Direct estimation of the global distribution of vertical velocity within cirrus clouds

Abstract Cirrus clouds determine the radiative balance of the upper troposphere and the transport of water vapor across the tropopause. The representation of vertical wind velocity, W, in atmospheric models constitutes the largest source of uncertainty in the calculation of the cirrus formation rate...

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Autores principales:	Donifan Barahona, Andrea Molod, Heike Kalesse
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/839a40c8a7f7428ba1189b490656155a
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spelling	oai:doaj.org-article:839a40c8a7f7428ba1189b490656155a2021-12-02T11:52:22ZDirect estimation of the global distribution of vertical velocity within cirrus clouds10.1038/s41598-017-07038-62045-2322https://doaj.org/article/839a40c8a7f7428ba1189b490656155a2017-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-07038-6https://doaj.org/toc/2045-2322Abstract Cirrus clouds determine the radiative balance of the upper troposphere and the transport of water vapor across the tropopause. The representation of vertical wind velocity, W, in atmospheric models constitutes the largest source of uncertainty in the calculation of the cirrus formation rate. Using global atmospheric simulations with a spatial resolution of 7 km we obtain for the first time a direct estimate of the distribution of W at the scale relevant for cirrus formation, validated against long-term observations at two different ground sites. The standard deviation in W, σ w , varies widely over the globe with the highest values resulting from orographic uplift and convection, and the lowest occurring in the Arctic. Globally about 90% of the simulated σ w values are below 0.1 m s−1 and about one in 104 cloud formation events occur in environments with σ w > 0.8 m s−1. Combining our estimate with reanalysis products and an advanced cloud formation scheme results in lower homogeneous ice nucleation frequency than previously reported, and a decreasing average ice crystal concentration with decreasing temperature. These features are in agreement with observations and suggest that the correct parameterization of σ w is critical to simulate realistic cirrus properties.Donifan BarahonaAndrea MolodHeike KalesseNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-11 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Donifan Barahona Andrea Molod Heike Kalesse Direct estimation of the global distribution of vertical velocity within cirrus clouds
description	Abstract Cirrus clouds determine the radiative balance of the upper troposphere and the transport of water vapor across the tropopause. The representation of vertical wind velocity, W, in atmospheric models constitutes the largest source of uncertainty in the calculation of the cirrus formation rate. Using global atmospheric simulations with a spatial resolution of 7 km we obtain for the first time a direct estimate of the distribution of W at the scale relevant for cirrus formation, validated against long-term observations at two different ground sites. The standard deviation in W, σ w , varies widely over the globe with the highest values resulting from orographic uplift and convection, and the lowest occurring in the Arctic. Globally about 90% of the simulated σ w values are below 0.1 m s−1 and about one in 104 cloud formation events occur in environments with σ w > 0.8 m s−1. Combining our estimate with reanalysis products and an advanced cloud formation scheme results in lower homogeneous ice nucleation frequency than previously reported, and a decreasing average ice crystal concentration with decreasing temperature. These features are in agreement with observations and suggest that the correct parameterization of σ w is critical to simulate realistic cirrus properties.
format	article
author	Donifan Barahona Andrea Molod Heike Kalesse
author_facet	Donifan Barahona Andrea Molod Heike Kalesse
author_sort	Donifan Barahona
title	Direct estimation of the global distribution of vertical velocity within cirrus clouds
title_short	Direct estimation of the global distribution of vertical velocity within cirrus clouds
title_full	Direct estimation of the global distribution of vertical velocity within cirrus clouds
title_fullStr	Direct estimation of the global distribution of vertical velocity within cirrus clouds
title_full_unstemmed	Direct estimation of the global distribution of vertical velocity within cirrus clouds
title_sort	direct estimation of the global distribution of vertical velocity within cirrus clouds
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/839a40c8a7f7428ba1189b490656155a
work_keys_str_mv	AT donifanbarahona directestimationoftheglobaldistributionofverticalvelocitywithincirrusclouds AT andreamolod directestimationoftheglobaldistributionofverticalvelocitywithincirrusclouds AT heikekalesse directestimationoftheglobaldistributionofverticalvelocitywithincirrusclouds
_version_	1718395054938128384

Direct estimation of the global distribution of vertical velocity within cirrus clouds

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