The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis
Abstract In situ atmospheric observations in the central Arctic are few and mostly from near the surface. A majority are from coastal regions whereas soundings over the Arctic Ocean are rare. This limits our understanding of the Arctic atmosphere, in particular aloft. It has been established that th...
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crwiley:10.1002/qj.380 2024-09-15T17:53:37+00:00 The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis Tjernström, Michael Graversen, Rune Grand 2009 http://dx.doi.org/10.1002/qj.380 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.380 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.380 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Quarterly Journal of the Royal Meteorological Society volume 135, issue 639, page 431-443 ISSN 0035-9009 1477-870X journal-article 2009 crwiley https://doi.org/10.1002/qj.380 2024-08-27T04:32:49Z Abstract In situ atmospheric observations in the central Arctic are few and mostly from near the surface. A majority are from coastal regions whereas soundings over the Arctic Ocean are rare. This limits our understanding of the Arctic atmosphere, in particular aloft. It has been established that the vertical thermal structure is often stably stratified; this has been termed the ‘Arctic inversion’. It has also been established that near‐surface warming in the Arctic has been larger than the global mean warming during the last several decades. To estimate climate trends in this data‐sparse region, reanalysis data have often been used. In this paper we analyse the vertical thermal structure of the lower troposphere over the Arctic Ocean, using soundings from the SHEBA project. We find a strong annual cycle with strong surface inversions occurring only during autumn and winter, typically 500–800 metres deep and ∼10 °C strong. Summer is dominated by weaker elevated inversions at ∼100–400 m, a few hundred metres deep. Interestingly, this latter type of inversion also occurs frequently in winter, almost half the time. These soundings thus indicate that associating Arctic winter only with strong surface inversions is not entirely correct. We also compare these soundings to the ERA‐40 reanalysis data. Systematic biases in ERA‐40 in the SHEBA region include a near‐surface warm bias, on average ∼0.5–1.0 °C, and a slight mid‐troposphere cool bias. There is a significant difference in ERA‐40 performance statistics for the SHEBA year comparing with years without soundings for the same region. The analysis increment—a measure of the impact of the observations in the assimilation process—confirms this. For example, the assimilation of the SHEBA soundings reduces the near‐surface warm bias by about 50%. However, the overall vertical structure and its annual variation are surprisingly insensitive to the assimilation of the soundings, and are in fact well represented by ERA‐40. We speculate that the main improvement in ... Article in Journal/Newspaper Arctic Ocean Wiley Online Library Quarterly Journal of the Royal Meteorological Society 135 639 431 443 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract In situ atmospheric observations in the central Arctic are few and mostly from near the surface. A majority are from coastal regions whereas soundings over the Arctic Ocean are rare. This limits our understanding of the Arctic atmosphere, in particular aloft. It has been established that the vertical thermal structure is often stably stratified; this has been termed the ‘Arctic inversion’. It has also been established that near‐surface warming in the Arctic has been larger than the global mean warming during the last several decades. To estimate climate trends in this data‐sparse region, reanalysis data have often been used. In this paper we analyse the vertical thermal structure of the lower troposphere over the Arctic Ocean, using soundings from the SHEBA project. We find a strong annual cycle with strong surface inversions occurring only during autumn and winter, typically 500–800 metres deep and ∼10 °C strong. Summer is dominated by weaker elevated inversions at ∼100–400 m, a few hundred metres deep. Interestingly, this latter type of inversion also occurs frequently in winter, almost half the time. These soundings thus indicate that associating Arctic winter only with strong surface inversions is not entirely correct. We also compare these soundings to the ERA‐40 reanalysis data. Systematic biases in ERA‐40 in the SHEBA region include a near‐surface warm bias, on average ∼0.5–1.0 °C, and a slight mid‐troposphere cool bias. There is a significant difference in ERA‐40 performance statistics for the SHEBA year comparing with years without soundings for the same region. The analysis increment—a measure of the impact of the observations in the assimilation process—confirms this. For example, the assimilation of the SHEBA soundings reduces the near‐surface warm bias by about 50%. However, the overall vertical structure and its annual variation are surprisingly insensitive to the assimilation of the soundings, and are in fact well represented by ERA‐40. We speculate that the main improvement in ... |
format |
Article in Journal/Newspaper |
author |
Tjernström, Michael Graversen, Rune Grand |
spellingShingle |
Tjernström, Michael Graversen, Rune Grand The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
author_facet |
Tjernström, Michael Graversen, Rune Grand |
author_sort |
Tjernström, Michael |
title |
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
title_short |
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
title_full |
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
title_fullStr |
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
title_full_unstemmed |
The vertical structure of the lower Arctic troposphere analysed from observations and the ERA‐40 reanalysis |
title_sort |
vertical structure of the lower arctic troposphere analysed from observations and the era‐40 reanalysis |
publisher |
Wiley |
publishDate |
2009 |
url |
http://dx.doi.org/10.1002/qj.380 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fqj.380 https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/qj.380 |
genre |
Arctic Ocean |
genre_facet |
Arctic Ocean |
op_source |
Quarterly Journal of the Royal Meteorological Society volume 135, issue 639, page 431-443 ISSN 0035-9009 1477-870X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/qj.380 |
container_title |
Quarterly Journal of the Royal Meteorological Society |
container_volume |
135 |
container_issue |
639 |
container_start_page |
431 |
op_container_end_page |
443 |
_version_ |
1810429511046529024 |