Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements
Surface heat fluxes from four atmospheric reanalyses in the Southern Ocean are evaluated using air–sea measurements obtained from the Aurora Australis during off-winter seasons in 2010–12. The icebreaker tracked between Hobart, Tasmania (ca. 42°S), and the Antarctic continent, providing in situ benc...
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Norwegian Polar Institute
2019
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ftdoajarticles:oai:doaj.org/article:d3b653fd4a7142da894d64c977ef5c02 2023-05-15T13:40:20+02:00 Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements Lisan Yu Xiangze Jin Eric W. Schulz 2019-06-01T00:00:00Z https://doi.org/10.33265/polar.v38.3349 https://doaj.org/article/d3b653fd4a7142da894d64c977ef5c02 EN eng Norwegian Polar Institute https://polarresearch.net/index.php/polar/article/view/3349/9300 https://doaj.org/toc/1751-8369 1751-8369 doi:10.33265/polar.v38.3349 https://doaj.org/article/d3b653fd4a7142da894d64c977ef5c02 Polar Research, Vol 38, Iss 0, Pp 1-25 (2019) Surface fluxes surface energy budget overestimation bias underestimation bias surface meteorology icebreaker-based meteorological measurements Environmental sciences GE1-350 Oceanography GC1-1581 article 2019 ftdoajarticles https://doi.org/10.33265/polar.v38.3349 2022-12-31T14:01:33Z Surface heat fluxes from four atmospheric reanalyses in the Southern Ocean are evaluated using air–sea measurements obtained from the Aurora Australis during off-winter seasons in 2010–12. The icebreaker tracked between Hobart, Tasmania (ca. 42°S), and the Antarctic continent, providing in situ benchmarks for the surface energy budget change in the Subantarctic Southern Ocean (58–42°S) and the eastern Antarctic marginal ice zone (MIZ, 68–58°S). We find that the reanalyses show a high-level agreement among themselves, but this agreement reflects a universal bias, not a “truth.” Downward shortwave radiation (SW↓) is overestimated (warm biased) and downward longwave radiation (LW↓) is underestimated (cold biased), an indication that the cloud amount in all models is too low. The ocean surface in both regimes shows a heat gain from the atmosphere when averaged over the seven months (October–April). However, the ocean heat gain in reanalyses is overestimated by 10–36 W m−2 (80–220%) in the MIZ but underestimated by 6–20 W m−2 (7–25%) in the Subantarctic. The biases in SW↓ and LW↓ cancel out each other in the MIZ, causing the surface heat budget to be dictated by the underestimation bias in sensible heat loss. These reanalyses biases affect the surface energy budget in the Southern Ocean by meaningfully affecting the timing of the seasonal transition from net heat gain to net heat loss at the surface and the relative strength of SW↓ at different regimes in summer, when the length-of-day effect can lead to increased SW↓ at high latitudes. Article in Journal/Newspaper Antarc* Antarctic aurora australis Polar Research Southern Ocean Directory of Open Access Journals: DOAJ Articles Antarctic Southern Ocean The Antarctic Polar Research 38 0 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Surface fluxes surface energy budget overestimation bias underestimation bias surface meteorology icebreaker-based meteorological measurements Environmental sciences GE1-350 Oceanography GC1-1581 |
spellingShingle |
Surface fluxes surface energy budget overestimation bias underestimation bias surface meteorology icebreaker-based meteorological measurements Environmental sciences GE1-350 Oceanography GC1-1581 Lisan Yu Xiangze Jin Eric W. Schulz Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
topic_facet |
Surface fluxes surface energy budget overestimation bias underestimation bias surface meteorology icebreaker-based meteorological measurements Environmental sciences GE1-350 Oceanography GC1-1581 |
description |
Surface heat fluxes from four atmospheric reanalyses in the Southern Ocean are evaluated using air–sea measurements obtained from the Aurora Australis during off-winter seasons in 2010–12. The icebreaker tracked between Hobart, Tasmania (ca. 42°S), and the Antarctic continent, providing in situ benchmarks for the surface energy budget change in the Subantarctic Southern Ocean (58–42°S) and the eastern Antarctic marginal ice zone (MIZ, 68–58°S). We find that the reanalyses show a high-level agreement among themselves, but this agreement reflects a universal bias, not a “truth.” Downward shortwave radiation (SW↓) is overestimated (warm biased) and downward longwave radiation (LW↓) is underestimated (cold biased), an indication that the cloud amount in all models is too low. The ocean surface in both regimes shows a heat gain from the atmosphere when averaged over the seven months (October–April). However, the ocean heat gain in reanalyses is overestimated by 10–36 W m−2 (80–220%) in the MIZ but underestimated by 6–20 W m−2 (7–25%) in the Subantarctic. The biases in SW↓ and LW↓ cancel out each other in the MIZ, causing the surface heat budget to be dictated by the underestimation bias in sensible heat loss. These reanalyses biases affect the surface energy budget in the Southern Ocean by meaningfully affecting the timing of the seasonal transition from net heat gain to net heat loss at the surface and the relative strength of SW↓ at different regimes in summer, when the length-of-day effect can lead to increased SW↓ at high latitudes. |
format |
Article in Journal/Newspaper |
author |
Lisan Yu Xiangze Jin Eric W. Schulz |
author_facet |
Lisan Yu Xiangze Jin Eric W. Schulz |
author_sort |
Lisan Yu |
title |
Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
title_short |
Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
title_full |
Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
title_fullStr |
Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
title_full_unstemmed |
Surface heat budget in the Southern Ocean from 42°S to the Antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker Aurora Australis measurements |
title_sort |
surface heat budget in the southern ocean from 42°s to the antarctic marginal ice zone: four atmospheric reanalyses versus icebreaker aurora australis measurements |
publisher |
Norwegian Polar Institute |
publishDate |
2019 |
url |
https://doi.org/10.33265/polar.v38.3349 https://doaj.org/article/d3b653fd4a7142da894d64c977ef5c02 |
geographic |
Antarctic Southern Ocean The Antarctic |
geographic_facet |
Antarctic Southern Ocean The Antarctic |
genre |
Antarc* Antarctic aurora australis Polar Research Southern Ocean |
genre_facet |
Antarc* Antarctic aurora australis Polar Research Southern Ocean |
op_source |
Polar Research, Vol 38, Iss 0, Pp 1-25 (2019) |
op_relation |
https://polarresearch.net/index.php/polar/article/view/3349/9300 https://doaj.org/toc/1751-8369 1751-8369 doi:10.33265/polar.v38.3349 https://doaj.org/article/d3b653fd4a7142da894d64c977ef5c02 |
op_doi |
https://doi.org/10.33265/polar.v38.3349 |
container_title |
Polar Research |
container_volume |
38 |
container_issue |
0 |
_version_ |
1766132533637939200 |