Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model
This paper addresses the effect of interannual variability in jet stream orientation on weather systems over the North Atlantic basin (NAB). The observational analysis relies on 65 yr of NCEP-NCAR reanalysis (1948-2012). The total daily kinetic energy of the geostrophic wind (GTKE) is taken as a mea...
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ftcdlib:oai:escholarship.org/ark:/13030/qt9qn6h8sx 2023-05-15T17:28:36+02:00 Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model Feliks, Y Robertson, AW Ghil, M 3227 - 3248 2016-08-01 application/pdf https://escholarship.org/uc/item/9qn6h8sx unknown eScholarship, University of California qt9qn6h8sx https://escholarship.org/uc/item/9qn6h8sx public Journal of the Atmospheric Sciences, vol 73, iss 8 Meteorology & Atmospheric Sciences Atmospheric Sciences article 2016 ftcdlib 2021-04-16T07:11:00Z This paper addresses the effect of interannual variability in jet stream orientation on weather systems over the North Atlantic basin (NAB). The observational analysis relies on 65 yr of NCEP-NCAR reanalysis (1948-2012). The total daily kinetic energy of the geostrophic wind (GTKE) is taken as a measure of storm activity over the North Atlantic. The NAB is partitioned into four rectangular regions, and the winter average of GTKE is calculated for each quadrant. The spatial GTKE average over all four quadrants shows striking year-to-year variability and is strongly correlated with the North Atlantic Oscillation (NAO). The GTKE strength in the northeast quadrant is closely related to the diffluence angle of the jet stream in the northwest quadrant. To gain insight into the relationship between the diffluence angle and its downstream impact, a quasigeostrophic baroclinic model is used. The results show that an initially zonal jet persists at its initial latitude over 30 days or longer, while a tilted jet propagates meridionally according to the Rossby wave group velocity, unless kept stationary by external forcing. A Gulf Stream-like narrow sea surface temperature (SST) front provides the requisite forcing for an analytical steady-state solution to this problem. This SST front influences the atmospheric jet in the northwest quadrant: It both strengthens the jet and tilts it northward at higher levels, while its effect is opposite at lower levels. Reanalysis data confirm these effects, which are consistent with thermal wind balance. The results suggest that the interannual variability found in the GTKE may be caused by intrinsic variability of the thermal Gulf Stream front. Article in Journal/Newspaper North Atlantic North Atlantic oscillation University of California: eScholarship |
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University of California: eScholarship |
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topic |
Meteorology & Atmospheric Sciences Atmospheric Sciences |
spellingShingle |
Meteorology & Atmospheric Sciences Atmospheric Sciences Feliks, Y Robertson, AW Ghil, M Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
topic_facet |
Meteorology & Atmospheric Sciences Atmospheric Sciences |
description |
This paper addresses the effect of interannual variability in jet stream orientation on weather systems over the North Atlantic basin (NAB). The observational analysis relies on 65 yr of NCEP-NCAR reanalysis (1948-2012). The total daily kinetic energy of the geostrophic wind (GTKE) is taken as a measure of storm activity over the North Atlantic. The NAB is partitioned into four rectangular regions, and the winter average of GTKE is calculated for each quadrant. The spatial GTKE average over all four quadrants shows striking year-to-year variability and is strongly correlated with the North Atlantic Oscillation (NAO). The GTKE strength in the northeast quadrant is closely related to the diffluence angle of the jet stream in the northwest quadrant. To gain insight into the relationship between the diffluence angle and its downstream impact, a quasigeostrophic baroclinic model is used. The results show that an initially zonal jet persists at its initial latitude over 30 days or longer, while a tilted jet propagates meridionally according to the Rossby wave group velocity, unless kept stationary by external forcing. A Gulf Stream-like narrow sea surface temperature (SST) front provides the requisite forcing for an analytical steady-state solution to this problem. This SST front influences the atmospheric jet in the northwest quadrant: It both strengthens the jet and tilts it northward at higher levels, while its effect is opposite at lower levels. Reanalysis data confirm these effects, which are consistent with thermal wind balance. The results suggest that the interannual variability found in the GTKE may be caused by intrinsic variability of the thermal Gulf Stream front. |
format |
Article in Journal/Newspaper |
author |
Feliks, Y Robertson, AW Ghil, M |
author_facet |
Feliks, Y Robertson, AW Ghil, M |
author_sort |
Feliks, Y |
title |
Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
title_short |
Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
title_full |
Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
title_fullStr |
Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
title_full_unstemmed |
Interannual variability in north Atlantic weather: Data analysis and a quasigeostrophic model |
title_sort |
interannual variability in north atlantic weather: data analysis and a quasigeostrophic model |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
https://escholarship.org/uc/item/9qn6h8sx |
op_coverage |
3227 - 3248 |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
Journal of the Atmospheric Sciences, vol 73, iss 8 |
op_relation |
qt9qn6h8sx https://escholarship.org/uc/item/9qn6h8sx |
op_rights |
public |
_version_ |
1766121368346165248 |