Supersaturation Variability and Cirrus Ice Crystal Size DistributionsSource: Journal of the Atmospheric Sciences:;2014:;Volume( 071 ):;issue: 008::page 2905DOI: 10.1175/JAS-D-13-0404.1Publisher: American Meteorological Society
Abstract: mall-scale dynamical variability affects atmospheric supersaturation and therefore the development of ice clouds via uptake of water vapor on ice crystals. This variability and its implications for ice growth are difficult to capture experimentally and theoretically. By interpreting supersaturation as a stochastic variable, the authors examine the average temporal behavior of, and the link between, supersaturation fluctuations and ice crystal size distributions in upper-tropospheric cirrus clouds. The authors classify cirrus types according to their ability to dampen supersaturation fluctuations owing to depositional growth of cloud ice and study how size distributions in them respond to supersaturation variability, investigating the possibility of the occurrence of ice-supersaturated states within cirrus. Typical time scales for growth and damping impacts on supersaturation are minutes and minutes to hours, respectively, and are highly variable among cirrus types and within single clouds. Transient deviations from saturated equilibrium states can occur depending on the ice crystal number concentration and size and on the strength of the small-scale dynamical forcing. Supersaturation preferentially occurs in cloud regions with few small ice crystals. The authors demonstrate that supersaturation fluctuations in very thin tropical tropopause cirrus create long-lived supersaturated states. Furthermore, they potentially generate few large ice crystals, broadening size distributions, and significantly enhance water mass fluxes due to sedimentation. Although not studied here, they may also allow new ice crystals to nucleate. Implications of these findings for those clouds to dehydrate air entering the lower stratosphere are discussed and future research needs are outlined.
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contributor author | Kärcher, B. | |
contributor author | Dörnbrack, A. | |
contributor author | Sölch, I. | |
date accessioned | 2017-06-09T16:57:09Z | |
date available | 2017-06-09T16:57:09Z | |
date copyright | 2014/08/01 | |
date issued | 2014 | |
identifier issn | 0022-4928 | |
identifier other | ams-76961.pdf | |
identifier uri | http://onlinelibrary.yabesh.ir/handle/yetl/4219465 | |
description abstract | mall-scale dynamical variability affects atmospheric supersaturation and therefore the development of ice clouds via uptake of water vapor on ice crystals. This variability and its implications for ice growth are difficult to capture experimentally and theoretically. By interpreting supersaturation as a stochastic variable, the authors examine the average temporal behavior of, and the link between, supersaturation fluctuations and ice crystal size distributions in upper-tropospheric cirrus clouds. The authors classify cirrus types according to their ability to dampen supersaturation fluctuations owing to depositional growth of cloud ice and study how size distributions in them respond to supersaturation variability, investigating the possibility of the occurrence of ice-supersaturated states within cirrus. Typical time scales for growth and damping impacts on supersaturation are minutes and minutes to hours, respectively, and are highly variable among cirrus types and within single clouds. Transient deviations from saturated equilibrium states can occur depending on the ice crystal number concentration and size and on the strength of the small-scale dynamical forcing. Supersaturation preferentially occurs in cloud regions with few small ice crystals. The authors demonstrate that supersaturation fluctuations in very thin tropical tropopause cirrus create long-lived supersaturated states. Furthermore, they potentially generate few large ice crystals, broadening size distributions, and significantly enhance water mass fluxes due to sedimentation. Although not studied here, they may also allow new ice crystals to nucleate. Implications of these findings for those clouds to dehydrate air entering the lower stratosphere are discussed and future research needs are outlined. | |
publisher | American Meteorological Society | |
title | Supersaturation Variability and Cirrus Ice Crystal Size Distributions | |
type | Journal Paper | |
journal volume | 71 | |
journal issue | 8 | |
journal title | Journal of the Atmospheric Sciences | |
identifier doi | 10.1175/JAS-D-13-0404.1 | |
journal fristpage | 2905 | |
journal lastpage | 2926 | |
tree | Journal of the Atmospheric Sciences:;2014:;Volume( 071 ):;issue: 008 | |
contenttype | Fulltext |