The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia)
Motivated by the record-breaking heatwaves of early 2017, the synoptic structure and evolution of summer (December–February) heatwaves in the Sydney area is investigated through composite and trajectory analyses. In the upper troposphere, the main features of the composite structure are an isolated...
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ftdatacite:10.5445/ir/1000120169 2023-05-15T18:25:58+02:00 The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) Parker, Tess Quinting, Julian Reeder, Michael 2020 PDF https://dx.doi.org/10.5445/ir/1000120169 https://publikationen.bibliothek.kit.edu/1000120169 en eng Bureau of Meteorology Creative Commons Namensnennung – Nicht kommerziell – Keine Bearbeitungen 4.0 International Open Access info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de CC-BY-NC-ND Text article-journal Journal Article ScholarlyArticle 2020 ftdatacite https://doi.org/10.5445/ir/1000120169 2021-11-05T12:55:41Z Motivated by the record-breaking heatwaves of early 2017, the synoptic structure and evolution of summer (December–February) heatwaves in the Sydney area is investigated through composite and trajectory analyses. In the upper troposphere, the main features of the composite structure are an isolated upper-tropospheric anticyclonic potential vorticity (PV) anomaly to the south-east of Australia and cyclonic anomalies to the east and south. Back trajectories starting from within the upper-tropospheric anticyclonic PV anomaly on the first day of the heatwave fall into two groups: those that are diabatically cooled in the final 72 h and those that are diabatically heated. Those that are cooled come predominantly from the upstreammiddle troposphere over the Indian Ocean. The change in the potential temperature of these parcels is less than 3K, and so their motion is effectively adiabatic. In contrast, those parcels that are heated in the final 72 h are drawn predominantly from the lower half of the troposphere over the south-western part of the continent. As they ascended, their potential temperature increases by 10K in the mean due to latent heating. At low-levels, the main features of the composite are an anticyclone centred in the Tasman Sea, a broad low over the Southern Ocean and associated anomalous warmnorthwesterlies over the Sydney area. Five days prior to the heatwave, air parcels that become part of the near surface air mass are located predominantly offshore to the east and south of the continent. The anomalously high surface temperatures can be explained by adiabatic compression and surface sensible heating. For the next 48 h, the air parcels subside and their potential temperature changes little, whereas their temperature increases by around 15Kthrough adiabatic compression. In the final 72 h, as the parcels approach the surface and are entrained into the boundary layer, the potential temperature and temperature both increase by 5K, presumably through surface sensible heating. The record-breaking heatwaves of January and February 2017 are found to be very representative of previous heatwaves in the Sydney area, and in the mean they are synoptically very similar to heatwaves in Victoria, although dynamically there are differences. Text Southern Ocean DataCite Metadata Store (German National Library of Science and Technology) Southern Ocean Indian |
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DataCite Metadata Store (German National Library of Science and Technology) |
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English |
description |
Motivated by the record-breaking heatwaves of early 2017, the synoptic structure and evolution of summer (December–February) heatwaves in the Sydney area is investigated through composite and trajectory analyses. In the upper troposphere, the main features of the composite structure are an isolated upper-tropospheric anticyclonic potential vorticity (PV) anomaly to the south-east of Australia and cyclonic anomalies to the east and south. Back trajectories starting from within the upper-tropospheric anticyclonic PV anomaly on the first day of the heatwave fall into two groups: those that are diabatically cooled in the final 72 h and those that are diabatically heated. Those that are cooled come predominantly from the upstreammiddle troposphere over the Indian Ocean. The change in the potential temperature of these parcels is less than 3K, and so their motion is effectively adiabatic. In contrast, those parcels that are heated in the final 72 h are drawn predominantly from the lower half of the troposphere over the south-western part of the continent. As they ascended, their potential temperature increases by 10K in the mean due to latent heating. At low-levels, the main features of the composite are an anticyclone centred in the Tasman Sea, a broad low over the Southern Ocean and associated anomalous warmnorthwesterlies over the Sydney area. Five days prior to the heatwave, air parcels that become part of the near surface air mass are located predominantly offshore to the east and south of the continent. The anomalously high surface temperatures can be explained by adiabatic compression and surface sensible heating. For the next 48 h, the air parcels subside and their potential temperature changes little, whereas their temperature increases by around 15Kthrough adiabatic compression. In the final 72 h, as the parcels approach the surface and are entrained into the boundary layer, the potential temperature and temperature both increase by 5K, presumably through surface sensible heating. The record-breaking heatwaves of January and February 2017 are found to be very representative of previous heatwaves in the Sydney area, and in the mean they are synoptically very similar to heatwaves in Victoria, although dynamically there are differences. |
format |
Text |
author |
Parker, Tess Quinting, Julian Reeder, Michael |
spellingShingle |
Parker, Tess Quinting, Julian Reeder, Michael The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
author_facet |
Parker, Tess Quinting, Julian Reeder, Michael |
author_sort |
Parker, Tess |
title |
The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
title_short |
The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
title_full |
The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
title_fullStr |
The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
title_full_unstemmed |
The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
title_sort |
synoptic-dynamics of summertime heatwaves in the sydney area (australia) |
publisher |
Bureau of Meteorology |
publishDate |
2020 |
url |
https://dx.doi.org/10.5445/ir/1000120169 https://publikationen.bibliothek.kit.edu/1000120169 |
geographic |
Southern Ocean Indian |
geographic_facet |
Southern Ocean Indian |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_rights |
Creative Commons Namensnennung – Nicht kommerziell – Keine Bearbeitungen 4.0 International Open Access info:eu-repo/semantics/openAccess https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de |
op_rightsnorm |
CC-BY-NC-ND |
op_doi |
https://doi.org/10.5445/ir/1000120169 |
_version_ |
1766207728570597376 |