Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks
The estimated century-long trends in the Southern Ocean climate are uncertain, as the data used to estimate these changes are relatively short (~60 years) compared to possible long-term climate variability found in the region. Due to the lack of longer land-based meteorological records, logbooks of...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/308474 2024-01-21T10:01:48+01:00 Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks Teleti, Praveen 2020-02-01 application/pdf https://www.repository.cam.ac.uk/handle/1810/308474 https://doi.org/10.17863/CAM.55560 eng eng University of Cambridge Christs https://doi.org/10.17863/CAM.31530 https://www.repository.cam.ac.uk/handle/1810/308474 doi:10.17863/CAM.55560 All Rights Reserved https://www.rioxx.net/licenses/all-rights-reserved/ Southern Ocean Antarctic historical climate data-rescue whaling Thesis Doctoral Doctor of Philosophy (PhD) PhD in Polar Studies 2020 ftunivcam https://doi.org/10.17863/CAM.5556010.17863/CAM.31530 2023-12-28T23:20:26Z The estimated century-long trends in the Southern Ocean climate are uncertain, as the data used to estimate these changes are relatively short (~60 years) compared to possible long-term climate variability found in the region. Due to the lack of longer land-based meteorological records, logbooks of Christian Salvesen Whaling Company’s whaling ships operating in the Southern Ocean in the 1930s and 1950s are investigated in this thesis. A historical climate dataset is produced from the meteorological observations from the whaling logbooks. The mean sea-level pressure (MSLP) changes across the Southern Ocean diverge: for example, in the northern reaches (55°S latitudinal band) MSLP in the historical period (the 1930s and 1950s) is found to be lower than modern climatology (1981-2010). It is in contrast to the southern reaches (65°S latitudinal band) where MSLP is found to be decreasing over the same period. A historical Southern Annular Mode (SAM) index from 1930-1960 is generated from the whaling dataset, and a significant positive trend is found. Subsequently, historical cyclonic frequency is estimated using a semi-supervised cyclone identification algorithm. The average number of cyclones per year for the historical period is statistically lower than the average for the 1999-2008 period over a control area in the Weddell Sea. Finally, the whaling dataset is assimilated into two (CERA-20C and 20CRv2c) current- generation reanalyses using an offline data assimilation method. The uncertainty in MSLP fields over the assimilation window decreased in both reanalyses by ∼40% in the area of observations post-assimilation. Overall it is shown that meteorological observations from the whaling logbooks can be utilised to reconstruct historical climate in terms of MSLP variability, climate modes (e.g. SAM) and identification of individual cyclones, and to improve the representation of past climate in the reanalyses. In summary, it has been demonstrated that the Southern Ocean climate near the Antarctic coast in the ... Doctoral or Postdoctoral Thesis Antarc* Antarctic Southern Ocean Weddell Sea Apollo - University of Cambridge Repository Antarctic Southern Ocean The Antarctic Weddell Sea Weddell Salvesen ENVELOPE(-61.333,-61.333,-64.400,-64.400) |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
Southern Ocean Antarctic historical climate data-rescue whaling |
spellingShingle |
Southern Ocean Antarctic historical climate data-rescue whaling Teleti, Praveen Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
topic_facet |
Southern Ocean Antarctic historical climate data-rescue whaling |
description |
The estimated century-long trends in the Southern Ocean climate are uncertain, as the data used to estimate these changes are relatively short (~60 years) compared to possible long-term climate variability found in the region. Due to the lack of longer land-based meteorological records, logbooks of Christian Salvesen Whaling Company’s whaling ships operating in the Southern Ocean in the 1930s and 1950s are investigated in this thesis. A historical climate dataset is produced from the meteorological observations from the whaling logbooks. The mean sea-level pressure (MSLP) changes across the Southern Ocean diverge: for example, in the northern reaches (55°S latitudinal band) MSLP in the historical period (the 1930s and 1950s) is found to be lower than modern climatology (1981-2010). It is in contrast to the southern reaches (65°S latitudinal band) where MSLP is found to be decreasing over the same period. A historical Southern Annular Mode (SAM) index from 1930-1960 is generated from the whaling dataset, and a significant positive trend is found. Subsequently, historical cyclonic frequency is estimated using a semi-supervised cyclone identification algorithm. The average number of cyclones per year for the historical period is statistically lower than the average for the 1999-2008 period over a control area in the Weddell Sea. Finally, the whaling dataset is assimilated into two (CERA-20C and 20CRv2c) current- generation reanalyses using an offline data assimilation method. The uncertainty in MSLP fields over the assimilation window decreased in both reanalyses by ∼40% in the area of observations post-assimilation. Overall it is shown that meteorological observations from the whaling logbooks can be utilised to reconstruct historical climate in terms of MSLP variability, climate modes (e.g. SAM) and identification of individual cyclones, and to improve the representation of past climate in the reanalyses. In summary, it has been demonstrated that the Southern Ocean climate near the Antarctic coast in the ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Teleti, Praveen |
author_facet |
Teleti, Praveen |
author_sort |
Teleti, Praveen |
title |
Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
title_short |
Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
title_full |
Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
title_fullStr |
Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
title_full_unstemmed |
Reconstruction of the historical climate of the Southern Ocean from whaling ships’ logbooks |
title_sort |
reconstruction of the historical climate of the southern ocean from whaling ships’ logbooks |
publisher |
University of Cambridge |
publishDate |
2020 |
url |
https://www.repository.cam.ac.uk/handle/1810/308474 https://doi.org/10.17863/CAM.55560 |
long_lat |
ENVELOPE(-61.333,-61.333,-64.400,-64.400) |
geographic |
Antarctic Southern Ocean The Antarctic Weddell Sea Weddell Salvesen |
geographic_facet |
Antarctic Southern Ocean The Antarctic Weddell Sea Weddell Salvesen |
genre |
Antarc* Antarctic Southern Ocean Weddell Sea |
genre_facet |
Antarc* Antarctic Southern Ocean Weddell Sea |
op_relation |
https://doi.org/10.17863/CAM.31530 https://www.repository.cam.ac.uk/handle/1810/308474 doi:10.17863/CAM.55560 |
op_rights |
All Rights Reserved https://www.rioxx.net/licenses/all-rights-reserved/ |
op_doi |
https://doi.org/10.17863/CAM.5556010.17863/CAM.31530 |
_version_ |
1788691966580490240 |