Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere
Specular meteor radars (SMRs) and partial reflection radars (PRRs) have been observing mesospheric winds for more than a solar cycle over Germany ( ∼ 54 ∘ N) and northern Norway ( ∼ 69 ∘ N). This work investigates the mesospheric mean zonal wind and the zonal mean geostrophic zonal wind from the Mic...
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ftdoajarticles:oai:doaj.org/article:bc1c3e8101f54e8b8805c88cab9b153d 2023-05-15T17:43:37+02:00 Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere J. Jaen T. Renkwitz J. L. Chau M. He P. Hoffmann Y. Yamazaki C. Jacobi M. Tsutsumi V. Matthias C. Hall 2022-01-01T00:00:00Z https://doi.org/10.5194/angeo-40-23-2022 https://doaj.org/article/bc1c3e8101f54e8b8805c88cab9b153d EN eng Copernicus Publications https://angeo.copernicus.org/articles/40/23/2022/angeo-40-23-2022.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-40-23-2022 0992-7689 1432-0576 https://doaj.org/article/bc1c3e8101f54e8b8805c88cab9b153d Annales Geophysicae, Vol 40, Pp 23-35 (2022) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2022 ftdoajarticles https://doi.org/10.5194/angeo-40-23-2022 2022-12-31T11:09:04Z Specular meteor radars (SMRs) and partial reflection radars (PRRs) have been observing mesospheric winds for more than a solar cycle over Germany ( ∼ 54 ∘ N) and northern Norway ( ∼ 69 ∘ N). This work investigates the mesospheric mean zonal wind and the zonal mean geostrophic zonal wind from the Microwave Limb Sounder (MLS) over these two regions between 2004 and 2020. Our study focuses on the summer when strong planetary waves are absent and the stratospheric and tropospheric conditions are relatively stable. We establish two definitions of the summer length according to the zonal wind reversals: (1) the mesosphere and lower-thermosphere summer length (MLT-SL) using SMR and PRR winds and (2) the mesosphere summer length (M-SL) using the PRR and MLS. Under both definitions, the summer begins around April and ends around middle September. The largest year-to-year variability is found in the summer beginning in both definitions, particularly at high latitudes, possibly due to the influence of the polar vortex. At high latitudes, the year 2004 has a longer summer length compared to the mean value for MLT-SL as well as 2012 for both definitions. The M-SL exhibits an increasing trend over the years, while MLT-SL does not have a well-defined trend. We explore a possible influence of solar activity as well as large-scale atmospheric influences (e.g., quasi-biennial oscillation (QBO), El Niño–Southern Oscillation (ENSO), major sudden stratospheric warming events). We complement our work with an extended time series of 31 years at middle latitudes using only PRR winds. In this case, the summer length shows a breakpoint, suggesting a non-uniform trend, and periods similar to those known for ENSO and QBO. Article in Journal/Newspaper Northern Norway Directory of Open Access Journals: DOAJ Articles Norway Annales Geophysicae 40 1 23 35 |
institution |
Open Polar |
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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 J. Jaen T. Renkwitz J. L. Chau M. He P. Hoffmann Y. Yamazaki C. Jacobi M. Tsutsumi V. Matthias C. Hall Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Specular meteor radars (SMRs) and partial reflection radars (PRRs) have been observing mesospheric winds for more than a solar cycle over Germany ( ∼ 54 ∘ N) and northern Norway ( ∼ 69 ∘ N). This work investigates the mesospheric mean zonal wind and the zonal mean geostrophic zonal wind from the Microwave Limb Sounder (MLS) over these two regions between 2004 and 2020. Our study focuses on the summer when strong planetary waves are absent and the stratospheric and tropospheric conditions are relatively stable. We establish two definitions of the summer length according to the zonal wind reversals: (1) the mesosphere and lower-thermosphere summer length (MLT-SL) using SMR and PRR winds and (2) the mesosphere summer length (M-SL) using the PRR and MLS. Under both definitions, the summer begins around April and ends around middle September. The largest year-to-year variability is found in the summer beginning in both definitions, particularly at high latitudes, possibly due to the influence of the polar vortex. At high latitudes, the year 2004 has a longer summer length compared to the mean value for MLT-SL as well as 2012 for both definitions. The M-SL exhibits an increasing trend over the years, while MLT-SL does not have a well-defined trend. We explore a possible influence of solar activity as well as large-scale atmospheric influences (e.g., quasi-biennial oscillation (QBO), El Niño–Southern Oscillation (ENSO), major sudden stratospheric warming events). We complement our work with an extended time series of 31 years at middle latitudes using only PRR winds. In this case, the summer length shows a breakpoint, suggesting a non-uniform trend, and periods similar to those known for ENSO and QBO. |
format |
Article in Journal/Newspaper |
author |
J. Jaen T. Renkwitz J. L. Chau M. He P. Hoffmann Y. Yamazaki C. Jacobi M. Tsutsumi V. Matthias C. Hall |
author_facet |
J. Jaen T. Renkwitz J. L. Chau M. He P. Hoffmann Y. Yamazaki C. Jacobi M. Tsutsumi V. Matthias C. Hall |
author_sort |
J. Jaen |
title |
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
title_short |
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
title_full |
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
title_fullStr |
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
title_full_unstemmed |
Long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the Northern Hemisphere |
title_sort |
long-term studies of mesosphere and lower-thermosphere summer length definitions based on mean zonal wind features observed for more than one solar cycle at middle and high latitudes in the northern hemisphere |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/angeo-40-23-2022 https://doaj.org/article/bc1c3e8101f54e8b8805c88cab9b153d |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Northern Norway |
genre_facet |
Northern Norway |
op_source |
Annales Geophysicae, Vol 40, Pp 23-35 (2022) |
op_relation |
https://angeo.copernicus.org/articles/40/23/2022/angeo-40-23-2022.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-40-23-2022 0992-7689 1432-0576 https://doaj.org/article/bc1c3e8101f54e8b8805c88cab9b153d |
op_doi |
https://doi.org/10.5194/angeo-40-23-2022 |
container_title |
Annales Geophysicae |
container_volume |
40 |
container_issue |
1 |
container_start_page |
23 |
op_container_end_page |
35 |
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1766145739166056448 |