Volcanos and El Niño: signal separation in Northern Hemisphere winter
The frequent coincidence of volcanic forcing with El Niño events disables the clear assignment of climate anomalies to either volcanic or El Niño forcing. In order to select the signals, a set of four different perpetual January GCM experiments was performed (control, volcano case, El Niño case and...
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ftpubman:oai:pure.mpg.de:item_2604152 2023-08-20T04:06:58+02:00 Volcanos and El Niño: signal separation in Northern Hemisphere winter Kirchner, I. Graf, H. 1995 application/pdf http://hdl.handle.net/21.11116/0000-0001-9037-E http://hdl.handle.net/21.11116/0000-0001-9039-C http://hdl.handle.net/21.11116/0000-0001-903A-B eng eng info:eu-repo/semantics/altIdentifier/doi/10.1007/BF00215736 http://hdl.handle.net/21.11116/0000-0001-9037-E http://hdl.handle.net/21.11116/0000-0001-9039-C http://hdl.handle.net/21.11116/0000-0001-903A-B info:eu-repo/semantics/openAccess Climate Dynamics Report / Max-Planck-Institut für Meteorologie info:eu-repo/semantics/article 1995 ftpubman https://doi.org/10.1007/BF00215736 2023-08-01T23:16:17Z The frequent coincidence of volcanic forcing with El Niño events disables the clear assignment of climate anomalies to either volcanic or El Niño forcing. In order to select the signals, a set of four different perpetual January GCM experiments was performed (control, volcano case, El Niño case and combined volcano/El Niño case) and studied with advanced statistical methods for the Northern Hemisphere winter. The results were compared with observations. The signals for the different forcings are discussed for three variables (temperature, zonal wind and geopotential height) and five levels (surface, 850 hPa, 500 hPa, 200 hPa and 50 hPa). The global El Niño signal can be selected more clearly in the troposphere than in the stratosphere. In contrast, the global volcano signal is strongest in the stratospheric temperature field. The amplitude of the perturbation for the volcano case is largest in the Atlantic region. The observed effect of local cooling due to the volcanic reduction of shortwave radiation over large land areas (like Asia) in subtropical regions, the observed advective warming over Eurasia and the advective cooling over Greenland are well simulated in the model. The radiative cooling near the surface is important for the volcano signal in the subtropics, but it is weak in high latitudes during winter. A statistically significant tropospheric signal of El Niño forcing occurs in the subtropics and in the midlatitudes of the North Pacific. The local anomalies in the El Niño forcing region in the tropics, and the warming over North America in middle and high latitudes are simulated as observed. The combined signal is different from a simple linear combination of the separate signals. It leads to a climate perturbation stronger than for forcing with El Niño or stratospheric aerosol alone and to a somewhat modified pattern. © 1995 Springer-Verlag. Article in Journal/Newspaper Greenland Max Planck Society: MPG.PuRe Greenland Pacific Climate Dynamics 11 6 341 358 |
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Open Polar |
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Max Planck Society: MPG.PuRe |
op_collection_id |
ftpubman |
language |
English |
description |
The frequent coincidence of volcanic forcing with El Niño events disables the clear assignment of climate anomalies to either volcanic or El Niño forcing. In order to select the signals, a set of four different perpetual January GCM experiments was performed (control, volcano case, El Niño case and combined volcano/El Niño case) and studied with advanced statistical methods for the Northern Hemisphere winter. The results were compared with observations. The signals for the different forcings are discussed for three variables (temperature, zonal wind and geopotential height) and five levels (surface, 850 hPa, 500 hPa, 200 hPa and 50 hPa). The global El Niño signal can be selected more clearly in the troposphere than in the stratosphere. In contrast, the global volcano signal is strongest in the stratospheric temperature field. The amplitude of the perturbation for the volcano case is largest in the Atlantic region. The observed effect of local cooling due to the volcanic reduction of shortwave radiation over large land areas (like Asia) in subtropical regions, the observed advective warming over Eurasia and the advective cooling over Greenland are well simulated in the model. The radiative cooling near the surface is important for the volcano signal in the subtropics, but it is weak in high latitudes during winter. A statistically significant tropospheric signal of El Niño forcing occurs in the subtropics and in the midlatitudes of the North Pacific. The local anomalies in the El Niño forcing region in the tropics, and the warming over North America in middle and high latitudes are simulated as observed. The combined signal is different from a simple linear combination of the separate signals. It leads to a climate perturbation stronger than for forcing with El Niño or stratospheric aerosol alone and to a somewhat modified pattern. © 1995 Springer-Verlag. |
format |
Article in Journal/Newspaper |
author |
Kirchner, I. Graf, H. |
spellingShingle |
Kirchner, I. Graf, H. Volcanos and El Niño: signal separation in Northern Hemisphere winter |
author_facet |
Kirchner, I. Graf, H. |
author_sort |
Kirchner, I. |
title |
Volcanos and El Niño: signal separation in Northern Hemisphere winter |
title_short |
Volcanos and El Niño: signal separation in Northern Hemisphere winter |
title_full |
Volcanos and El Niño: signal separation in Northern Hemisphere winter |
title_fullStr |
Volcanos and El Niño: signal separation in Northern Hemisphere winter |
title_full_unstemmed |
Volcanos and El Niño: signal separation in Northern Hemisphere winter |
title_sort |
volcanos and el niño: signal separation in northern hemisphere winter |
publishDate |
1995 |
url |
http://hdl.handle.net/21.11116/0000-0001-9037-E http://hdl.handle.net/21.11116/0000-0001-9039-C http://hdl.handle.net/21.11116/0000-0001-903A-B |
geographic |
Greenland Pacific |
geographic_facet |
Greenland Pacific |
genre |
Greenland |
genre_facet |
Greenland |
op_source |
Climate Dynamics Report / Max-Planck-Institut für Meteorologie |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1007/BF00215736 http://hdl.handle.net/21.11116/0000-0001-9037-E http://hdl.handle.net/21.11116/0000-0001-9039-C http://hdl.handle.net/21.11116/0000-0001-903A-B |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.1007/BF00215736 |
container_title |
Climate Dynamics |
container_volume |
11 |
container_issue |
6 |
container_start_page |
341 |
op_container_end_page |
358 |
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1774718344589475840 |