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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ftdoajarticles:oai:doaj.org/article:74f77f012da54aeab9e5a6da50c2dcf1 2023-05-15T18:25:54+02:00 The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) Michael Reeder Julian Quinting Tess Parker 2019-01-01T00:00:00Z https://doaj.org/article/74f77f012da54aeab9e5a6da50c2dcf1 EN eng CSIRO Publishing https://www.publish.csiro.au/es/pdf/ES19004 https://doaj.org/toc/2206-5865 2206-5865 https://doaj.org/article/74f77f012da54aeab9e5a6da50c2dcf1 Journal of Southern Hemisphere Earth Systems Science, Vol 69, Iss 1, Pp 116-130 (2019) Meteorology. Climatology QC851-999 Environmental sciences GE1-350 article 2019 ftdoajarticles 2022-12-31T06:09:26Z 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 warm northwesterlies 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 ... Article in Journal/Newspaper Southern Ocean Directory of Open Access Journals: DOAJ Articles Indian Southern Ocean |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Meteorology. Climatology QC851-999 Environmental sciences GE1-350 |
spellingShingle |
Meteorology. Climatology QC851-999 Environmental sciences GE1-350 Michael Reeder Julian Quinting Tess Parker The synoptic-dynamics of summertime heatwaves in the Sydney area (Australia) |
topic_facet |
Meteorology. Climatology QC851-999 Environmental sciences GE1-350 |
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 warm northwesterlies 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 ... |
format |
Article in Journal/Newspaper |
author |
Michael Reeder Julian Quinting Tess Parker |
author_facet |
Michael Reeder Julian Quinting Tess Parker |
author_sort |
Michael Reeder |
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 |
CSIRO Publishing |
publishDate |
2019 |
url |
https://doaj.org/article/74f77f012da54aeab9e5a6da50c2dcf1 |
geographic |
Indian Southern Ocean |
geographic_facet |
Indian Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
Journal of Southern Hemisphere Earth Systems Science, Vol 69, Iss 1, Pp 116-130 (2019) |
op_relation |
https://www.publish.csiro.au/es/pdf/ES19004 https://doaj.org/toc/2206-5865 2206-5865 https://doaj.org/article/74f77f012da54aeab9e5a6da50c2dcf1 |
_version_ |
1766207604691828736 |