Channelling of high-latitude boundary-layer flow
Due to the stability of the boundary-layer stratification, high-latitude winds over complex terrain are strongly affected by blocking and channelling effects. Consequently, at many low-lying communities in the Canadian Archipelago, including Cape Dorset and Iqaluit considered in this study, surface...
Main Authors: | , |
---|---|
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2008
|
Subjects: | |
Online Access: | https://doaj.org/article/ead7bb64dce046a392ef8a0c5456eb48 |
id |
ftdoajarticles:oai:doaj.org/article:ead7bb64dce046a392ef8a0c5456eb48 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:ead7bb64dce046a392ef8a0c5456eb48 2023-05-15T15:48:59+02:00 Channelling of high-latitude boundary-layer flow N. Nawri R. E. Stewart 2008-01-01T00:00:00Z https://doaj.org/article/ead7bb64dce046a392ef8a0c5456eb48 EN eng Copernicus Publications http://www.nonlin-processes-geophys.net/15/33/2008/npg-15-33-2008.pdf https://doaj.org/toc/1023-5809 https://doaj.org/toc/1607-7946 1023-5809 1607-7946 https://doaj.org/article/ead7bb64dce046a392ef8a0c5456eb48 Nonlinear Processes in Geophysics, Vol 15, Iss 1, Pp 33-52 (2008) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2008 ftdoajarticles 2022-12-31T04:33:46Z Due to the stability of the boundary-layer stratification, high-latitude winds over complex terrain are strongly affected by blocking and channelling effects. Consequently, at many low-lying communities in the Canadian Archipelago, including Cape Dorset and Iqaluit considered in this study, surface winds for the most part are from two diametrically opposed directions, following the orientation of the elevated terrain. Shifts between the two prevailing wind directions can be sudden and are associated with geostrophic wind directions within a well defined narrow range. To quantitatively investigate the role of large-scale pressure gradients and the quasi-geostrophic overlying flow, an idealised dynamical system for the evolution of channelled surface winds is derived from the basic equations of motion, in which stability of stationary along-channel wind directions is described as a function of the geostrophic wind. In comparison with long-term horizontal wind statistics at the two locations it is shown that the climatologically prevailing wind directions can be identified as stationary states of the idealised wind model, and that shifts between prevailing wind directions can be represented as stability transitions between these stationary states. In that sense, the prevailing local wind conditions can be interpreted as attracting states of the actual flow, with observed surface winds adjusting to a new stable direction as determined by the idealised system within 3–9 h. Over these time-scales and longer it is therefore advantageous to determine the relatively slow evolution of the observationally well-resolved large-scale pressure distribution, instead of modelling highly variable surface winds directly. The simplified model also offers a tool for dynamical downscaling of global climate simulations, and for determining future scenarios for local prevailing wind conditions. In particular, it allows an estimation of the sensitivity of local low-level winds to changes in the large-scale atmospheric circulation. Article in Journal/Newspaper Canadian Archipelago Cape Dorset Iqaluit Directory of Open Access Journals: DOAJ Articles Cape Dorset ENVELOPE(-76.482,-76.482,64.179,64.179) |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
spellingShingle |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 N. Nawri R. E. Stewart Channelling of high-latitude boundary-layer flow |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Due to the stability of the boundary-layer stratification, high-latitude winds over complex terrain are strongly affected by blocking and channelling effects. Consequently, at many low-lying communities in the Canadian Archipelago, including Cape Dorset and Iqaluit considered in this study, surface winds for the most part are from two diametrically opposed directions, following the orientation of the elevated terrain. Shifts between the two prevailing wind directions can be sudden and are associated with geostrophic wind directions within a well defined narrow range. To quantitatively investigate the role of large-scale pressure gradients and the quasi-geostrophic overlying flow, an idealised dynamical system for the evolution of channelled surface winds is derived from the basic equations of motion, in which stability of stationary along-channel wind directions is described as a function of the geostrophic wind. In comparison with long-term horizontal wind statistics at the two locations it is shown that the climatologically prevailing wind directions can be identified as stationary states of the idealised wind model, and that shifts between prevailing wind directions can be represented as stability transitions between these stationary states. In that sense, the prevailing local wind conditions can be interpreted as attracting states of the actual flow, with observed surface winds adjusting to a new stable direction as determined by the idealised system within 3–9 h. Over these time-scales and longer it is therefore advantageous to determine the relatively slow evolution of the observationally well-resolved large-scale pressure distribution, instead of modelling highly variable surface winds directly. The simplified model also offers a tool for dynamical downscaling of global climate simulations, and for determining future scenarios for local prevailing wind conditions. In particular, it allows an estimation of the sensitivity of local low-level winds to changes in the large-scale atmospheric circulation. |
format |
Article in Journal/Newspaper |
author |
N. Nawri R. E. Stewart |
author_facet |
N. Nawri R. E. Stewart |
author_sort |
N. Nawri |
title |
Channelling of high-latitude boundary-layer flow |
title_short |
Channelling of high-latitude boundary-layer flow |
title_full |
Channelling of high-latitude boundary-layer flow |
title_fullStr |
Channelling of high-latitude boundary-layer flow |
title_full_unstemmed |
Channelling of high-latitude boundary-layer flow |
title_sort |
channelling of high-latitude boundary-layer flow |
publisher |
Copernicus Publications |
publishDate |
2008 |
url |
https://doaj.org/article/ead7bb64dce046a392ef8a0c5456eb48 |
long_lat |
ENVELOPE(-76.482,-76.482,64.179,64.179) |
geographic |
Cape Dorset |
geographic_facet |
Cape Dorset |
genre |
Canadian Archipelago Cape Dorset Iqaluit |
genre_facet |
Canadian Archipelago Cape Dorset Iqaluit |
op_source |
Nonlinear Processes in Geophysics, Vol 15, Iss 1, Pp 33-52 (2008) |
op_relation |
http://www.nonlin-processes-geophys.net/15/33/2008/npg-15-33-2008.pdf https://doaj.org/toc/1023-5809 https://doaj.org/toc/1607-7946 1023-5809 1607-7946 https://doaj.org/article/ead7bb64dce046a392ef8a0c5456eb48 |
_version_ |
1766384075361222656 |