Global and regional discrepancies between early-twentieth-century coastal air and sea surface temperature detected by a coupled energy-balance analysis
Global and regional discrepancies between early-twentieth-century coastal air and sea surface temperature detected by a coupled energy-balance analysis
A major uncertainty in reconstructing historical sea surface temperature (SST) before the 1990s in- volves correcting for systematic offsets associated with bucket and engine-room intake temperature measurements. A recent study used a linear scaling of coastal station-based air temperatures (SATs) to infer nearby SSTs, but the physics in the coupling between SATs and SSTs generally gives rise to more complex regional air–sea temperature differences. In this study, an energy-balance model (EBM) of air–sea thermal coupling is adapted for predicting near-coast SSTs from coastal SATs. The model is shown to be more skillful than linear-scaling approaches through cross-validation analyses using instrumental records after the 1960s and CMIP6 simulations between 1880 and 2020. Improved skill primarily comes from capturing features reflecting air–sea heat fluxes dominating temperature vari- ability at high latitudes, including damping high-frequency wintertime SAT variability and reproducing the phase lag between SSTs and SATs. Inferred near-coast SSTs allow for intercalibrating coastal SAT and SST measurements at a variety of spatial scales. The 1900–40 mean offset between the latest SST estimates available from the Met Office (HadSST4) and SAT-inferred SSTs range between 21.68C (95% confidence interval: [21.78, 21.48C]) and 1.28C ([0.88, 1.68C]) across 108 3 108 grids. When further averaged along the global coastline, HadSST4 is signifi- cantly colder than SAT-inferred SSTs by 0.208C ([0.078, 0.358C]) over 1900–40. These results indicate that historical SATs and SSTs involve substantial inconsistencies at both regional and global scales. Major outstanding questions involve the distribution of errors between our intercalibration model and instrumental records of SAT and SST as well as the degree to which coastal intercalibrations are informative of global trends.
Air-sea interaction, Bias, Climate change, Sea surface temperature, Surface temperature
2205-2220
Chan, Duo
4c1278dc-7f39-4b67-b1cd-3f81f55f4906
Gebbie, Geoffrey
b175e22b-563d-4925-9649-1eb980c2a315
Huybers, Peter
48e9a517-aa2a-40f1-96ef-06d76b19291c
1 April 2023
Chan, Duo
4c1278dc-7f39-4b67-b1cd-3f81f55f4906
Gebbie, Geoffrey
b175e22b-563d-4925-9649-1eb980c2a315
Huybers, Peter
48e9a517-aa2a-40f1-96ef-06d76b19291c
Chan, Duo, Gebbie, Geoffrey and Huybers, Peter
(2023)
Global and regional discrepancies between early-twentieth-century coastal air and sea surface temperature detected by a coupled energy-balance analysis.
Journal of Climate, 36 (7), .
(doi:10.1175/JCLI-D-22-0569.1).
Abstract
A major uncertainty in reconstructing historical sea surface temperature (SST) before the 1990s in- volves correcting for systematic offsets associated with bucket and engine-room intake temperature measurements. A recent study used a linear scaling of coastal station-based air temperatures (SATs) to infer nearby SSTs, but the physics in the coupling between SATs and SSTs generally gives rise to more complex regional air–sea temperature differences. In this study, an energy-balance model (EBM) of air–sea thermal coupling is adapted for predicting near-coast SSTs from coastal SATs. The model is shown to be more skillful than linear-scaling approaches through cross-validation analyses using instrumental records after the 1960s and CMIP6 simulations between 1880 and 2020. Improved skill primarily comes from capturing features reflecting air–sea heat fluxes dominating temperature vari- ability at high latitudes, including damping high-frequency wintertime SAT variability and reproducing the phase lag between SSTs and SATs. Inferred near-coast SSTs allow for intercalibrating coastal SAT and SST measurements at a variety of spatial scales. The 1900–40 mean offset between the latest SST estimates available from the Met Office (HadSST4) and SAT-inferred SSTs range between 21.68C (95% confidence interval: [21.78, 21.48C]) and 1.28C ([0.88, 1.68C]) across 108 3 108 grids. When further averaged along the global coastline, HadSST4 is signifi- cantly colder than SAT-inferred SSTs by 0.208C ([0.078, 0.358C]) over 1900–40. These results indicate that historical SATs and SSTs involve substantial inconsistencies at both regional and global scales. Major outstanding questions involve the distribution of errors between our intercalibration model and instrumental records of SAT and SST as well as the degree to which coastal intercalibrations are informative of global trends.
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More information
Accepted/In Press date: 5 November 2022
e-pub ahead of print date: 6 March 2023
Published date: 1 April 2023
Additional Information:
Funding Information:
Acknowledgments. We thank Dr. Young-Oh Kwon for discussion and comments on the project. We acknowledge three anonymous reviewers for comments that improved the readability of the paper. D. Chan is supported by the Woods Hole Oceanographic Institute Weston Howland Jr. Postdoctoral Fellowship. G. Gebbie is supported by NSF OCE-82280500. P. Huybers is supported by NSF Grant 2123295. The authors have no conflict of interests to declare.
© 2023 American Meteorological Society
Keywords:
Air-sea interaction, Bias, Climate change, Sea surface temperature, Surface temperature
Identifiers
Local EPrints ID: 481954
URI: http://eprints.soton.ac.uk/id/eprint/481954
ISSN: 0894-8755
PURE UUID: 8b57f813-c16c-4a4f-b085-c0a5f8cca628
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Date deposited: 14 Sep 2023 16:33
Last modified: 18 Mar 2024 04:15
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Author:
Duo Chan
Author:
Geoffrey Gebbie
Author:
Peter Huybers
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