Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals
Multidecadal changes in regional climate can occur as a forced response to changing greenhouse gases and aerosols, as a result of natural internal climate variability, or due to their combination. Internal climate variability is frequently associated with regional changes in large-scale circulation....
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Stockholm University Press
2022-04-01
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| Series: | Tellus: Series A, Dynamic Meteorology and Oceanography |
| Subjects: | |
| Online Access: | https://a.tellusjournals.se/articles/49 |
| _version_ | 1797995630830813184 |
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| author | Erik Kjellström Felicitas Hansen Danijel Belušić |
| author_facet | Erik Kjellström Felicitas Hansen Danijel Belušić |
| author_sort | Erik Kjellström |
| collection | DOAJ |
| description | Multidecadal changes in regional climate can occur as a forced response to changing greenhouse gases and aerosols, as a result of natural internal climate variability, or due to their combination. Internal climate variability is frequently associated with regional changes in large-scale circulation. We investigate how changes in Scandinavian temperature and precipitation conditions during 1961–2020 can be linked to changes in the atmospheric large-scale circulation. The study is based on data from the ERA5 reanalysis and on Swedish average conditions based on observations from the Swedish Meteorological and Hydrological Institute. In general, it is shown that all seasons have become warmer and there is a predominance for more precipitation in the last 30 years. The results also show a clear decrease in daily temperature variability for winter and an increase in summer while there is no similar systematic change for precipitation. Further, we use a circulation type classification technique for identifying ten different circulation types for each calendar month in the 1961–2020 period. Results indicate that changes between the two periods can partly be related to changes in large-scale circulation due to changes in the frequencies of different circulation types. However, it is also clear that the contribution from frequency-related changes to the total change is comparatively low for most months and that changes also within the circulation types are required to explain the total change. The main conclusion of the study is that during the last 30 years it has mostly been warmer than in the preceding 30 years for the same type of weather situation for all months in the year. Consequently, internal climate variability, as represented by changes in the large-scale atmospheric circulation, cannot explain the observed changes in the Scandinavian temperature and precipitation. |
| first_indexed | 2024-04-11T10:03:36Z |
| format | Article |
| id | doaj.art-0e3f0eaa8b274deb9e36d3730a6cee35 |
| institution | Directory Open Access Journal |
| issn | 1600-0870 |
| language | English |
| last_indexed | 2024-04-11T10:03:36Z |
| publishDate | 2022-04-01 |
| publisher | Stockholm University Press |
| record_format | Article |
| series | Tellus: Series A, Dynamic Meteorology and Oceanography |
| spelling | doaj.art-0e3f0eaa8b274deb9e36d3730a6cee352022-12-22T04:30:17ZengStockholm University PressTellus: Series A, Dynamic Meteorology and Oceanography1600-08702022-04-0174110.16993/tellusa.4935Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate NormalsErik Kjellström0Felicitas Hansen1Danijel Belušić2Rossby Centre, Swedish Meteorological and Hydrological Institute, SMHI, Norrköping, SE-602 19; Department of Meteorology and Bolin Centre for climate research, Stockholm University, Stockholm, SE-106 91Rossby Centre, Swedish Meteorological and Hydrological Institute, SMHI, Norrköping, SE-602 19, SE; Institute of Coastal Systems, Helmholtz-Zentrum Hereon, Geesthacht, DE-21502Rossby Centre, Swedish Meteorological and Hydrological Institute, SMHI, Norrköping, SE-602 19, SE; Department of Geophysics, Faculty of Science, University of Zagreb, 10000 ZagrebMultidecadal changes in regional climate can occur as a forced response to changing greenhouse gases and aerosols, as a result of natural internal climate variability, or due to their combination. Internal climate variability is frequently associated with regional changes in large-scale circulation. We investigate how changes in Scandinavian temperature and precipitation conditions during 1961–2020 can be linked to changes in the atmospheric large-scale circulation. The study is based on data from the ERA5 reanalysis and on Swedish average conditions based on observations from the Swedish Meteorological and Hydrological Institute. In general, it is shown that all seasons have become warmer and there is a predominance for more precipitation in the last 30 years. The results also show a clear decrease in daily temperature variability for winter and an increase in summer while there is no similar systematic change for precipitation. Further, we use a circulation type classification technique for identifying ten different circulation types for each calendar month in the 1961–2020 period. Results indicate that changes between the two periods can partly be related to changes in large-scale circulation due to changes in the frequencies of different circulation types. However, it is also clear that the contribution from frequency-related changes to the total change is comparatively low for most months and that changes also within the circulation types are required to explain the total change. The main conclusion of the study is that during the last 30 years it has mostly been warmer than in the preceding 30 years for the same type of weather situation for all months in the year. Consequently, internal climate variability, as represented by changes in the large-scale atmospheric circulation, cannot explain the observed changes in the Scandinavian temperature and precipitation.https://a.tellusjournals.se/articles/49weather type classificationcirculation typeclimate changereanalysissweden |
| spellingShingle | Erik Kjellström Felicitas Hansen Danijel Belušić Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals Tellus: Series A, Dynamic Meteorology and Oceanography weather type classification circulation type climate change reanalysis sweden |
| title | Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals |
| title_full | Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals |
| title_fullStr | Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals |
| title_full_unstemmed | Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals |
| title_short | Contributions from Changing Large-Scale Atmospheric Conditions to Changes in Scandinavian Temperature and Precipitation Between Two Climate Normals |
| title_sort | contributions from changing large scale atmospheric conditions to changes in scandinavian temperature and precipitation between two climate normals |
| topic | weather type classification circulation type climate change reanalysis sweden |
| url | https://a.tellusjournals.se/articles/49 |
| work_keys_str_mv | AT erikkjellstrom contributionsfromchanginglargescaleatmosphericconditionstochangesinscandinaviantemperatureandprecipitationbetweentwoclimatenormals AT felicitashansen contributionsfromchanginglargescaleatmosphericconditionstochangesinscandinaviantemperatureandprecipitationbetweentwoclimatenormals AT danijelbelusic contributionsfromchanginglargescaleatmosphericconditionstochangesinscandinaviantemperatureandprecipitationbetweentwoclimatenormals |