneous hydrolysis at high latitudes

Formation of atmospheric halos and applicability of geometric optics for calculating single-scattering properties of hexagonal ice crystals: Impacts of aspect ratio and ice crystal size

Effect of Cavities on the Optical Properties of Bullet Rosettes: Implications for Active and Passive Remote Sensing of Ice Cloud Properties

Contact Info

Product

Resources

About

The role of ice in N<sub>2</sub>O<sub>5</sub> heterogeneous hydrolysis at high latitudes

The role of ice in N<sub>2</sub>O<sub>5</sub> heterogeneous hydrolysis at high latitudes